Recovery Of Acid Research Articles

Recovery of Bio-Based Fumaric Acid By Electrochemically Induced pH Shift Crystallization

The heterotrophic microbial production of platform chemicals is gaining increasing interest due to the growing need to replace fossil resources by renewable alternatives. Carboxylic acids such as fumaric acid are important building blocks for high-value bio-based chemicals [1]. Fumaric acid is used as an acidulant, as an antibacterial agent, and as a precursor for polymers and pharmaceuticals [2,3].A major challenge commercializing the microbial production route is the recovery and the purification of fumaric acid after fermentation. Bio-production of fumaric acid has not yet reached industrial scale due to high additive consumption during the acid- and base-induced pH shift in the downstream process. The inevitable co-production of saline waste deteriorates process economics further and raises ecological concerns.Therefore, we propose a new electrochemical downstream process, which reduces the use of pH adjustment agents [4]. This downstream process incorporates an electrolysis cell to adjust the pH value. During electrolysis, protons are produced at the anode and hydroxide ions are produced at the cathode by the electrochemical splitting of water. In conventional water electrolysis, protons or hydroxide ions migrate through a membrane to balance the charge in the electrolysis cell. Consequently, the pH value is constant in the electrolysis cell chambers. In pH shift electrolysis, a salt is added to the electrolyte. The salt provides additional ions to maintain electroneutrality in both electrolysis cell chambers. In this way, protons and hydroxide ions are retained in their respective chambers of the electrolysis cell and a pH difference is created between the anode and cathode. During acidification in the anode chamber, the fumaric acid salt from the fermentation is protonated. Subsequently, fumaric acid crystallizes in the electrolysis cell in high yields due to its low solubility. Afterwards, fumaric acid crystals can be easily separated from fermentation broth. Simultaneously, a base is produced at the cathode, which can be used to maintain a neutral pH in the fermentation. Consequently, saline waste production and its drawbacks are avoided.This work presents the pH shift with an electrolysis cell and the simultaneous crystallization of fumaric acid in the anode chamber. Next, the process is analyzed using on-line and off-line analytics such as Raman spectroscopy and high-performance liquid chromatography.[1] Bozell, J. J., & Petersen, G. R. (2010). Technology development for the production of biobased products from biorefinery carbohydrates - The US Department of Energy’s “Top 10” revisited. Green Chem, 12(4), 525-728. DOI: 10.1039/B922014C[2] Xu, Q., Li, S., Huang, H., & Wen, J. (2012). Key technologies for the industrial production of fumaric acid by fermentation. Biotechnol Adv, 30(6), 1685-1696. DOI: 10.1016/j.biotechadv.2012.08.007[3] Roa Engel, C. A., Straathof, A. J., Zijlmans, T. W., van Gulik, W. M., & van der Wielen, L. A. (2008). Fumaric acid production by fermentation. Appl Microbiol Biotechnol, 78, 379-389. DOI: 10.1007/s00253-007-1341-x[4] Kocks, C., Wall, D., & Jupke, A. (2022). Evaluation of a Prototype for Electrochemical pH-Shift Crystallization of Succinic Acid. Materials, 15(23), 8412. DOI: 10.3390/ma15238412

Extraction, separation and purification of fatty acid ethyl esters for biodiesel and DHA from Thraustochytrid biomass.

A novel approach for in situ transesterification, extraction, separation, and purification of fatty acid ethyl esters (FAEE) for biodiesel and docosahexaenoic acid (DHA) from Thraustochytrid biomass has been developed. The downstream processing of Thraustochytrids oil necessitates optimization, considering the higher content of polyunsaturated fatty acids (PUFA). While two-step methods are commonly employed for extracting and transesterifying oil from oleaginous microbes, this may result in oxidation/epoxidation of omega-3 oil due to prolonged exposure to heat and oxygen. To address this issue, a rapid single-step method was devised for in situ transesterification of Thraustochytrid oil. Through further process optimization, a 50% reduction in solvent requirement was achieved without significantly impacting fatty acid recovery or composition. Scale-up studies in a 4L reactor demonstrated complete FAEE recovery (99.98% of total oil) from biomass, concurrently enhancing DHA yield from 16% to nearly 22%. The decolorization of FAEE oil with fuller's earth effectively removed impurities such as pigments, secondary metabolites, and waxes, resulting in a clear, shiny appearance. High-performance liquid chromatography (HPLC) analysis indicated that the eluted DHA was over 94.5% pure, as corroborated by GC-FID analysis.

Absolute Quantification of Hepatitis B Core Antigen (HBcAg) Virus-like Particles and Bound Nucleic Acids.

Effective process development towards intensified processing for gene delivery applications using Hepatitis B core Antigen (HBcAg) virus-like particles (VLPs) relies on analytical methods for the absolute quantification of HBcAg VLP proteins and bound nucleic acids. We investigated a silica spin column (SC)-based extraction procedure, including proteinase K lysis and silica chromatography, for the absolute quantification of different species of nucleic acids bound to HBcAg VLPs analyzed by dye-based fluorescence assays. This revealed load-dependent nucleic acid recoveries of the silica-SC-based extraction. We also developed a reversed-phase high-performance liquid chromatography (RP-HPLC) method to separate and quantify the HBcAg proteins and the bound nucleic acids simultaneously without prior sample treatment by dissociation reagents. The method demonstrated sufficient linearity, accuracy, and precision coefficients and is suited for determining absolute protein and nucleic acid concentrations and HBcAg protein purities at various purification stages. Both the silica-SC-based extraction and the RP-based extraction presented overcome the limitations of analytical techniques, which are restricted to relative or qualitative analyses for HBcAg VLPs with bound nucleic acids. In combination with existing analytics, the methods for an absolute quantification of HBcAg VLPs and bound nucleic acids presented here are required to evaluate downstream purification steps, such as the removal of host cell-derived nucleic acids, concurrent protein loss, and efficient loading with therapeutic nucleic acids. Hence, the methods are key for effective process development when using HBcAg VLP as potential gene delivery vehicles.

Aqueous two-phase systems based on cholinium ionic liquids for the recovery of ferulic and p-coumaric acids from rice husk hydrolysate

Aqueous two-phase systems based on cholinium ionic liquids for the recovery of ferulic and p-coumaric acids from rice husk hydrolysate

Protocol Development for Yielding High Quality DNA and RNA from Archived Formalin-Fixed Paraffin Embedded Tissues

Introduction: While genetic analysis of archived formalin-fixed paraffin embedded (FFPE) tissue specimens would be a significant research resource, extraction of high-quality DNA and RNA from these specimens is a significant challenge. Storage duration, tissue handling and tissue preservation processes as well as their interactions with the nucleic acids could influence the quality and integrity of the DNA or RNA required for genetic analysis.
 Objectives: The goal of this study was to establish a protocol to extract high quality DNA and RNA from the FFPE tissues for further use in quantitative PCR analysis.
 Methods: For the purposes of this study, human FFPE biopsy tissues from lung, liver, colon and kidney were obtained from a single center biorepository. GeneJET Genomic DNA Purification Kit (Catalog # K0722) obtained from Thermo Fisher Scientific and RecoverAll Total Nucleic Acid Isolation Kit obtained from Life Technologies were modified and used for extraction of DNA and RNA, respectively. Briefly, modifications involved extending reagent incubation times, increasing sample volumes and wash steps, and increased final nucleic acids recovery and concentration steps. Eight sections around 8-10 ?m thick were microtomed for each tissue sample and used for extraction. The purity of the nucleic acids obtained was verified using Nanodrop Spectrophotometer.
 Results: The average DNA yield from eight sections for each of the tissues was 270±184 ng/?l and for RNA was 296±188 ng/?l. Nucleic acid quality was assessed by measuring the 260nm/280nm absorbance ratio for protein contamination as well as the 260nm/230nm absorbance ratio for salt contamination. Both were found to be within acceptable ranges. RNA was reverse transcribed to cDNA and qPCR was successfully performed on both DNA and cDNA samples.
 Conclusions: These results indicate that protocols using the silica-based membrane technology can yield high quality DNA and RNA that can be successfully used for downstream genetic analysis.

Kinetics of silica-assisted pyro-hydrolysis of CaCl2 waste for the recovery of hydrochloric acid (HCl): Effect of interaction between CaCl2 and SiO2

Pyro-hydrolysis of CaCl2 waste for HCl acid regeneration is a circular process enabling the sustainable development of the critical energy mineral extraction industry. However, the lack of detailed kinetic information has posed challenges in implementing this technology. An acidic additive such as silica (i.e., SiO2) is essential to make this reaction thermodynamically available, yet its reaction kinetics are still unknown. This study aims to reveal the detailed reaction kinetics of the SiO2-assisted pyro-hydrolysis of CaCl2 under two typical industrial settings for the feeding of reactants, physical mixing of powders and spray feeding where CaCl2 solution is expected to initially undertake drying and subsequently deposit onto the solid silica powders for a close contact. The isothermal experiment results revealed that the HCl release rate is strongly temperature-dependent. Comparatively, the CaCl2-deposited silica demonstrated a significantly faster release of HCl than the physically mixed sample, achieving 92% HCl release within 30 min at 800 °C. SEM analysis confirmed a closer inter-particle contact for the CaCl2-deposited sample, which is responsive to the accelerated HCl release. In addition, the experimental results were successfully fitted by a variable activation energy model which discovered a steady increase of the activation energy with the progression of the HCl release for both feedstock modes. This is primarily due to the continuous change on the formation of intermediates. The model also confirmed a lower activation energy for the CaCl2-deposited sample than its physically mixed counterpart at any given conversion extent of CaCl2. In contrast, for the physically mixed sample, the loose inter-particle contact led to the formation of a stable intermediate, Ca(OH)Cl, which can readily reverse to CaCl2, thereby slowing down the overall HCl release rate.

Optimized Recovery of Viral DNA and RNA from Blood Plasma for Viral Metagenomics.

Metagenomics is vastly improving our ability to discover new viruses, as well as their possible associations with disease. However, metagenomics has also changed our understanding of viruses in general. This is because we can find viruses in healthy hosts in the absence of disease, which changes the perspective of viruses as mere pathogens and offers a new perspective in which viruses function as important components of ecosystems. In concrete, human blood metagenomics has revealed the presence of different types of viruses in apparently healthy subjects. These viruses are human anelloviruses and, to a lower extent, human pegiviruses. Viral metagenomics' major challenge is the correct isolation of the viral nucleic acids from a specific sample. For the protocol to besuccessful, all steps must be carefullychosen, in particular those that optimize the recovery of viral nucleic acids. Here, we present a procedure that allows the recovery of both DNA and RNA viruses from plasma samples.

Extraction of Bioactive Compounds from Spent Coffee Grounds Using Ethanol and Acetone Aqueous Solutions.

Given global coffee consumption, substantial quantities of spent coffee grounds (SCGs) are generated annually as a by-product of brewing coffee. SCG, although rich in bioactive compounds, is nowadays disposed of. The objective of this study is to compare, for the first time and from the same SCG, the efficiency of ethanol-water mixtures and acetone-water mixtures for the recovery of total polyphenols, chlorogenic acid, and caffeine. Acetone at 20% (m/m) was the most convenient solvent to extract all three bioactive compounds simultaneously, yielding 4.37 mg of GAE/g SCG for total polyphenols, chlorogenic acid (0.832 mg 5-CQA/g SCG), and caffeine (1.47 mg/g SCG). Additionally, this study aims to address some challenges associated with the industrial-scale utilization of SCG as a raw material, encompassing factors such as pre-treatment conditions (natural drying and oven drying), storage duration, and the kinetics of the extraction process. No significant difference was observed between the natural drying and oven drying of SCG. In terms of storage duration, it is advisable to process the SCG within less than 3-4 months of storage time. A significant decline of 82% and 70% in chlorogenic acid (5-CQA) and caffeine contents, respectively, was observed after eight months of storage. Furthermore, the kinetic study for the recovery of total polyphenols revealed that the optimal extraction times were 10 min for acetone at 20% and 40 min for water, with a yield increase of 28% and 34%, respectively. What is remarkable from the present study is the approach considered, using the simplest operating conditions (minimal time and solvent-to-solid ratio, and ambient temperature); hence, at an industrial scale, energy and resource consumption and equipment dimensions can be together reduced, leading to a more industrially sustainable extraction process.

Sustainable treatment of boron industry wastewater with precipitation-adsorption hybrid process and recovery of boron species

Boron removal from wastewater has been investigated by using various processes, including ion exchange resins, membrane processes and adsorption. Each method has various advantages and disadvantages, but most produce excessive waste in addition to high operational costs. Therefore, more sustainable methods are required for wastewater containing high concentrations of boron. In this study, a sustainable treatment process was developed for wastewater containing high concentrations of boron. This study investigated the removal of boron from wastewater by Al(OH)3 sorption. The reuse of adsorbent (Al(OH)3) and the potential recovery of boric acid was the main goal of the study. It was observed that although lower concentrations of boron were obtained at pH 10.5 (980 mg/L and 635 mg/L at pH of 9.0 and 10.5, respectively), the amount of sorbed boron at pH 9 was substantially higher (94.7 mg B/g Al(OH)3 and 27.8 mg B/g Al(OH)3 at pH of 9.0 and 10.5, respectively). This was attributed to the higher initial boron concentrations and the formation of boric acid and polyborate complexes at pH 9.0. Results showed that polyborate species sorption was an outer sphere complex formation, which led to the desorption of boron as pH lowered. Adsorbed boron species to Al(OH)3 could effectively be desorbed at low pH values (pH<5.0); which allows Al(OH)3 to be used in successive adsorption studies. Approximately 55% of boron recovery from pretreated wastewater was possible with the effective reuse of adsorbent. A net profit of 2.85 $/m3 could be obtained based on the amounts of chemical consumptions and boron recovery.

Two wastes into one resource: Carbide slag-driven anaerobic fermentation of excess sludge towards short-chain fatty acids recovery

The anaerobic fermentation has been regarded as promising technology for short-chain fatty acids (SCFAs) recovery from excess sludge. Despite that various treatment approaches have been developed, the sustainable waste utilization of carbide slag in enhancing anaerobic fermentation has rarely been reported. It demonstrated that the carbide slag-derived alkaline condition dominantly contributed to triggering extracellular polymeric substance disruption and microbial cell lysis by protein molecule deconstruction. Considerable sludge hydrolysis was facilitated owing to extracellular and intracellular organic matter release, solubilizing 14.73 % of total solid organic matters in 4-h treatment. Correspondingly, massive SCFAs of 2219.70 mg COD/L (mainly acetate) were produced through 8-day anaerobic fermentation, with the improved acidification and the inhibited methanogenesis. Approximately 83.03–96.21 % of the recoverable SCFAs were extracted after sludge conditioning and solid–liquid separation, providing remarkable economic benefit of 196.23 CNY/ton VSS and carbon-emission reduction of 0.069–0.347 ton CO2/ton VSS. The findings proposed an innovative and sustainable carbide slag-driven anaerobic fermentation strategy for SCFAs recovery and waste stabilization, with low heavy metal residual and negligible environmental risks in “two wastes into one resource” pattern.

In situ adsorption of itaconic acid from fermentations of Ustilago cynodontis improves bioprocess efficiency

BackgroundReducing the costs of biorefinery processes is a crucial step in replacing petrochemical products by sustainable, biotechnological alternatives. Substrate costs and downstream processing present large potential for improvement of cost efficiency. The implementation of in situ adsorption as an energy-efficient product recovery method can reduce costs in both areas. While selective product separation is possible at ambient conditions, yield-limiting effects, as for example product inhibition, can be reduced in an integrated process.ResultsAn in situ adsorption process was integrated into the production of itaconic acid with Ustilago cynodontis IAmax, as an example of a promising biorefinery process. A suitable feed strategy was developed to enable efficient production and selective recovery of itaconic acid by maintaining optimal glucose concentrations. Online monitoring via Raman spectroscopy was implemented to enable a first process control and understand the interactions of metabolites with the adsorbent. In the final, integrated bioprocess, yield, titre, and space–time yield of the fermentation process were increased to values of 0.41 gIA/gGlucose, 126.5 gIA/L and 0.52 gIA/L/h. This corresponds to an increase of up to 30% in comparison to the first extended batch experiment without in situ product removal. Itaconic acid was recovered with a purity of at least 95% and high concentrations above 300 g/L in the eluate.ConclusionIntegration of product separation via adsorption into the bioprocess was successfully conducted and improved the efficiency of itaconic acid production. Raman spectroscopy was proven to be a reliable tool for online monitoring of various metabolites and facilitated design and validation of the complex separation and feed process. The general process concept can be transferred to the production of various similar bioproducts, expanding the tool kit for design of innovative biorefinery processes.

Study of the Effect of Water Content in Deep Eutectic Phases on the Extraction of Fatty Acids from Microalgae Biomass

Microalgae, as some of the oldest life forms on Earth, are of significant interest to industry and in terms of environmental policies, due to their ability to perform photosynthesis and consume atmospheric carbon dioxide. Moreover, they contain a wide variety of value-added compounds such as amino acids and proteins, carbohydrates, and fatty acids, which can be exploited in multiple fields like medicine, cosmetics, nutritional supplements, and for the production of biodiesel. In this article, Nannochloropsis gaditana, a type of microalgae that inhabits both fresh and salt water, is studied for fatty acid recovery using deep eutectic solvents (DES). This microalgae species is a natural source of eicosapentaenoic acid (EPA), an omega-3 compound that is commonly used in the nutritional industry. There are numerous extraction techniques and pretreatments to obtain these compounds. In this work, DES are studied as extractive agents due to their advantages as neoteric solvents. Specifically, this work focuses on an assessment of the effect of the composition of DES on the extraction yield of fatty acids from microalgae. Several DES compositions based on choline chloride, ethylene glycol, and fructose are studied to analyze the influence of water content in these phases. The results show that water content significantly influences recovery yields. The DES with higher extractive capacity were those based on choline chloride, ethylene glycol, and water at a molar ratio of 1:2:2. This composition offered 48.7% of the yield obtained with a conventional solvent like methanol for the recovery of EPA (11.2 mg/g microalgae). Furthermore, the choline chloride-fructose-based DES shows the capability of selective extractions of fatty acids with low carbon content—choline chloride:fructose:water (molar ratio 2:1:2) can extract 0.14 mg of decanoic acid/g of microalgae, indicating that this DES composition can recover 35.7% more decanoic acid in comparison to methanol.

Globally optimal scheduling of an electrochemical process via data-driven dynamic modeling and wavelet-based adaptive grid refinement

Electrochemical recovery of succinic acid is an electricity intensive process with storable feeds and products, making its flexible operation promising for fluctuating electricity prices. We perform experiments of an electrolysis cell and use these to identify a data-driven model. We apply global dynamic optimization using discrete-time Hammerstein–Wiener models to solve the nonconvex offline scheduling problem to global optimality. We detect the method’s high computational cost and propose an adaptive grid refinement algorithm for global optimization (AGRAGO), which uses a wavelet transform of the control time series and a refinement criterion based on Lagrangian multipliers. AGRAGO is used for the automatic optimal allocation of the control variables in the grid to provide a globally optimal schedule within a given time frame. We demonstrate the applicability of AGRAGO while maintaining the high computational expenses of the solution method and detect superior results to uniform grid sampling indicating economic savings of 14.1%.

Performance evaluation of green and integrated extraction approaches for the recovery of fatty acids, polysaccharides, and proteins from brown macroalgae for a sustainable biorefinery

Performance evaluation of green and integrated extraction approaches for the recovery of fatty acids, polysaccharides, and proteins from brown macroalgae for a sustainable biorefinery

Production, purification and recovery of caproic acid, Volatile fatty acids and methane from Opuntia ficus indica

Opuntia ficus-indica can grow in arid and semi-arid environments characterized by low water and nutrients availability. These features make it a more sustainable alternative to the common energy crops for biorefinery purposes. This work focused on the potential benefits of anaerobic processes applied to this plant. Specifically, it considered i) the substrate preparation, demonstrating the effect of the apparent viscosity on the process; ii) the evaluation of biomethane, Volatile Fatty Acids (VFAs), and caproic acid production in semi-continuous mode at different hydraulic retention times; iii) the purification of the Fatty Acids-rich output through pressure-driven membrane filtration. The rheology analysis found that a 5 %w/w water dilution of the substrate is needed to lower the apparent viscosity to 173 cP, which is below the acceptable apparent viscosity level of 200 cP for a good bioreactor mixing. Keeping this condition, the semi-continuous trials with the best biomethane performance was at HRT of 20 days, with 210 mLCH4/gVS and 232 mLCH4/gCODin of production and specific yield, respectively. The VFAs and caproic acid production reached their best at Hydraulic Retention Time 5, with 26 and 7.9 gCOD/L of VFAs and caproic acid, corresponding to specific yields of 79 and 30 % respectively. Pressure-driven filtration at 330 kDa allowed to obtain a permeate with a VFAs and caproic acid content of 96.72%w/w. Finally, the adsorption and desorption tests allowed to separate caproic acid from the permeate and to concentrate it from about 7.5 gCOD/L to about 26 gCOD/L.

Synthesis of a Grease Thickener from Cashew Nut Shell Liquor.

Thickener, also known as a gelling agent, is a critical component of lubricating greases. The most critical property of thickener, temperature resistance, is determined by the molecular structure of the compounds. Currently, all high-temperature-resistant thickeners are based on 12-hydroxystearic acid, which is exclusively produced from castor oil. Since castor oil is also an important reagent for other processes, finding a sustainable alternative to 12-hydroxystearic acid has significant economic implications. This study synthesises an alternative thickener from abundant agricultural waste, cashew nut shell liquor (CNSL). The synthesis and separation procedure contains three steps: (i) forming and separating calcium anacardate by precipitation, (ii) forming and separating anacardic acid (iii) forming lithium anacardate. The obtained lithium anacardate can be used as a thickener for lubricating grease. It was found that the recovery of anacardic acid was around 80%. The optimal reaction temperature and time conditions for lithium anacardate were 100 °C and 1 h, respectively. The method provides an economical alternative to castor and other vegetable oils. The procedure presents a simple pathway to produce the precursor for the lubricating grease from agricultural waste. The first reaction step can be combined with the existing distillation of cashew nut shell processing. An effective application can promote CNSL to a sustainable feedstock for green chemistry. The process can also be combined with recycled lithium from the spent batteries to improve the sustainability of the battery industry.

Advancing PFAS characterization: Enhancing the total oxidizable precursor assay with improved sample processing and UV activation

Per- and polyfluoroalkyl substances (PFAS) encompass over 9000 chemicals utilized in various industrial and commercial applications. However, the quantification of PFAS using standard commercial analytical methods is currently limited to <50 selected compounds. To address this issue, the total oxidizable precursor (TOP) assay was developed, allowing for the oxidative conversion of previously undetectable PFAS precursors into measurable PFAS. This study investigated different sample processing methods to address post-oxidation PFAS loss identified in literature. Using PFOS as a probe molecule, up to 50 % loss of PFOS was identified during sample work-up. It was determined that the use of mass-labelled PFOS and methanolic acetic acid to chemically quench the sample post-oxidation improved PFOS recovery and allowed for correction of any remaining PFOS loss. The use of ultraviolet (UV) light was then investigated as an activator in contrast to the standard thermal activation method. A comparative evaluation was conducted to assess the recovery and conversion of perfluorooctanoic acid (PFOA), PFOS, and 6:2 fluorotelomer sulfonate (6:2 FTS) using both the heat-activated and UV-activated TOP assays. Results demonstrated that the UV-activated TOP assay achieved complete (100 %) oxidation of 6:2 FTS within 7.5 min, resulting in a total yield of generated perfluorinated carboxylic acids (PFCAs) at 108 ± 8 %. The study concluded by investigating the UV-activated TOP assay for its application on various aqueous film forming foam (AFFF) formulations and two AFFF samples drained from military aircraft rescue firefighting vehicles (ARFFVs). Analysis of these AFFF samples were supported by high resolution mass spectrometry and an expanded analytical suite, identifying several fluorotelomer precursors. The findings of this study provide compelling evidence that modifications in sample processing, work-up procedures, expansion of initial PFAS calibration standards, and UV-activation methods enhance the TOP assay, positioning it as a more reliable and quantitative analytical tool for PFAS characterization.

Liquid-liquid extraction of sinapic acid from a mustard seed by-product using a hollow fiber membrane contactor

This study focuses on the recovery of sinapic acid using liquid–liquid extraction (LLE) assisted by a hollow fiber membrane contactor (HFMC) from an aqueous feed obtained through the hydrolysis of mustard bran. The hydrolyste contains 230 ± 36 mg/L of sinapic acid, with a natural pH of 4. A screening was performed with solvents of different chemical nature (alcohol, ester, ketone, ether, cyclic ether). Data showed that all the solvents tested gave an extraction efficiency of more than 80 % for pH < 5, whereas the initial concentration of sinapic acid in the aqueous feed has little impact on the extraction efficiency. Four of the solvents tested were selected for use in the HFMC: two volatile (CPME, MIBK) and two non-volatile (octanol, octyl acetate). The solubility of the volatile solvents in the feed phase was found to be an important factor to consider in evaluating the HFMC (2.6 ± 0.5 % and 1.07 ± 0.05 % v/v with MIBK and CPME, respectively). Mass transfer coefficients with volatile solvents (25 ± 1 x10-6 and 15.3 ± 0.5 x10-6 m/s for MIBK and CPME, respectively) exceeded those of non-volatile solvents (4.1 ± 0.2 x10-6 and 4.5 ± 0.5 x10-6 for octanol and octyl acetate, respectively) by 4- to 6-fold. Extraction was intensified by increasing the initial concentration of sinapic acid in the feed phase and by increasing the feed-to-solvent ratio. CPME demonstrated optimal recovery efficiency at a phase ratio of 8:1 (v/v), yielding 0.9 g of sinapic acid per liter of CPME used.

Efficient recovery and characterization of humic acids from municipal and manure composts: A comparative study

The recovery of humic acids from low-quality compost obtained in municipal solid waste treatment plants provides opportunities for its valorization. This study compares the recovery and properties of the humic acids obtained from municipal mixed waste compost (MMWC) and manure compost. The effects of temperature, time, and KOH concentration on the ratio of humic acids in the extracted liquid and the content of organic carbon of the precipitates were investigated by response surface methodology. Optimal conditions were 30 °C and 24 h for both composts, with a KOH concentration of 0.53 M for MMWC and 0.25 M for manure compost. The manure compost provided a liquid extract richer in humic acids than MMWC (76.6 % vs. 33.7 %), but the precipitates presented similar organic carbon contents (38.1 % vs. 42.4 %). Regarding composition, both humic acids presented higher organic carbon and nitrogen contents than the composts used as feedstock. The extraction and further precipitation of humic acids reduced the concentration of heavy metals. Humic acids from manure compost have a slightly higher average molecular weight (2650 Da) than those from MMWC (1980 Da), while both present similar C/N ratios and degree of aromaticity. Most contaminants of emerging concern present in the original composts were not detected in the humic acids. Thus, it was demonstrated that MMWC constitutes an attractive source of humic acids with properties similar to those obtained from a high-quality compost and, therefore, with potential economic value.

Harnessing imidazole containing crosslinked AEM for HCl resurrection from industrial spent effluent by integrated diffusion dialysis and electrodialysis: Effect of small and macromolecular crosslinker

Herein, we report the preparation of crosslinked copolymer-based AEMs via a one-pot mechanism. AEMs were prepared by the nucleophilic substitution reaction of polyacrylonitrile-co-polyvinyl imidazole (PAN-co-PVI) copolymer (AN: VI = 63:37 mol/mol) with the small and macromolecular crosslinker. The AEM was then used for the separation and concentration of hydrochloric acid from its simulated waste mixture with ferrous chloride of the electroplating industry using diffusion dialysis (DD) followed by electrodialysis (ED). The separation has also been performed by the integrated approach of DD and ED processes. DD performance was carried out with three different crosslinked membranes namely M-PCMSt, M-XDC, and M-XDB synthesized using poly-chloromethyl styrene (PCMSt), xylene dichloride (XDC), and xylene dibromide (XDB) as crosslinker respectively. The DD performances were compared by measuring the diffusion coefficient and separation factor. M-PCMSt prepared using a macromolecular crosslinker (PCMSt) exhibited the highest crosslinking density and lowest extractable (%) in DMF due to strong network formation and lowest free volume. Due to its lowest water uptake and high mechanical strength in both water and acid swollen states, it was further used to concentrate the acid by ED and integrated the DD-ED process separately. A ∼2.49 and 1.575 times higher recovery was achieved by integrated process from DD and ED separately. Different parameters such as the effect of membrane-stack designing, current density, the effect of feed solution concentration, the effect of the volume ratio, flow rate of the circulating initial solution, and influence of gravity have been optimized. M-PCMSt shows the best separation behaviour with >92% recovered acid purity and ∼94.5 % acid recovery at 4 mAcm-2 current density which is better than polyethylene poly-(4-methyl styrene)-based interpolymer membrane.