Adsorption of Ethylenediaminetetraacetic Acid on a Gel-Type Ion-Exchange Resin for Purification of Liquid Waste Containing Cs Ions

Vanadium(V) Removal from Aqueous Solutions and Real Wastewaters onto Anion Exchangers and Lewatit AF5

Adsorption abilities of weakly (Purolite A830), weakly basic/chelating (Purolite S984), and strongly basic (Lewatit MonoPlus SR7, Purolite A400TL, Dowex PSR2, Dowex PSR3) ion exchange resins of different functional groups and microporous Lewatit AF5 without functional groups towards vanadium(V) ions were studied in batch and column systems. In the batch system, the influence of the sorbent mass (0.01–0.1 g), pH (2–10), the phase contact time (1–1440 min),and the initial concentration (5–2000 mg/L) were studied, whereas in the column system, the initial concentrations (50, 100, and 200 mg/L) with the same bed volume and flow rate (0.4 mL/min) were studied. Desorption agents HCl and NaOH of 0.1–1 mol/L concentration were used for loaded sorbent regeneration. The pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models as well as the Langmuir, Freundlich, Temkin, and Dubinin–Radushkevich isotherm models were used to describe kinetic and equilibrium data to acquire improved knowledge on the adsorption mechanism. The desorption efficiency was the largest using 0.5 mol/L NaOH for all sorbents under discussion. Purolite S984, Purolite A830, and Purolite A400TL, especially Purolite S984, are characterized by the best removal ability towards vanadium(V) from both model and real wastewater.

Preparation of Slow-Release Insecticides from Biogas Slurry: Effectiveness of Ion Exchange Resin in the Adsorption and Release of Ammonia Nitrogen

The insecticidal ingredient in a biogas solution being fully utilized by cation exchange resin to produce slow-release insecticide is of great social value. In this work, the feasibility of ammonia nitrogen in a biogas slurry loaded on resin as a slow-release insecticide was evaluated by studying the effect of adsorption and the slow release of ammonia nitrogen by resin. The effects of the ammonia nitrogen concentration, resin dosage, adsorption time and pH value on the ammonia nitrogen adsorption by the resin were studied. The results showed that the ion exchange resin had a good adsorption effect on the ammonia nitrogen. With the increase of the resin dosage, time and ammonia nitrogen concentration, the adsorption capacity increased at first and then stabilized. The ammonia nitrogen adsorption capacity reached its maximum value (1.13 mg) when the pH value was 7. The adsorption process can be fitted well by the Langmuir isothermal adsorption equation and quasi-second-order kinetic model. Additionally, the release rate of the ammonia nitrogen increased with the increasing sodium chloride concentration. The adsorption capacity of ammonia nitrogen by the D113 (resin type) resin decreased by 15.8% compared with the ammonium chloride solution. The report shows that the ion exchange resin has a good adsorption effect on ammonia nitrogen, which is of guiding significance for expanding the raw materials for slow-release insecticides, improving the utilization rate of biogas slurry and cleaner production of slow-release insecticides from biogas slurry. Additionally, all variables showed statistical differences (p < 0.05).

Selenide-chitosan as High-performance Nanophotocatalyst for Accelerated Degradation of Pollutants

Water pollution is one of the major global challenges today. Water bodies are contaminated by the heavy release of waste effluents of textile industries, which includes intensively colored dye pollutants. Herein, a ternary nanocomposite of bismuth copper selenide with small particle size and ternary metal selenide (TMS)-chitosan microspheres (TMS-CM) of the spherical porous surface were successfully synthesized. SEM, XRD, EDX, FTIR, and UV/Vis spectrophotometry analysis revealed the structural and morphological characteristics of the newly synthesized nanocomposites. SEM imaging showed the average diameter of TMS nanoparticle to be 33 nm. The crystal size was calculated as 6.33 nm and crystalline structure as orthorhombic using XRD findings. EDX confirmed the presence of Bi, Cu, and Se in the ternary nanocomposite. The bandgap of 1.8 eV was calculated from Tauc's plot for the TMS nanocomposite. SEM confirmed the successful synthesis of spherical TMS-CM microspheres of porous surface morphology with an average size of 885.6 μm. The presence of chitosan microspheres in the synthesis of TMS nanocomposite was identified by FTIR spectral analysis. Furthermore, highly efficient photocatalytic degradation (up to 95.4%) of ARS was achieved within 180 min at pH 4.0 using 0.5 g of TMS-CM in sunlight. The first-order kinetic model fitted well to the photocatalytic decontamination of ARS using TMS-CM with a rate constant of 6.1x10^-2  min^-1 . The TMS-CM gave attractive results and high efficiency in photocatalytic degradation of ARS dye after reusing and regeneration of up to seven successive cycles. The newly synthesized nanophotocatalyst could be efficiently used for the decontamination of dye polluted water from textile industries.

Cesium ion-exchange resin using sodium dodecylbenzenesulfonate for binding to Prussian blue

Radioactive Cs ions are extremely harmful to the human body, causing cancers and other diseases. Treatments were performed on radioactive Cs present in wastewater after use in industrial or medical fields. Prussian blue (PB) has been widely used for the removal of Cs ions from water but its colloidal structure hinders reuse, making it problematic for practical use. To solve this problem, we used a commercial macroporous polymer resin as a PB matrix. To provide an efficient anchor for PB, the surface of the polymer resin was decorated with sodium dodecylbenzenesulfonate to produce a negatively charged surface. The successful chemical binding between the polymer resin and PB prevented leakage of the latter during adsorption and crosslinked structure of the matrix provided regeneration of the adsorbent. The adsorbent maintained its removal efficiency after five repeats of the regeneration process. The PB-based, Cs ion-exchange resin showed excellent selectivity toward Cs ions and good reusability, maintaining its high adsorption capacity.