Choline chloride based natural deep eutectic solvent for destabilization and separation of stable colloidal dispersions

Green hybrid coagulants for water treatment: An innovative approach using alum and bentonite clay combined with eco-friendly plant materials for batch and column adsorption

Textile industries contribute to water pollution through synthetic dye discharge. This study explores the use of natural bio-coagulants to remove acid dyes from wastewater, investigating factors like pH, coagulant dose, dye concentration, contact time, and temperature for optimal results. The optimum pH and coagulants capabilities of (CAAPP, CAAPH, CBAGL, CBAPP and CBAPH) were 3 (49.6 mg/g), 3 (42.5 mg/g), 3 (38.9 mg/g), 4 (35.7 mg/g), 4 (34.1 mg/g), and 4 (29.4 mg/g) respectively, while treating of selected BRF-221 dyes from water solution. The acidic range (3-4) was found to have the best pH for the maximal coagulation, and the optimal dose were found to be 0.05 g/50 mL. The equilibrium was attained within 45-60 min for all coagulants. After 60 min of shaking, the maximum coagulation capacities (21.9, 21.02, 16.5, 27.9, 25.3, and 23.4 mg/g) of several coagulant composites (CAAGL, CAAPP, CAAPH, CBAGL, CBAPP, CBAPH) were determined. The initial BRF-221 dye concentration in the range of 10-200 mg/L was considered as optimum for gaiting maximum elimination of dye using different coagulants. At a dye value of 100 mg/L of BRF-221, maximal coagulation capacities CAAGL (179.19 mg/g), CAAPP (166.06 mg/g), CAAPH (141.60 mg/g), and CBAGL (126.49 mg/g), CBAPP (113.9 mg/g), CBAPH (93.08 mg/g) were attained. The study found 35 °C to be the optimal temperature for maximum acid dye removal using bio-coagulants. Increasing temperature reduced coagulation capacity, indicating an exothermic process. Freundlich and Langmuir isotherms showed suitability for pseudo-first-order and pseudo-second-order kinetics in biosorption. Thermodynamic parameters were assessed for process feasibility. Effective coagulants demonstrated sensitivity to electrolyte variations. In column studies, adjusting parameters achieved maximum coagulation efficiency for removing BRF-221 dyes. The study successfully applied optimal parameters to remove real textile effluents at a practical scale. SEM, FT-IR, BET and XRD characterized coagulants, providing insights into stability and morphology.

Deep Eutectic Solvent as a New Zeta Potential Altering Chemical for Sand Agglomeration

Fines migration can cause various issues, such as plugging of the sand screen and damage to tubings. There are two chemical sand control methods: consolidation and agglomeration. Consolidation works by injection of a solvent into the formation to harden over time and hold the sand in place, while agglomeration works by altering chemical properties of the sand surface to attract and clump up sand. Various chemicals have been used for research in sand control. Some chemicals for consolidation, mostly resins, have been effective in consolidating sand but may cause permeability impairment, which will reduce production. Some chemicals for agglomeration such as a polymer with amines have been less effective or are nonbiodegradable. In this work, a novel deep eutectic solvent (DES) and ionic polymer combination as a fines stabilizer is formulated in-house and tested through extensive experimental study. The development of chemicals is based on agglomeration principles which determine the range of zeta potential reduction that can be achieved to destabilize, coagulate, and flocculate the fine particles together with different combinations of DESs and ionic polymers tested systematically using the design of experiment (DoE) method. The chemicals are then tested for compatibility with reservoir fluids in the jar test. The optimized formulation is characterized by thermogravimetric analysis (TGA) for limit of temperature degradation and laser particle size analysis (LPSA) for the extent of particle size. The novelty of this work is the development of a greener and more cost-saving in-house DES and ionic polymer combination as a fines stabilizer chemical, which is effective for both injection or production wells after stimulation or enhanced oil recovery (EOR) treatments. Due to the tunable nature of the DES, the formulated chemical can be tailored for various reservoir conditions to cater to specific requirements.

Efficient phosphorus recovery from waste activated sludge: Pretreatment with natural deep eutectic solvent and recovery as vivianite

Recycling phosphorus from waste activated sludge (WAS) is an effective method to address the nonrenewable nature of phosphorus and mitigate environmental pollution. To overcome the challenge of low phosphorus recovery from WAS due to insufficient disintegration, a method using a citric acid-based natural deep eutectic solvent (CA-NADES) assisted with low-temperature pretreatment was proposed to efficiently release and recover phosphorus. The results of 31P nuclear magnetic resonance (NMR) confirmed that low-temperature pretreatment promoted the conversion of organic phosphorus (OP) to inorganic phosphorus (IP) and enhanced the effect of CA-NADES. Changes in the three-dimensional excitation-emission matrix (3D-EEM) and flow cytometry (FCM) indicated that the method of CA-NADES with low-temperature thermal simultaneously release IP and OP by disintegrating sludge flocs, dissolving extracellular polymeric substances (EPS) structure, and cracking cells. When 5 % (v/v) of CA-NADES was added and thermally treated at 60 °C for 30 min, 43 % of total phosphorus (TP) was released from the sludge. The concentrations of proteins and polysaccharides reached 826 and 331 mg/L, respectively, which were 6.30 and 14.43 times higher than those of raw sludge. The dewatering and settling of the sludge were also improved. Metals were either enriched in the solid phase or released into the liquid phase in small quantities (most efficiencies of less than 10 %) for subsequent clean recovery. The released phosphorus was successfully recovered as vivianite with a rate of 90 %. This study develops an efficient, green, and sustainable method for phosphorus recovery from sludge using NADES and provides new insights into the high-value conversion of sludge.

Green and highly effective extraction of bioactive flavonoids from Fructus aurantii employing deep eutectic solvents-based ultrasonic-assisted extraction protocol

In China, Jiang Fructus aurantii (JFA) has attracted increasing interest as a famous traditional herbal medicine and valuable economic food for its valuable medicinal and industrial properties. In the current work, contrasted with conventional extraction techniques, natural flavonoids from JFA (naringin and neohesperidin) were extracted with remarkable effectiveness utilizing a sustainable deep eutectic solvents combined ultrasonic-assisted extraction (DESs-UAE) protocol. The optimal extraction capacity can be achieved by mixing 30 % water with a molar ratio of 1:3 for choline chloride and ethylene glycol, as opposed to the classical extraction solvents of 95 % ethanol, methanol, and water. Moreover, the DESs-UAE extraction programs were also systematically optimized employing Box-Behnken design (BBD) trials, and the eventual findings suggested that the best parameters were a 27 % water content in DES, a 16 mL/g liquid-solid ratio, a 72 min extraction time, and a 62 °C extraction temperature, along with the corresponding greatest contents of NAR (48.18 mg/g) and NEO (34.50 mg/g), respectively. Notably, by comparison with the pre-optimization data, the optimized DES extraction efficiency of flavonoids is markedly higher. Thereafter, the characterization of the solvents before and after extraction, as well as the differences between the four extraction solvent extracts, were compared using the FT-IR analyses. Furthermore, SEM results suggested that the penetration and erosion abilities of the plant cell wall of DES-1 were stronger than those of the other three traditional solvents, thus allowing more release of flavonoid compounds. In conclusion, the present research develops a straightforward, sustainable, and exceedingly efficient approach for the extraction of bioactive flavonoids from JFA, which has the potential to facilitate the efficient acquisition of active ingredients from TCM.

A review on natural based deep eutectic solvents (NADESs): fundamentals and potential applications in removing heavy metals from soil

Natural based deep eutectic solvent (NADES) is a promising green solvent to replace the conventional soil washing solvent due to the environmental benign properties such as low toxicity, high biodegradability, high polarity or hydrophilicity, and low cost of fabrication process. The application of NADES is intensively studied in the extraction of organic compounds or natural products from vegetations or organic matters. Conversely, the use of the solvent in removing heavy metals from soil is severely lacking. This review focuses on the potential application of NADES as a soil washing agent to remove heavy metal contaminants. Hydrophilicity is an important feature of a NADES to be used as a soil washing solvent. In this context, choline chloride is often used as hydrogen bond acceptor (HBA) whereby choline chloride based NADESs showed excellent performance in the extraction of various solutes in the past studies. The nature of NADES along with its chemistry, preparation and designing methods as well as potential applications were comprehensively reviewed. Subsequently, related studies on choline chloride-based NADES in heavy metal polluted soil remediation were also reviewed. Potential applications in removing other soil contaminants as well as the limitations of NADES were discussed based on the current advancements of soil washing and future research directions were also proposed.

Exploring the mechanism of solubilization and release of isoliquiritigenin in deep eutectic solvents

Isoliquiritigenin (ISL) is a natural medicinal product with extensive pharmacological activities. However, its low solubility limits its application. Therefore, this study aimed to explore the solubilization and release mechanism of the ISL using deep eutectic solvents (DESs). The choline chloride (ChCl) and oxalic acid (OA)/malic acid (MA)/gallic acid (GA) were used to synthesize ChCl-OA/MA/GA DESs, and the solubility of ISL in these DESs was studied to explore the solubilization mechanism of ISL. The thermodynamic properties of DESs were characterized using differential scanning calorimetry (DSC). The molecular interactions in DESs were studied using spectroscopy and molecular dynamics (MD) simulations. The relative density of DESs was measured using a pycnometric method, its accuracy was validated by comparing it with the MD simulation. The release of ISL from ChCl-OA/MA/GA eutectogels was studied using Carbomer 940 as the thickener, and the release mechanism of ISL in the eutectogels was explored by the drug release kinetic model. The solubility study found that the solubility of ISL in ChCl-OA/MA/GA DESs is 30073, 5055, and 68,103 times higher than that in an aqueous solution. In addition, further studies using MD simulations revealed that enhancing the interactions between ISL and solvent molecules can improve the solubility of ISL in DESs. In vitro release studies showed that the release of ISL in ChCl-OA/MA/GA eutectogels followed a first-order release model, with correlation coefficients of 0.9812, 0.9916, and 0.9961, respectively. In conclusion, the study of the solubilization and release mechanism of ISL in DESs provides new ideas and methods for the study of poorly soluble drugs, which is expected to improve the efficacy and clinical application value of drugs.

Microwave-ultra-fast recovery of valuable metals from spent lithium-ion batteries by deep eutectic solvents

The large-scale use of electric vehicles produced massive discarded lithium-ion batteries, containing many recyclable valuable metals and toxic and harmful substances. Biodegradable and recyclable deep eutectic solvent (DES) is considered a green recycling technology for spent LIBs. Herein, we proposed a microwave-enhanced approach to shorten the leaching time in the urea/lactic acid: choline chloride: ethylene glycol DES system. The dipole moments induced by urea or lactic acid on LiCoO₂ surface increased over two orders of magnitude under the high electric field. Because of this, over 90 % of Li and Co can be fast leached at 4 min and 160 W in the urea/lactic acid: choline chloride: ethylene glycol DES system. Meanwhile, we established two models to explain the leaching mechanism of metal ions from their leaching kinetics and micro-level behavior, and named them dot-etching and layer-peeling processes, respectively. By further analyzing, we found that the dot-etching can be attributed to the synergistic effect of reduction and coordination, which caused the surface of leaching residues porous. The layer-peeling process depends on neutralization, and the leaching residues had a smooth surface in this process. This work highlights the effect of microwave-enhanced strategy and DES surface chemistry on spent electrode materials recovery.

Effect of natural deep eutectic solvents on thermal stability, syneresis, and viscoelastic properties of high amylose starch

This work aimed to use natural deep eutectic solvents to modify the thermal, textural, freeze-thaw, and rheological properties of high amylose rice starch. Three different natural deep eutectic solvents (NADES) composed of sugar and organic acids were applied to modify the properties of starch dispersion. In presence of NADES, the onset temperature of starch was decreased, in comparison with starch in aqueous and glycerol medium. During thermal decomposition, starch with the aqueous and glycerol systems showed two-step weight losses whereas with NADES starch showed single-stage weight losses or decomposition. Moreover, negligible syneresis was observed for starch-NADES dispersion after 3rd cycle of the freeze-thaw process. The flow behavior of starch-NADES dispersion follows Herschel-Bulkley models as R² (0.996 ≤ R² ≤ 0.999) are higher than the Mizrahi-Berk model. The flow behavior index (n) of starch-NADES dispersion was closer to 1, indicated a nearly Newtonian fluid. The loss modulus (G″) value of starch-NADES dispersions was markedly higher than the corresponding storage modulus (G') value and thus materials behaved like viscoelastic liquid. The present study manifested a green way to modify the properties of the high amylose starch to improve the processing stability.