Regeneration Of Resin Research Articles

Enhanced denitrification performance of granular sludge for the treatment of waste brine from ion exchange resin process

Ion exchange resin process is a widely used process in wastewater treatment plants, but its waste brine is characterized by high salinity and nitrate concentration, leading to costly treatment. This study innovatively explored the use of an up-flow anaerobic sludge bed (USB) for the treatment of waste brine from ion exchange resin process, following a pilot-scale ion exchange resin process. Specifically, the D890 ion exchange resin was employed for nitrate removal from secondary effluent, with resin regeneration using 4% NaCl solution. The USB was inoculated with anaerobic granular sludge and acclimated under various single-factor conditions, which revealed the optimal pH range of 6.5–9, salt concentration of 2%, hydraulic retention time of 12 h, C/N ratio of 3.3, and up-flow velocity of 1.5 m/h for reactor operation. This study provides a novel approach for the cost-effective treatment of waste brine from ion exchange resin process. The study found that the denitrification efficiency was highest when the NO3−-N concentration was around 200 mg/L, with NO3−-N and TN removal rates exceeding 95% and 90%, respectively, under optimal operating conditions. Characterization of the granular sludge during different phases of the operation revealed a significant increase in proteobacteria and gradually became the dominant species over time. This study presents a novel, cost-effective approach to treat waste brine from ion exchange resin process, and the long-term stable operation of the reactor offers a reliable option for resin regeneration wastewater treatment.

Adsorptive recovery of volatile fatty acids from wastewater fermentation broth

This work developed an adsorptive separation and recovery process for anaerobically generated volatile fatty acids (VFAs) from swine wastewater fermentation. Batch adsorption studies were conducted using several weak anion exchange resins and synthetic adsorbent resins to identify a suitable candidate. Relite RAM2 with a tertiary amine functional group showed the highest adsorption (over 98%) of hexanoic acid. Under the different pH values (1.8–7.5) and extraction temperatures (30–50 °C), the highest adsorption was observed at a pH of 3.2, which is below the pKa of hexanoic acid, at all the evaluated temperatures. A full factorial design was used to optimize the resin and VFA concentrations, wherein over 99% adsorption could be achieved when the ratio of VFA to resin was below 0.23 (g/g) for model solution (VFAs in water). The adsorption equilibrium could be achieved within 30 min of contact time and 0.5% w/v NaOH was identified as a suitable desorption agent. Under the optimal conditions, 65–72% of VFAs present in fermentation broth was adsorbed, which was increased to 72–76% by using fresh resins. The VFAs adsorption and recovery efficiency were maintained for 9 successive cycles without requiring extensive resin washing and regeneration for both model solution and fermentation broth. Overall, the work presents a comprehensive study for resin adsorption to recover VFAs and provides a potential industrial-relevant process to recover VFAs from fermentation broth.

Boron continuous recovery from brines by the multicolumn simulated moving bed process with boron chelating resin

The objective of this work is to develop an advanced adsorption process to continuously recover and remove boron from brines. Firstly, the adsorption and desorption performances of boron on the commercially available N-methylglucamine resin (D403 resin) are evaluated, then, the cyclic adsorption and desorption process is investigated experimentally in the fixed bed adsorber for boron recovery from brine. It is confirmed that the cyclic process involves five steps, such as boron recovery from brine, water washing 1 to remove the retained brine, boron desorption to obtain boron-rich solution, water washing 2 to recover the retained HCl solution, and resin regeneration for the reuse. Furthermore, the seven-column simulated moving bed (SMB) process with four zones is designed and investigated experimentally. Experimental results demonstrate that boron can be recovered continuously from brine in adsorption zone, and boron-rich solution is obtained continuously in desorption zone. When the inlet brine contains a low boron content (for example 296.5 mg/L), most boron in brine can be recovered by the seven-column SMB unit with 96.8 % boron adsorption efficiency, and the discharged brine contains 8.77 mg/L boron, approximately meeting the environmental protection requirement for the limitation of boron emission. Therefore, the simultaneous recovery and removal of boron from brine can be achieved by the proposed multicolumn SMB process.

Ion Exchange MIEX® GOLD Resin as a Promising Sorbent for the Removal of PFAS Compounds

Per- and polyfluoroalkyl substances (PFASs) are synthetic compounds, which have been widely produced, used, and recently identified as extremely toxic chemicals, and are responsible for serious environmental and human health risks. In this study, the removal efficiency of MIEX® GOLD resin was tested against six PFAS compounds including perfluorobutanoic acid (PFBA), perfluorobutanesulfonic acid (PFBS), perfluorohexanoic acid (PFHxA), perfluorohexanesulfonic acid (PFHxS), perfluorooctanoic acid (PFOA), and perfluorooctanesulfonic acid (PFOS). The removal of PFASs and the regeneration of resin (NaCl-saturated methanol) were achieved via adsorption and desorption mechanisms. In all cases, the removal efficiency was greater than 99% where the volume ratio of 1 ppm PFAS to resin was maintained at 50-bed volume. Furthermore, the adsorption capacity of MIEX® GOLD resin was studied for PFOA and PFHxS and achieved 1.05 ± 0.01 g PFOA adsorption and 1.01 ± 0.04 g PFHxS adsorption per gram of resin. In addition, a detailed study on the interference of natural organic matter (NOM) and inorganic matter was carried out against PFHxA, PFOA, and PFOS. The presence of 10 ppm NOM (5 ppm tannic acid + 5 ppm humic acid) and 25 ppm inorganic matter (5 ppm nitrate + 20 ppm sulfate) showed no noticeable interference in the removal of selected PFAS compounds. Compared to sulfonic acid-containing PFASs, the interference of organic and inorganic matter on carboxylic acid-containing PFASs was slightly higher. The regeneration of PFAS-adsorbed resin was studied using a mixed solution containing 70% methanol and saturated NaCl. Desorption of PFHxS, PFOS, and PFOA was found to be 98.3, 100, and 43.3%, respectively. The results again indicate that the resin regeneration is strongly affected by the functional group of PFASs; i.e., resin with sulfonic acid-containing PFAS is much easier to regenerate than carboxylic acid-containing PFAS compounds. All the PFAS analyses were performed by using mass spectroscopy and liquid chromatography–mass spectroscopy. In conclusion, this study confirms the remarkable efficiency of MIEX® GOLD resin in removing PFAS compounds, even in the presence of a high concentration of organic and inorganic interferences, and its capacity to be regenerated for repeated usage. These advantages make MIEX® GOLD a promising product for the remediation of PFAS-contaminated water. This study in the broader sense proves that MIEX® GOLD is a promising adsorbent and provides the ground for future study to treat contaminated groundwater.

Review of fluorine removal methods from aqueous solutions

Introduction. The high-quality water conditioning problem does not disappear from the agenda of chemists, biologists, and ecologists. Fluoride content is an important water quality indicator, as fluoride can have both positive and negative effects on the human body. The purpose of this work is a critical review of methods for removing fluorine compounds from natural surface and underground waters, and from wastewater. An analysis of 77 modern scientific articles was performed, the advantages and disadvantages of such methods as precipitation and co-precipitation, methods using semipermeable membranes, dialysis and electrocoagulation, ion exchange and sorption methods were determined.
 Results and discussion. It was determined that the precipitation and co-precipitation methods use of chemical reagents, so they are quite expensive, and the sediments formed in the defluoridation process are subject to disposal. Membrane methods do not require the chemicals addition, are highly efficient and easy to control, but at the same time, defluoridation removes other ions that are present in water and are important indicators of the drinking water quality. A significant disadvantage of membrane methods is that a major amount of brine is formed during the treatment process, which also creates a disposal problem. Dialysis and electrocoagulation methods have the advantages and disadvantages of electrochemical methods: they provide high quality water, but this is accompanied by increased electricity consumption, the use of limited service life electrodes. Along with the high degree of water defluoridation, ion exchange methods are characterized by high cost, as well as significant water consumption for such technological processes as loosening, regeneration and washing of ion-exchange resins. An additional problem is the flushing and rinsing wastewater disposal. Sorptive fluoride removal is the most promising and widely used method. The main advantages include the method simplicity, non-deficiency and availability of sorbents. Effective sorbents are natural minerals, foremost, clinoptilolite, nepheline, low-quality phosphorites and apatites, glauconite, basalt tuffs, which are abundant in the subsoil of Ukraine. Unlike other methods, the spent materials are easily disposed of, or can be used as additives in the production of silicate materials, for example, bricks.
 Conclusions. Promising fluoride removal methods are sorption methods using natural mineral and modified sorbents.

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.

Box-Behnken Response Surface Method to Optimize Amine Liquid Purification Process Based on Ion Exchange

In the process of recycling MDEA (N-methyldiethanolamine) solution in a terminal decarburization system of CNOOC, the quality of MDEA solution was deteriorated due to the generation and accumulation of impurities such as solid suspended solids and heat stable salts, which led to blockage and unstable operation of pipeline equipment in the decarburization system, thus affecting the CO₂ removal effect of the solution, the Box-Behnken effect surface method was used to design the three main factors of the ion exchange-based amine purification process: the continuous adsorption time of the amine solution, the resin regeneration temperature and the resin regeneration time. Taking the conductivity of the MDEA solution after purification as the response function, a corresponding mathematical model was established to optimize the test method, and the correlation coefficient R² (R²=0.9418) of the regression equation obtained was greater than 0.9, indicating that the predicted value had a high correlation with the experimental value, and the test method was optimized accordingly. The best test conditions obtained were: the continuous adsorption time of amine solution was 50 min, the resin regeneration temperature was 40°C, and the resin regeneration time was 30 min. Under this condition, the conductivity of the purified MDEA solution was 1.56 ms/cm, and the salt content was 0.8%. The experiment was repeated 3 times according to this method, and the salt content of the MDEA solution after purification was ≯0.8%, which met the technological requirements. The Box-Behnken experimental design method was feasible for amine solution purification process optimization screening based on ion exchange, and the predicted value of the mathematical model was consistent with the experimental observation value.

A Study on Brining Process for Regeneration of Ion Exchange Resin. Part I: Pre-treatment and Brining

A Study on Brining Process for Regeneration of Ion Exchange Resin. Part I: Pre-treatment and Brining

Разработка укрупнённого адсорбера для переработки продуктивных растворов

Productive solutions obtained after leaching of ores have a complex composition, including a variety of non-ferrous and heavy metal cations. The method of extracting nickel from productive solutions after leaching of sulfide and lateritic ores is the most important process in hydrometallurgical processing. Sorption by ion-exchange resins is an alternative to existing technologies for nickel recovery from productive solutions. The ability to selectively extract nickel and regenerate makes polymeric ion-exchange resins one of the most popular sorbents in the modern world. The polymer resin sorption process avoids wastage of reagents, costly filtration, and poor nickel selectivity compared to other metal ions associated with solvent extraction processes. In order to conduct experimental studies of sorption using Amberlite IRC 748 polymer resin, it is necessary to calculate and design an adsorber. The objectives of the study include the determination of the geometric parameters of the adsorber, the parameters of the sorption/desorption process and the development of a process flow diagram. As a result of the research, an enlarged adsorber has been designed to extract nickel from the productive solution after bacterial-chemical oxidation of cobalt-copper-nickel sulfide ore, and a process flow diagram for the process of obtaining nickel salts from the productive solution has been developed. The volume of the adsorber, its height, diameter, diameter of the inlet fitting, the height of the sorbent layer, the required resin flow rate, and the duration of the process before regeneration are determined. To ensure the continuity of the process, taking into account the duration of bacterial-chemical oxidation, periodic regeneration of the sorbent, the number of adsorbers in a common installation is taken to be two. When the adsorption stage occurs in one of the apparatuses, the stage of regeneration and drying of the polymer resin proceeds in the other. The estimated sorption capacity of Amberlite IRC 748 resin was taken as 21.6 g of nickel per 0.1 kg of adsorbent. Resin desorption has been supposed to be carried out with a 10 % sulfuric acid solution, at a flow rate of 5 l/h.

Application of Cation Resin Regeneration for Ferrous (Fe2+) and Manganese (Mn2+) Removal from Shallow Groundwater using Packed-Bed Column with Thomas Model

One of the factors influencing freshwater contamination is caused by pollutants and organic matter from anthropogenic activities. The appearance of ferrous and manganese metal ions in water systems, especially in shallow groundwater, has become a significant problem. When reacted in the air, an extreme amount of metal ferrous may cause turbidness and severe odor, particularly carrying a dark-brown color to fabrics. Water distribution can also easily be obstructed by iron bacteria in the pipes. It is similar to iron, and manganese has a detrimental effect on the natural environment, human hygiene, and sanitation. The higher influent ferrous and manganese concentration led to the adsorption process getting saturated quicker and a steeper breakthrough curve. The saturation time (ttotal) of the adsorption for ferrous concentration decreased from 430 minute (2 mg/l) to 420 minute (4 mg/l) to 380 minute (6 mg/l) with the elevation of Fe2+ influent concentration. In comparison, the saturation time for manganese concentration dropped from 463 minute (2 mg/l) to 460 minute (4 mg/l) to 420 minute (6 mg/l). Ferrous adsorption capacity (qeq) grew between 0.0046 mg/g and 0.0838 mg/g, followed by a growth in influent concentration. It is similar to manganese. The adsorption performace raised between 0.0216 mg/g and 0.109 mg/g. The Thomas model’s R Square (R2) indicates a better fitting (0.788 – 0.8922) with field data.

A New Sustainable Multistep Catalytic Process from Benzene to Caprolactam: Amination, Hydroximation and Beckmann Rearrangement Promoted and Catalyzed by Trifluoroacetic Acid.

Here we report some results on a 3 steps benzene caprolactam process via amination, aniline Hydroxymation and Beckmann rearrangement. The amination proceeds with hydroxylamine trifluoroacetate, with 97% of conversion and selectivity of 90%, catalyzed by V compounds. We achieve 98% of conversion and 95% of selectivity in the hydroxymation of aniline in the presence of hydroxylamine trifluoroacetate, sulfonic resin and Pd/C. While in the absence of the resin, hydrogenation of hydroxylamine trifluoroacetate occurs readily to the ammonium salt. The reaction occurs likely by the exchanged hydroxylamine and the aniline reduction intermediate. The use of hydroxylamine trifluoroacetate, instead of the chloride, favors the sustainability of the process by avoiding the ammonium chloride formation. The absence of salt except those derived from the trifluoroacetic acid allows a complete reuse of the trifluoroacetic acid and the only byproduct is ammonium nitrate obtained by resin regeneration. Beckmann rearrangement of the so produced cyclohexanone oxime occurs easily after diethyl ether evaporation and additions of a solution trifluoroacetic acid acetonitrile in high yield and selectivity.Graphical New three steps caprolactam process via benzene amination and aniline hydrogenation. Supplementary InformationThe online version contains supplementary material available at 10.1007/s10562-022-04207-9.

Hydrated Electron Degradation of PFOA Laden on Ion-Exchange Resins in the Presence of Natural Organic Matter

This study aimed to probe the interactions of hydrated electrons (eaq–) and perfluorooctanoic acid (PFOA)-laden ion-exchange (IX) resins in the presence of natural organic matter (NOM). PFOA and Suwannee River NOM-loaded resins were prepared through the removal of PFOA in simulated natural water with weak-base anion (WBA) resins (IRA67). Adsorption tests reveal that sorbed NOM was much more abundant than cosorbed PFOA, highlighting the role of NOM in resin saturation. Ensuing UV/SO32– treatment of PFOA/NOM-laden resins (pH 10.0) under a dissolved oxygen-free condition indicates that eaq– generated could effectively degrade sorbed and aqueous PFOA, the latter of which derived from desorption of PFOA due to pH increase. Finally, cyclic adsorption-UV/SO32– treatment tests demonstrate that the PFOA sorbed on the WBA resins could be mostly degraded over six cycles. However, eaq– could not effectively decompose cosorbed NOM, resulting in a gradual decrease in the recovered PFOA adsorption capability with the cycle number. This study spotlights that eaq– can decompose PFOA sorbed on the WBA resins in the presence of NOM. The UV/SO32– process, when jointly used with appropriate strategies for mitigating cosorbed NOM, can enable a promising on-site resin regeneration process with PFOA degradation while producing a relatively small volume of regenerant waste.

Segmented regeneration of ion exchange resins used for natural organic matter removal

This study investigated the feasibility of using segmented regeneration for ion exchange (IX) resins used for natural organic matter (NOM) removal. For the first part of the study, regeneration batch tests were conducted for resins solely loaded with sulfate (i.e. ResinSulfate) or NOM (i.e. ResinNOM). We found that ResinSulfate can be fully regenerated using a lower brine concentration (40 g NaCl/L vs 100 g NaCl/L) with a much faster desorption rate compared to ResinNOM (time to reach equilibrium: < 3 min vs approximately 60 min). For the second part of the study, resins recovered from a pilot plant were regenerated in bench-scale columns using conventional (2 bed volume (BV) of 80 g NaCl/L) and segmented regeneration strategies (10 g NaCl/L followed by 120 g NaCl/L), and different volumetric ratios between low-concentration brine and high-concentration brine were assessed for segmented regeneration. It was determined that the optimal segmented regeneration, which uses 3 BV of low-concentration brine followed by 0.8 BV of high-concentration brine, achieved an equivalent regeneration efficiency (77 %) to conventional regeneration while reducing salt usage by 21 % and improving the brine use efficiency from 16 % to 21 %.

Disposal of MIEX desorbent at high salinity by ZVI/H2O2 Fenton-like system: Optimization, performance and mechanisms

Magnetic ion exchange resin (MIEX) pretreatment has been widely used to enhance the performance of waterworks, but the high-salinity organic desorbent produced during the resin regeneration is difficult to be safely disposed of. The present study aimed to investigate the removal of DOM and retention of salts from MIEX desorbent via zero-valent iron (ZVI)-assisted Fenton reaction. ZVI/H2O2 mediated Fenton reaction was further validated by various analytical approaches such as 3D-EEM, Molecular weight distribution, Zeta potential, size, dissolution of iron ions, etc. In batch experiments, 73.26% reduction of DOC and 97.66% of UV254 were achieved in 40 min at optimal H2O2 concentration (20 mM), 2 g/L dose of ZVI, and pH of 3, respectively. The removal of organics was ascribed to the direct oxidation of ZVI/H2O2 and flocculation of the iron released during the oxidation. It should be noted that the high concentration of Cl- in system favored the organic removal and its enhanced performance lied in the production and oxidation of HOCl/OCl-. The treated liquid can be reused to regenerate the saturated resin with only a small amount of salt supplementation to obtain a similar recovery performance to that of a freshly configured 10% NaCl solution. Moreover, the retrieval and utilization of ZVI particles and other properties of MIEX desorbent after ZVI/H2O2 treatment were all promising and up to the mark: after four reuses, the mineralization of organic matter differs by 8.81% from the first time, which could be compensated by supplying new ZVI. This research will facilitate the recycling of resin desorbate and expand the market for MIEX applications.

Membrane-free electrodeionization using graphene composite electrode to purify copper-containing wastewater.

Membrane-free electrodeionization (MFEDI) technology involves in situ electric regeneration of ion exchange resin, and is used to efficiently purify copper-containing wastewater, so that both the wastewater and copper may be reused. The electrode is the core functional component of a MFEDI system. Electrode-selection greatly influences the electric regeneration efficiency, water recovery and energy consumption of MFEDI processes. In this study, a graphene composite electrode was developed to improve MFEDI-system performance. A graphene composite electrode and conventional platinum-plated titanium electrode were both characterized by scanning electron microscopy (SEM) and electrochemical testing. Furthermore, the treatment and electrical regeneration properties of MFEDI systems with these two electrodes were investigated. The specific surface area of the electrode increased after graphene loading, while the oxygen evolution potential decreased. Wastewater treatment experiments demonstrated that MFEDI systems with graphene composite electrodes effectively removed copper from wastewater. The study also highlighted that the electroregeneration efficiency of the MFEDI system was improved by loading with graphene; the average copper concentration in the regeneration solution increased by 1.4 times to 50.4 mg/L, while the energy consumption decreased from 1.55 to 1.48 kWh/m3, and the water recovery rate increased from 85 to 90%.

Sustainable Recovery of Ionic Resources from Resin Regeneration Wastewater: Long-Term Evaluation, Membrane Fouling Analysis, and Cleaning

Sustainable Recovery of Ionic Resources from Resin Regeneration Wastewater: Long-Term Evaluation, Membrane Fouling Analysis, and Cleaning

The fractal pack: New equipment for ion exchange operations in the sugar industry

The fractal pack is a new patented ion exchange configuration that is conceptually similar to a plate and frame filter press and contains a number of ion exchange plates held within a frame. With bed depths as shallow as 3 to 24 inches, this ion exchange system design results in a substantial reduction in capital cost by delivering the following benefits: compact equipment, modularity (by easy addition or removal of resin chambers from the existing frame), inexpensive capacity expansion / reduction and reduced installation costs. Furthermore, the capital and operating costs benefit from reductions in cycle times (and hence reduced resin fouling), regenerant use (and hence reduced chemical consumption and waste production), pressure drop, water consumption and product dilution. Increased resin loadings and longer life may also be possible. The plates are manufactured from corrosion resistant materials, making it possible to use aggressive resin regeneration chemicals if necessary. Testing has been carried out on both a small pilot / bench scale as well as a large pilot scale for several potential applications across a range of industries. In the sugar industry, successful performance has been demonstrated in the decolorization and softening of juice and syrups. Experimental work at various scales has confirmed that performance is maintained on scale-up to fractal pack plates of full industrial size.

Modeling and optimization of electrodeionization process for the energy-saving of ultrapure water production

Electrodeionization (EDI) is essential for producing ultrapure water in power plants and high-tech industries. Compared with the traditional ion exchange process, EDI does not require high-pollution resin regeneration by acid and alkali reagents. However, the process is markedly energy-intensive, and thus it is crucial to reduce the energy consumption. The reduction may be achieved by optimizing the operating conditions and module design. Previous mathematical models of the EDI process have been based on the mass transfer mechanism of ion removal. However, the water dissociation reactions, which are crucial for the energy efficiency of ion removal and thus EDI optimization, have rarely been considered. In particular, the design of EDI modules has not been studied. In this study, the water dissociation reactions in the EDI model were considered to simulate the ion removal process and energy consumption. In addition, the design variables of the equipment configuration and the operating conditions of an industrial-scale EDI module were optimized to reduce the energy consumption via nonlinear programming. The results show that the energy consumption of the current industrial EDI operation can be reduced by 22.4% when only the operating conditions are optimized. Furthermore, the optimization of the design and operation, based on the annual cost, will lead to a 50.4% decrease in the annual cost. The developed modeling and optimization method will play a critical role in an energy-saving operation and low-cost design of the EDI process.

Semi-industrial testing of silver production scheme from waste solutions of ion exchange resin regeneration

Sorption technology using anion exchange resin is used in the processing of gold-bearing ores of the Muruntau deposit. Studies have shown that despite the high selectivity for gold, silver and other associated non-ferrous metals, which are valuable from the point of view of the integrated use of mineral raw materials, are sorbed to some extent by ion-exchange resin. Studies have shown that it is possible in principle to extract silver from acidic waste solutions by precipitation using various precipitating reagents. This article presents the results of semi-industrial tests of the scheme for obtaining silver from waste solutions of ion exchange resin regeneration. The final product was a silver ingot with a metal content of 87,7%. In the future, anodes can be cast from the resulting silver ingot and 99,99% silver can be obtained by electrochemical method. При переработке золотосодержащих руд месторождения «Мурунтау» применяется сорбционная технология с использованием анионообменной смолы. Исследования показали, что несмотря на высокую селективность по золоту, ионообменной смолой в некоторой степени сорбируются серебро и другие попутные цветные металлы, имеющие ценность с точки зрения комплексного использования минерального сырья. Исследования показали принципиальную возможность извлечения серебра со сбросных кислых растворов путем осаждения с применением разных реагентов-осадителей. В данной статье приведены результаты полупромышленных испытаний схемы получения серебра из сбросных растворов регенерации ионообменной смолы. Конечным продуктом явился слиток серебра с содержанием 87,7% металла. В дальнейшем из полученного серебряного слитка можно отлить аноды и электрохимическим методом получить серебро высшей пробы 99,99%.

Valorization of Spent Sugarcane Fermentation Broth as a Source of Phenolic Compounds

A methodology based on a solid phase extraction (SPE) was optimized for the recovery of phenolic compounds from the spent fermentation broth generated from Biofene® (trans-β-farnesene) production. For this purpose, two resins (XAD-2 and HP-20) and three desorption solutions (water, 50/50 ethanol/water, and ethanol) were tested. The most efficient resin revealed to be the HP-20, using ethanol as desorption solution, reaching an overall total phenolic compound recovery of ca. 80% when 6 BV (bed volume) of both feed and ethanol were applied. The optimization of the resin’s process cycle pointed to 15 BV feed to be treated per cycle and using the same volume of ethanol in the desorption step, with no need for an extra resin regeneration step, stably yielding 48% total phenolic compound recovery from the spent broth for at least 4 cycles, translating into 60 BV of feed being treated per BV of resin, and with the resin being still perfectly active. The extract was characterized using LC−ESI−UHR−QqTOF−MS, and a total of 82 and 15 compounds were identified, in negative and positive ionization modes, respectively. Organic acids were the main class of compounds identified in the phenolic-rich extract, followed by phenolic compounds, saccharides, peptides or amino acids and vitamins. Additionally, the extract revealed a significant antioxidant capacity (914.1 ± 51.6 and 2764.5 ± 142.8 µmol Trolox equivalents/g-dw, respectively, with ABTS and ORAC methodologies), which might be interesting for a wide variety of applications.