Novel and highly efficient functionalized bentonite for elimination of Cu2+ and Cd2+ from aqueous wastes

The aim of this study was to synthesize novel and highly efficient functionalized material (BNMPTS) for selective elimination of Cu²⁺ and Cd²⁺ from aqueous waste. The detailed insights of solid/solution interactions were investigated by X-Ray photoelectron spectroscopic analyses. The grafting of silane caused for significant decrease in specific surface area of bentonite from 41.14 to 4.65 m²/g. The functionalized material possessed significantly high sorption capacity (12.59 mg/g for Cu²⁺ and 13.19 mg/g for Cd²⁺) and selectivity for these cations. The material showed very high elimination efficiency at a wide range of pH ~2.0 to 7.0 for Cu²⁺, ~3.0 to 10.0 for Cd²⁺ and concentration (1.0 to 25.0 mg/L) for Cu²⁺ and Cd²⁺. A rapid uptake of these two cations achieved an apparent equilibrium within 60 minutes of contact. The increased level of background electrolyte concentrations (0.0001 to 0.1 mol/L) did not affect the elimination efficiency of these two cations by BNMPTS. Moreover, the common coexisting ions did not inhibit the removal of these toxic ions. Furthermore, high breakthrough volumes i.e., 1.4 and 3.69 L for Cu²⁺, 2.6 and 6.64 L for Cd²⁺ was obtained using 0.25 and 0.50 g of BNMPTS respectively in a fixed-bed column operations.

Capillary electrophoresis with capacitively coupled contactless conductivity detection: Recent applications in food control

Food quality control has become much more important during the last decade and demanded the development of robust, efficient, sensitive, and cost-effective analytical techniques. Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C4D) is a powerful separation method based on the different migration time rate of components in the background electrolyte solution, and it is suitable for all charged ions. There is a large number of compound groups in food that can be determined by the CE-C4D method, such as amino acids, biogenic amines, fatty acids, food additives, sweeteners, and nutrients. This paper provides an overview of recent applications of the CE-C4D in food analysis over the last decade. General conclusions and future prospects of applicability of the CE-C4D method in food analysis are presented.

Study on development of an analytical procedure to quantify glyphosate by capillary electrophoresis method and its application for beverage

Nowadays, the issue of fresh food, drinks, and residue analysis of toxic compounds in food and drinks is increasingly interested in society. In this study, an analytical procedure for quantitative analysis of the glyphosate residue in beverages such as tea infusion and beer was developed based on the capillary electrophoresis method with capacitively-coupled contactless conductivity detector combined with sample preparation using solid phase extraction technique. The analytical conditions optimised for capillary electrophoresis equipment included: histidine/acetic acid background electrolyte solution with histidine concentration of 1 mM and pH value was adjusted to 2.75 by acetic acid; a separation voltage was 20 kV was applied and a high voltage injection at 20 kV for 10 seconds was chosen. The optimised analytical procedure has resulted in a low detection limit of glyphosate (0.42 μg/l), the repeatability and reproducibility expressed by the relative standard deviation of the peak area and migration time were both less than 10%, a wide linear range, and the obtained recovery efficiency of glyphosate on different drinks were achieved to values ranging from 88.7 to 96.3%.

Optimisation of analytical conditions for simultaneous determination of phenol and chlorophenols by capillary electrophoresis with indirect laser-induced fluorescence detection

This work presented a capillary electrophoresis method with indirect laser-induced fluorescence detection for the simultaneous determination of phenol and four chlorophenol derivatives. The separation was obtained within 20 minutes with a background electrolyte composed of 5 mM borax and 1 mM fluorescein (pH=9.75), 17 kV of applied voltage, and 120 s of hydrostatic injection. At the optimal conditions, the limit of detections for phenolic compounds was in the range of 0.08-0.23 mg/l, and the RSD data of repeatability and reproducibility were less than 8.0% for both migration times and peak areas. This developed method was applied to analyse concentrations of phenolic compounds in surface water and wastewater samples, with the recoveries ranging from 59.4 to 102.5%.

Software development for calculating concentration in a buffer to the preparation of background electrolyte in the analytical method of capillary electrophoresis

pH buffers of weak organic acids and bases are essential in capillary electrophoresis (CE) analyses, primarily when contactless conductivity detectors (C4D) are used. However, the preparation of a buffer with a known concentration of one component for use as a background electrolyte (BGE) in CE-C4D usually requires a pH adjustment to the desired value and an approximate calculation to estimate the concentration of the second component. This study developed software that allowed determining the concentration of one component when knowing the concentration of another component and the pH of the solution, taking into account the influence of ionic strength. The software was built in C# language with Windows Form interface on Microsoft Visual Studio. With the concentrations calculated from the developed software, the differences (|ΔpH|) between pH values of the obtained BGEs in practice and the desired values were smaller than 0.07, corresponding to the errors of less than 2%.

Hybrid materials precursor to natural bentonite in the decontamination of Alizarin Yellow from aqueous solutions

The present study aims to investigate the insights of Alizarin Yellow removal by hybrid materials precursor to natural bentonite. The hybrid materials employed are bentonite modified with hexadecyltrimethylammonium bromide (HDTMA) (BnH) and aluminium pillared HDTMA bentonite (BnAH). Surface morphology of materials are obtained with scanning electron microscopy-Energy dispersive X-ray analysis (SEM-EDX). The batch reactor operations conducted in the removal of Alizarin Yellow by these solids for various parametric studies which enabled to deduce the mechanism involved at solid/solution interface. Sorption capacity and selectivity was increased significantly using hybrid materials in the removal of AY. Hybrid materials showed very high removal capacity of AY and apparently unaffected at varied pH (4.0−10.0) and sorptive concentrations 1.0 to 25.0 mgL^-1. Kinetic studies indicated that an apparent equilibrium occurred within 5–10 min of contact and the kinetic data was better fitted to the pseudo-second-order kinetic model. The percent removal of AY was not affected by increasing the background electrolyte (NaCl) concentration to 0.1 molL^-1 and in presence of several co-existing ions. It is revealed that the hybrid materials are found more organophilic and AY molecule bound with strong forces at the surface of hybrid materials.

Simultaneous Determination of Ciprofloxacin and Ofloxacin in Animal Tissues with the Use of Capillary Electrophoresis with Transient Pseudo-Isotachophoresis

We have developed a precise and accurate method for the determination of ciprofloxacin and ofloxacin in meat tissues. Our method utilizes capillary electrophoresis with a transient pseudo-isotachophoresis mechanism and liquid–liquid extraction during sample preparation. For our experiment, a meat tissue sample was homogenized in pH 7.00 phosphate buffer at a ratio of 1:10 (tissue mass: buffer volume; g/mL). The extraction of each sample was carried out twice for 15 min with 600 µL of a mixture of dichloromethane and acetonitrile at a 2:1 volume ratio. We then conducted the electrophoretic separation at a voltage of 16 kV and a temperature of 25 °C using a background electrolyte of 0.1 mol/L phosphate–borate (pH 8.40). We used the UV detection at 288 nm. The experimentally determined LOQs for ciprofloxacin and ofloxacin were 0.27 ppm (0.8 nmol/g tissue) and 0.11 ppm (0.3 nmol/g tissue), respectively. The calibration curves exhibited linearity over the tested concentration range of 2 to 10 nmol/g tissue for both analytes. The relative standard deviation of the determination did not exceed 15%, and the recovery was in the range of 85–115%. We used the method to analyze various meat tissues for their ciprofloxacin and ofloxacin contents.

Selective cobalt and nickel electrodeposition for lithium-ion battery recycling through integrated electrolyte and interface control

Molecularly-selective metal separations are key to sustainable recycling of Li-ion battery electrodes. However, metals with close reduction potentials present a fundamental challenge for selective electrodeposition, especially for critical elements such as cobalt and nickel. Here, we demonstrate the synergistic combination of electrolyte control and interfacial design to achieve molecular selectivity for cobalt and nickel during potential-dependent electrodeposition. Concentrated chloride allows for the speciation control via distinct formation of anionic cobalt chloride complex (CoCl42-), while maintaining nickel in the cationic form ([Ni(H2O)5Cl]+). Furthermore, functionalizing electrodes with a positively charged polyelectrolyte (i.e., poly(diallyldimethylammonium) chloride) changes the mobility of CoCl42- by electrostatic stabilization, which tunes cobalt selectivity depending on the polyelectrolyte loading. This strategy is applied for the multicomponent metal recovery from commercially-sourced lithium nickel manganese cobalt oxide electrodes. We report a final purity of 96.4 ± 3.1% and 94.1 ± 2.3% for cobalt and nickel, respectively. Based on a technoeconomic analysis, we identify the limiting costs arising from the background electrolyte, and provide a promising outlook of selective electrodeposition as an efficient separation approach for battery recycling.

Validated Capillary Zone Electrophoretic Determination of Avanafil and Dapoxetine Hydrochloride in their Pure form and Pharmaceutical Preparation

Aims: In this study, a simple, green, and rapid capillary zone electrophoresis (CZE) method coupled with a diode array detector (DAD) was applied for the analysis of avanafil (AVA) and dapoxetine hydrochloride (DAP) as a binary mixture using vardenafil (VAR) as an internal standard (IS) in pure form and pharmaceutical formulation. Methodology: The separation was done using fused silica capillary (58.5 cm total length, 50 cm effective length, and 50 μm internal diameter) and the running background electrolyte (BGE) was 100 mM acetate buffer at pH 3.6. During the separation process, the applied voltage was 30 KV, while the temperature was 25 °C. The sample injection was applied at a pressure of 50 mbar for 10 s, and detection was carried out at 210 nm for DAP and 248 nm for AVA and VAR. Results: Analysis of the tested drugs and the internal standard was carried out in less than 6.5 min, where the migration times were 4.29, 4.90, and 6.02 min for IS, DAP and AVA respectively. The proposed method showed linearity in the concentration range 5-80 and 5-70 μg/mL with correlation coefficients 0.9996 and 0.9999 for AVA and DAP respectively. The limit of detection (LOD) was 0.523 and 0.531 for AVA and DAP respectively, while the limit of quantification (LOQ) was 1.585 and 1.608 in respective order. The Peak purity and identity in the proposed method were validated by DAD. Conclusion: The proposed CZE method was validated according to ICH guidelines and applied successfully for the estimation of AVA and DAP in their combined pharmaceutical preparation.

The efficiency of nano-TiO2 and γ-Al2O3 in copper removal from aqueous solution by characterization and adsorption study

Water pollution is a major global challenge given the increasing growth in the industry and the human population. The present study aims to investigate the efficiency of TiO2 and γ-Al2O3 nanoadsorbents for removal of copper (Cu(II)) from aqueous solution as influenced by different chemical factors including pH, initial concentration, background electrolyte and, ionic strength. The batch adsorption experiment was performed according to standard experimental methods. Various isotherm models (Freundlich, Langmuir, Temkin, and Dubinin–Radushkevich) were fitted to the equilibrium data. According to geochemical modeling data, adsorption was a predominant mechanism for Cu(II) removal from aqueous solution. Calculated isotherm equations parameters were evidence of the physical adsorption mechanism of Cu(II) onto the surface of the nanoparticles. The Freundlich adsorption isotherm model could well fit the experimental equilibrium data at different pH values. The maximum monolayer adsorption capacity of TiO2 and γ-Al2O3 nanosorbents were found to 9288 and 3607 mg kg−1 at the highest pH value (pH 8) and the highest initial Cu(II) concentration (80 mg L−1) respectively. Copper )Cu(II) (removal efficiency with TiO2 and γ-Al2O3 nanoparticles increased by increasing pH. Copper )Cu(II) (adsorption deceased by increasing ionic strength. The maximum Cu(II) adsorption (4510 mg kg−1) with TiO2 nanoparticles was found at 0.01 M ionic strength in the presence of NaCl. Thermodynamic calculations show the adsorption of Cu(II) ions onto the nanoparticles was spontaneous in nature. Titanium oxide (TiO2) nanosorbents could, therefore, serve as an efficient and low-cost nanomaterial for the remediation of Cu(II) ions polluted aqueous solutions.