Method of manufacturing cellulose ether from agricultural residues

Abstract

Disclosed is a method of manufacturing at least one cellulose ether from agricultural residues. The method comprises: subjecting the agricultural residues to a pretreatment process to produce a cellulosic base material; incubating the cellulosic base material in a controlled condition; and processing the incubated cellulosic base material mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

Description

[0001] METHOD OF MANUFACTURING CEUEUEOSE ETHER FROM AGRICUETURAE RESIDUES

[0002] TECHNICAL FIELD

[0003] The present disclosure relates generally to manufacturing of cellulose ether from agricultural residues. More specifically, the present disclosure relates to methods of manufacturing cellulose ether from agricultural residues.

[0004] BACKGROUND

[0005] Polymeric rheology modifiers or cellulose ethers such as Hydroxypropyl cellulose (HPC), Hydroxypropyl Methylcellulose (HPMC), Hydroxyethyl Methylcellulose (HEMC), and Hydroxyethyl Cellulose (HEC) are widely used in industries due to their water-soluble and film-forming properties. They are primarily produced from cellulose, which is conventionally derived from cellulose rich agricultural residues such as wood pulp or cotton fibres. The synthesis of cellulose ether typically involves a two-step process: alkalization followed by etherification. Various grades of cellulose ether are produced based on different viscosity ranges, determined by processing conditions and cellulose source.

[0006] Conventional methods of obtaining cellulose for production of various cellulose ethers, especially from wood pulp, are highly energy and chemical-intensive. The Kraft process, commonly used in wood pulp production, is notorious for its environmental impact, including high energy consumption and pollutant discharge. Additionally, using wood cellulose powder poses challenges in achieving uniform alkali metal hydroxide dispersion during alkalization, affecting the consistency and quality of the cellulose ether. Furthermore, cotton pulp, though less intensive to process, also faces limitations in producing a wide range of cellulose ether with varying degree of viscosities.

[0007] Some alternative methods attempt to overcome the limitations of wood pulp by using dilute alkali metal hydroxide solutions to reduce unwanted side reactions. However, this results in lower yields and insufficient dispersion of the alkali metal. Furthermore, most conventional processes continue to rely on wood cellulose or cotton, which are either costly or have restricted versatility in terms of viscosity ranges. Current methods also often lead to excessive waste and require additional purification steps to achieve the desired cellulose ether grade.

[0008] Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with conventionally inefficient and unreliable methods of manufacturing cellulose ether.

[0009] SUMMARY

[0010] The present disclosure seeks to provide a method of manufacturing cellulose ether from agricultural residues. An aim of the present disclosure is to provide a solution that overcomes at least partially the problems encountered in prior art.

[0011] The aim of the present disclosure is to provide a method of manufacturing different types of cellulose ether of varying degrees of viscosity in an efficient and sustainable manner. The aim of the present disclosure is achieved by a method of manufacturing cellulose ether from agricultural residues, as defined in the appended independent claims to which reference is made to. Advantageous features are set out in the appended dependent claims.

[0012] In one aspect, the present disclosure provides a method of manufacturing at least one cellulose ether from agricultural residues, the method comprising:

[0013] subjecting the agricultural residues to a pretreatment process to produce a cellulosic base material;

[0014] incubating the cellulosic base material in a controlled condition; and processing the incubated cellulosic base material mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

[0015] In an embodiment, the method further comprises conditioning the synthesized cellulose ether into a predetermined final product form. In an embodiment, the pretreatment process comprises:

[0016] subjecting the agricultural residues to an acidic pretreatment process under a first set of conditions, and

[0017] subjecting the acidic agricultural residues to an alkaline pretreatment process under a second set of conditions to obtain the cellulosic base material. In an embodiment,

[0018] the acidic pretreatment process comprises using an acidic reaction medium selected from a group comprising at least one of: sulfuric acid, hydrochloric acid, nitric acid, maleic acid, zeolites, aluminium chloride, ferric chloride, and wherein the acidic reaction medium is at a concentration in range of 0.5 to 1.5 volume percent; and

[0019] the alkaline pretreatment process comprises using a first alkaline reaction medium selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, and wherein the first alkaline reaction medium is at a concentration of 4 to 6 weight percent (wt.%), wherein the first set of conditions and the second set of conditions comprises: a time duration in a range of 20 to 50 minutes, and a temperature in a range of 120 to 160 degrees Celsius.

[0020] In an embodiment, the pretreatment process further comprises bleaching the cellulosic base material, using a bleaching agent, at a temperature in a range of 50 to 80 degrees Celsius for a time duration in a range of 40 to 120 minutes, wherein the bleaching agent is selected from at least one of: peroxide, quaternary ammonium salt, sodium chlorite, sodium sulphite.

[0021] In an embodiment, the step of incubating the cellulosic base material comprises mixing the cellulosic base material having moisture in a concentration in a range of to 80 weight percent with a second alkaline reaction medium in a concentration in a range of 17 to 27 weight percent, in the controlled condition, wherein the second alkaline reaction medium is selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, and

[0022] wherein the controlled condition comprises: setting an inert environment comprising at least one inert gas, temperature in a range of 25 to 35 degrees Celsius for a time duration in a range of 6 to 12 hours.

[0023] In an embodiment, the method further comprises removing excess content of the second alkaline reaction medium from the cellulosic base material, to ensure that the residual moisture content of the cellulosic base material is less than 50 weight percent.

[0024] In an embodiment,

[0025] the alkylating agent comprises at least one of: propylene oxide, acetyl chloride, chloroacetic acid, ethyl chloride, methyl chloride, dimethyl sulphate; and the at least one cellulose ether comprises at least one of: hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxyethyl methylcellulose (HEMC), hydroxyethyl cellulose (HEC)

[0026] In an embodiment, the cellulose ether is hydroxypropyl cellulose (HPC) and the alkylating agent is propylene oxide, and wherein a molar ratio of anhydrous glucose unit to propylene oxide is in a range of 1:7 to 1:25, and a quantity of propylene oxide being determined based on a desired intrinsic viscosity of the cellulosic base material.

[0027] In an embodiment, the method further comprises reacting the processed cellulosic base material with the alkylating agent in presence of an inert dispersant selected from a group comprising at least one of: toluene, tetrahydrofuran, isopropyl alcohol, an aqueous solution of at least one of: toluene, tetrahydrofuran, isopropyl alcohol. In an embodiment, reacting the processed cellulosic base material with the alkylating agent results in a multi-stage etherification process, wherein the multistage etherification process comprises maintaining the cellulosic base material, at an agitation rate of 200 to 400 revolutions per minute, at temperatures of:

[0028] 20 degrees Celsius for 1 to 2 hours for a first stage, 40 degrees Celsius for 3 to 4 hours for a second stage, and

[0029] 60 degrees Celsius for 6 to 10 hours for a third stage.

[0030] In an embodiment, conditioning the synthesized cellulose ether into a predetermined final product form comprises

[0031] adjusting the pH of the reaction mixture to between 6 and 7 using a fifty percent weight sulfuric acid solution;

[0032] purifying the hydroxypropyl cellulose product through washing with hot water at temperatures between 85 to 90 degrees Celsius to remove salts; and converting into a powdered form using one of a: spray dryer, vacuum dryer, or fluidized bed dryer under optimized conditions.

[0033] In an embodiment, the agricultural residues are selected from the group consisting of sugarcane bagasse, rice straw, wheat straw, hemp fibres, and cotton linters. Embodiments of the present disclosure substantially eliminate or at least partially address the aforementioned problems in the prior art, and enable a novel, reliable and energy-conscious method of manufacturing hydroxypropyl cellulose from agricultural residues.

[0034] Throughout the description and claims of this specification, the words "comprise”, "include”, "have", and "contain" and variations of these words, for example "comprising" and "comprises" , mean "including but not limited to", and do not exclude other components, items, integers or steps not explicitly disclosed also to be present. Moreover, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[0035] BRIEF DESCRIPTION OF THE DRAWINGS

[0036] FIG. 1 illustrates a flow chart depicting steps of a method of manufacturing at least one cellulose ether from agricultural residues, in accordance with an embodiment of the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS

[0037] The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practising the present disclosure are also possible.

[0038] In one aspect, the present disclosure provides a method of manufacturing at least one cellulose ether from agricultural residues, the method comprising:

[0039] subjecting the agricultural residues to a pretreatment process to produce a cellulosic base material;

[0040] incubating the cellulosic base material in a controlled condition; and processing the incubated cellulosic base material mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

[0041] The aforementioned method offers several key advantages over conventional approaches for manufacturing at least one cellulose ether. Firstly, the method provides enhanced control over the viscosity of the at least cellulose ether by precisely optimizing reaction parameters, including alkalization and etherification stages. By utilizing the cellulosic base material derived from renewable agricultural residues, such as sugarcane bagasse, rice straw, and cotton linters, the method addresses sustainability concerns while significantly reducing both the energy and chemical input required compared to traditional wood pulp sources. Additionally, the method improves reaction efficiency and minimizes waste generation, resulting in higher-quality cellulose derivatives with fewer purification steps. These benefits collectively lead to the production of at least one cellulose ether with tailored properties suitable for a wide range of industrial applications, allowing for greater flexibility in meeting specific product demands. The disclosed method not only enhances the sustainability of cellulose sourcing but also ensures superior process efficiency and product performance. Throughout the present disclosure, the term cellulose ether refers to a chemical compound derived from cellulose by subjecting the same to a sequence of specialized thermal and chemical reactions. In other words, cellulose ether is a derivative of cellulose which are produced by chemically modifying the hydroxyl functional groups (-OH) on the glucose units in natural cellulose by introducing ether functional groups. The cellulose ether is a water-soluble derivative of cellulose dominantly used in various food, pharmaceuticals, cosmetics, paints, and construction materials.

[0042] The term "cellulose" refers to a naturally occurring polysaccharide composed of linear chains of P (1— >4) linked D-glucose units, which is a principal structural component of the cell walls in agricultural residues. Notably, cellulose is a fibrous, water-insoluble organic material used in various industries such as manufacturing, chemical, cosmetics and pharmaceutical (specifically in form of cellulose ether). Structurally, the cellulose consists of long, unbranched chains of glucose molecules, which confer mechanical strength and chemical reactivity. Functionally, the cellulose acts as the precursor material that, upon activation and etherification, is transformed into the at least one cellulose ether.

[0043] In this regard, throughout the present disclosure, the term "etherification" refers to a chemical process in which ether groups (-OR) are introduced onto cellulose structure matrix (specifically interacting with hydroxy group (-OH) therein), resulting in the formation of the at least one cellulose ether.

[0044] Throughout the present disclosure, the term "agricultural residues" refers to residual materials or substances generated as a result of agricultural processes or activities. Specifically, agricultural residues typically include any organic matter or residues that remain after the primary agricultural product has been harvested or processed. The agricultural residues may also refer to raw materials harvested directly from agricultural practices, such as cellulose rich crops like cotton. Examples of agricultural residues may include, but are not limited to, crop residues, straw, husks, stems, leaves, stalks, shells, pomace, and other biomass materials. In the present disclosure, the agricultural residues are selected from the group comprising: sugarcane bagasse, rice straw, wheat straw, hemp fibres, cotton linters. Optionally, the agricultural residues may be selected from at least one of the following: corn stover, rice husk, banana stem. It may be appreciated that the agricultural residues may also be any other crops, plants and agricultural materials, which are rich in cellulose content.

[0045] The agricultural residues are subjected to a pretreatment process which allows easy separation of cellulose content from a lignocellulosic matrix of the agricultural residues. The term ''lignocellulosic matrix" refers to the structural composite of cellulose, hemicellulose, and lignin naturally present in the agricultural residues. The lignocellulosic matrix forms the primary framework of plant cell walls, wherein cellulose microfibrils are embedded within a hemicellulosic-lignin complex that provides rigidity and resistance to chemical or enzymatic degradation. In this regard, the pretreatment process results in production of a cellulosic base material. The term "cellulosic base material" refers to refers to a biomass substrate comprising cellulose as a principal structural component and from where the cellulose content can be easily extracted, which serves as a feedstock for processing, conversion, or derivatization into intermediate or end products (i.e., cellulose ether of varying degree of viscosity). The cellulosic base material may be derived from agricultural residues or from naturally cellulose-rich materials obtained from agricultural processes. Optionally, the cellulosic base material originates from agricultural residues containing lignin, hemicellulose, and other associated biomolecules, and therefore may require additional treatment prior to the pretreatment process to render the cellulose fraction more accessible. Alternatively, optionally, the cellulosic base material is constituted by agricultural residues that are inherently cellulose-rich, such as cotton linter or equivalent high-purity fibrous by-products, wherein the cellulose is naturally exposed, and therefore additional treatment (prior to the pretreatment process) is not required.

[0046] In context of the present disclosure, the pretreatment process refers to at least one step that is performed on the agricultural residue received from a source (such as agricultural harvest, industrial source and so on). The term "additional treatment" as used herein refers to thermochemical process performed on the agricultural residue before and / or after the pretreatment process. In this context, optionally, the additional step may involve subsequent chemical treatment, such as acid treatment with mild acidic solution after the pretreatment process that will further decompose the lignocellulosic matrix of the pretreated agricultural residues. Optionally, the additional treatment may also include prior treatment steps, including physical, chemical, thermal processes such as sorting, resizing (i.e., size reduction), washing, contaminant removal, dewatering / drying and so on, which are performed prior to the pretreatment process to enhance efficiency of the pretreatment process. In this context, dimension of the agricultural residues is reduced to a desirable size suitable for further processing, typically ranging from 1 to 5 cm in size. Subsequently, soil removal ensures removal of any extraneous matter adhering to the agricultural residues, thereby enhancing the efficiency of the subsequent processes. It may be appreciated that the step of soil removal comprises any suitable segregation and elimination techniques including washing, drying and so on. Afterwards, dewatering / drying involves removal of excess moisture from the agricultural byproducts, which facilitates subsequent processing steps and prevents issues such as microbial growth.

[0047] Optionally, the pretreatment process comprises:

[0048] subjecting the agricultural residues to an acidic pretreatment process under a first set of conditions, and

[0049] subjecting the acidic agricultural residues to an alkaline pretreatment process under a second set of conditions to obtain the cellulosic base material. In this regard, the agricultural residues are subjected to and acidic pretreatment process where a suitable acidic reaction medium is allowed to chemically interact with the agricultural residues. In this context the term "acidic reaction medium" refers to a solution of at least one suitable acid, having desired acidity to efficiently perform aforementioned chemical interaction. This chemical interaction leads to weakening of and / or breaking down of complex bonds of the lignocellulosic matrix. In other words, the acidic pretreatment process refers to a chemical treatment that results in weakening of and / or breaking down of complex bonds of the lignocellulosic matrix and as a result making cellulose content access. In this context, during the acidic pretreatment process lignin and hemicellulose content breaks down, allowing for enhanced cellulose accessibility. Notably, the agricultural residues, selected from the group consisting of sugarcane bagasse, rice straw, wheat straw, hemp fibres, and cotton linters, are initially processed to remove contaminants and non-cellulosic components. The acidic pretreatment process is performed under the first set of conditions. The term "first set of conditions" refers to a set of conditions carefully set to promote chemical interaction between the suitable acidic reaction medium and the agricultural residue. Subsequent to acidic pretreatment process, the agricultural residues are subjected to an alkaline pretreatment process, wherein a suitable alkaline reaction medium interacts with the acidic agricultural residues (obtained after acidic pretreatment process) to further degrade lignin and remove any residual hemicellulose, resulting in formation of the cellulosic base material that is suitable for subsequent processing steps. In this context the term "alkaline reaction medium" refers to a solution of at least one suitable alkali, having desired alkalinity to efficiently perform required chemical interaction therefore breaking down the lignin and hemicellulose further. Similarly, the alkaline pretreatment process is performed under the second set of conditions. The term "second set of conditions" refers to a set of conditions carefully set to promote chemical interaction between the acidic agricultural residue and the suitable alkaline reaction medium. The technical advantage is that the aforementioned combination of acidic and alkaline pretreatment and in the aforementioned sequence (i.e., acidic pretreatment followed by alkaline pretreatment) ensures that the cellulosic base material produced is of sufficient purity and structure to enable efficient conversion into at least cellulose ether during further processing.

[0050] Optionally, the acidic pretreatment process comprises using an acidic reaction medium selected from a group comprising at least one of: sulfuric acid, hydrochloric acid, nitric acid, maleic acid, zeolites, aluminium chloride, ferric chloride, and wherein the acidic reaction medium is at a concentration in range of 0.5 to 1.5 volume percent; and

[0051] the alkaline pretreatment process comprises using a first alkaline reaction medium selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, and wherein the first alkaline reaction medium is at a concentration of 4 to 6 weight percent, wherein the first set of conditions and the second set of conditions comprises: a time duration in a range of 20 to 50 minutes, and a temperature in a range of 120 to 160 degrees Celsius.

[0052] In this regard, the aforementioned acidic reaction medium (selected from a group comprising at least one of: sulfuric acid, hydrochloric acid, nitric acid, maleic acid, zeolites, aluminium chloride, ferric chloride) exhibit excellent ability to targets hemicellulose-cellulose bindings to separate them therefore enhances fractionation of the lignocellulosic matrix of the agricultural residues. Similarly, the aforementioned first alkaline reaction medium (selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea) provide required basic / alkaline pH properties to enhance the fractionation of the agricultural residues by lowering an activation energy of the fractionation process. The aforementioned concentration ranges for both the acidic reaction medium and the first alkaline reaction medium are most suitable for promoting such chemical interactions. It may be appreciated that the concentration ranges of both the acidic reaction medium and the first alkaline reaction medium are selected depending on the type of agricultural residues, amount of agricultural residues that need to be preprocessed and so on. It may be further appreciated that both the acidic pretreatment and alkaline pretreatment processes are performed under aforementioned temperature range for the aforementioned time duration. In this regard, either or both of the the acidic pretreatment and alkaline pretreatment processes are performed for time duration in the range from 20, 25, 30, 35, 40 or 45 minutes up to 25, 30, 35, 40, 45 or 50 minutes, and at the temperature in the range from 120, 125, 130, 135, 140, 145, 150 or 155 degrees Celsius up to 125, 130, 135, 140, 145, 150, 155 or 160 degrees Celsius. It may be appreciated that the first set of conditions and the second set of conditions may be same or different, within the aforementioned ranges, for the acidic pretreatment process and the alkaline pretreatment process, depending on the process requirements, and type of the agricultural residue. The technical advantage is that the acidic pretreatment process and the alkaline pretreatment process expose and liberate cellulose from its protective matrix, enhancing purity and yield.

[0053] Optionally, the pretreatment process further comprises bleaching the cellulosic base material, using a bleaching agent, at a temperature in a range of 50 to 80 degrees Celsius for a time duration in a range of 40 to 120 minutes, wherein the bleaching agent is selected from at least one of: peroxide, quaternary ammonium salt, sodium chlorite, sodium sulphite. In this regard, the step of bleaching is performed after execution of acidic and alkaline pretreatment processes. The step of bleaching is performed using the bleaching agent which refers to a chemical compound that interacts with the cellulosic base material to remove or oxidize residual colourimparting substances, lignin fragments, or other chromophoric impurities remaining after acidic and alkaline pretreatment processes. The bleaching agent facilitates whitening, purification, and enhancement of cellulose brightness by oxidizing or reducing the non-cellulosic components. Moreover, the aforementioned bleaching agents (peroxide, quaternary ammonium salts, sodium chlorite, and sodium sulphite) are selected because they effectively remove residual lignin, pigments, and chromophoric impurities without degrading the cellulose structure. Peroxide provides strong oxidative action with minimal cellulose damage and produces environmentally benign by-products (mainly water and oxygen). Sodium chlorite generates chlorine dioxide in situ, which efficiently oxidizes lignin fragments under controlled acidity. Sodium sulphite acts as a mild reducing agent that prevents cellulose oxidation and preserves fibre integrity. Quaternary ammonium salts enhance bleaching efficiency by disrupting lignin-cellulose interactions and improving reagent penetration. Similarly, the aforementioned temperature range of 50 to 80 degree Celsius ensures sufficient reaction kinetics for oxidative or reductive bleaching while preventing thermal degradation of cellulose. In this context, the temperature may be from 50, 55, 60, 65, 70 or 75 degree Celsius up to 55, 60, 65, 70, 75 or 80 degree Celsius. Similarly, the time duration in the range of 40-120 minutes provides an optimal balance between complete removal of colorants and maintaining polymer chain stability. For example, the time duration may be 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110 or 115 minutes up to 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115 or 120 minutes. Collectively, these conditions yield a high-purity, bright, and structurally intact cellulose substrate, superior to conventional chlorinebased systems that risk fibre embrittlement and generate toxic effluents. In this context, the step of bleaching is performed at a moderate temperature (within the aforementioned temperature range) to avoid degradation of the cellulose structure, while the duration of treatment is optimized (within the aforementioned time duration) to ensure maximum removal of lignin without compromising the molecular integrity of the cellulose. The technical advantage is that the aforementioned step of bleaching results in a purified, brightened cellulose material that is further suitable for conversion into the at least one cellulose ether.

[0054] Moreover, the method comprises incubating the cellulosic base material, obtained after pretreatment process, in a controlled condition which will further decompose the lignocellulosic matrix making the cellulose accessible. The cellulosic base material obtained is subjected to a second alkaline reaction medium under the controlled condition. The term "incubating” refers to a process of allowing the cellulosic base material to remain / soak in the second alkaline reaction medium, under controlled physical and chemical conditions for a predetermined duration to facilitate a specific chemical or structural transformation within the material matrix. The step of incubation allows the alkaline ions (from the second alkaline reaction medium) to penetrate the hydrated fibrous network, enabling partial delignification and swelling of the cellulose microfibrils, thereby enhancing accessibility and reactivity for subsequent bleaching or enzymatic conversion. The controlled incubation further prevents oxidative or thermal degradation and ensures uniform treatment efficiency across the substrate. In other words, incubating comprises maintaining the cellulosic base material with an alkaline reaction medium under controlled inert, temperature, and time conditions to promote selective delignification.

[0055] Optionally, the step of incubating the cellulosic base material comprises mixing the cellulosic base material having moisture in a concentration in a range of 60 to 80 weight percent with a second alkaline reaction medium in a concentration in a range of 17 to 27 weight percent, in the controlled condition, wherein the second alkaline reaction medium is selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, and

[0056] wherein the controlled condition comprises: setting an inert environment comprising at least one inert gas, temperature in a range of 25 to 35 degrees Celsius for a time duration in a range of 6 to 12 hours.

[0057] In this regard, the second alkaline reaction medium may be same as the first alkaline reaction medium or may be a different alkali selected from aforementioned group. The term "controlled, condition" refers to a regulated set up designed to optimally execute the incubation process which allows further degradation of the lignocellulosic matrix allowing ease of access to the cellulose content. In this regard, after the pretreatment process (i.e., after sequential execution of both acidic pretreatment and alkaline pretreatment processes), the obtained cellulosic base material, is incubated under the controlled condition that is setting and / or maintaining an inert environment comprising at least one inert gas, at a temperature (within aforementioned range), and for time duration (within specified range). The term inert environment refers to a chemically inactive environment, and the term "inert gas" refers to a gaseous content within the inert environment that does not get involved in any chemical reaction with the cellulosic base material incubated in the second alkaline reaction medium. The inert gas may be but not limited to, nitrogen, argon and so on. The aforementioned step of incubation, under the controlled condition ensures that minimal exposure to reactive gases such as oxygen or carbon dioxide, is minimized, in order to prevent any unwanted chemical interaction. The use of the inert gas such as nitrogen or argon ensures that the reaction between the cellulosic base material and the second alkaline reaction medium is not inhibited by unwanted side reactions.

[0058] It may be appreciated that the second alkaline reaction medium facilitates further breakdown of residual lignin and enhances the reactivity of the cellulose fibres by creating an optimal environment for cellulose modification. The incubation period and controlled conditions promote uniform exposure of the cellulosic material to the alkaline medium, resulting in an activated cellulose structure suitable for subsequent chemical modifications.

[0059] Moreover, the step of incubating comprises controlled alkaline treatment under moisture-balanced and inert conditions to facilitate selective delignification and structural swelling of cellulose without degradation. The moisture concentration in the aforementioned range of 60 to 80 wt.% ensures adequate hydration of the lignocellulosic network, allowing penetration and uniform distribution of the alkaline medium. The second alkaline reaction medium, maintained within the aforementioned concentration range of 17 to 27 wt.%, provides sufficient hydroxide ion concentration to disrupt ester and ether linkages in lignin and hemicellulose while preserving cellulose crystallinity. In this context, the moisture concentration may be 60, 62, 64, 66, 68, 70, 72, 74, 76 or 78 wt.% up to 62, 64, 66, 68, 70, 72, 74, 76, 78 or 80 wt. %, and the concentration of the second alkaline reaction medium may be 17, 18, 19, 20, 21, 22, 23, 24, 25 or 26 wt.% up to 21, 22, 23, 24, 25, 26 or 27 wt.%. The moisture content and the second alkaline reaction medium concentration are optimized to promote efficient interaction between the alkaline medium and the cellulose fibres, enabling a high degree of cellulose reactivity. Notably, carrying out the incubation step in a controlled inert atmosphere, at the aforementioned temperature range of 25 to 35 degree Celsius promotes gradual ion diffusion and reaction equilibrium, maintaining structural integrity and minimizing fibril scission. For example, the temperature may be 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 degree Celsius up to 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35 degree Celsius. Similarly, incubation time duration in the aforementioned range of 6 to 12 hours enables complete diffusion-driven interaction between hydroxyl groups and alkali species, resulting in efficient lignin removal and fibre swelling. For example, the time duration may be 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11 or 11.5 hours up to 8.5, 9, 9.5, 10, 10.5, 11, 11.5 or 12 hours. The time duration in the aforementioned range allows for thorough alkalization of cellulose fibres, ensuring sufficient activation for subsequent processing. Collectively, these conditions ensure enhanced cellulose accessibility, improved porosity, and uniform reaction kinetics, producing a high-purity fibrous substrate suitable for subsequent bleaching or enzymatic processing. The aforementioned embodiment offers a technically superior alternative to high-temperature alkali treatments by balancing reaction efficiency with preservation of cellulose molecular weight and minimizing chemical consumption.

[0060] Optionally, the step of incubating the cellulosic base material further comprises removing excess content of the second alkaline reaction medium from the cellulosic base material, to ensure that the residual moisture content of the cellulosic base material is less than 50 weight percent (wt.%). In this context, subsequent to the activation of the cellulosic base material, excess content of the second alkaline reaction medium is removed to ensure that the residual moisture content of the cellulosic base material is less than 50 weight percent which is suitable for further processing i.e., etherification or production of cellulose ether of varying purty, varying degree of viscosity and grades. Upon completion of the incubation step, the excess content of the second alkaline reaction medium is removed from the cellulosic base material through methods such as filtration, centrifugation, or washing. This step ensures that the concentration / content of the second alkaline reaction medium in the cellulosic material is reduced, leaving behind a residual moisture content of less than 50% by weight. The controlled removal of excess sodium hydroxide is necessary to prevent over- alkalization of the cellulose and to prepare the cellulosic material for subsequent steps in the process while maintaining the structural integrity of the activated cellulose fibres. Furthermore, the second alkaline reaction medium is separated from the cellulosic base material is recovered and subsequently fortified with additional amount of the second alkaline reaction medium to restore its original concentration for reuse. The technical advantage of the aforementioned is that this step enhances cellulose stability, reaction efficiency, and reproducibility while enabling production of high-grade of the at least one cellulose ether with reduced chemical consumption.

[0061] The method also comprises a step of processing the incubated cellulosic base material mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

[0062] After incubation, the cellulosic base material is subjected to mechanical processing to reduce the particle size and increase the surface area, thereby enhancing its reactivity. The mechanically processed cellulosic base material is then allowed to react with the alkylating agent, which modifies the cellulose structure through etherification, resulting in the production of the at least one cellulose ether. The term "alkylating agent" refers to a chemical compound or reagent configured to introduce an alkyl group (-CnJLn+l) into the molecular structure of the cellulosic base material through a substitution or addition reaction, thereby forming cellulose ethers or alkyl- substituted derivatives. The alkylating agent reacts with the activated hydroxyl groups present on the cellulose backbone under controlled alkaline conditions to form stable ether linkages. The aforementioned reaction (between the processed cellulosic base material and the alkylating agent) is carried out in a controlled environment to ensure efficient alkylation, where the hydroxyl groups of the cellulose react with the alkylating agent to form hydroxypropyl cellulose. The conditions are carefully regulated to achieve the desired degree of substitution and molecular structure of the hydroxypropyl cellulose, suitable for its intended applications.

[0063] Optionally,

[0064] the alkylating agent comprises at least one of: propylene oxide, acetyl chloride, chloroacetic acid, ethyl chloride, methyl chloride, dimethyl sulphate; and the at least one cellulose ether comprises at least one of: hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxyethyl methylcellulose (HEMC), hydroxyethyl cellulose (HEC).

[0065] In this context, the alkylating agent is selected based on its reactivity and ability to introduce the desired alkyl group into the cellulose structure. Each of the listed alkylating agents reacts with the hydroxyl groups of cellulose to form an ether linkage, thereby modifying the cellulose to produce the at least one cellulose. In this regard, In certain embodiments, the alkylating agent (at least one of: propylene oxide, acetyl chloride, chloroacetic acid, ethyl chloride, methyl chloride, dimethyl sulphate) is selected based on desired product characteristics and the target properties of the final product (of the produced at least one cellulose ether) such as degree of substitution, solubility, viscosity, thermal stability and purity. The use of the aforementioned alkylating agent ensures efficient alkylation, and their compatibility with the cellulosic base material facilitates the etherification process under controlled conditions. Notably, the alkylating agent is typically employed following the incubation and moisture-adjustment steps to ensure optimal reactivity and minimize side reactions.

[0066] Moreover, the method enables production of the at least one cellulose ether from aforementioned list i.e., hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxyethyl methylcellulose (HEMC), or hydroxyethyl cellulose (HEC). Each of the aforementioned type of the at least one cellulose ether has distinct substituent chemistry and tunable physicochemical properties and therefore has variable application sectors. Notably, the aforementioned at least one cellulose ether is derived through controlled etherification of cellulose (obtained from cellulosic base material through incubation and mechanical processing) using a suitable alkylating agent, producing polymers with tailored hydroxyl substitution patterns that govern solubility, viscosity, thermal stability, and film-forming ability. HPC imparts high thermoplasticity and water solubility, making it suitable for applications requiring transparency and flexibility. HPMC combines hydroxypropyl and methyl substitutions, providing excellent film strength, surface adhesion, and thermal gelation properties. HEMC offers balanced hydrophilicity and mechanical integrity, improving water retention and stability in formulations. HEC, with hydroxyethyl substitution, enhances viscosity and compatibility in aqueous systems. Collectively, these types of the at least one cellulose ether are selected because they enable controlled modification of rheological behavior, stability, and performance across diverse industrial applications, while being nontoxic, biodegradable, and derived from renewable sources. Technical advantages are that the use of these specific cellulose ethers ensures consistent process ability, improved functional versatility, and enhanced product quality compared to unmodified or singly substituted cellulose derivatives.

[0067] Optionally, the cellulose ether is hydroxypropyl cellulose (HPC) and the alkylating agent is propylene oxide, and wherein a molar ratio of anhydrous glucose unit to propylene oxide is in a range of 1 :7 to 1 :25, and a quantity of propylene oxide being determined based on a desired intrinsic viscosity of the cellulosic base material. In this regard, a specific type of at least one cellulose ether i.e., hydroxypropyl cellulose (HPC), is produced by reacting the cellulosic base material with propylene oxide as the alkylating agent under controlled alkaline conditions to introduce hydroxypropyl substituents onto the cellulose backbone. In this case, the molar ratio of anhydrous glucose unit to propylene oxide, maintained within the range of 1:7 to 1:25. The said ratio is carefully selected to control the degree of substitution (DS) and thus the intrinsic viscosity, solubility, and mechanical properties of the resulting HPC. A lower ratio yields partially substituted cellulose with moderate viscosity and higher crystallinity, while a higher ratio promotes greater chain substitution, resulting in improved flexibility, water solubility, and transparency. Moreover, the quantity of propylene oxide is therefore determined according to the desired intrinsic viscosity, which directly correlates with molecular weight and governs the rheological and film-forming behaviour of the product. The reaction is typically conducted after the activation and moisture adjustment steps, ensuring that reactive hydroxyl groups on the cellulose are accessible for efficient etherification. Technical advantage is that the disclosed method allows and enables the precise tailoring of HPC properties, yielding a thermoplastic, water-soluble, and chemically stable polymer suitable for diverse applications such as coatings, pharmaceutical excipients, and biodegradable films, while maintaining reproducible quality and efficient reagent utilization.

[0068] Optionally, the method further comprising reacting the processed cellulosic base material with the alkylating agent in presence of an inert dispersant selected from a group comprising at least one of: toluene, tetrahydrofuran, isopropyl alcohol, an aqueous solution of at least one of: toluene, tetrahydrofuran, isopropyl alcohol. In this regard, the term "inert dispersant" refers to a chemical compound or reagent capable of facilitating uniform dispersion and controlled reaction kinetics during etherification. The inert dispersant is chosen for its chemical inertness toward both cellulose and the alkylating agent, ensuring that no side reactions or degradation occur while maintaining homogeneous mixing of the reaction components. In this regard, toluene, when used as the inert dispersant, serves as an effective non-polar dispersant that minimizes cellulose aggregation and controls reaction heat. Similarly, tetrahydrofuran provides superior solvent-substrate interaction enabling enhanced accessibility of hydroxyl groups, and isopropyl alcohol balances polarity and miscibility, improving reagent distribution and controlling viscosity. The use of aqueous mixtures of these dispersants moderates reactivity, reduces solvent load, and aids in subsequent separation. The reaction is typically conducted following the activation and moisture adjustment stages, wherein cellulose hydroxyl groups are exposed for substitution. Technical advantage: employing such inert dispersants ensures uniform etherification, minimized cellulose degradation, controlled viscosity development, and enhanced reaction yield, resulting in a cellulose ether product of high purity, consistent substitution, and reproducible performance characteristics. In other words, the processed cellulosic base material reacts with the alkylating agent under influence of the inert dispersant. During the etherification process, inert dispersant such as isopropyl alcohol is introduced to facilitate the even distribution of the alkylating agent within the cellulosic base material. The inert dispersant helps to prevent aggregation of cellulose fibres and ensures that the reaction proceeds uniformly. The chemical inert nature of the inert dispersant ensures that it does not participate in the reaction itself, maintaining the integrity of the alkylation process while enhancing the efficiency of the etherification reaction.

[0069] Optionally, reacting the processed cellulosic base material with the alkylating agent results in a multi-stage etherification process, wherein the multi-stage etherification process comprises maintaining the cellulosic base material, at an agitation rate of 200 to 400 revolutions per minute, at temperatures of:

[0070] 20 degrees Celsius for 1 to 2 hours for a first stage;

[0071] 40 degrees Celsius for 3 to 4 hours for a second stage; and

[0072] 60 degrees Celsius for 6 to 10 hours for a third stage.

[0073] In this regard, the term "multi-stage etherification process" refers to a series of steps that results in etherification of the cellulosic base material yielding the at least one cellulose ether. The multi-stage etherification process designed to achieve gradual and controlled substitution of hydroxyl groups across the cellulose backbone. In other words, the multi-stage etherification process is conducted in a stepwise manner to control the reaction rate and achieve optimal substitution of the hydroxyl group of the cellulosic base material with the alkylating agent. In the first stage, the temperature is maintained at 20°C for 1 to 2 hours, allowing the initial reaction to occur at a slower rate. The first stage allows initial absorption and diffusion of the alkylating agent into the cellulose matrix without premature reaction, promoting even reagent distribution. The temperature is then increased to 40°C for 3 to 4 hours, in the second stage to promote further alkylation, followed by a final increase to 60°C for 6 to 10 hours, in the third stage, where the reaction reaches completion. The second stage activates the etherification process, enabling controlled nucleophilic substitution of hydroxyl sites while minimizing by-product formation. The third stage completes the reaction by ensuring conversion of residual reactive sites and stabilization of the ether linkages formed. This stepwise temperature elevation allows progressive reaction kinetics, minimizing cellulose chain scission and preventing localized over-substitution. The entire process is conducted under controlled agitation, ranging from 200 to 400 revolutions per minute, ensuring thorough mixing of the reactants and uniformity in the product formation. This staged temperature profile allows for precise control over the etherification process, optimizing the degree of substitution and the physical properties of the at least one cellulose ether. The technical advantage of the multi-stage etherification is that this step-wise process ensures uniform substitution, enhanced molecular weight control, and reproducible viscosity, yielding cellulose ethers of high structural uniformity, stability, and consistent performance across industrial and formulation applications. Optionally, the method further comprises conditioning the synthesized cellulose ether into a predetermined final product form. In this regard, this step is performed to achieve desired physical, chemical, and functional characteristics of the produced at least one cellulose ether in a form suitable for its intended application. The conditioning process involves post-reaction treatment steps such as neutralization, washing, filtration, drying, milling, or granulation, which collectively remove residual reactants, solvents, and by-products while stabilizing the polymer structure. These steps may be carried out under controlled temperature and humidity conditions to prevent thermal degradation and to achieve uniform moisture distribution across the material. The final product form may include powder, granule, flake, or film, depending on target properties such as solubility, dispersibility, viscosity control, or film-forming behaviour. The conditioning stage is typically performed after completion of etherification and purification to ensure product stability and ease of handling. The technical advantage of this step is that this step enables customization of product morphology, consistent performance, and extended shelf life, ensuring that the cellulose ether exhibits optimized reactivity, processability, and application- specific functionality in its final usable form. In this context, the step of conditioning involves a series of steps aimed at refining the produced at least one cellulose ether, ensuring it meets specific performance and quality standards. The step of conditioning may include various procedures such as drying, size reduction, or other forms of physical transformation that are intended to result in a final product suitable for industrial or commercial application. The exact form of the final product may vary depending on the desired application of the at least one cellulose ether, including, but not limited to, powdered, granular, or film-like forms.

[0074] Optionally, conditioning the synthesized at least one cellulose ether into a predetermined final product form comprises:

[0075] treating the at least one cellulose ether with a secondary acidic reaction medium while adjusting the pH of the secondary acidic reaction medium to a value in a range of 6 to 7, at a concentration of 50 wt.% wherein the secondary acidic reaction medium is sulfuric acid solution;

[0076] purifying the acidic at least one cellulose ether through washing with hot water at temperature in a range of 85 to 90 degrees Celsius to remove salts; and converting the purified at least one cellulose ether into a powdered form using one of a: spray dryer, vacuum dryer, or fluidized bed dryer under optimized conditions.

[0077] In this context, the step of conditioning begins by treating the synthesized at least one cellulose ether with the secondary acidic reaction medium, preferably but not limited to, a sulfuric acid solution at a concentration of 50 wt.%, while maintaining the pH in the range of 6 to 7. This mild acid treatment neutralizes residual alkaline species and terminates any unreacted etherification activity without compromising the polymer backbone. The partially neutralized product is then purified by washing with hot water maintained at 85-90 °C, effectively removing inorganic salts and low-molecular-weight impurities formed during the neutralization step, thereby improving the purity and stability of the cellulose ether. Subsequently, the purified cellulose ether is converted into powdered form using a spray dryer, vacuum dryer, or fluidized bed dryer operated under optimized conditions to ensure uniform particle size, controlled moisture content, and preservation of molecular weight. Technical advantage is that this integrated conditioning approach yields a high-purity, stable, and free-flowing cellulose ether powder with consistent viscosity, solubility, and processability, making it ideally suited for diverse industrial and pharmaceutical applications.

[0078] Optionally, the step of pH adjustment is initiated once the etherification reaction of the at least one cellulose ether is deemed complete, as indicated by observable reaction parameters such as a pressure drop within the 0.5 to 1.2 bar range. The pH adjustment is performed by introducing a 50% wt. of the secondary acidic reaction medium (into a mixture comprising the synthesized at least one cellulose ether, the alkylating agent and the inert dispersant) which neutralizes the alkalinity, ensuring that the pH stabilizes within the optimal range of 6 to 7. This pH adjustment is critical for ensuring the stability of the at least one cellulose ether in its final product form and prepares the material for subsequent purification.

[0079] Furthermore, optionally, the purification process involves washing the at least one cellulose ether with hot water at temperatures of 85 to 90°C, which effectively removes residual salts and byproducts from the material. Following this, the at least one cellulose ether is transformed into a powdered form through drying using equipment such as a spray dryer, vacuum dryer, or fluidized bed dryer. The drying conditions are optimized to achieve the desired particle size, moisture content, and bulk density, thereby ensuring that the final product meets the required specifications for its intended application.

[0080] Optionally, the present disclosure provides the method of manufacturing hydroxypropyl cellulose from agricultural residues. Notably, hydroxypropyl cellulose (HPC) is a cellulose derivative obtained through the chemical modification of cellulose. The modification typically involves the introduction of hydroxypropyl groups (-OCH2CH(OH)CHs) onto the cellulose backbone. This chemical modification enhances certain properties of cellulose, making HPC soluble in both water and organic solvents, and improving its film-forming, thickening, and emulsifying characteristics. HPC find applications across various industries, including pharmaceuticals (as a tablet binder or coating), cosmetics (as a thickener), and surface treatments (for coatings and adhesives).

[0081] The method further comprises conditioning the synthesized hydroxypropyl cellulose into a predetermined final product form. After the synthesis of hydroxypropyl cellulose, the product is subjected to a conditioning process designed to transform the material into its desired end-use form. Optionally, the method of manufacturing at least one cellulose ether from agricultural residues, leveraging sustainable, renewable feedstock for industrial applications. The conversion of these residues into a high-value chemical derivative such as HPC also promotes the valorisation of biomass waste, contributing to circular economies. The method of manufacturing at least one cellulose ether from agricultural residues, as disclosed in the present disclosure, is eco-friendly and cost-effective method. The disclosed method aids in efficient production various grades of cellulose ether with minimal environmental impact, and carbon footprint. The disclosed method helps in reducing energy usage and waste generation during production of the cellulose from agricultural residues and subsequent production of various grades and types of cellulose ether therefrom. By efficiently managing and controlling various operational / production parameters such as temperature, chemical (acid or alkaline) concentration, stirring speed, and so on, the disclosed method provides ways to obtain high yield of cellulose ether of different grades and purity. The disclosed method offers flexibility in the utilization of biomass resources (i.e., the agricultural residues) thereby promoting green technology.

[0082] EXPERIMENTAL PART

[0083] In various preferable experimental setups, various stages and parameters of cellulose ether production were assessed and tabulated. In an experimental set up, selected alkylating agent was propylene oxide, the molar ratio of anhydrous glucose unit to propylene oxide ranges from 1:7 to 1:25, wherein the quantity of propylene was determined based on the desired intrinsic viscosity of the cellulosic base material. The intrinsic viscosity of the cellulosic base material was measured using Cupriethylenediamine (CED) hydroxide solution, allowing for precise correlation with the molar ratio of anhydrous glucose unit (AGU) to propylene oxide (PO). The molar ratio of AGU to PO was adjusted according to the target viscosity of the target cellulose ether namely, hydroxypropyl cellulose, ensuring the final product's suitability for specific applications. The following table 1 illustrates the relationship between intrinsic viscosity (measured in CED cp / g), the AGU / PO molar ratio, and the resultant hydroxypropyl cellulose viscosity at 25°C:

[0084] TABLE 1:

[0085] s. Intrinsic Viscosity AGU / PO Molar HPC Viscosity at 25°C (2-4% No. (qsp / C) Ratio wt. solution)

[0086] 1 200-600 1:7 40 cp (2% wt. solution) 2 400-900 1:15 100 cp (4% wt. solution) 3 400-900 1:23 5680 cp (4% wt. solution) 4 1300-1800 1:15 460 cp (2% wt. solution) 5 1300-1800 1:23 1900 cp (2% wt. solution) 6 4000-6000 1:23 16500 cp (2% wt. solution)

[0087]

[0088] This 'Table 1' demonstrates how the intrinsic viscosity of the cellulose pulp, when adjusted in line with the molar ratio of AGU to PO, resulted in hydroxypropyl cellulose with tailored viscosity profiles.

[0089] As observed, a molar ratio of 1 :7 produced hydroxypropyl cellulose with a viscosity of 40 cp in a 2% wt. solution, while a higher molar ratio of 1 :23 produced viscosities as high as 16500 cp. The controlled use of propylene oxide enabled precise manipulation of the final product’s characteristics, ensuring that the final product met the desired performance requirements. DETAILED DESCRIPTION OF THE DRAWINGS

[0090] Referring to FIG. 1, illustrated is a flow chart 100 depicting steps of a method of manufacturing at least one cellulose ether from agricultural residues, in accordance with an embodiment of the present disclosure. At step 102, the agricultural residues are subjected to a pretreatment process to produce a cellulosic base material. At step 104, the pretreated cellulosic base material is incubated in a controlled condition. At step 106, the incubated cellulosic base material is processed mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

[0091] The aforementioned steps are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.

Claims

CLAIMSWe Claims:

1. A method of manufacturing at least one cellulose ether from agricultural residues, the method comprising:subjecting the agricultural residues to a pretreatment process to produce a cellulosic base material;incubating the cellulosic base material in a controlled condition; and processing the incubated cellulosic base material mechanically and reacting the same with an alkylating agent to synthesize the at least one cellulose ether.

2. The method as claimed in claim 1, further comprising conditioning the synthesized cellulose ether into a predetermined final product form.

3. The method as claimed in claim 1, wherein the pretreatment process comprises:subjecting the agricultural residues to an acidic pretreatment process under a first set of conditions, andsubjecting the acidic agricultural residues to an alkaline pretreatment process under a second set of conditions to obtain the cellulosic base material.

4. The method as claimed in claim 3, whereinthe acidic pretreatment process comprises using an acidic reaction medium selected from a group comprising at least one of: sulfuric acid, hydrochloric acid, nitric acid, maleic acid, zeolites, aluminium chloride, ferric chloride, and wherein the acidic reaction medium is at a concentration in range of 0.5 to 1.5 volume percent; andthe alkaline pretreatment process comprises using a first alkaline reaction medium selected from a group comprising at least one of: sodium hydroxide,potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, and wherein the first alkaline reaction medium is at a concentration of 4 to 6 weight percent, wherein the first set of conditions and the second set of conditions comprises: a time duration in a range of 20 to 50 minutes, and a temperature in a range of 120 to 160 degrees Celsius.

5. The method as claimed in claim 1, wherein the pretreatment process further comprises bleaching the cellulosic base material, using a bleaching agent, at a temperature in a range of 50 to 80 degrees Celsius for a time duration in a range of 40 to 120 minutes, wherein the bleaching agent is selected from at least one of: peroxide, quaternary ammonium salt, sodium chlorite, sodium sulphite.

6. The method as claimed in claim 1, wherein the step of incubating the cellulosic base material comprisesmixing the cellulosic base material having moisture in a concentration in a range of 60 to 80 weight percent with a second alkaline reaction medium in a concentration in a range of 17 to 27 weight percent, in the controlled condition, wherein the second alkaline reaction medium is selected from a group comprising at least one of: sodium hydroxide, potassium hydroxide, mono-ethanol amine, lithium hydroxide, calcium hydroxide, ammonium hydroxide, sodium carbonate, triethylamine, urea, andwherein the controlled condition comprises: setting an inert environment comprising at least one inert gas, temperature in a range of 25 to 35 degrees Celsius for a time duration in a range of 6 to 12 hours.

7. The method as claimed in claim 6, the step of incubating the cellulosic base material further comprises removing excess content of the second alkaline reaction medium from the cellulosic base material, to ensure that the residual moisture content of the cellulosic base material is less than 50 weight percent.

8. The method as claimed in claim 1, whereinthe alkylating agent comprises at least one of: propylene oxide, acetyl chloride, chloroacetic acid, ethyl chloride, methyl chloride, dimethyl sulphate; and the at least one cellulose ether comprises at least one of: hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), hydroxyethyl methylcellulose (HEMC), hydroxyethyl cellulose (HEC).

9. The method as claimed in claim 8, wherein the cellulose ether is hydroxypropyl cellulose (HPC) and the alkylating agent is propylene oxide, and wherein a molar ratio of anhydrous glucose unit to propylene oxide is in a range of 1:7 to 1:25, and a quantity of propylene oxide being determined based on a desired intrinsic viscosity of the cellulosic base material.

10. The method as claimed in claim 1 , further comprising reacting the processed cellulosic base material with the alkylating agent in presence of an inert dispersant selected from a group comprising at least one of: toluene, tetrahydrofuran, isopropyl alcohol, an aqueous solution of at least one of: toluene, tetrahydrofuran, isopropyl alcohol.

11. The method as claimed in claim 1 , wherein reacting the processed cellulosic base material with the alkylating agent results in a multi-stage etherification process, wherein the multi-stage etherification process comprises maintaining the cellulosic base material, at an agitation rate of 200 to 400 revolutions per minute, at temperatures of:20 degrees Celsius for 1 to 2 hours for a first stage;40 degrees Celsius for 3 to 4 hours for a second stage; and60 degrees Celsius for 6 to 10 hours for a third stage.

Images