Ethylene glycol-induced metal alkoxides via phase-transfer catalyst as multi-talented adsorbents for boosted adsorption performance of toxic anions/oxyanions from waters

Enhanced removal of toxic Cr(vi) and Pb(ii) from water using carboxylic terminated Ti3C2Tx nanosheets

The discharge of Cr(vi)and Pb(ii) contaminants into water resources through industrial waste induces a considerable risk to human and marine life, which demands an effective removal of these toxic metal ions (MI) from the aquatic environment. This study presents a remarkable adsorption performance of the carboxylic terminated Ti3C2Tx nanosheets synthesized using ammonium bifluoride and citric acid and applied as adsorbents for the removal of Cr(vi)and Pb(ii) from water. Adsorption efficiency was evaluated under sonication, MI concentration, and solution temperature at pH 5.5. Maximum adsorption capacities of 1090 mg g-1 and 1135 mg g-1 for Cr(vi) and Pb(ii) were attained within 7 and 4 minutes, respectively. Moreover, adsorption kinetic and isotherm studies were conducted, and the experimental data was found to fit well with pseudo-second-order reaction and Freundlich models. It was also established that the main interactions to drive the adsorption reactions were the electrostatic forces between the adsorbates and Ti3C2Tx adsorbent. Furthermore, (-COOH) and (-OH) terminal groups were the main contributors to the adsorption of Cr(vi) and Pb(ii) pollutants through an ion exchange mechanism. Besides the ion exchange mechanism, chemical coordination, entrapment of the adsorbates, and van der Waals forces lead to a physiochemical interaction between the MI and Ti3C2Tx nanosheets. In addition, Ti3C2Tx nanosheets showed better selectivity towards Pb(ii) removal than Cr(vi) in an aqueous solution. The nanosheets also exhibited more than 80% removal efficiency even after six cycles of regeneration and reusability. Additionally, Ti3C2Tx nanosheets offered superior adsorption performance for Cr(vi) and Pb(ii) compared to previously reported titanium carbide MXenes and activated carbon-based adsorbents. Hence, these high-quality and efficient Ti3C2Tx nanosheets can potentially eradicate other hazardous MI contaminants from wastewater.

Magnesium ferrite-reinforced polypyrrole hybrids as an effective adsorbent for the removal of toxic ions from aqueous solutions: Preparation, characterization, and adsorption experiments

Contaminated waters with high contents of toxic anions are detrimental to the human health and wildlife. Thus, the quality of drinking water should be carefully monitored. Adsorption technique has been determined to be a reasonable strategy out of several methods used to remove toxic anions from water. Novel MgFe₂O₄-reinforced polypyrrole (Ppy@x%MgFe₂O₄) (x = 1%, 2%, and 5% of MgFe₂O₄) hybrids were synthesized from a pyrrole monomer and MgFe₂O₄ using a simple chemical oxidation method. The fabricated hybrids were studied for their capability to remove PO₄^3-, NO₃^-, and Cr(VI) from aqueous solutions. The results showed that PO₄^3-, NO₃^-, and Cr(VI) removal was highly pH-dependent. The adsorption isotherms of hybrids were fitted well by the Langmuir model, with the maximum adsorption efficiency of 116.90, 76.14, and 138.60 mg/g for PO₄^3-, NO₃^-, and Cr(VI), respectively. In addition, the above-mentioned toxic anions could be efficiently desorbed from spent Ppy@x%MgFe₂O₄ using a 0.1 M NaOH solution, and the hybrids exhibited good regenerability. The prepared materials are promising candidates for PO₄^3-, NO₃^-, and Cr(VI) removal and exhibit high adsorption efficiency, rapid adsorption-desorption behavior, and appropriate recovery from the aqueous medium under external magnetic field.