Gel-type Resin Research Articles

Gel-type resin loaded with nano-hydrated ferric oxide for the removal of anions from papermaking wastewater

The main anions in papermaking wastewater are sulfate and chloride. In this paper, a strongly basic gel-type anion exchange resin (201×7) loaded with 20 ~ 200nm hydrated ferric oxide was prepared by dispersion impregnation with ethanol. The modified resin enhances the ability to remove sulfate by complexation of ligands to cause sulfate to form outer and inner sphere complexes on hydrated ferric oxide. The modified resin was dependent on acidic conditions, and the maximum exchange capacity for sulfate was enhanced by 14.2% under the optimal pH, exchange time, and ion concentration conditions. Competitive exchange experiments showed that the removal effect of the modified resin on chloride was almost unchanged under different chloride, sulfate ratios, and the degree of improvement of the removal effect on sulfate decreased from 9.5 ~ 5.5% with the increase of chloride ratio. The removal of sulfate by the modified resin was consistent with the proposed secondary kinetics and Langmuir adsorption model. In addition, the modified resin maintained 88% reuse after four desorption-adsorption cycles and achieved a regeneration rate of 93.1% after was eluted with HCl and reloaded with hydrated ferric oxide. The expected removal effect was well achieved when the resin was applied to the actual wastewater treatment. The above results indicate that the hydrated ferric oxide modification can improve the ability of the 201×7 resin to remove sulfate from water, and is a promising method for removing anions from papermaking wastewater.

Sorption/desorption and degradation of long- and short-chain PFAS by anion exchange resin and UV/sulfite system

A combined sorption/desorption and UV/sulfite degradation process was investigated for achieving efficient elimination of PFAS from water. Two gel-type resins, Purolite A532E and A600, and one macroporous resin, Purolite A860, were firstly tested for the sorption of individual PFPrA, PFHxA, PFOA, PFOS, and GenX at different concentrations. Sorption data and density functional theory (DFT) calculations revealed that electrostatic interactions predominated for short-chain PFAS sorption and hydrophobic interactions played a more significant role for long-chain PFAS than for short-chain PFAS. A600 and A860 were selected for desorption tests with 0.025% NaOH, 5% NaCl, and 5% NH4Cl solution with or without 20% ethanol (EtOH) due to their high sorption capacity for all target PFAS. The mixture of 5% NH4Cl and 20% EtOH as the desorption solution typically showed the highest desorption efficiency. PFOS was the most resistant for desorption but its desorption could be enhanced by stronger mixing conditions (in 5% NaCl + 20% EtOH). Direct degradation of studied PFAS in the desorption solution (0.025% NaOH, 5% NaCl, and 5% NH4Cl) by UV/sulfite achieved 97.6–100% degradation and 46.6–86.1% defluorination. EtOH hindered degradation and thus should be separated from the water before UV/sulfite degradation.

Effective oxidation and adsorption of As(III) in water by nanoconfined Ce-Mn binary oxides with excellent reusability

Herein, a highly efficient As(III) purifier Ce-Mn@N201 with excellent reusability was developed by stepwise precipitating hydrated cerium(IV) oxides (HCO) and hydrated manganese(IV) oxides (HMO) inside N201, a widely-used gel-type anion exchange resin. Owing to confinement of unique nanopores in N201, the in-situ generated nanoparticles (NPs) inside Ce-Mn@N201 were highly dispersed with ultra-small sizes of around 2.6 nm. Results demonstrated that HMO NPs effectively oxidized As(III) to As(V) with the conversion of Mn(IV) to Mn(II), while the generated Mn2+ was mostly re-adsorbed onto the negatively-charged surface of HMO NPs. During the regeneration process by simple alkaline treatment, the re-adsorbed Mn2+ was firstly precipitated as (hydr)oxides of Mn(II) and then oxidized to HMO NPs by dissolved oxygen to fully refresh its oxidation capacity. Though HCO NPs mainly served as adsorbent for arsenic, they could partially oxidize As(III) to As(V) at the beginning, while the oxidation capacities continuously diminished with the irreversible conversion of Ce(IV) to Ce(III). In 10 consecutive adsorption-regeneration cycle, Ce-Mn@N201 efficiently decontaminated As(III) from 500 μg/L to below 5 μg/L with Mn2+ leaching less than 0.3% per batch. During 3 cyclic fixed-bed adsorptions, Ce-Mn@N201 steadily produced 8500–9150 bed volume (BV) and 3150–3350 BV drinkable water from the synthesized and real groundwater, respectively, with Mn leaching in effluent constantly < 100 μg/L.

Estimation of specific reactivities of commercial gel-type resins through modeling the chain sequences distribution

This study evaluates the reactivity of acidic resins through mathematical modeling. To assess the reactivity of resins, a copolymerization model was used, making it possible to estimate chain sequences distribution along their polymeric matrices. A model for the reaction catalyzed by these resins, whose equations were based on power law and molar balances, was coupled to the copolymerization model to describe the whole process. Resin properties were collected from the literature and compared to data provided by the copolymerization model, resulting in a linear correlation between the weighted average chain densities measured by ISEC and the total concentration of sequences between cross-links (R 2 = 0.988). The prediction ability of the developed model was compared to a literature approach, which depends on an experimental characterization of the resins by Inverse Steric Exclusion Chromatography (ISEC). Akaike Information Criterion revealed that the models exhibit comparable predictive capabilities, demonstrating that the developed model is able to simulate reactions catalyzed by gel-type resins without requiring equipment for morphology characterization.

Dewatering Spent Ion-Exchange Resins with Supercritical CO2

ABSTRACT A process for dewatering spent ion exchange resins (gel and porous) used in nuclear power plants by supercritical CO2 (sCO2) is described. The amount of water removed by sCO2 is much higher than that expected from solubility considerations alone. Water from gel-type resins is both dissolved by and emulsified in sCO2. Emulsification also occurs in the absence of solids when water alone is contacted by sCO2. It is not a factor for microporous resins where an additional mechanism, viscous fingering, is involved. It appears that bulk water is emulsifiable but not if it is held in pores. Dewatering via viscous fingering has been previously invoked for matrices such as wood and sludge. The resins can be dewatered and dried with sequential batches of sCO2 at sub-boiling temperatures. The CO2 can then be potentially reused after expansion and separation from the entrained water. Partial decompression of the water-laden sCO2 would lead to cooling, which would drop the water solubility substantially. A reduction of temperature from 90 oC to 65oC reduces the solubility of water in sCO2 by a factor of five. The condensed water could then be separated with a hydrocyclone. The footprint of sCO2 is much smaller than the conventional drying process. The energy costs are also much lower because evaporation of water is avoided.

Separation of Boron and Arsenic from Geothermal Water with Novel Gel-Type Chelating Ion Exchange Resins: Batch and Column Sorption-Elution Studies

In this research, the removal of boron and arsenic from geothermal water was examined by using novel N-methyl-d-glucamine functionalized gel-like resins (abbreviated as 1JW and 2JW) synthesized by the membrane emulsification method. The outcomes were compared with those of commercially available boron selective chelating ion exchange resin (Diaion CRB 05). According to the results obtained with the novel resins, it was possible to reduce both boron and arsenic concentrations in geothermal water by using these novel gel-like chelating resins below their permissible levels for agricultural irrigation (&lt;1 mg B/L) and drinking water (&lt;0.01 mg As/L) by using the batch method. The optimum resin concentration required for almost complete boron removal (more than 95%) with the two chelating resins was determined to be 2 g/L. The novel gel-like chelating resins 1JW and 2JW achieved 94% of arsenic removal by using the resin concentration of 8 g/L, while the required resin concentration was 32 g/L for 94% of arsenic removal using commercially available Diaion CRB05 resin. In addition, the column performance characteristics of the novel chelating resins for the separation of boron were studied, and the results were compared to those obtained with Diaion CRB05. According to the column data obtained, the total resin capacities of the Diaion CRB05, 1JW, and 2JW resins were calculated as 6.29, 5.08, and 4.64 mg B/mL-resin, respectively.

Efficient adsorption of alginate oligosaccharides by ion exchange resin based on molecular simulation and experiments

Alginate oligosaccharides (AOS) with low polymerization have gained considerable attention due to their unique physiological activities. However, the lack of understanding regarding the mechanism of action for resin selection and optimization of separation processes has impeded their precise chromatographic separation and large-scale production. Here, the adsorption–desorption characteristics of AOS on the resins with varying solid phase composition, including backbones, functional groups, crosslinking degrees, and counterions resin structures, were analyzed using simulations and experiments. The simulation results revealed that the structural differences of AOS are characterized by their electrostatic potential and lowest unoccupied molecular orbital energy level. Based on molecular simulations, we predicted that the basic anion resin with a styrene backbone would be suitable for AOS separation. Subsequently, we constructed SM-7Cl resin based on the simulation results and performed static adsorption experiments to verify the prediction. SM-7Cl resin demonstrated noteworthy adsorption–desorption performance for AOS, with an adsorption capacity of 471.2 mg/g and a desorption rate of 89.45%. The fitting adsorption isotherm was consistent with the Freundlich model, indicating that the adsorption proceeded spontaneously. The equilibrium times for AOS adsorption on the gel-type resin and the macroporous resin, which both followed a pseudo-second-order kinetic model, were 30 min and 60 min, respectively. This study provides optimized chromatographic media and separation processing that can be implemented for the amplification of chromatographic separation in AOS production.

Preparation of a new gel-type lignin-based cationic adsorption resin for efficient removal of Ca2+ from aqueous solutions

Presently, most studies on modified lignin focused on the adsorption to heavy metal cations, but rarely to Ca2+ in hard water. Therefore, this work prepared a new gel-type lignin-based cationic adsorption resin (E-LSAF) through the crosslinking and curing of alkali lignin grafted by sodium sulfite sulfonated acetone to remove Ca2+ in water. Under the determined optimum synthesis conditions, E-LSAF with a highest sulfonic group content of 1.99 mmol/g was obtained. Structural and physicochemical measuring results showed E-LSAF was a gel-type resin, owning strong hydrophilicity, high mechanical strength, excellent thermal stability and acid-alkaline resistance. Adsorption results indicated the adsorption of E-LSAF to Ca2+ was well-fitted by Langmuir model, and the maximum adsorption capacity reached 45.8 mg/g. Pseudo-second-order model can describe this adsorption process well, suggesting it a chemisorption process. Dynamic column adsorption results showed E-LSAF could transform hard water into soft or even very soft water. The regeneration efficiency still maintained 80 % after 5 cycles. The adsorption mechanism was attributed to electrostatic attraction, ion exchange and complexation. This work provided a high-performance lignin-based cationic adsorption material with high adsorption capacity to Ca2+ and excellent acid-alkaline resistance, which filled the research gap of using modified sulfonated lignin to remove Ca2+ from water.

Commercial Gel-Type Ion Exchange Resin Enables Large-Scale Production of Ultrasmall Nanoparticles for Highly Efficient Water Decontamination

• Gel-type anion exchange resin enables large-scale production of sub-5 nm particles. • The nanocomposites are millimetric beads applicable in flow-through systems. • Sub-5 nm HFO exhibit >3 times As(III/V) adsorption capacities than 17 nm HFO. • Adsorption capability is fully refreshed for cyclic use by using NaOH-NaCl solution. • The nanocomposite column produces 4800 BV clean water from simulated groundwater. Nanotechnology presents innovative solutions in advanced water treatment; however, its application is limited by the challenging large-scale production of ultrasmall (< 5 nm) nanoparticles (NPs) with extraordinary decontamination reactivity and the difficulty of handling such tiny NPs in engineering. To address these challenges, we propose a straightforward route for synthesizing ultrasmall NPs using the commercial gel-type anion exchange resin N201 as the host. N201 is a millimeter-scale poly(styrene- co -divinylbenzene) bead modified with quaternary ammonium groups. Nanoparticles of hydrated ferric oxide (HFO), hydrated manganese oxide (HMO), cadmium sulfide (CdS), and zero-valent iron (ZVI) were obtained through simple impregnation-precipitation in N201, and all of the NPs possessed an ultrasmall size of sub-5 nm. A pilot-scale production assay indicated that the synthetic system could be enlarged proportionally to prepare massive sub-5 nm HFO. Regarding the underlying mechanism, each N201 bead contained a continuous water phase, allowing the rapid diffusion of the reactants (7 s for diffusion from the bead surface to the center), resulting in burst nucleation to produce ultrasmall NPs with a narrow size distribution. Moreover, the crosslinked polymer chains provided a confined space (< 5 nm diameter) to prevent the excessive growth of the formed NPs. Owing to the millimetric N201 host, the resultant nanocomposite can be applied in flow-through systems. The batch and column adsorption assays demonstrate the dramatically enhanced adsorption performance of the ultrasmall HFO toward As(III/V) than the ∼17 nm analogs. This study can advance the widespread use of nanotechnology in practical water treatment.

Elimination of free fatty acid from palm oil by adsorption process using a strong base anion exchange resin

Deacidification is one of the important processes to obtain a suitable raw feedstock for the production of bio-transformer oil. This work proposed an alternative process for reducing the acidity of refined palm oil by adsorption of the free fatty acids (FFAs) using anion exchange resins (AER). The effect of the types of functional groups (tertiary amine and quaternary ammonium group) and the resin structure (gel and macroporous structure) of the commercially available resins were characterized and investigated for their adsorption ability. The adsorption kinetic and experimental conditions such as adsorption time, the moisture content in resin, and resin amount were studied. The gel-type strong-base anion exchange resins exhibited the best performance for the FFAs removal. This result suggests that the quaternary ammonium functional groups in the resin have a high dissociation capacity for anion exchange and the gel-type resins easily access by the FFAs molecules. The effect of types of functional groups is stronger than that of the resin structure. The adsorption mechanism mainly occurred via an ion exchange equilibrium rather than the hydrogen bond complex. The FFAs adsorption on the resins conformed to the pseudo-second-order kinetic model. Under optimum conditions (room temperature, atmospheric pressure, resin dosage of 0.4 wt%, and 8 h adsorption time), the Pall Tec PTA304 resin reduced the acidity in palm oil from 0.5 to 0.02 mg KOH/g with the adsorption capacity at the equilibrium of 589.5 mg/g, achieving approximately 95 % FFAs removal. The negative values of ΔGads0 and ΔHads0 demonstrated that the FFAs adsorption on the Pall Tec PTA304 resin was a spontaneous and exothermic process. This study provides an insight into the interactions between FFAs and anion exchange resins that is useful for further development of palm based bio-transformer oil.

Removal and destruction of perfluoroalkyl ether carboxylic acids (PFECAs) in an anion exchange resin and electrochemical oxidation treatment train

Perfluoroalkyl ether carboxylic acids (PFECAs) are a group of emerging recalcitrant contaminants that are being developed to replace legacy per- and polyfluoroalkyl substances (PFAS) in industrial applications and that are generated as by-products in fluoropolymer manufacturing. Here, we report on the removal and destruction of four structurally different PFECAs using an integrated anion exchange resin (AER) and electrochemical oxidation (ECO) treatment train. Results from this work illustrated that (1) flow-through columns packed with PFAS-selective AERs are highly effective for the removal of PFECAs and (2) PFECA affinity is strongly correlated with their hydrophobic features. Regeneration of the spent resin columns revealed that high percentage (e.g., 80%) of organic cosolvent is necessary for achieving 60-100% PFECA release, and regeneration efficiency was higher for a macroporous resin than a gel-type resin. Treatment of spent regenerants showed (1) >99.99% methanol removal was achieved by distillation, (2) >99.999% conversion of the four studied PFECAs was achieved during the ECO treatment of the still bottoms after 24 hours with an energy per order of magnitude of PFECA removal (EE/O) <1.03 kWh/m3 of total groundwater treated, and (3) >85% of the organic fluorine was recovered as inorganic fluoride. Trifluoroacetic acid (TFA), perfluoropropionic acid (PFPrA), and perfluoro-2-methoxyacetic acid (PFMOAA) were confirmed via high-resolution mass spectrometry as transformation products (TPs) in the treated still bottoms, and two distinctive degradation schemes and four reaction pathways are proposed for the four PFECAs. Lastly, dissolved organic matter (DOM) inhibited uptake, regeneration, and oxidation of PFECAs throughout the treatment train, suggesting pretreatment steps targeting DOM removal can enhance the system's treatment efficiency. Results from this work provide guidelines for developing effective separation-concentration-destruction treatment trains and meaningful insights for achieving PFECA destruction in impacted aquatic systems.

Batch screening of weak base ion exchange resins for optimized extraction of acetic acid under fermentation conditions

Acetic acid is a valuable chemical with high demand for applications in food, pharmaceutical, polymer and other industries. A total of 10% acetate in the world is produced through bio-based processes such as fermentation. Such processes require cost-effective separation technologies to make the bio-acetate product competitive on the markets. Ion exchange resins can efficiently extract acetate from the fermentation broths and due to their re-usability after regeneration, can be cost-effective with lower operation and maintenance costs. To facilitate better process design, kinetics of acetate adsorption by six different basic ion exchange resins: Amberlite FPA-53, Amberlite IRA-67, Dowex-66, Dowex Marathon WBA-2, Amberlite IRA-96 and Amberlite IRA-400; was studied using well-known linear and non-linear adsorption isotherm models. The study showed that Amberlite FPA-53 (213 mg/g wet resin) had the highest acetate adsorption capability followed by Amberlite IRA-67 (202 mg/g wet resin) and Dowex-66 (191 mg/g wet resin). Of the tested models, the acetate adsorption onto these resins was found to fit well with the Langmuir model. It was found that there was a significant effect of acetic acid concentration and pH on acetate adsorption using gel-type and macroporous resins, especially at high initial concentrations of acetate in the broth. The study further showed, that under fermentation conditions (pH of 5–7), the adsorption capacity of all the resins was lower than at the pKa for acetic acid.

Parametric and kinetic study of solvent-free synthesis of solketal using ion exchange resin.

The ketalization reaction of glycerol with acetone for solketal formation was performed using a gel-type ion exchange resin, Indion 225H in a solvent-free medium. The experimental parameters molar ratio, catalyst loading, rate of stirring, and temperature were analyzed and evaluated for their impact on the conversion of glycerol. A kinetic model based on the Langmuir-Hinshelwood-Hougen-Watson (LHHW) equation described the kinetics of the heterogeneous system. The parameters were evaluated using the ode45 solver and Genetic Algorithm (GA) optimization function on MATLAB software. The activation energy for the ketalization of glycerol was found to be 39.3 kJ/mol, the enthalpy of adsorption of water was -23 kJ/mol. The present work provides an economical path for the valorization of biodiesel-derived glycerol.

Broad-Spectrum Photo-Antimicrobial Polymers Based on Cationic Polystyrene and Rose Bengal.

New strategies to fight bacteria and fungi are necessary in view of the problem of iatrogenic and nosocomial infections combined with the growing threat of increased antimicrobial resistance. Recently, our group has prepared and described two new readily available materials based on the combination of Rose Bengal (singlet oxygen photosensitizer) and commercially available cationic polystyrene (macroporous resin Amberlite® IRA 900 or gel-type resin IRA 400). These materials showed high efficacy in the antimicrobial photodynamic inactivation (aPDI) of Pseudomonas aeruginosa. Here, we present the photobactericidal effect of these polymers against an extended group of pathogens like Escherichia coli, Enterococcus faecalis, Staphylococcus aureus, and the opportunistic yeast Candida albicans using green light. The most interesting finding is that the studied materials are able to reduce the population of both Gram-positive and Gram-negative bacteria with good activity, although, for C. albicans, in a moderate manner. In view of the results achieved and especially considering the inexpensiveness of these two types of photoactive polymers, we believe that they could be used as the starting point for the development of coatings for self-disinfecting surfaces.

Utilization of gel-type polystyrene host for immobilization of nano-sized hydrated zirconium oxides: A new strategy for enhanced phosphate removal

The urgent need for eutrophication control motivated the development of many novel adsorbents for enhanced phosphate polishing removal. Among these, zirconium-based nanomaterial was regarded as an effective kind because of its ability to bind phosphate specifically via inner-sphere complexation. In this study, we proposed a new strategy to improve the efficiency of zirconium oxides (HZO) nanoparticles by immobilizing them onto a gel-type anion exchange resin covalently attached with ammonium groups, denoted as HZO@N201. A previously developed macro-porous polymeric nanocomposite HZO@D201 was used for comparison. The immobilized nanoparticles in HZO@N201 were well dispersed in the gel matrix, manifesting smaller particle size and richer surface hydroxyl groups in comparison to HZO@D201. As a result of the structural merits in collective, HZO@N201 not only exhibited superior phosphate adsorptive capacity and affinity towards phosphate to HZO@D201, but also facilitate phosphate diffusion, based on isotherm, pH and kinetic tests. Mechanistic study by XPS and 31P SS-NMR substantiated the selective phosphate adsorption pathway as the formation of inner-sphere complexes by HZO@N201, which exhibited enhanced reactivity than HZO@D201. Lastly, fixed-bed runs of HZO@N201 was conducted, achieving an effective treatable volume of 2000 BV, which was 600 BV more than HZO@D201. Additional adsorption-regeneration cycle confirmed its reusability and potential for practical application. We believe the gel-type polymeric host could facilitate the formation and dispersion of smaller sized nanoparticles, exposing more surface hydroxyl groups highly accessible to phosphate. The results of this paper offer insights to a new strategy for immobilization of functional nanoparticles aiming at enhanced adsorptive removal of phosphate.

Esterification of furfuryl alcohol to butyl levulinate over ion-exchange resins

The esterification of furfuryl alcohol with 1-butanol was successfully tested at low initial butanol/furfuryl alcohol molar ratio values (4 and 8) in the temperature range 80–110 °C over different ion-exchange resins. The polymerization reaction of furfuryl alcohol also occurs, being more affected by the initial 1-butanol to furfuryl alcohol molar ratio than temperature under the conditions tested. The accessibility to acid centers conditioned the activity of ion-exchange resins. While for gel-type resins this can be related to the specific volume of the swollen polymer, for macroreticular resins there is a compromise between permanent porosity (for stiff resins) and the existence of a very flexible gel-phase zone for low crosslinked macroreticular resins. The maximum yield to butyl levulinate obtained was 63% at 110 °C and a molar butanol/furfuryl alcohol ratio of 8 on the macroreticular resin Amberlyst 39.

Liquid-phase synthesis of butyl levulinate with simultaneous water removal catalyzed by acid ion exchange resins

The liquid-phase synthesis of butyl levulinate by esterification of levulinic with an excess of 1-butanol (initial molar ratio 1:3) and simultaneous water removal has been studied at atmospheric pressure and at the boiling point of the reacting medium. The catalytic performance of ten commercial sulfonic resins has been compared: four gel-type and six macroreticular. For both type of resins the levulinic acid conversion was complete after 4–6h and no byproducts derived from the acid were detected. Selectivity of 1-butanol towards the ester was about 95%, di-butyl ether and butenes being the detected 1-butanol-derived byproducts. Among the tested catalysts, gel-type resins with low crosslinking degree showed the highest activity, what could be attributed to a higher accessibility to active centers in polar medium. In additional experiments where initial reactants content was at stoichiometric relation, the levulinic acid conversion was lower (82–85%), while selectivity of 1-butanol towards the ester was slightly higher, because of the lower 1-butanol concentration.

Solvent and substituent effects in hydrogenation of aromatic ketones over Ru/polymer catalyst under very mild conditions

The paper reports on the solvent and the substituent effects in hydrogenation of aromatic ketones (acetophenone and its derivatives) in the presence of Ru catalyst supported on functionalized gel-type methacrylate-styrene resin under very mild conditions (1 bar H2, 40 °C). The investigated solvents included methanol, 2-propanol, tetrahydrofuran, toluene, isooctane, and cyclohexane, with and without addition of water. The best catalytic activity was obtained in biphasic solvent system consisting of isooctane/water (1:1). In methanol and 2-propanol the beneficial role of water was observed. The effects are discussed in terms of solvent protic/aprotic and polar/apolar properties. The impact of substituents depended on their electron-donating/withdrawing character, and on the position on the aromatic ring of acetophenone. The presence of electron donating substituents tended to increase the reaction rate, and the electron withdrawing group slowed down the process. Steric effect was observed for methylacetophenone isomers with CH3 group at ortho, meta and para positions.

Biodiesel production using gel-type cation exchange resin at different ionic forms

In this study, a strong acidic-type cation exchange resin was used in the transesterification of corn oil to fatty acid methyl esters (FAME). The gel-type cation exchange resin (Purolite-PD206) was used in H+ and Na+ forms to utilize ion-exchange resin as effective heterogeneous catalyst in the production of biodiesel. Effect of ionic forms of ion exchange resin on free fatty acid (FFA) conversion and composition was investigated by using different amounts of ion exchange resin (12, 16, and 20 wt%), various mole ratios of methanol to oil (1:6, 1:12, and 1:18 mol/mol), reaction temperatures (63, 65, and 67°C), and reaction time (24, 36, and 48 h) during transesterification reaction. The highest FFA conversions of 73.5% and 79.45% were obtained at conditions of 20 wt% of catalyst, 65°C of reaction temperature, 18:1 as methanol to oil ratio, and 48 h of reaction time for H+ and Na+ forms of ion exchange resin, respectively. These results were obtained from regression equations established by using analysis of variance (ANOVA) model according to the experimental results of selected parameters. Gas chromatography analysis revealed that FAME is mainly composed of C16:0 (palmitic), C18:1 (oleic), and C18:2 (linoleic) acids of methyl ester.

Sugarcane bagasse mild alkaline fractionation and production of purified fractions by pulse chromatography with water

Sugarcane bagasse (SCB) was treated under mild alkaline conditions (solid:liquid ratio of 1:20 (w/v), 1.5% NaOH (w/v), 60 °C, 6 h) to fractionate the lignocellulose in order to produce a typical mild alkaline extract from a lignocellulosic biomass. The solid residue was enriched in cellulose, while the SCB alkaline extract contained lignin and hemicelluloses, but also inorganic salts, five phenolic monomers and acetic acid. After concentration of the alkaline extract by evaporation, low pressure chromatography with water as eluent was performed to produce purified fractions. Two different strong acid cation (SAC) exchange resins were tested: one gel-type resin and one macroporous-type resin. The lignin and hemicelluloses were separated from the inorganic salts by the gel-type SAC exchange resin. On this resin, the phenolic monomers were partitioned regarding the presence or absence in their structure of a carboxyl group. On the macroporous-type SAC exchange resin, the largest sugar oligomers and lignin oligomers were obtained in a fraction free of inorganic salts, phenolic monomers and acetic acid.