Amberlyst A26 Research Articles

Hybrid membrane distillation and ion exchange process for resources recovery from mining wastewater

This work aims to achieve a process intensification through the hybridization of direct contact membrane distillation (DCMD) and ion exchange (IX) to increase resource recovery (water, H2SO4, Copper (Cu), Nickel (Ni), and Cobalt (Co)) from a gold mining wastewater. An increase in maximum recovery rate was achieved by the DCMD in the hybrid configurations – from 34 to 52 %. Recovery of Cu, Ni and Co is best achieved by NH4OH (4 mol/L), however with considerable carryover. Conversely, selective recovery can be achieved by different eluting agents H2SO4 0.1 mol/L to recover Co (~80 %), H2SO4 1 mol/L to recover Ni (~47 %), and NH4OH 4 mol/L to recover Cu (~26 %), with a lower carryover of other ions (<14 %). Scale-up calculations showed that the Amberlyst A26 mass required for the hybrid IX (batch) is 2.4× lower than the Dowex M4195, which resulted from the exchange capacity and selectivity. Conversely, the estimated Amberlyst A26 mass required for the hybrid IX (fixed-bed) was higher due to the higher initial concentration of H₂SO₄. Lastly, CapEX ranged from 0.2 to 5.6 M US$, and OpEX from 2.61 to 11.42 US$/m3. Considering earnings with the recovered resources the hybrid fixed-bed configurations are a clear choice due to the lowest payback times (<4 years).

Kinetics, Equilibrium and Thermodynamic Studies on Removal of Oleic Acid from Sunflower Oil onto Amberlyst A21

Amberlyst A21 was used for the oleic acid adsorption from sunflower oil (SFO). The impacts of parameters such as contact time, temperature, and mass ratio of adsorbent on oleic acid adsorption were studied. The characterization of Amberlyst A21 before and after adsorption was performed by using Fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). The adsorption reached equilibrium 480 minutes later. The increase in temperature and the amount of adsorbent caused an increase in the amount of adsorbed oleic acid. The adsorption kinetics, isotherms, and thermodynamics were studied. The pseudo-first order kinetics well described the adsorption for all studied temperatures. The Langmuir, Freundlich, and Dubinin−Radushkevich isotherms and thermodynamic analysis were investigated at equilibrium. The suitability of the Langmuir and Freundlich isotherms indicated that the adsorption takes place under monolayer and heterogeneous surfaces. Thermodynamical results showed that adsorption occurs spontaneously and endothermic.

Membrane distillation and ion exchange combined process for mining wastewater treatment, water reuse, and byproducts recovery

In this paper, we propose the combination of direct contact membrane distillation (DCMD) and ion exchange (IX) as an alternative for (i) generating reuse water and (ii) recovering byproducts from the DCMD concentrate by IX, from gold mining wastewater. The DCMD showed a steady flux (5.49 L/m2.h), ions rejection >99.7%, and a permeate recovery rate of 33.9%. The batch equilibrium results showed that the Amberlyst A26 had a strong affinity for H2SO4 (2897.9 mg/g). Conversely, Amberlite IRC747 and Dowex M4195 showed affinity towards Cu (83.4 and 103.1 mg/g), Ni (26.3 and 89.9 mg/g), and Co (6.5 and 24.4 mg/g). Batch kinetics showed that the rate-limiting step was intraparticle diffusion. Batch recovery of H2SO4 (1265 mg/L) from Amberlyst A26 could be achieved with H2O. Although the recovery of Cu (198.6 mg/L, 91.5%), Ni (62.4 mg/L, 30%), and Co (20.1 mg/L, 41.3%) from the Amberlite IRC747 could be achieved H2SO4 (1 mol/L), carryover of impurities was found. On the other hand, the recovery from the Dowex M4195 with NH4OH 4 mol/L was higher and carryover was lower. The fixed-bed tests showed that the ions breakthrough followed the same order as in the batch and they reached the breakpoint faster at higher feed velocity (8 BV/h compared to 4 BV/h). Elution from the Amberlyst A26 fixed bed achieved 7497.4 mg/L of H2SO4 with only 4.1% of carryover from other ions. The Dowex M4195 elution can achieve high selectivity when increasing the eluting agents' strength (H2SO4 0.1 and 1 mol/L, followed by NH4OH 4 mol/L) are used. By that, separated fractions of Cu, Ni, and Co could be recovered by each agent.

Adsorptive Removal of Direct Azo Dyes from Textile Wastewaters Using Weakly Basic Anion Exchange Resin

Direct dyes are still widely used for coloring a variety of materials due to their ease of use and the wide range of colors available at a moderate cost of production. In the aquatic environment, some direct dyes, especially the azo type and their biotransformation products, are toxic, carcinogenic and mutagenic. Hence the need for their careful removal from industrial effluents. It was proposed adsorptive retention of C.I. Direct Red 23 (DR23), C.I. Direct Orange 26 (DO26) and C.I. Direct Black 22 (DB22) from effluents using anion exchange resin of tertiary amine functionalities Amberlyst A21 (A21). Applying the Langmuir isotherm model, the monolayer capacities were calculated as 285.6 mg/g for DO26 and 271.1 mg/g for DO23. The Freundlich isotherm model seems to be the better one for the description of DB22 uptake by A21, and the isotherm constant was found to be 0.609 mg1-1/n L1/n/g. The kinetic parameters revealed that the pseudo-second-order model could be used for the description of experimental data rather than the pseudo-first-order model or intraparticle diffusion model. The dye adsorption decreased in the presence of anionic and non-ionic surfactants, while their uptake was enhanced in the presence of Na2SO4 and Na2CO3. Regeneration of the A21 resin was difficult; a slight increase in its efficiency was observed using 1M HCl, 1 M NaOH and 1 M NaCl solutions in 50% v/v methanol.

Novel chromatographic purification of succinic acid from whey fermentation broth by anionic exchange resins.

Replacement of the petroleum-based refineries with the biorefinery is regarded as an essential step towards a "zero" waste (circular) economy. Biobased succinic acid (SA) is listed by the United States Department of Energy among the top ten chemicals with the potential to replace chemicals from petroleum synthesis with renewable sources. Purification of bio-based succinic acid from fermentation by-products such as alcohols, formic acid, acetic acid and lactic is a major drawback of fermentative SA production. This study addresses this issue through a novel chromatographic separation using three distinct anionic resins: Amberlite IRA958 Cl (strong base anion exchange resin), Amberlite HPR 900 OH (strong base anion exchange resin) and Amberlyst A21 (week base anion exchange resin). The influence of process variables such as flow rate (0.18 BV/h, 0.42 BV/h and 0.84 BV/h), eluent concentration (1%, 5% and 10% HCl) and temperature (20, 30 and 40°C) were investigated. The results indicated SA separation efficiency of 76.1%, 69.3% and 81.2% for Amberlyst A21, Amberlite HPR 900 OH and Amberlite IRA958 Cl, respectively. As the regenerant HCl concentration increased from 1 to 10%, calculated succinic acid separation efficiencies decreased from 80.3 to 70.7%. Notably, as the regenerant strength increased from 1 to 10%, the total amount of organic acids desorbed from the resin sharply increased. At operation temperatures of 20, 30 and 40°C, SA separation efficacies were 81.2%, 73.9% and 76.4%, respectively. The insights from this study will be of great value in design of chromatographic separation systems for organic acids.

Production of biodiesel and water conservation through conversion of free fatty acids from a domestic wastewater drain

ABSTRACT Wastewater discharge from restaurants, hotels, household kitchens, confectionaries, meat, fruits, and vegetable processing units contain free fatty acids (FFAs) from fats, oils, and greases (FOG). These FFAs are one of the major causes of sewer overflows and blockages that cause health and environmental issues. This study has investigated the use of sewer wastewater as a source of lipids for the production of alkyl esters (Biodiesel) and provides a characterization of the resulting processed water. Amberlyst A21 basic resin in a column reactor was used to recover the FFAs by adsorption from an oily layer collected from the domestic wastewater drain (Chakri drain, Rawalpindi, Pakistan) having a 33.0 ± 2.08% oily fraction with 59.7 ± 1.1% FFAs. The recovered ethanol washed FFAs from the Amberlyst A21 surface were then turned into Fatty Acid Ethyl Esters (FAEEs) in the presence of an acidic resin catalyst Amberlyst 15. The esterification reaction was studied at temperatures 50, 60, and 70°C, molar ratios of 1:2 to 1:3, acidic resin weight % of 2 to 6, and reaction time of 2 to 8 hr, respectively. A maximum FFAs conversion into esters of 91.38 ± 1.13% was noted at an esterification temperature of 70°C, molar ratio of 1:3, acidic resin weight of 6%, and a reaction time of 8 h. The fractional distillation of the esterified reaction product at 100°C improved the ester content in the reaction mixture up to 96.6 ± 0.18%, with a distilled biodiesel yield of 95.52 ± 0.21%. The collected top oily layer from sewer drain wastewater was found to have a density 947.31 kg/m3, kinematic viscosity 32.69 mm2/sec, flash point 283°C, and LHV and HHV of 26 and 28 MJ/kg, respectively, while for the produced biodiesel the density was 886 kg/m3, kinematic viscosity 4.3 mm2/sec, flash point 137°C, and LHV and HHV of 39 and 41 MJ/kg was noted, respectively. Only oily layer free wastewater after passing through PAC was found to meet Pakistan NEQS, with COD <150 mg/L, pH 6–8, Alkalinity <1000 mg/L, and Ammonia-nitrogen <40 mg/L. For every 1000 gallons of domestic sewer drain wastewater treated per 8 h work shift or 3 work shifts in a day with FFAs recovered and their conversion into biodiesel, a net profit of 54.89 and 93.32 million Pakistani rupees can be gained in the first year and then in successive years, respectively. Thus, this research provides a way to produce renewable energy fuel, biodiesel from the waste lipids (FFAs) of wastewater drains to meet the energy requirements and a solution for the conservation of water bodies.

Effect of cetrimonium bromide (CTAB) surfactant on Pd(II) removal efficiency from electroless plating solutions

The impact of cetrimonium bromide (CTAB) surfactant on the Pd sorption characteristics of Amberlyst A21 resin in the presence of cetrimonium bromide (CTAB) surfactant was evaluated for solution chemical complexity in this study. With ethylenediaminetetraacetic acid (EDTA) and ammonium hydroxide (NH4OH), the chemical complexity is brought forward. At an ideal parametric range of 2 pH, 1.6 g L−1 adsorbent dosage, 780 min contact time, 50–300 mg L−1 Pd concentration, and 25 °C working temperature, batch adsorptive characteristics were investigated. In the addition of CTAB surfactant, the resin moderately improved the removal efficiency of Pd from synthetic ELP solutions, with maximal absorption (104.17 mg g−1) observed at 2 CMC (critical micelle concentration) CTAB concentration.

Volatile Fatty Acid Recovery from Anaerobic Fermentate: Focusing on Adsorption and Desorption Performances

The purification and concentration of volatile fatty acids (VFAs) after acidogenic fermentation represent the key steps for their industrial use. In this study, different batch adsorption tests were performed on single VFAs using powdered activated carbon (PAC), Lewatit VP OC 1065, Amberlyst A21, and VFA mixtures using Lewatit and Amberlyst. Adsorption yields of approximately 70% for PAC and 86–96% for Lewatit and Amberlyst were achieved on the single VFA tests at an initial concentration of 5 g/L. The VFA mixture tests at 25 g/L showed lower yields: 40 and 27% for Lewatit and Amberlyst, respectively. Batch desorption tests were performed adopting two desorbents, ethanol, and water at various NaOH concentrations (1, 0.1, and 0.01 M) and at decreasing volumes (5, 3, and 2 mL). The optimization of the adsorption and desorption operations allowed the final VFA concentrations of 85–90 g/L to be reached. The best adsorbent, Lewatit, and the best desorption conditions were applied on a real fermentate with an initial VFA concentration of approximately 18 g/L, obtaining a final VFA content three times higher than in the original solution.

Physicochemical Interactions in Systems C.I. Direct Yellow 50—Weakly Basic Resins: Kinetic, Equilibrium, and Auxiliaries Addition Aspects

Intensive development of many industries, including textile, paper or plastic, which consume large amounts of water and generate huge amounts of wastewater-containing toxic dyes, contribute to pollution of the aquatic environment. Among many known methods of wastewater treatment, adsorption techniques are considered the most effective. In the present study, the weakly basic anion exchangers such as Amberlyst A21, Amberlyst A23 and Amberlyst A24 of the polystyrene, phenol-formaldehyde and polyacrylic matrices were used for C.I. Direct Yellow 50 removal from aqueous solutions. The equilibrium adsorption data were well fitted to the Langmuir adsorption isotherm. Kinetic studies were described by the pseudo-second order model. The pseudo-second order rate constants were in the range of 0.0609–0.0128 g/mg·min for Amberlyst A24, 0.0038–0.0015 g/mg·min for Amberlyst A21 and 1.1945–0.0032 g/mg·min for Amberlyst A23, and decreased with the increasing initial concentration of dye from 100–500 mg/L, respectively. There were observed auxiliaries (Na2CO3, Na2SO4, anionic and non-ionic surfactants) impact on the dye uptake. The polyacrylic resin Amberlyst A24 can be promising sorbent for C.I. Direct Yellow 50 removal as it is able to uptake 666.5 mg/g of the dye compared to the phenol-formaldehyde Amberlyst A23 which has a 284.3 mg/g capacity.

Amberlyst A21 catalyzed Morita-Baylis-Hillman reaction

Amberlyst A21 ion exchange resin was used as a recyclable catalyst for the Morita-Baylis-Hillman reaction. The use of Amberlyst A21 as heterogeneous catalyst provided Morita-Baylis-Hillman adducts in excellent yields (up to 98%) in propanol with relatively shorter reaction times at room temperature. Besides, Amberlyst A21 can be readily recovered and reused eight times without significant loss of catalytic activity.

Preservation of minor components and deacidification of rice bran oil using strong anionic resin

Rice bran oil presents high levels of tocopherols/tocotrienols and gamma-oryzanol, which are recognized for their nutraceutical effects. However, these minor compounds can be sensitive to the traditional refining processes, which necessarily include a deacidification step. Therefore, alternative processes are required to preserve these nutraceuticals in the deacidified oil. This study aimed to investigate an alternative deacidification process based on strongly basic anion exchange resin. Aiming to evaluate the adsorption process efficiencies, breakthrough curves were obtained for systems containing Amberlyst A26 OH and a miscella composed of 50% by mass of degummed rice bran oil, with natural acidity (9.74% by mass), and n-propanol. The resin showed a high capacity for removing free fatty acids (90%–99% removal efficiency), and the adsorption process yielded deacidified rice bran oil with a reduced phosphorus content (2.2 mg/kg), preserving 83% of the gamma-oryzanol and 100% of the tocopherols/tocotrienols. Practical applications A softer deacidification process than traditional methods is proposed in this study. It permits to remove free fatty acids, preserving minor compounds of interest, notably nutraceutical compounds in the deacidified oil. The use of anion exchange resins in this step of refining process minimizes the effluent generation when compared to chemical refining, besides could be accomplished under milder conditions of pressure and temperature than physical refining.

Quaternary ammonium hydroxide‐functionalized g‐C3N4 catalyst for aerobic hydroxylation of arylboronic acids to phenols

AbstractA new and efficient metal‐free approach toward the synthesis of phenols via an aerobic hydroxylation of arylboronic acids by using a novel quaternary ammonium hydroxide g‐C3N4 catalyst has been described. The functionalized quaternary ammonium hydroxide (g‐C3N4‐OH) has been prepared from graphitic carbon nitride (g‐C3N4) scaffold by converting the residual –NH2 and –NH groups to quaternary methyl ammonium iodide by performing a methylation reaction with methyl iodide followed by ion‐exchange with 0.1 N KOH or anion exchange resin Amberlyst A26 (OH‐ form) by post‐synthetic modification. The resultant g‐C3N4‐OH was characterized by XRD, FTIR, field‐emission scanning electron microscope (FESEM), high‐resolution transmission electron microscope (HRTEM), N2 adsorption/desorption isotherms, and acid–base titration. Tested as solid‐base catalysts, the g‐C3N4‐OH showed excellent catalytic activity in the aerobic hydroxylation reaction by converting a variety of arylboronic acids to the corresponding phenols in high yields. More importantly, the g‐C3N4‐OH solid‐base has been successfully reused four times with the minor loss of initial catalytic activity (10.5%).

Optimization of the production of biofuel form Jatropha oil using a recyclable anion-exchange resin

The study of an anion-exchange resin (Amberlyst A26 (OH)) catalyzed transesterification of Jatropha (Jatropha curcas L.) oil was conducted to determine the effects of three variables: reaction temperature, ethanol: oil molar ratio and catalyst amount, on Jatropha oil conversion (XJO) and fatty acid ethyl esters yield’s (YFAEEs). The modified central composite design that involved three independent factors (temperature, ethanol: oil molar ratio and the catalyst present) with two levels, but not included the non-linear stage, was employed to optimize the process. From the main factors and their interactions, the ethanol: oil molar ratio was found to highly affect the XJO and YFAEEs. In this study, the statistical analysis showed that curvature is not significant (p ≤ 0.05), and thus, from the model regression equations, linear model was found to be more suitable to optimize the responses. By using the regression analysis and the response surface plots, the optimum XJO and YFAEEs of 37.63% and 36.31%, respectively were predicted to be obtained at the optimum temperature of 55 °C, ethanol: oil molar ratio of 35:1 and catalyst amount of 15%. Employing higher amount of catalyst reduced the XJO and YFAEEs, particularly, when the variable interacted with the reaction temperature.

Adsorptive Removal of Remazol Brilliant Blue R from Water by Using a Macroporous Polystyrene Resin: Isotherm and Kinetic Studies

The pollution of surface and drinking water with dyes is one growing problem. The present manuscript explains the application of a macroporous polystyrene resin called Amberlyst A21, as a new effective adsorbent in the removal of Remazol Brilliant Blue R dye from aqueous solutions. The Remazol Brilliant Blue R adsorption on the Amberlyst A21 was characterized based on various parameters such as solution pH, initial dye concentration, contact time and adsorbent dosage. The best adsorption conditions were: solution pH 2, contact time 150 min, Amberlyst A21 dosage of 1.0 g/L at 25 °C. The morphology of Amberlyst A21 was analyzed by FTIR and SEM techniques. Amberlyst A21 exhibited enhanced Remazol Brilliant Blue R removal behavior with maximum adsorption capacity of 208.33 mg/g based on the Langmuir isotherm model, which was higher than those of other previously reported adsorbents. Kinetic investigations showed that a pseudo-first order model was more suitable than the pseudo-second order model. The results indicate that Amberlyst A21, as an adsorbent, has great potential especially in the area of dye removal.

Combinatorial optimality of functional groups, process parameters, and Pd(II) adsorption-desorption characteristics for commercial anion exchange resins-synthetic electroless plating systems.

Considering combinatorial optimality of functional group analysis, speciation, solution chemistry complexity, Pd(II) adsorption-desorption characteristics, this article addresses the competence and efficacy of anion exchange resins namely Amberlite IRA958, Dowex Marathon MSA, Lewatit TP214, and Amberlyst A21 commercial resins. Based on preliminary batch adsorption experiments conducted in the range of 2-10 pH, 0.2-2 g L-1 adsorbent dosage, and 5-1080-min contact time, the optimal adsorption process parameters refer to 4 pH, 1.6, and 1.4 g L-1 adsorbent dosage, and 840- and 720-min contact time for Amberlite IRA958 and Dowex Marathon MSA resins, respectively. Among alternate models, the best-fit models refer to the Freundlich isotherm and pseudo-second-order kinetic models to represent Pd(II) adsorption data obtained for both Dowex Marathon MSA and Amberlite IRA958 resins. Based on the Langmuir isotherm, the maximum monolayer adsorption capacity was evaluated to be 185.16 and 166.67 mg g-1 for Dowex Marathon MSA and Amberlite IRA958 resins, respectively. For model electroless plating solutions as adsorbate system possessing desired solution chemistry complexity and resin cost, nitrogen- and oxygen-containing Amberlyst A21 resin is concluded to be optimal resin. This is not in agreement with the generalized rule of thumb that considers sulfur-nitrogen functional group containing commercial resins to be effective than resins with nitrogen-oxygen functional groups. Due to functional group interactions with the noble metal, no other by-products or exchanged chemicals have been produced in due course of Pd(II) adsorption process, which can be also regarded as an added advantage of the process. Graphical abstract.

Amberlyst A21 İle Everzol Black Boyasının Adsorpsiyonu: İzoterm ve Kinetik Çalışmalar

Bu çalışmada Everzol Black boyasının sulu çözelti ortamından giderimi Amberlyst A21 ile incelenmiştir. pH, temas süresi ve başlangıç boya derişimi gibi değişik parametrelerin boya adsorpsiyonu üzerine etkileri çalışılmıştır. Langmuir, Freundlich ve Temkin izoterm modelleri denge adsorpsiyon verilerinin analizi için kullanılmıştır. Ayrıca adsorpsiyon kinetik verileri yalancı birinci ve ikinci dereceden kinetik modeller kullanılarak incelenmiştir. Çalışma sonuçlarına göre Amberlyst A21 ile Everzol Black giderimi Langmuir izoterm modeli ve yalancı birinci dereceden adsorpsiyon kinetiği ile tanımlanabilir.

Utilization of Anion Exchange Resins: Amberlyst A21 for Sulfate Reduction in Drinking Ground Water and its Characterization

AbstractSulfate (SO4)-2 is ubiquitous in groundwater, with both natural and anthropogenic sources. At high levels, sulfate can give water a bitter or astringent taste and can have mild laxative effectsThe aim of this work is to present experimental results on the evaluation and removal of Sulfate ions from drinking ground water in Wadi El-Assiuti – Egypt using anion exchange resin: Amberlyst A21. The drinking groundwater samples were collected from different places of El-Fath region (Assiut Government) Egypt Amberlyst A21 was characterized by swelling, solubility, thermal properties like: thermal gravimetric analysis (TGA) and differential thermal gravimetric (DTG), X-ray diffraction analysis, and scanning electron microscopy (SEM) were also determined and the data were discussed. Moreover, the present study, anion exchange resins was used to the removal of sulphate (SO4)-2 from ground water used as a drinking water. The effects of different parameters such as different resin dose, pH and contact time were examined. The results show that anion exchange resin (Amberlyst A21) has good affinity towards sulfate (SO4)-2 ion removal that uses especial conditions such as large weight of resin or long time for treatment. And the loading increases with acidity. The Langmuir constants model for (SO4)-2 ions are fitted well on the adsorption isotherms. The RL value in the present investigation was equal or less than one, indicating that the adsorption of (SO4)-2 ion by Amberlyst A21 is favorable.

Catalytic isomerization of glucose to fructose using heterogeneous solid Base catalysts in a continuous-flow tubular reactor: Catalyst screening study

Isomerization reactions of glucose into fructose in aqueous media were studied in a continuous-flow tubular reactor using different heterogeneous solid base catalysts, including calcined-rehydrated hydrotalcite, magnesium oxide, Amberlyst A21 ion exchange resin and two commercial hydrotalcite catalysts. The catalysts were characterized and their activities for glucose isomerization were compared. The most active catalyst was found to be magnesium oxide, which showed the highest glucose conversion (36.3%) and highest fructose yield (22.8%) at 100 °C. Among all catalysts, the calcined-rehydrated hydrotalcite showed the highest selectivity towards fructose, reaching 78% at 100 °C. It was also found that increasing the reaction temperature had positive effects on glucose conversion and fructose yield for both activated hydrotalcite and MgO catalysts. The fructose yield at 120 °C attained 19.5% and 25.1% with the activated hydrotalcite and MgO catalysts, respectively. The catalytic activity of hydrotalcite calcined at 450 °C for glucose isomerization reaction was found to be greater that calcined at 350 °C. The hyrdotalcite and magnesium oxide catalysts were observed to be stable in the four hours of continuous tests on stream. TGA analyses of the used catalysts proved the formation of undesired insoluble by-products, mainly humins, on the surface of the used catalysts.

Role of protonation and functional groups in Pd(II) recovery and reuse characteristics of commercial anion exchange resin-synthetic electroless plating solution systems

Deliberating upon the role of solution chemistry complexity, protonation, speciation and pertinent functional groups on the adsorption-desorption characteristics, this work targets the efficacy of Lewatit TP-214 and Amberlyst A21 commercial anion exchange resins for Pd(II) recovery and reuse from synthetic electroless plating (ELP) solutions. For both resins, batch adsorption experiments involved optimality of pH, contact time, adsorbent dosage followed with concentration effect and kinetic studies. Equilibrium, kinetic, and thermodynamic models were considered for their fitness with the obtained Pd(II) batch adsorption characteristics. Among both resins, Lewatit TP-214 resin provided better performance in terms of adsorption and desorption characteristics along with optimal combinations of pH (8), equilibrium time (300 min), and adsorbent dosage (2 g L−1). Overall, both resins provided significantly lower Pd(II) absorption capacity and removal% for ELP systems in comparison with aqueous solutions. This is due to the inhibitory role of Ethylenediaminetetraacetic acid (EDTA) and ammonia during Pd(II) binding with active sites on the resins. The obtained desorption characteristics and associated Pd (II) adsorption and desorption mechanisms are promising to further commercial application of the said resins.

Recovering ferulic acid from wheat bran enzymatic hydrolysate by a novel and non-thermal process associating weak anion-exchange and electrodialysis

Abstract Agricultural by-products such as wheat bran and straw are rich in arabinoxylans. Composed of a main chain of β-(1,4) linked xylose ramified by arabinose and ferulic acid, these polymers are sources of valuable molecules, in particular ferulic acid and monomeric (xylose, arabinose and glucose) and oligomeric carbohydrates. Enzymatic hydrolysis using hemicellulasic cocktails obtained from Thermobacillus xylanilyticus provide an eco-friendly alternative to acid or alkaline deconstruction. In this article, downstream purification of the enzymatic hydrolysate of wheat bran with a weak anion-exchange resin (Amberlyst A21- Dow) in free-base form was studied and optimized to reach concentrated ferulate fractions in environment-friendly conditions. A demineralization step by homopolar electrodialysis prior to anion-exchange allowed most of the competing inorganic anions to be removed from the hydrolysate. The capacity of fixation of ferulic acid on the active sites of the resin was increased, as well as purity and concentration of the basic eluate, consequently. Ferulic acid could therefore be crystallized by adjusting the pH of the eluate. 83% was crystallized and purity (NMR) reached 90–95%. At last, 52% of ferulic acid released from wheat bran by the hemicellulasic cocktail was purified and recovered as a solid. Moreover, more than 50 BV (Bed Volume) of the hydrolysate could be recovered during the resin saturation step as rather pure carbohydrates under monomeric (xylose, arabinose and glucose) and oligomeric (xylobiose, xylotriose and xylotetraose) form.