Feed Solution Concentration Research Articles

Copper Extraction Using LIX 84 as a Mobile Carrier in the Emulsion Liquid Membrane Process

Extensive research has been conducted to address the growing global demand for copper by exploring effective methods of extraction and recovery across various industries. The emulsion liquid membrane (ELM) has emerged as a viable option for efficiently extracting and recovering metals from waste solutions. Due to its advantageous features, the extraction and recovery of copper from a simulated copper solution was investigated. In the ELM, various parameters can affect the stability and efficiency of copper extraction which include agitation speed, treat ratio (TR), stripping agent, and carrier concentration. However, certain parameters such as homogenizer speed, emulsification time, surfactant concentration, extraction time, and pH of the simulated feed solution were kept constant in this study. The most favourable parameters for achieving maximum copper extraction and recovery were determined such as TR of 1:3, agitation speed (250 rpm), LIX 84 (0.2 M) in kerosene as the carrier, and H2SO4 (0.5 M) as the stripping agent. Using these conditions, approximately 74% of the copper was extracted while 37% was recovered with an acceptable ELM stability indicated by a 20% membrane swelling. This research demonstrates the significant potential of the ELM process for extracting copper from wastewater generated by various industries.

Chiral metal-organic cage modified polyvinylidene fluoride membrane via metal phenolic networks for enantioseparation

High-performance chiral membrane materials hold great promise for the separation of pharmacological enantiomers. The key to achieving high-enantioselective chiral membrane separation is the development of suitable chiral membrane materials. However, traditional chiral separation membranes still face several limitations, including the main problem of the permeability-selectivity trade-off. In this study, a kind of novel chiral metal–organic cage (MOC) modified polyvinylidene fluoride (PVDF) membrane, namely PVDF@TA-Zn@MOC, was fabricated successfully by growing the chiral MOC [Zn3L2] onto the surface of PVDF substrate membranes induced by tannic acid (TA)-Zn2+ (TA-Zn) networks. In brief, ultrathin TA-Zn2+ metal-phenolic network coating was first adhered onto the surface of PVDF substrate membranes, followed with the in-situ growth of chiral MOC [Zn3L2] that was triggered by the coordination-enabled adhesion of Zn2+. A series of chiral PVDF@TA-Zn@MOC membranes were prepared with different hydrophilic properties and MOC loading by adjusting the concentrations of TA and metal/ligand. The transport and separation performances of these membranes were investigated for the mandelic acid (MA) enantiomers, and as a result, when the addition of TA was 1 mg and the metal ion concentration was 3.125 × 10-3 mol·L-1, the chiral membrane PVDF@TA-Zn@MOC-2 exhibited the most extraordinary entrapment ability in both permeability and selectivity for D-MA with an enantiomeric excess value of up to 71 % at a feed solution concentration of 300 ppm for 6 h under the neutral conditions. This method allows for the construction of the chiral hydrophilic MOC nanocoating membranes, which has the potential to broaden the applications of chiral MOC.

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.

Development of long-acting injectable suspensions by continuous antisolvent crystallization: An integrated bottom-up process

Our present work elucidated the operational feasibility of direct generation and stabilization of long-acting injectable (LAI) suspensions of a practically insoluble drug, itraconazole (ITZ), by combining continuous liquid antisolvent crystallization with downstream processing (i.e., centrifugal filtration and reconstitution). A novel microchannel reactor-based bottom-up crystallization setup was assembled and optimized for the continuous production of micro-suspension. Based upon the solvent screening and solubility study, N-methyl pyrrolidone (NMP) was selected as the optimal solvent and an impinging jet Y-shaped microchannel reactor (MCR) was selected as the fluidic device to provide a reproducible homogenous mixing environment. Operating parameters such as solvent to antisolvent ratio (S/AS), total jet liquid flow rates (TFRs), ITZ feed solution concentration and the maturation time in spiral tubing were tailored to 1:9 v/v, 50 mL/min, 10 g/100 g solution, and 96 h, respectively. Vitamin E TPGS (0.5% w/w) was found to be the most suitable excipient to stabilize ITZ particles amongst 14 commonly used stabilizers screened. The effect of scaling up from 25 mL to 15 L was evaluated effectively with in situ monitoring of particle size distribution (PSD) and solid-state form. Thereafter, the suspension was subjected to centrifugal filtration to remove excess solvent and increase ITZ solid fraction. As an alternative, an even more concentrated wet pellet was reconstituted with an aqueous solution of 0.5% w/w Vitamin E TPGS as resuspending agent. The ITZ LAI suspension (of 300 mg/mL solid concentration) has the optimal PSD with a D10 of 1.1 ± 0.3 µm, a D50 of 3.53 ± 0.4 µm and a D90 of 6.5 ± 0.8 µm, corroborated by scanning electron microscopy (SEM), as remained stable after 548 days of storage at 25 °C. Finally, in vitro release methods using Dialyzer, dialysis membrane sac were investigated for evaluation of dissolution of ITZ LAI suspensions. The framework presented in this manuscript provides a useful guidance for development of LAI suspensions by an integrated bottom-up approach using ITZ as model API.

Nutrient recovery from freshwater aquaculture effluent by employing seawater driven zeolite-assisted forward osmosis process

This study focused on recovering nutrients from inland freshwater aquaculture effluent which contains dilute nutrients such as ammonium (NH4+) and phosphate (PO43-) ions. Forward osmosis (FO) process with the assistance of Mg-zeolite Y was employed to recover PO43- through chemical precipitation while NH4+ recovery was achieved by regenerating the zeolite. It showed that zeolite-assisted FO process requires 56.56 ± 2.88 h to dewater 87.5% of the feed solution while standalone FO process took only 51.08 ± 2.99 h. The difference in duration was due to the supplement of Mg2+ that reduces osmotic pressure gradient. The ammonium sorption process of Mg-zeolite Y introduced Mg2+ into the feed solution and facilitated the precipitation of PO43-. Phosphate recovery from the Ca-rich solution from standalone FO process resulted in amorphous calcium phosphate (ACP) with co-precipitation of calcite and dolomite. The zeolite-assisted FO process at pH 10.5 yielded optimal results with 98.46% phosphate recovery, forming mainly amorphous magnesium phosphate (AMP). Subsequently, a two-step precipitation process was proposed to recover Mg2+ as brucite. The concentrated feed solutions from the cycles underwent the proposed two-step precipitation study, resulting in 0.507 g/L of AMP and 5.4077 g/L of brucite. An average of 88.7% NH4+ recovery with high reuse efficiency of Mg-zeolite Y using magnesium sulfate as regenerating solution could be achieved. Reusability studies showed consistent or slightly higher water flux during the dewatering process. The composition of spent regenerant was investigated, and its reuse as liquid fertilizer was feasible after dilution.

Energy, exergy, economic and environment analysis of standalone forward osmosis (FO) system for domestic wastewater treatment

Energy, exergy, economic and environmental analysis is applied to a novel FO system. The system is designed to achieve minimal/zero liquid discharge with low specific energy consumption. Up to 43 % recovery is obtained with desired output in terms of salinity of diluted draw solution and concentrated feed solution. The specific energy required to produce diluted draw and concentrated feed solutions for the proposed application is as low as 0.0285 kWh/m3. In this study, DS-Lumen/AL-DS mode shows specific energy savings of 49.5 % in performed cases compared to FS-Lumen/AL-FS mode using a less flow rate of draw solution. The process design is done to reach the appropriate salinity level at the system outlet. The feed solution connection is in the series between membranes, which helps to dilute the draw solution, while the draw solution connection is in parallel between membranes to achieve desired salinity level at the outlet. The influence of the feed and draw solution temperature and flow rate on the membrane performance is observed. Capital and operating costs of the membrane and other costs, such as tank and chemical solution costs, are significant contributors to the total cost. The specific solution (total output of FO system) cost is estimated at 0.23 $/m3. Environmental analysis suggests that the deployment of solar energy as an energy source of the system reduces 93.06 % of CO2 emissions compared to fossil fuel (coal).

CFD simulation of osmotic membrane distillation using hollow fiber membrane contactor: Operating conditions and concentration polarization effects

Inorganic salts, when present in high concentrations, can disrupt the osmotic balance of aquatic organisms, leading to physiological and ecological harm. Osmotic membrane distillation (OMD) is an emerging technique for recovering inorganic salts from wastewater. The process involves the transfer of water vapor from a feed solution (FS) to a permeate stream due to the difference in vapor pressure across a hydrophobic membrane. It thus results in a concentrated solution at the feed outlet and purified water at the permeate side. OMD is preferred due to its straightforward scale-up and low energy requirements. In this research, a steady state 2-D axisymmetric computational fluid dynamics (CFD) model is developed to study the recovery of sodium carbonate (Na2CO3) from aqueous feed solution through OMD in a hollow fiber membrane contactor (HFMC). Aqueous sodium chloride (NaCl) solution was taken as an osmotic solution (OS). The numerical convection-diffusion mass, momentum transport, and Happel equations were scripted in COMSOL Multiphysics™ version 6.0 software. The model computed the water transport from FS to OS. Computed water flux well matched with the literature based experimental results. Simulations were carried out to investigate the parametric effects, including Reynold’s number, FS and OS concentration and the module geometrical parameters to establish an optimized operating conditions and module geometry and to achieve the desired FS concentration. Results showed that a 2-fold rise in OS concentration increased the transmembrane water flux 4-fold. However, the flow rates of both FS and OS did not significantly affect the flux. On the other hand, concentration polarization (CP) showed dependence on the FS concentration, tortuosity, and Reynolds number. A membrane tortuosity of 1.6, feed concentration of 75 g L−1, OS concentration of 300 g L−1, and a FS Reynolds number in the turbulent flow range can result in higher transmembrane flux and lower chances of CP development.

Why is the film model fundamentally wrong but still able to correlate the experimental data in membrane processes?

The film model that predicts a logarithmic dependence of permeate velocity on feed solute concentration in membrane separation processes is fundamentally wrong because the primary mass balance equation in the model is inapplicable to the total solute. Based on mass balance relationships on the retained solute, The permeate velocity in crossflow membrane separation processes can be rigorously shown to be a cube root function of the retained solute concentration. Furthermore, the reported good fitness of the film model to the experimental permeate velocities can be shown just to be a delusion of curve fitting mainly due to the adjustable parameters in the model.

Improving surface characteristics and operational parameters of polyvinyl chloride ultrafiltration membranes: How to manipulate the performance of thin film composite forward osmosis membranes?

The environmental and economic costs are pivotal aspects that should be considered before the commercialization of any membrane separation-based process. Particularly, realizing this goal relies entirely on the key role played by fabrication and operational parameters. Herein, we introduced a systematic investigation for constructing thin-film composite (TFC) - forward osmosis (FO) membranes for direct fertigation applications. To the best of our knowledge, PVC membrane was rarely used as a porous top surface substrate for TFC-FO membranes. The PVC substrate porous structure and polyamide (PA) active layer were manipulated by variating their concentrations and reaction time to optimize the FO membrane performance. All necessary characterization tools were employed to visualize the fabricated TFC membrane's surface characteristics. The influence of feed solution concentration, membrane orientation, flow rate, and draw solutes on the FO work was also methodically tested. Results demonstrated that the porous structure-substrate membrane host polymer content had imparted a significant role in tailoring the TFC-FO performance concerning permeability and back-solute flux. The water flux was improved by 44.3 % with decreasing of the PVC amount, whereas water flux was improved by 48.13 % with decreasing of the M-phenylenediamine monomer (MPD) content from 3 to 1 wt% at constant tri-mesoylchloride monomer (TMC) content of 0.1 wt% in IP reaction conditions of a thin film. This was gone hand in hand with optimal operational conditions harnessed for optimizing the FO process.

An efficient data-driven desalination approach for the element-scale forward osmosis (FO)-reverse osmosis (RO) hybrid systems

Freshwater shortages are a consequence of the rapid increase in population, and desalination of saltwater has gained popularity as an alternative water treatment method in recent years. To date, the forward osmosis-reverse osmosis (FO-RO) hybrid technology has been proposed as a low-energy and environmentally friendly next-generation seawater desalination process. Scaling up the FO-RO hybrid system significantly affects the success of a commercial-scale process. However, neither the ideal structure nor the membrane components for plate-and-frame FO (PFFO) and spiral-wound FO (SWFO) are known. This study aims to explore and optimize the performance of SWFO-RO and PFFO-RO hybrid element-scale systems in the desalination of seawater. The results showed that both hybrid systems could yield high water recovery under optimal operating conditions. The prediction of the system performance (water flux and reverse salt flux) by artificial intelligence was considerably better (R > 0.99, root mean square error <5%) than that of conventional mass balance models. A Markov-based decision tree successfully classified the water flux level in hybrid systems. An optimal set of operational conditions for each membrane system was proposed. For example, in RO, a combination of the feed solution (FS) flow rate (≥17.5 L/min), FS concentration (<17,500 ppm), and operation pressure (<35 bar) would result in high water permeability (>40 LMH). In addition, five SWFO elements and four PFFO elements should be the optimal numbers of FO membranes in the hybrid FO-RO system for effective seawater desalination, especially for long-term operation.

Reduction of Concentrating Poisonous Metallic Radicals from Industrial Wastewater by Forward and Reverse Osmosis

The research aims to use a new technology for industrial water concentrating that contains poisonous metals and recovery quantities from pure water. Therefore, the technology investigated is the forward osmosis process (FO). It is a new process that use membranes available commercial and this process distinguishes by its low cost compared to other process. Sodium chloride (NaCl) was used as draw solution to extract water from poisonous metals solution. The driving force in the FO process is provided by a different in osmotic pressure (concentration) across the membrane between the draw and poisonous metals solution sides. Experimental work was divided into three parts. The first part includes operating the forward osmosis process using TFC membrane as flat sheet for NaCl. The operating parameters studied were: draw solutions concentration (10 – 95 g/l), draw solution flow rate (12-36 I/h), temperature of draw solution (30 and 40°C), feed solution concentration (10 -210 mg/l), feed solution flow rate (10 -50 l/h), temperature of feed solution (30 and 40°C) and Pressure (0.4 bar). The second part includes operating the forward osmosis process using CTA membrane as flat sheet for NaCl. The operating parameters studied were: draw solution concentration (15 – 95 g/l), feed solution concentration (10-210 mg/l). Constant temperature was maintained at 30°C. The last part includes operating the reverse osmosis process using TFC membrane as spiral wound module in order to separate NaCl salt from draw solution and obtain on pure water so as to usefully in different uses and also obtain on solution of NaCl concentrate which was recirculated to forward osmosis process. It is then used as draw solution. The operating parameter studied was: feed solution flow rate (15-55 l/h). The experimental results show that the water flux increases with increasing draw solution concentration, feed solution flow rate, temperature of draw solution and decreases with increasing feed solution concentration, draw solution flow rate and temperature of feed solution. The experiments also show that CTA membrane gives higher water flux than TFC membrane for forward osmosis operation.

Water Recovery from Brine Solution by Forward Osmosis Process

The present work aims to study the possibility of utilization a forward osmosis desalination process as an alternative method to extract water from brine solution rejected from reverse osmosis process. Experiments conducted in a laboratory–scale forward osmosis (FO) unit in cross flow flat sheet membrane cell yielded water flux ranging from (0.0315 to 0.56 L/m2 .min) when using CTA membrane,and ranging from (0.419 to 2.785 L/m2 .min) for PA membrane under 0.4 bar. Two possible membrane orientations were tested. Sodium chloride with high concentrations was used as draw solution solute. The effect of membrane orientation on internal concentration polarization (ICP) was studied. Two regimes of ICP; dilutive and concentrative were described and characterized and their governing equations were applied. Also the effect of draw and feed solution concentrations and flow rate were studied. It was found that the experimental water flux were lower than the theoretical water flux. Using of PA membrane under pressure was resulted in a higher flux of desalinated water than when CTA used alone without pressure under the same operating conditions.

Forward Osmosis Process for the Treatment of Wastewater from Textile Industries

This paper was aimed to study the efficiency of forward osmosis (FO) process as a new application for the treatment of wastewater from textile effluent and the factors affecting the performance of forward osmosis process.The draw solutions used were magnesium chloride (MgCl2), and aluminum sulphate (Al2 ( SO4)3 .18 H2O), and the feed solutions used were reactive red, and disperse blue dyes.Experimental work were includes operating the forward osmosis process using thin film composite (TFC) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), feed solutions concentration (5 – 30 mg/l), draw solutions flow rate (10 – 50 l/hr), feed solutions flow rate (20-60 l/hr), constant pressure and temperature were maintained at 0.5 bar and 30ºC respectively. And includes operating the forward osmosis process using cellulose triacetate (CTA) membrane as flat sheet for different draw solutions and feed solutions. The operating parameters studied were : draw solutions concentration (10 – 90 g/l), and feed solutions concentration (5 – 30 mg/l), constant temperature at 30ºC. It was found that water flux increases with increasing draw solution concentration, and feed solution flow rate and decreases with increasing draw solution flow rate and feed solution concentration for TFC and CTA. It was found MgCl2 given water flux larger than Alum. And also found that reactive red given water flux larger than disperse blue.The experiments also show that CTA membrane gives higher water flux than TFC membrane for forward osmosis operation. The increase in water flux for CTA is about 12.85% than TFC.

Evaluating dye recovery and reusability potential from dyebath effluent using forward osmosis membranes for minimum liquid discharge

This study focuses on the evaluation of dye recovery and reuse potential from denim and polyester effluents using forward osmosis (FO). A cationic surfactant, tetraethylammonium bromide (TEAB), was used as the draw solution (DS). After optimizing the DS and feed solution (FS) concentrations and temperatures in batch experiments, a DS concentration of 0.75 M was selected at a 60 °C temperature for the semi-continuous mode. It generated a high flux of 18 L/m2/h and a low reverse solute flux (RSF) of 0.4 g/m2/h with 100% dye rejection. Dye reconcentration of 82–98% was achieved in the dyebath effluents. The unique property of surfactants to combine hundreds of monomers into micelle resulted in negligible RSF. Reversible fouling was observed on the membrane active layer, and NaOH and citric acid cleaning achieved about 95% of flux recovery. The functional groups on the membrane's active layer remained undisturbed due to foulant interactions showing its chemical stability against reactive dyes. Recovered dye characterization using 1D proton nuclear magnetic resonance (1HNMR) analysis depicted a 100% structural resemblance to the original dye. Hence, it can be reused for dyeing the next batch. Diluted TEAB solution can be used as fabric detergent and softener within the same textile industry in the finishing process. A minimum liquid and persistent pollutant (dyes) discharge is achieved by adopting the methodology proposed in this work with a strong potential of translating it to an industrial scale.

Forward-Reverse Osmosis Processes for Oily Wastewater Treatment

In this study, the feasibility of Forward–Reverse osmosis processes was investigated for treating the oily wastewater. The first stage was applied forward osmosis process to recover pure water from oily wastewater. Sodium chloride (NaCl) and magnesium chloride (MgCl2) salts were used as draw solutions and the membrane that was used in forward osmosis (FO) process was cellulose triacetate (CTA) membrane. The operating parameters studied were: draw solution concentrations (0.25 – 0.75 M), oil concentration in feed solution (FS) (100-1000 ppm), the temperature of FS and draw solution (DS) (30 - 45 °C), pH of FS (4-10) and the flow rate of both DS and FS (20 - 60 l/h). It was found that the water flux and oil concentration in FS increase by increasing the concentration of draw solutions, the flow rate of FS and the temperature for a limit (40oC), then, the water flux and oil concentration decrease with increasing the temperature because of happening the internal concentration polarization phenomenon. By increasing the oil concentration in FS and the flow rate of the DS, the water flux and oil concentration in FS decreased, while it had a fluctuated behavior with increasing pHof oily wastewater. It was found also that MgCl2 gives water flux higher than NaCl. So the values of resistance to solute diffusion within the membrane porous support layer were 55.93 h/m and 26.21 h/m for NaCl and MgCl2 respectively. The second stage was applied reverse osmosis process using polyamide (thin film composite (TFC)) membrane for separating the fresh water from a diluted (NaCl) solution using different parameters such as draw solution concentration (0.08–0.16 M), feed flow rate (20–40 l/h).

Investigation of Crystal Size Distribution in Purification of Terephthalic Acid from Polyester Textile Industry Waste by Reactive Crystallization

The purification of terephthalic acid recovered from an alkali-reduction wastewater by reactive crystallization was investigated. The crude terephthalic acid was reacted with sodium hydroxide solution to form a salt of disodium terephthalate, then acidified with sulfuric acid to get the terephthalic acid with higher purity. Effects of time, pH, concentration, and flow rate of secondary feed solutions, temperature, and stirring rate on Crystal Size Distribution (CSD) of terephthalic acid precipitate were investigated. The results showed that CSD was influenced by the concentration of reactants and the pH solution. On the other hand, time, temperature, flow rate of secondary solution, and stirring rate had no significant effects on the CSD, which the mean size of crystals ±3 μm. The mean size of crystals at solution pH 5, 4, and 3 were 6.03, 9.42, and 10.34 μm, respectively; meanwhile, at concentrations of 0.5, 0.3, and 0.1 M, were 7.57, 3.24, and 3.09 μm, respectively. The semi-batch reactive crystallization with double-feeding at constant pH and temperature produced monodispersed crystals. However, this method needs to be carried out more than once for terephthalic acid purification, which is intended for polyethylene terephthalate (PET) polymerization.

Hierarchical mesoporous spherical Zn(4-hzba) MOF for efficient adsorption of Strontium and Caesium ions from aqueous solution

This paper describes the synthesis of mesoporous spherical Zn(4-hzba) MOF with the formula of {[Zn(μ-4-hzba)2]2}n utilizing 4-hydrazinyl benzoic acid (4-hzba) linker by solvothermal method. And investigates its adsorptive efficiency towards strontium (Sr2+) and caesium (Cs+) by varying contact time, pH, and feed solution concentration. 10 mg of Zn(4-hzba) MOF show maximum adsorption capacity of 275.2 mg/g for Sr2+ and 335.05 for Cs+ at pH 4 from a 100 mg/L sample solution within 100 min at room temperature. Among the Langmuir, Freundlich and Temkin adsorption isotherms studies, the Langmuir isotherm was well fitted for Sr2+ and Cs+ adsorption onto MOF, demonstrating the monolayer adsorption. Experimental data and pseudo-second-order kinetic studies showed that chemisorption is the dominant process. High adsorption efficiency was demonstrated by electrostatic interaction between positively charged Sr2+/Cs+ and the negatively charged surface of the MOF at pH 4 was proved by zeta potential analysis. IR, SEM, XPS analysis and Langmuir adsorption studies support the monolayer surface complexation mechanism. While the ion exchange mechanism followed by surface complexation of Sr2+/ Cs+ with replacement of hydrogen in H2NNH- of the MOF. In order to acquire a good picture of the ion exchange mechanism, and Sr2+/Cs+ exchanged MOF were optimized, and the binding energies of Sr2+ (2.19 kJ/mol) and MOF Cs+ (2.06 kJ/mol) were calculated by DFT method using Gaussian 16. Recycle studies of Zn(4-hzba) MOF show 80% recovery of Sr2+ and Cs+ even after seven cycles. The adsorption of Sr2+ and Cs+ was influenced by dosage, initial concentration of metal ions, pH solution, contact time, and coexisting ions of Na, K, Ca, and Mg. Adsorption efficiency of Sr2+ and Cs+ ions in simulated seawater was 92.3% and 96.7%, respectively.

Li1.5Al0.5Ge1.5(PO4)3 membrane electrodialysis for lithium enrichment

Highly purified LiOH is a common raw material of cathode active materials of lithium-ion batteries. Its demand is rapidly increasing with the fast development of the electric vehicles. The traditional enrichment process of LiOH relying on water evaporation requires a lot of energy. Here, we demonstrate the ability of NASICON-type Li1.5Al0.5Ge1.5(PO4)3 membrane electrodialysis to enrich the LiOH aqueous solution with a low concentration. This Li1.5Al0.5Ge1.5(PO4)3 membrane electrodialysis could extract 99.7% and 96.5% of Li+ in 0.1, and 0.01 M LiOH feed solution, respectively, into 1 M LiOH receiving solution. And the transmembrane resistance between feed solution and receiving solution increased by 37.4, 389.5, and 964.6 Ω cm2, compared to the value for 1 M of LiOH feed solution as the feed solution concentration decreased to 0.1, 0.01 and 0.001 M, respectively. This quantitative assessment method for the resistance variation is crucial to the potential separation application of Li1.5Al0.5Ge1.5(PO4)3 membrane electrodialysis in salt-lake brine.

Efficient nitrate reduction in water using an integrated photocatalyst adsorbent based on chitosan-titanium dioxide nanocomposite.

Globally, there exists a huge concern on the increased discharge of nitrates to the natural water resources out of various anthropogenic activities as it causes serious environmental pollution and associated harmful effects. In the present work, sol-gel-derived functional nanocomposites based on silver (Ag) and nitrogen (N)-doped titanium dioxide (TiO2)-coated chitosan nanocomposites were successfully synthesized in the form of beads, and their application for the reduction of nitrates in water was studied. The synthesized nanocomposite beads were characterized for their structural, textural, and morphological features using X-ray diffraction analysis, Fourier transform infrared spectroscopy, UV-visible spectroscopy, BET surface area analysis, Scanning electron microscopy, Transmission electron microscopy, and X-ray photoelectron spectroscopy. A uniform coating of doped titania species on the chitosan porous structure was achieved through electrostatic interaction. Adsorption/photocatalytic reduction of nitrates was further carried out using functional nanocomposite beads by monitoring the nitrate concentration of the model contaminated water, in an adsorption study under dark condition and photocatalytic study under UV/sunlight for a definite time period. Drying conditions of the nanocomposite beads were found to have a significant effect on the adsorption cum photocatalytic efficiencies of the nanocomposite. The freeze-dried chitosan-titania nanocomposite beads containing 0.5mol% Ag exhibited an adsorption efficiency of ~ 43.5% (under dark for 30min) and photocatalytic reduction capability of ~ 95% (under sunlight for 2h), whereas the oven dried beads of the same composition exhibits adsorption and photocatalytic efficiencies of 40% (under dark for 30min) and 70% (under UV light for 2h) respectively, towards the reduction of nitrate ions in an aqueous solution. Continuous flow adsorption cum photocatalytic study using the oven-dried nanocomposite beads was also carried out with the help of an experimental setup fabricated in-house and under varying experimental conditions such as flow rate, bed height, and concentration of feed solution. Nitrate reduction efficiency of 87.6% and an adsorption capacity of 7.9mgg-1 were obtained for the nanocomposite beads in the continuous flow adsorption cum photocatalysis experiment for up to 8h when using an inlet concentration of 100ppm, bed height 12cm, and flow rate 5.0mLmin-1. A representative fixed-bed column adsorption experiment performed with oven dried nanocomposite beads in a real groundwater sample collected from the Palakkad District of Kerala shows promising results for nitrate reduction (85.9% efficiency) along with a significant removal rate for the other anions as well. Thus, the adsorption cum photocatalytic nitrate reduction efficiency of the functional nanocomposite material makes them suitable for the reduction of nitrates from water/wastewater through an integrated nanocomposite approach.

Recombinant production in Escherichia coli of a β-galactosidase fused to a cellulose-binding domain using low-cost inducers in fed-batch cultivation

This study aimed to determine the effects of different feeding strategies in fed-batch cultivations on the production of β-galactosidase fused to a cellulose-binding domain (CBD) by Escherichia coli C41(DE3) using a bench bioreactor. The highest enzyme activities (∼17,000 U/L) were obtained in fed-batch cultivations controlled by DO-stat and induced with lactose (5 g/L) at 18 h of cultivation. Under these cultivation conditions, the maximum values of β-galactosidase yields per substrate, β-galactosidase yields per biomass, and QP were approximately 950 U/gglucose, 1100 U/gcells, and 540 U/L.h, respectively, using Terrific Broth as culture medium and concentrated feed solution (2 ×). The dairy coproducts were efficient in inducing the expression of the recombinant enzyme, having reached the highest values of β-galactosidase-CBD activity after 40 h of cultivation. The maximum enzyme activities obtained when using whey permeate or ricotta whey as inducers were 22,950 or 24,640 U/L, respectively. Using the optimal temperature of E. coli growth before induction and ricotta whey as an inducer increased enzyme productivity in 50%. Plasmid construction showed high stability (>94%) throughout E. coli cultivation. This study demonstrated the feasibility of using the DO-stat feeding strategy to produce β-galactosidase-CBD employing ricotta whey as an inducer of enzyme expression.