A system for the adsorption of cobalt(ii) ions from aqueous solutions
The use of activated carbon from date palm trunk waste optimizes cobalt (II) ion removal in wastewater, addressing inefficiencies and costs of conventional methods, enhancing environmental sustainability and economic viability.
Patent Information
- Application Number
- DE202025101010
- Authority / Receiving Office
- DE · DE
- Patent Type
- Utility models
- Current Assignee / Owner
- Filing Date
- 2025-02-26
- Publication Date
- 2025-04-24
- Estimated Expiration
- 2035-02-28
AI Technical Summary
Existing wastewater treatment methods for removing cobalt (II) ions are inefficient, costly, and require extensive infrastructure, which is a challenge for countries with limited resources, leading to environmental pollution and health risks.
A system using activated carbon produced from date palm trunk waste through controlled pyrolysis and activation processes, optimizing adsorption performance to efficiently remove cobalt (II) ions from aqueous solutions.
The system achieves high adsorption capacity and efficiency, reducing pollution and operational costs, promoting sustainable waste utilization and contributing to a circular economy.
Abstract
Description
[0001] The present invention relates to an adsorption system for removing cobalt(II) ions from aqueous solutions using activated carbon derived from date palm fruit waste. It focuses in particular on optimizing adsorption performance through controlled pyrolysis and activation processes. The invention is applicable to wastewater treatment, heavy metal remediation, and pollution control.
[0002] With rapid population growth and industrialization, the volume of wastewater containing heavy metals has increased significantly, posing a serious environmental and health risk. Existing wastewater treatment methods, such as chemical precipitation, ion exchange, and membrane filtration, often require large infrastructure, high operating costs, and complex maintenance. Many countries, especially those with limited space and resources, struggle to construct such large-scale wastewater treatment plants. Furthermore, conventional treatment methods may not be efficient enough to remove cobalt(II) ions from wastewater, leading to long-term pollution and environmental damage. Therefore, there is an urgent need for an affordable, scalable, and highly effective method for removing heavy metals like cobalt(II) from wastewater.
[0003] Activated carbon is frequently used for water purification due to its high porosity and adsorption capacity. However, commercial production of activated carbon is expensive and relies on non-renewable sources. Activated carbon derived from biomass, particularly agricultural waste, represents a more sustainable and cost-effective alternative. Among the various biomass sources, date palm fruit waste is an abundant and underutilized resource, especially in the Middle East and North Africa. The high carbon content and unique structure of date palm waste make it a promising candidate for activated carbon production. However, the pyrolysis conditions and the activation process need to be optimized.
[0004] The present invention provides a novel and efficient system for the removal of cobalt(II) ions from date palm fruit waste using activated carbon. Through the careful selection of pyrolysis temperatures and activation conditions, this system increases adsorption efficiency and thus represents a viable alternative to conventional methods. The developed activated carbon not only surpasses the adsorption capacity of commercial products but also offers a cost-effective and environmentally friendly solution for wastewater treatment. This approach not only reduces heavy metal pollution but also promotes the utilization of agricultural waste, thereby contributing to a circular economy and sustainable environmental management.
[0005] One objective of the present disclosure is the use of waste from date fruits, promoting a sustainable and environmentally friendly adsorption material.
[0006] Another objective of the present disclosure is to produce a cost-effective alternative to commercial activated carbon.
[0007] Another objective of the present disclosure is the efficient removal of Co(II) ions with high adsorption capacity.
[0008] Another objective of the present disclosure is to achieve a rapid adsorption process that reaches equilibrium within 90 minutes.
[0009] Another objective of the present disclosure is to improve adsorption efficiency through controlled pyrolysis and activation.
[0010] Another objective of the present disclosure is the adaptation of the Freundlich isotherm, thereby ensuring its applicability in heterogeneous adsorption.
[0011] Another objective of the present disclosure is to operate across different temperatures and to demonstrate endothermic adsorption behavior.
[0012] Another objective of this disclosure is the potential for wastewater treatment, which contributes to environmental sustainability.
[0013] The present invention relates to a system that uses waste from date palms (Qush Zabad and Khenaizy) as a sustainable source for the production of activated carbon (AC).
[0014] Another embodiment of the present invention comprises a raw material processing unit for washing, drying and crushing date palm fruit waste, a pyrolysis and activation unit for thermal treatment under controlled conditions, and an adsorption and characterization unit for evaluating the Co(II) ion removal efficiency using analytical techniques such as FTIR, SEM-EDS and adsorption isotherm models.
[0015] Another embodiment of the present invention consists in collecting date palm waste (Qush Zabad and Khenaizy), washing it with deionized water, drying it for 24 hours at 60°C, grinding it into a fine powder and sieving it to a uniform particle size.
[0016] In a further embodiment of the present invention, the processed material is subjected to pyrolysis at 500°C, 600°C and 700°C in a nitrogen atmosphere, followed by physical activation with CO2 at 400°C to increase the porosity and adsorption capacity.
[0017] Another embodiment of the present invention consists in examining the produced activated carbon for functional groups using Fourier transform infrared spectroscopy (FTIR) and for surface morphology and elemental composition using scanning electron microscopy (SEM-EDS).
[0018] Another embodiment of the invention is the performance of batch adsorption studies with Co(II) solutions (10-100 ppm) at different contact times (up to 8 hours) and temperatures (25-45°C) to determine the adsorption capacity and efficiency.
[0019] In a further embodiment of the present invention, the equilibrium adsorption behavior of Co(II) ions on the produced activated carbon is evaluated using the isothermal models of Langmuir and Freundlich in order to determine the adsorption capacity and the surface interaction.
[0020] Another embodiment of the present invention is the monitoring of the adsorption efficiency over time, which shows a rapid initial metal uptake within 30 minutes, followed by a slower increase, with the commercially available activated carbon reaching saturation within one hour.
[0021] Another embodiment of the present invention consists in higher Co(II) concentrations reducing the removal efficiency due to saturation, with a decrease of 5% being observed at 100 ppm compared to 10 ppm for the prepared AC and a decrease of 10% for the commercial AC.
[0022] Another embodiment of the present invention consists in the fact that the adsorption efficiency increases with temperature up to 35 °C due to the increased ion mobility, but decreases at high metal concentrations at 45 °C, which indicates a transition from endothermic to exothermic adsorption.
[0023] The invention relates to a novel wastewater treatment system that uses activated carbon produced from waste from date palm fruit, particularly from the Qush Zabad and Khenaizy varieties, to effectively remove Co(II) ions from aqueous solutions. The process comprises controlled pyrolysis at temperatures of 500°C, 600°C, and 700°C under a nitrogen atmosphere, followed by physical activation with carbon dioxide at 400°C, resulting in an adsorbent with an improved pore structure and functional surface groups. This system, characterized by rapid adsorption kinetics and adherence to the Freundlich isotherm model, exhibits high adsorption efficiency, especially at elevated solution temperatures, and is thus a cost-effective and environmentally friendly alternative to commercial activated carbon. The components of the system are:
[0024] Raw material preparation unit: This unit involves the collection of date palm waste from the Khenaizy and Qush Zabad varieties. The collected fruit is washed with deionized water to remove dust and residue. The washed samples are then dried in an electric oven at 60°C for 24 hours. After drying, the samples are ground into a fine powder and sieved to ensure a uniform particle size for further processing.
[0025] Pyrolysis and activation unit: In this unit, ten grams of dried and sieved date palm fruit powder are thermally pyrolyzed in a tube furnace under a nitrogen gas atmosphere. Pyrolysis is carried out at 500°C, 600°C, and 700°C for two hours at a controlled heating rate of 10°C per minute. After pyrolysis, a one-hour physical activation with carbon dioxide gas at 400°C takes place, increasing the porosity and adsorption capacity of the activated carbon. The finished activated carbon product is then crushed and sieved to obtain particle sizes of 250–300 µm.
[0026] Adsorbent Characterization Unit: This unit ensures the functional efficiency of the produced activated carbon. The functional surface groups responsible for the adsorption properties are identified using Fourier-transform infrared spectroscopy (FTIR). Furthermore, the structural morphology and elemental composition of the activated carbon are investigated using scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectrometry (EDS).
[0027] Unit for Adsorption Experiments: In this unit, the adsorption efficiency of the prepared activated carbon in removing Co(II) ions from aqueous solutions is evaluated. Batch adsorption studies are conducted by varying the initial metal ion concentrations (10–100 mg / L), the contact time, and the solution temperature (25–45°C). In each experiment, 10 mg of activated carbon is added to conical flasks containing the Co(II) solution, which are then placed on an orbital shaker. The perception
[0028] Unit for the analysis of the adsorption isotherm: This unit determines the adsorption behavior of Co(II) ions using 0.01 g of any type of activated carbon. The adsorption equilibrium is analyzed using the Langmuir and Freundlich isotherm models, which provide information about the adsorption efficiency, capacity, and surface interactions of the activated carbon.
[0029] The characterization of the adsorbent produced with the aforementioned system includes a comprehensive analysis of the following parameters: FTIR analysis
[0030] FTIR analysis was performed to identify the functional groups responsible for the adsorption of Co(II) ions on activated carbon (AC) produced at different pyrolysis temperatures. The results indicate the presence of important functional groups that play a crucial role in metal ion adsorption. The results show that the characteristic peak occurs at 670 cm⁻¹. 1 was observed, corresponding to the elongation of the hydroxyl (-OH) group, which is known to facilitate metal ion bonding. The peaks at 2360 cm⁻¹ 1 and 2330 cm- 1were associated with the stretching vibrations of carbon dioxide (O=C=O), indicating the presence of surface carbonyl functional groups. The AC from Qush Zabad exhibited additional functional carboxyl groups in the range of 1660–1550 cm⁻¹. 1 The presence of these functional groups indicates that the produced activated carbon exhibits significant surface chemical modifications that improve its adsorption performance. SEM and EDS analysis
[0031] The morphological and elemental properties of activated carbon produced at different pyrolysis temperatures were analyzed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDS). SEM images showed that both the Qush Zabad and Khenaizy activated carbons exhibited a spherical shape and a smooth surface morphology. The surface of the produced activated carbon contained relatively large pores, contributing to its high adsorption capacity. In contrast, the commercially available activated carbon displayed a rough morphology with irregular shapes, highlighting the structural differences between the two adsorbents.
[0032] EDS analysis confirmed that the primary chemical composition of the produced activated carbon consisted of carbon and traces of oxygen and potassium. The carbon content of the produced activated carbon was higher than that of commercially available activated carbon. However, in addition to carbon (C), oxygen (O), and potassium (K), commercially available activated carbon contained a number of other elements, including magnesium (Mg), silicon (Si), aluminum (Al), sulfur (S), and calcium (Ca). The presence of these metals in commercially available AC is attributed to the natural uptake of heavy metals by trees from soils with high metal concentrations. The differences in composition suggest that the prepared activated carbon, derived from date palm waste, has a purer carbon structure, making it a promising candidate for adsorption applications.
[0033] Energy Dispersive Spectroscopy (EDS) analysis of the produced activated carbon (AC) shows that its primary chemical composition consists of carbon, with traces of oxygen and potassium at various pyrolysis temperatures. The AC derived from the Qush Zabad date fruit contains 98.88% carbon, 0.52% oxygen, and 0.61% potassium at 500°C, while at 600°C it consists of 98.67% carbon, 0.48% oxygen, and 0.86% potassium. Similarly, at 700°C, it contains 98.74% carbon, 0.92% oxygen, and 0.34% potassium. The activated carbon from the Khenaizy date fruit has a comparable composition, with a carbon content of 98.83%, 98.45% and 98.69% at pyrolysis temperatures of 500°C, 600°C and 700°C respectively.In contrast, commercially available activated carbon has a more diverse elemental composition, comprising 93.27% carbon, 1.46% oxygen, 0.72% potassium, 0.16% magnesium, 0.86% silicon, 0.33% aluminum, 0.26% sulfur and 2.94% calcium.
[0034] The effect of adsorption time on the removal efficiency of Co(II) ions was investigated using activated carbon (AC) from Qush Zabad and Khenaizy date fruits at different pyrolysis temperatures. Adsorption experiments were conducted while varying the contact time and maintaining a fixed initial Co(II) ion concentration. The adsorption process was influenced by factors such as mass diffusion, external mass transport, and chemical reaction kinetics. The aim of the experiments was to determine the optimal residence time for effective Co(II) removal while minimizing operating costs. Adsorption efficiency was evaluated by measuring the removal percentage at different time intervals, with a focus on comparing the performance of the produced activated carbon to commercially available activated carbon.
[0035] The results show that the percentage removal of Co(II) ions increased rapidly within the first 30 minutes, which is attributed to the high availability of exposed adsorption sites. With increasing contact time, the removal rate gradually slowed, indicating a reduction in available surface-active sites. Despite longer adsorption times, equilibrium was not reached with the prepared activated carbon, suggesting the need for additional activation treatment to improve pore accessibility. In contrast, the commercially available activated carbon reached saturation within 60 minutes for a 10 ppm Co(II) solution and 30 minutes for a 100 ppm solution.The adsorption efficiency of the AC produced from Qush Zabad at 500°C and Khenaizy at 700°C showed comparable results to commercial activated carbon when tested with a 100 ppm Co(II) solution, indicating the effectiveness of the produced adsorbents in removing metal ions.
[0036] The effects of the initial Co(II) ion concentration on the adsorption process were investigated using concentrations between 10 and 100 ppm. The results show that removal efficiency decreased with increasing initial concentration, particularly at the optimal contact time of 90 minutes. For example, the percentage removal of Co(II) ions at 100 ppm was approximately 5% lower than at 10 ppm when using activated carbon (AC) from Qush Zabad at 500°C and Khenaizy at 700°C. In contrast, commercially available activated carbon exhibited a 10% lower removal efficiency at higher concentrations. This decrease in adsorption efficiency at higher Co(II) concentrations is attributed to the saturation of available surface-active sites on the adsorbent.At lower ion concentrations, the ratio of available adsorption sites to metal ions is higher, resulting in higher adsorption efficiency, while at higher concentrations fewer active sites remain unoccupied, resulting in lower metal removal. Effect of solution temperature
[0037] The effect of solution temperature on the adsorption of Co(II) ions was investigated over a period of 8 hours, considering different ion concentrations and pyrolysis temperatures of activated carbons (ACs) produced from Qush Zabad and Khenaizy date fruit. The diffusion rate of the metal ions in the pores of both commercial and produced activated carbons was influenced by temperature fluctuations. As the solution temperature increased from 25°C to 35°C, the adsorption rate of Co(II) ions on commercial AC also increased, likely due to increased mobility of the metal ions and stronger binding at the active adsorption sites. This trend suggests an endothermic adsorption process.However, at higher metal concentrations (50 and 100 ppm), a further increase in temperature to 45 °C led to a decrease in adsorption rates, suggesting possible exothermic behavior due to desorption effects.
[0038] A similar adsorption behavior was observed for activated carbons from Qush Zabad and Khenaizy date fruits at different pyrolysis temperatures (500°C, 600°C and 700°C).
[0039] The results clearly indicate that the adsorption rates of the manufactured activated carbons followed the same trend as those of commercially available activated carbons, with higher adsorption rates at higher temperatures. This could be due to the increased mobility of the metal ions, leading to stronger interactions with the active adsorption sites. As shown from Fig.However, the results show that the adsorption capacity of commercially available activated carbon decreased less sharply at higher temperatures than that of the manufactured activated carbon. These results confirm that the adsorption of Co(II) ions on the manufactured activated carbon is predominantly endothermic, but can exhibit exothermic properties at higher temperatures and metal concentrations. Langmuir adsorption model
[0040] The Langmuir isotherm model was applied to describe the adsorption equilibrium of Co(II) ions on the prepared activated carbon derived from Qush Zabad and Khenaizy date palm fruit. This model assumes single-layer adsorption on a homogeneous surface without interactions between adsorbed ions at adjacent sites. The Langmuir equation was used to determine the adsorption parameters, with the constants (maximum adsorption capacity) and (binding site affinity) derived from the linear relationship between the equilibrium concentration and the amount of adsorbed ion. The results showed that the experimental data for Co(II) adsorption on the prepared activated carbon at a solution temperature of 35°C yielded an R² value of 0.9, indicating good agreement with the Langmuir model.However, under other conditions, the R2 values were below 0.9, indicating a deviation from the Langmuir model. This suggests that adsorption does not strictly follow monolayer behavior in all cases and that other mechanisms, such as multilayer adsorption or surface heterogeneity, may be involved. Adsorption isotherm: Freundlich model
[0041] The Freundlich adsorption isotherm was used to describe the adsorption behavior of Co(II) ions on activated carbon (AC) from the date palm fruits Qush Zabad and Khenaizy. This empirical model considers adsorption on a heterogeneous surface with interactions between the adsorbed molecules and characterizes a reversible and non-ideal process. The Freundlich equation was used to determine the adsorption capacity and the adsorption intensity, where a higher KF value indicates stronger adsorption and an nnn value between 1 and 2 suggests a favorable physicochemical adsorption process.
[0042] The experimental results showed that the adsorption capacity increased with rising solution temperature, suggesting an endothermic adsorption process. Adsorption with AC from Qush Zabad at 25°C and 45°C showed different KF values depending on the pyrolysis temperature. At 500°C, the KF values were 0.799, 0.543, and 0.775, while at 600°C they were 0.151, 0.734, and 1.041. At 700°C, the values were 0.176, 0.401, and 1.140, respectively. The results for AC from Khenaizy date fruit followed a similar trend. Furthermore, the regression coefficient (R²) for most experimental data was 0.99, confirming good agreement with Freundlich's isothermal model.
[0043] The adsorption process proved to be nonlinear and indicated heterogeneous surface adsorption, as the nnn values remained greater than 1 but less than 2. Furthermore, the results showed that the isothermal Freundlich parameters (n, KF, and R2) for AC from Qush Zabad were consistently higher than those for AC from Khenaizy, suggesting better adsorption efficiency and a stronger binding affinity for Co(II) ions in the former.
[0044] The parameters of the Freundlich adsorption isotherm for the removal of Co(II) ions from Qush Zabad date fruits using activated carbon (AC) varied with the pyrolysis and adsorption temperatures. At a pyrolysis temperature of 500°C, the adsorption intensity values were 1.438, 1.135, and 1.094 for adsorption temperatures of 25°C, 35°C, and 45°C, respectively, with corresponding adsorption capacities of 0.407, 0.543, and 0.775. The regression coefficient (R²R²R²) was close to 1, confirming a good fit to the Freundlich model. At 600°C, the adsorption intensity increased from 1.113 at 25°C to 1.459 at 45°C, with the KF values increasing from 0.151 to 1.041 and the R² values consistently above 0.99. Similarly, at 700°C, the adsorption intensity increased from 1.135 at 25°C to 1.515 at 45°C, while the KF values increased from 0.176 to 1.140 and the R² values remained close to 1.
[0045] Similar trends were observed for AC produced from Khenaizy date fruit. At a pyrolysis temperature of 500°C, the adsorption intensity (nnn) was 1.449 at 25°C, 1.183 at 35°C, and 1.446 at 45°C, with corresponding adsorption capacity (Kf) values of 0.473, 0.478, and 1.385, respectively. The regression coefficient (R²) ranged from 0.799 to 0.999. At 600°C, the adsorption intensity was lower, with nnn values of 0.931 at 25°C, 0.971 at 35°C, and 1.105 at 45°C, while the KKK values increased from 0.173 to 0.513 and the R2R^2R2 values remained above 0.97. At 700°C, the adsorption intensity ranged from 1.012 at 25°C to 0.999 at 45°C, with KF values from 0.192 to 0.394 and consistently high R2 values.
[0046] This system offers an efficient, sustainable, and cost-effective approach to wastewater treatment by utilizing date palm fruit waste for activated carbon production. By optimizing the adsorption of heavy metal ions, it provides an environmentally friendly solution to industrial and ecological challenges related to wastewater pollution.
Claims
[1] System for the adsorption of Co(II) ions from aqueous solutions, comprising: (a) a raw material processing unit configured to collect waste date palm fruits of the Khenaizy and Qush Zabad varieties, wash them with deionised water, dry them at 60°C for 24 hours, grind them into a fine powder and sieve the powder to obtain uniform particle sizes; b) a pyrolysis and activation unit functionally connected to the raw material preparation unit, wherein the dried and sieved powder is subjected to thermal pyrolysis in a tube furnace under a nitrogen gas atmosphere at temperatures of 500°C, 600°C and 700°C for two hours at a controlled heating rate of 10°C per minute, followed by physical activation using carbon dioxide gas at 400°C for one hour to increase porosity and adsorption capacity, after which the activated carbon is crushed and sieved to obtain particles in the size range of 250-300 µm; (c) an adsorbent characterisation unit configured to analyse the surface functional groups of the activated carbon by Fourier transform infrared spectroscopy (FTIR) and to evaluate its structural morphology and elemental composition by scanning electron microscopy (SEM) in conjunction with energy dispersive X-ray spectrometry (EDS); d) an adsorption test unit operatively connected to the adsorbent characterisation unit and configured to evaluate the adsorption efficiency of the activated carbon in removing Co(II) ions from aqueous solutions by conducting batch adsorption studies with varying initial Co(II) concentrations (10-100 mg / L), contact time and solution temperature (25-45°C), whereby 10 mg of activated carbon are placed in conical flasks containing Co(II) solutions and placed on an orbital shaker, with the percentage removal of Co(II) ions and the adsorption capacity being calculated using standard adsorption equations; (e) an adsorption isotherm analysis unit configured to determine the adsorption behaviour of Co(II) ions by evaluating equilibrium adsorption using the Langmuir and Freundlich isotherm models, whereby the adsorption capacity, efficiency and surface interaction properties of the activated carbon are determined based on experimental data; the system providing an efficient, cost-effective and environmentally sound solution for wastewater treatment by using date palm waste as a source of activated carbon, thereby optimising the removal of heavy metal ions and reducing industrial pollution. [2] The system of claim 1, wherein the raw material preparation unit further comprises a controlled grinding mechanism to ensure a uniform particle size distribution for improved adsorption performance. [3] The system of claim 1, wherein the pyrolysis and activation unit uses a gas flow regulator to maintain a uniform nitrogen and carbon dioxide environment for optimized activation of the carbon adsorbent. [4] The system of claim 1, wherein the adsorbent characterization unit further uses Brunauer-Emmett-Teller (BET) surface area analysis to determine the pore size distribution and surface area of the activated carbon. [5] The system of claim 1, wherein the adsorption experimental unit comprises a temperature-controlled orbital shaker to maintain precise solution temperatures during adsorption studies. [6] The system of claim 1, wherein the adsorption isotherm analysis unit determines adsorption kinetics by applying pseudo-first order and pseudo-second order kinetic models to evaluate the adsorption rate. [7] The system of claim 1, wherein the produced activated carbon can be regenerated and reused for multiple adsorption cycles to improve sustainability and reduce operating costs.