A comprehensive utilization method of rapeseed byproducts

Abstract

The application belongs to the field of high-value utilization of agricultural by-products, and relates to a comprehensive utilization method of rapeseed by-products, which comprises the following steps: (1) drying rapeseed meal and rapeseed shell to constant weight respectively, and then grinding and screening; (2) mixing the screened rapeseed meal and rapeseed shell with n-hexane at room temperature to perform defatting treatment; (3) mixing the rapeseed meal and rapeseed shell obtained in step (1) or (2) with an ethanol hydrochloride solution respectively to perform polyphenol extraction, and then centrifuging to obtain supernatant and bottom solid; (4) purifying the polyphenols in the supernatant by AB-8 resin after removing the ethanol hydrochloride, then eluting with ethanol, and then obtaining polyphenols through vacuum rotary evaporation and drying; and (5) obtaining modified residues from the bottom solid after drying, which are used for adsorbing heavy metal ions in water. The polyphenols in the rapeseed by-products, i.e., rapeseed meal and rapeseed shell, are extracted, and then the residues after extracting the polyphenols are modified, so that the residues have excellent heavy metal ion adsorption capacity.

Description

Technical Field

[0001] This invention relates to the field of heavy metal wastewater treatment, and in particular to a method for the comprehensive utilization of rapeseed by-products. Background Technology

[0002] Rapeseed (Brassicanapus L.) is one of the world's most important oilseed crops. The main byproducts of rapeseed oil extraction are rapeseed meal and rapeseed hulls. Rapeseed meal and hulls are primarily composed of protein, lignin, cellulose, and hemicellulose, similar to the main components of lignocellulose. Furthermore, due to their rich content of phenolic compounds, rapeseed meal and hulls are widely used as extraction raw materials. However, another neglected issue after extracting polyphenols from agricultural byproducts is how to handle the residues left after the extraction process. Uncontrolled disposal of these residues not only causes environmental pollution but also results in waste.

[0003] Currently, rapeseed by-products such as rapeseed meal and rapeseed hulls are mainly used as plant-based protein feed. However, the high fiber content in these by-products hinders animal digestion, and they also contain toxic components or anti-nutritional factors such as glucosinolates, tannins, or sinigrin. These drawbacks severely limit their application as plant protein in feed. To fully utilize rapeseed by-products and maximize their feed value, detoxification treatment is necessary. Extracting toxic components and anti-nutritional factors from rapeseed by-products and using the profits generated from these components to offset the by-product treatment costs, followed by using the detoxified rapeseed by-products as plant-based protein feed, is a common method of utilizing rapeseed by-products. It has also been reported that rapeseed waste can be used for continuous biosorption of micropollutants such as Pb(II) and Rb19 dyes. Furthermore, biochar obtained from the pyrolysis of rapeseed cake exhibits a strong affinity for Cu(II) and Zn(II), but a very low affinity for As(III), suggesting that rapeseed byproducts have the potential to remove many heavy metal pollutants. However, whether rapeseed meal, rapeseed hulls, and their residues can directly adsorb Cr(VI) without pyrolysis, thus reducing adsorbent costs, remains an unresolved issue. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a new method for the comprehensive utilization of rapeseed by-products, which extracts polyphenols from rapeseed by-products while modifying the residues to obtain a high-performance heavy metal adsorbent.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0006] A method for the comprehensive utilization of rapeseed by-products, comprising the following steps:

[0007] (1) The rapeseed meal and rapeseed hull were dried to constant weight, and then ground and sieved to obtain sieved rapeseed meal and sieved rapeseed hull; the sieved rapeseed meal was divided into two parts a and b, and the sieved rapeseed hull was divided into two parts a and b.

[0008] (2) Take the sieved rapeseed meal a and rapeseed hull a and mix them with n-hexane at room temperature according to a certain solid-liquid ratio for defatting treatment. After ultrasonic treatment, filter to obtain defatted rapeseed meal and defatted rapeseed hull, and air dry for later use.

[0009] (3) Rapeseed meal b, rapeseed hull b, defatted rapeseed meal, defatted rapeseed hull were mixed with hydrochloric acid ethanol solution at a certain solid-liquid ratio for polyphenol extraction, and then centrifuged to obtain the corresponding supernatant and bottom solids, namely rapeseed meal polyphenol supernatant and corresponding bottom solids I, defatted rapeseed meal polyphenol supernatant and corresponding bottom solids II, rapeseed hull polyphenol supernatant and corresponding bottom solids III, defatted rapeseed hull polyphenol supernatant and corresponding bottom solids IV;

[0010] (4) The four supernatants obtained in step (3) were removed by vacuum rotary evaporation to remove hydrochloric acid and ethanol, and then the polyphenols were purified by AB-8 resin. After elution with ethanol, they were then vacuum rotary evaporated and dried to obtain rapeseed meal polyphenols, defatted rapeseed meal polyphenols, rapeseed hull polyphenols and defatted rapeseed hull polyphenols, respectively.

[0011] (5) After drying the four bottom solids I, II, III and IV obtained in step (3), they are respectively modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue and modified defatted rapeseed hull residue.

[0012] According to the above scheme, in step (1), rapeseed meal and rapeseed hulls are ground and sieved using a 30-50 mesh sieve.

[0013] According to the above scheme, in step (2), the solid-liquid ratio is 1:2 to 1:4 by weight, and the ultrasonic treatment is carried out at room temperature for 20 to 60 minutes; this degreasing step can be repeated multiple times, such as 2 to 4 times.

[0014] According to the above scheme, in step (3), the solid-liquid ratio is 1:4 to 1:10 by weight, the mixing temperature is 40 to 55°C, the mixing speed is 100 to 200 rpm, and the mixing time is 1 to 1.5 hours; the centrifugation speed is 3000 to 5000 rpm, and the centrifugation time is 10 to 20 minutes; wherein, the hydrochloric acid ethanol solution is a 50% to 60% ethanol aqueous solution containing 1M hydrochloric acid.

[0015] According to the above scheme, in steps (4) and (5), the drying temperature is 50-60℃ and the drying time is 24-48 hours.

[0016] The modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue prepared by the above method are used as heavy metal ion adsorbents. The specific application method is as follows: the modified residue is added to the polluted water body to be treated, with an adsorbent dosage ranging from 0.05 g to 0.30 g / 30 mL. After adding the adsorbent, the pH of the polluted water body is adjusted to 2.0–7.0, the contact time ranges from 30 to 480 minutes, and the initial concentration of heavy metal ions in the polluted water body ranges from 100 to 1000 mg / L.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: The comprehensive utilization method of rapeseed by-products provided by this invention extracts polyphenols from rapeseed by-products while modifying the residues to obtain a high-performance heavy metal adsorbent. The comprehensive utilization method provided by this invention extracts polyphenols from rapeseed meal and rapeseed hulls, which possess free radical scavenging, antibacterial, and heavy metal ion adsorption properties, and can be used as supplements in food, pharmaceuticals, cosmetics, and other fields. Furthermore, this invention obtains modified residues simultaneously with polyphenol extraction, which can be used to adsorb heavy metal ions in water. Compared to rapeseed meal and rapeseed hulls, the residues after polyphenol extraction have a better ability to adsorb heavy metal ions. Attached Figure Description

[0018] Figure 1 The effects of raw materials and residues on the adsorption rate of Cr(VI) before and after polyphenol extraction from rapeseed by-products.

[0019] Figure 2 AD are scanning electron microscope images of rapeseed meal (A), defatted rapeseed meal (B), modified rapeseed meal residue (C), and modified defatted rapeseed meal residue (D).

[0020] Figure 3 AD are scanning electron microscope images of rapeseed hulls (A), defatted rapeseed hulls (B), modified rapeseed hull residues (C), and modified defatted rapeseed hull residues (D).

[0021] Figure 4 shows the Fourier transform infrared spectra of different adsorbents: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0022] Figure 5 shows the effect of pH on adsorption rate: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0023] Figure 6 shows the effect of adsorbent addition amount on adsorption rate: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0024] Figure 7 shows the effect of time on adsorption rate: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0025] Figure 8 shows the effect of initial Cr(VI) concentration on adsorption rate: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0026] Figure 9 shows the reusability of the adsorbents: rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue (A); rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, modified defatted rapeseed hull residue (B).

[0027] Figure 10 The adsorption effect of modified defatted rapeseed meal residue and modified defatted rapeseed hull residue on coexisting heavy metal ions was studied.

[0028] Figure 11 The effects of different concentrations of rapeseed meal polyphenols, defatted rapeseed meal polyphenols, rapeseed hull polyphenols, and defatted rapeseed hull polyphenols on the adsorption rate of hexavalent chromium were investigated.

[0029] Figure 12 The combined effect of polyphenols from four rapeseed by-products (rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull) and their corresponding modified residues on the adsorption rate of hexavalent chromium was investigated. Detailed Implementation

[0030] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the present invention is not limited to the following embodiments.

[0031] In Example 1 below, the 54% ethanol solution containing 1M hydrochloric acid was prepared as follows: a hydrochloric acid ethanol solution with a total volume of 1L, comprising 83mL concentrated hydrochloric acid, 540mL anhydrous ethanol and 377mL water, is equivalent to a hydrochloric acid ethanol solution with a molar concentration of 1M and a mass concentration of 54%.

[0032] Example 1

[0033] A method for the comprehensive utilization of rapeseed by-products, comprising the following steps:

[0034] (1) The rapeseed meal and rapeseed hull were dried at 60°C to constant weight, ground and then sieved using a 40-mesh sieve to obtain sieved rapeseed meal and sieved rapeseed hull respectively; the sieved rapeseed meal was divided into two parts a and b, and the sieved rapeseed hull was divided into two parts a and b.

[0035] (2) Take the sieved rapeseed meal a and rapeseed hull a and defatt them with hexane at room temperature. The solid-liquid ratio is 1:3 by weight. After ultrasonic treatment at room temperature for 40 minutes, filter them. Repeat the above defatting steps 3 times to obtain defatted rapeseed meal and defatted rapeseed hulls, and air dry them for later use.

[0036] (3) Rapeseed meal b, rapeseed hull b, defatted rapeseed meal, defatted rapeseed hull were mixed with 54% ethanol solution containing 1M hydrochloric acid at a weight solid-liquid ratio of 1:10. The mixture was stirred at 150 rpm for 1.5 hours at 55°C. Then it was centrifuged at 4000 rpm for 20 minutes to obtain the corresponding supernatant and bottom solids, namely rapeseed meal polyphenol supernatant and corresponding bottom solids I, defatted rapeseed meal polyphenol supernatant and corresponding bottom solids II, rapeseed hull polyphenol supernatant and corresponding bottom solids III, and defatted rapeseed hull polyphenol supernatant and corresponding bottom solids IV.

[0037] (4) The four supernatants obtained in step (3) were evaporated under vacuum to remove ethanol, and then the polyphenols were purified by AB-8 resin. They were then eluted with anhydrous ethanol, and after vacuum rotary evaporation and drying, rapeseed meal polyphenols, defatted rapeseed meal polyphenols, rapeseed hull polyphenols and defatted rapeseed hull polyphenols were obtained respectively.

[0038] (5) After drying the four bottom solids I, II, III and IV obtained in step (3), they are respectively modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue and modified defatted rapeseed hull residue.

[0039] Application Example 1

[0040] The modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue prepared in Example 1 were used as adsorbents in Cr(VI) adsorption tests, and their respective adsorption rates were calculated. Rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull were used as control examples.

[0041] The adsorbents used in the adsorption experiments were rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue, rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, and modified defatted rapeseed hull residue. The adsorption experiments were conducted in 125 mL Erlenmeyer flasks with 30 mL of Cr(VI) solution. The adsorption experiments were carried out in a constant-temperature shaker at 150 rpm at room temperature. The adsorption conditions were: pH 2.0, adsorbent dosage 0.05 g / 30 mL, contact time 300 min, and initial Cr(VI) concentration 100 mg / L. Finally, the residual amount of hexavalent chromium in the reaction system was measured, and the adsorption rate of the modified residues was calculated.

[0042] like Figure 1 It can be seen that, regardless of whether they are defatted or not, rapeseed meal, rapeseed hull, defatted rapeseed meal, and defatted rapeseed hull all exhibit strong adsorption capacity for hexavalent chromium. When the adsorbent dosage was 0.05 g / 30 mL, the adsorption capacity of rapeseed meal and defatted rapeseed meal for Cr(VI) reached 30.36 and 30.13 mg / g, respectively, with corresponding adsorption rates of 50.60% and 50.22%. Meanwhile, the removal efficiency of rapeseed hulls and defatted rapeseed hulls for Cr(VI) was only 35.62% and 36.10%, respectively, and the adsorption capacity of Cr(VI) also decreased to 21.37 and 21.66 mg / g. However, the Cr(VI) adsorption rates of modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue were 61.79%, 59.66%, 41.28%, and 46.49%, respectively, which increased by 22%, 19%, 16%, and 29% compared to the adsorption rates of rapeseed meal, defatted rapeseed meal, rapeseed hulls, and defatted rapeseed hulls for Cr(VI).

[0043] from Figure 2 A~D and Figure 3 As can be seen from A to D, the surface area of ​​the modified defatted rapeseed meal residue and the modified defatted rapeseed hull residue is increased, which increases the contact opportunity between the adsorbent and heavy metal ions, making it easier for the heavy metal ions to bind with the adsorbent.

[0044] As can be seen from Figure 4, the characteristic absorption peak of hydroxyl groups in modified defatted rapeseed meal residue and modified defatted rapeseed hull residue is enhanced compared with that in rapeseed meal and rapeseed hull. Heavy metal ions mainly bind to the adsorbent through hydroxyl and carboxyl groups, which is consistent with the increased adsorption rate of Cr(VI) by modified defatted rapeseed hull residue and modified defatted rapeseed hull residue.

[0045] Application Example 2

[0046] This application example investigates the effects of different adsorption parameters on rapeseed by-products using different adsorbents (modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue, with rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull as control adsorbents). The specific process is as follows:

[0047] Adsorption experiments were conducted in 125 mL Erlenmeyer flasks with 30 mL of Cr(VI) solution. The adsorption experiments were performed at room temperature in a constant-temperature shaker at 150 rpm. Unless otherwise specified, the typical adsorption conditions were: pH 2.0, adsorbent dosage 0.15 g / 30 mL, contact time 300 min, and initial Cr(VI) concentration 100 mg / L. The effects of pH (2.0, 3.0, 4.0, 5.0, 6.0, 7.0), adsorbent dosage (0.05, 0.10, 0.15, 0.20, 0.25, 0.30 g / 30 mL), contact time (30, 60, 120, 180, 240, 300, 360, 420, 480 min), and initial Cr(VI) concentration (100–1000 mg / L) on the adsorption effect were systematically investigated. All adsorption experiments were performed at least three times, and the results are as follows:

[0048] 1. pH Value. Adsorption studies were conducted within a pH range of 2.0–7.0 (Figure 5). Adsorption was performed using rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, modified defatted rapeseed meal residue, rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, and modified defatted rapeseed hull residue, respectively. The Cr(VI) adsorption capacity of all adsorbents gradually decreased with increasing pH. Taking defatted rapeseed meal residue and defatted rapeseed hull residue as examples, when the pH increased from 2 to 7, their Cr(VI) removal rates decreased from 98.91% and 96.79% to 29.91% and 20.01%, respectively. However, under any different pH conditions, the modified residues showed a stronger affinity for Cr(VI) than the unextracted polyphenol-containing raw materials (rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull). In addition to further demonstrating the improvement of Cr(VI) adsorption after phenolic extraction, pH 2.0 was selected as a suitable condition for further experiments.

[0049] 2. Adsorbent Dosage. To determine the minimum possible adsorption amount for the maximum adsorption of metal ions, the adsorbent dosage was varied, with 0.05 g, 0.10 g, 0.15 g, 0.20 g, 0.25 g, and 0.30 g added to 30 mL of a 100 mg / L Cr(VI) ion solution (Figure 6). Higher adsorbent dosages provided a more expansive adsorption surface, thus increasing the removal efficiency of Cr(VI) with increasing adsorbent dosage. When the adsorbent dosage was 0.30 g / 30 mL, the removal rates of all eight adsorbents reached over 99%. However, 0.15 g / 30 mL may be a turning point, after which the adsorption performance decreased sharply, and the removal rate increased slowly with further increases in adsorbent dosage. Therefore, considering the overall cost, an adsorbent dosage of 0.15 g / 30 mL was used in subsequent experiments.

[0050] 3. Contact Time. By varying the contact time, including 30, 60, 120, 180, 240, 300, 360, 420, and 480 minutes (Figure 7), the results showed that the longer the contact time, the higher the removal efficiency. However, the adsorption of Cr(VI) increased rapidly within the first 30 minutes. Within 30 minutes, the removal rates of Cr(VI) by rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull reached 77.12%, 76.35%, 57.18%, and 55.99%, respectively, with corresponding removal rates of 83.55%, 81.87%, 67.58%, and 76.15% for the residues (rapeseed meal residue, defatted rapeseed meal residue, rapeseed hull residue, and defatted rapeseed hull residue). At 300 minutes, the removal rates gradually reached an equilibrium value, with rapeseed meal achieving a removal rate of 95.06%, defatted rapeseed meal 94.75%, rapeseed hull 78.39%, and defatted rapeseed hull 78.03%. Compared to the four unextracted polyphenol-rich raw materials (rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull), their respective residue adsorption rates further increased, exceeding 98% and 90%, respectively. Therefore, at any contact time, the residues were more effectively removed for Cr(VI).

[0051] 4. Initial Cr(VI) Concentration. The effect of initial Cr(VI) ion concentration on adsorption capacity is shown in Figure 8, with initial concentrations ranging from 100 to 1000 mg / L. A mixture of 0.15 g adsorbent and 30 mL solution was thoroughly mixed at pH 2, and the sample was extracted after 300 min. It can be seen that the removal efficiency of Cr(VI) is highest at lower initial Cr(VI) concentrations, and decreases with increasing concentration. At low concentrations, they are adsorbed by specific adsorption sites. Due to the high concentration of heavy metal ions occupying the adsorbent surface, the adsorption process slows down due to surface saturation, eventually reaching an equilibrium state. When the initial concentration of Cr(VI) increased to 1000 mg / L, the affinity of Cr(VI) was as follows: defatted rapeseed meal residue (34.03%) > rapeseed meal residue (33.71%) > rapeseed meal (27.35%) > defatted rapeseed meal (24.99%); defatted rapeseed hull residue (27.43%) > rapeseed hull residue (23.63%) > rapeseed hull (22.52%) > defatted rapeseed hull (20.93%).

[0052] Application Example 3

[0053] This application example investigates the reusability and adsorption performance of four adsorbents: modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue. Rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull were used as control adsorbents. The specific process is as follows:

[0054] 1. Reusability Experiment. The adsorbent residue after Cr(VI) adsorption was desorbed using 0.1M NaOH solution. The specific procedure was as follows: 0.15g of the adsorbent after Cr(VI) adsorption was placed in 30mL of 0.1M NaOH solution and desorbed by shaking at 150 rpm for 3 hours at room temperature. The desorbed adsorbent was rinsed with deionized water until neutral and then dried. The adsorbent was reused to test a 100mg / L Cr(VI) solution, with the remaining reaction conditions as before. The above steps were repeated until four adsorption-desorption cycles were completed.

[0055] Figure 9 shows the Cr(VI) removal rates of the eight adsorbents at equilibrium after each regeneration cycle. Except for rapeseed meal and defatted rapeseed meal, the other six adsorbents had negligible effects on adsorption capacity at the end of the first, second, and third adsorption cycles. Due to the large number of reversible sites on the surface of rapeseed byproducts, all these adsorbents exhibited satisfactory regeneration capacity and high reusability, which may be effective in purifying polluted water and recovering heavy metal Cr(VI) through desorption. For rapeseed meal and defatted rapeseed meal with relatively high protein content, their Cr(VI) adsorption capacity gradually decreased with increasing cycle number, possibly due to the reduced number of amine groups acting as electron donors for Cr(VI) reduction after alkaline desorption. However, regardless of the cycle, modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue all showed stronger adsorption capacity than the original materials (rapeseed meal, defatted rapeseed meal, rapeseed hull, and defatted rapeseed hull) that had not undergone polyphenol extraction. In the fourth regeneration cycle, the adsorption capacities of rapeseed meal, defatted rapeseed meal, modified rapeseed meal residue, and modified defatted rapeseed meal residue decreased from 95.06%, 94.75%, 98.66%, and 98.91% to 61.92%, 64.52%, 75.60%, and 70.22%, respectively. Similarly, the adsorption capacities of rapeseed hull, defatted rapeseed hull, modified rapeseed hull residue, and modified defatted rapeseed hull residue decreased from 78.39%, 78.03%, 90.11%, and 96.79% to 62.02%, 61.97%, 67.41%, and 69.49%, respectively.

[0056] 2. Effect of coexisting ions on adsorption. A cationic pollution system was prepared using K₂Cr₂O₇, NiCl₂, CuCl₂, ZnCl₂, CdCl₂, and PbCl₂ as raw materials, with initial concentrations of Cr(VI), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) at 100 mg / L. Other adsorption conditions were: pH 2.0, adsorbent dosage 0.15 g / 30 mL, and contact time 300 min. The contents of Cr(VI), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) ions in the solution after the adsorption reaction were measured using ICP-OES (ICAPPRO, Thermo Fisher, USA).

[0057] Compared with other adsorbents, modified defatted rapeseed meal residue and modified defatted rapeseed hull residue exhibit the best adsorption capacity and reusability. Therefore, further in-depth research on their adsorption characteristics is needed. Since Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) are the most common coexisting ions in heavy metal wastewater, their effects on the adsorption of Cr(VI) by modified defatted rapeseed meal residue and modified defatted rapeseed hull residue were investigated in a multi-component system. Figure 10 As shown, under the same concentration of all metal ions, modified defatted rapeseed meal residue and modified defatted rapeseed hull residue exhibit a significant adsorption preference for Cr(VI). The adsorption efficiencies of the single-system modified defatted rapeseed meal residue and modified defatted rapeseed hull residue for Cr(VI) are 98.91% and 96.79%, respectively, while the adsorption efficiencies of the multi-component system are 76.92% and 71.31%, respectively. This result may be related to competition for limited functional sites. Furthermore, in terms of adsorption efficiency for other metal ions, Cd(II) (46.15%) showed the highest affinity for modified defatted rapeseed meal residue, followed by Cu(II) (43.00%), Pb(II) (37.63%), Ni(II) (30.60%), and Zn(II) (28.50%). The adsorption affinity of modified defatted rapeseed hull residue for metal ions was, in descending order: Cd(II) (47.35%) > Ni(II) (39.43%) > Pb(II) (38.31%) > Zn(II) (34.98%) > Cu(II) (23.63%). These differences further illustrate the different adsorption properties of modified defatted rapeseed meal residue and modified defatted rapeseed hull residue. Most importantly, both adsorbents can simultaneously adsorb multiple metal ions, demonstrating broader application and practical value in wastewater treatment.

[0058] Comparative Example 1

[0059] This comparative example investigates the effect of different proportions of four rapeseed by-product polyphenols and their corresponding modified residues on the adsorption rate of chromium ions. The specific steps are as follows:

[0060] 1. Four different polyphenols derived from rapeseed byproducts (0.5, 1.5, 2.5, and 5.0 mg) were weighed and added to a 30 mL reaction system, respectively. The effect of the polyphenols on the adsorption rate of chromium ions was then investigated. Experimental parameters: pH 2.0, initial Cr(VI) concentration 100 mg / L, shaker set to 150 rpm at room temperature for 300 minutes. Finally, the residual amount of Cr(VI) in the reaction system was measured, and the adsorption rate of the polyphenols was calculated. Figure 11 As shown.

[0061] 2. Four groups of rapeseed meal polyphenols (0.5, 1.5, 2.5, and 5.0 mg) were weighed out, and 0.05 g of the corresponding modified rapeseed meal residue was added to a 30 mL reaction system. Experimental parameters: pH 2.0, initial chromium ion concentration 100 mg / L, shaker set to 150 rpm at room temperature for 300 minutes. The residual amount of hexavalent chromium in the reaction system was measured, and the adsorption rate of Cr(VI) by the polyphenols was calculated. Rapeseed hull polyphenols, modified rapeseed meal polyphenols, and modified rapeseed hull polyphenols were tested under the same conditions as rapeseed meal polyphenols, for a total of 16 experiments. These experiments investigated the effect of remixing polyphenols and their corresponding modified residues on the chromium ion adsorption rate.

[0062] Figure 11 The adsorption rates of different concentrations of rapeseed meal polyphenols, defatted rapeseed meal polyphenols, rapeseed hull polyphenols, and defatted rapeseed hull polyphenols on Cr(VI) were calculated. It can be seen that rapeseed meal polyphenols, defatted rapeseed meal polyphenols, rapeseed hull polyphenols, and defatted rapeseed hull polyphenols all have the ability to adsorb Cr(VI), and the concentrations are positively correlated.

[0063] Figure 12 To investigate the effect of different concentrations of rapeseed by-product polyphenols and corresponding modified residues on the adsorption rate of chromium ions, this study aimed to study... Figure 11-12 Combination Figure 1 The results showed that when modified rapeseed meal residue, modified defatted rapeseed meal residue, modified rapeseed hull residue, and modified defatted rapeseed hull residue were remixed with the corresponding polyphenols, the adsorption rate of the mixture for Cr(VI) was lower than the theoretical value of the sum of the two. This indicates that separating polyphenols from rapeseed by-products can effectively improve the adsorption rate of rapeseed by-products for Cr(VI).

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for the comprehensive utilization of rapeseed by-products, characterized in that... It includes the following steps: (1) Pretreatment: The rapeseed meal and rapeseed hull were dried to constant weight, ground and sieved to obtain sieved rapeseed meal and sieved rapeseed hull; (2) Extraction: The sieved rapeseed meal and the sieved rapeseed hull were respectively mixed with hydrochloric acid ethanol solution for polyphenol extraction, and then centrifuged to obtain rapeseed meal polyphenol supernatant and corresponding bottom solids I, and rapeseed hull polyphenol supernatant and corresponding bottom solids II. (3) Purification: The two supernatants obtained in step (2) were removed by vacuum rotary evaporation to remove hydrochloric acid and ethanol, respectively. The polyphenols were then purified by AB-8 resin, eluted with ethanol, and then dried by vacuum rotary evaporation to obtain rapeseed meal polyphenols and rapeseed hull polyphenols, respectively. (4) Post-processing: The two bottom solids I and II obtained in step (2) are dried to obtain modified rapeseed meal residue and modified rapeseed hull residue, respectively; (5) Apply the modified rapeseed meal residue and modified rapeseed hull residue obtained in step (4) to the heavy metal ion adsorbent; In the extraction step, the solid-liquid ratio by weight is 1:4 to 1:10, the mixing temperature is 40 to 55°C, the mixing speed is 100 to 200 rpm, and the mixing time is 1 to 1.5 hours; the centrifugation speed is 3000 to 5000 rpm, and the centrifugation time is 10 to 20 minutes; the hydrochloric acid ethanol solution is an aqueous solution of ethanol containing hydrochloric acid, with a hydrochloric acid concentration of 0.8 to 1.2 M and an ethanol mass percentage of 50 to 60%; in the purification and post-treatment steps, the drying temperature is 50 to 60°C, and the drying time is 24 to 48 hours.

2. A method for the comprehensive utilization of rapeseed by-products, characterized in that... It includes the following steps: (1) Pretreatment: The rapeseed meal and rapeseed hull were dried to constant weight, ground and sieved to obtain sieved rapeseed meal and sieved rapeseed hull; (2) Degreasing: Take the sieved rapeseed meal and rapeseed hull and mix them with n-hexane at room temperature for degreasing treatment. After ultrasonic treatment, filter to obtain defatted rapeseed meal and defatted rapeseed hull, respectively, and air dry for later use. (3) Extraction: Defatted rapeseed meal and defatted rapeseed hull were respectively mixed with hydrochloric acid ethanol solution for polyphenol extraction, and then centrifuged to obtain defatted rapeseed meal polyphenol supernatant and corresponding bottom solids III, and defatted rapeseed hull polyphenol supernatant and corresponding bottom solids IV. (4) Purification: The two supernatants obtained in step (3) were removed by vacuum rotary evaporation to remove hydrochloric acid and ethanol, respectively. The polyphenols were then purified by AB-8 resin, eluted with ethanol, and then vacuum rotary evaporated and dried to obtain defatted rapeseed meal polyphenols and defatted rapeseed hull polyphenols, respectively. (5) Post-processing: The two bottom solids III and IV obtained in step (3) are dried to obtain modified defatted rapeseed meal residue and modified defatted rapeseed hull residue, respectively. (6) The modified defatted rapeseed meal residue and modified defatted rapeseed hull residue obtained in step (5) are applied to heavy metal ion adsorbents; In the extraction step, the solid-liquid ratio by weight is 1:4 to 1:10, the mixing temperature is 40 to 55°C, the mixing speed is 100 to 200 rpm, and the mixing time is 1 to 1.5 hours; the centrifugation speed is 3000 to 5000 rpm, and the centrifugation time is 10 to 20 minutes; the hydrochloric acid ethanol solution is an aqueous solution of ethanol containing hydrochloric acid, with a hydrochloric acid concentration of 0.8 to 1.2 M and an ethanol mass percentage of 50 to 60%; in the purification and post-treatment steps, the drying temperature is 50 to 60°C, and the drying time is 24 to 48 hours.

3. A method for comprehensive utilization of rapeseed by-products according to claim 1 or 2, characterized in that... In the pretreatment step, rapeseed meal and rapeseed hulls are ground and sieved using a 30-50 mesh sieve.

4. A method for comprehensive utilization of rapeseed by-products according to claim 2, characterized in that... During the degreasing step, the solid-liquid ratio by weight is 1:2 to 1:4, and the mixture is ultrasonically treated at room temperature for 20 to 60 minutes. The degreasing step is repeated multiple times.

5. A method for comprehensive utilization of rapeseed by-products according to claim 1 or 2, characterized in that... The specific application method is as follows: the modified residue is added to the polluted water body to be treated as an adsorbent, and the amount of adsorbent added ranges from 0.05g to 0.30g / 30mL. After adding the adsorbent, the pH of the polluted water body to be treated is adjusted to 2.0 to 7.0, the contact time ranges from 30 to 480 minutes, and the initial concentration of heavy metal ions in the polluted water body to be treated ranges from 100 to 1000 mg / L.

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