Facile synthesis of polyethyleneimine-reinforced PHTA resin for efficient Cr(VI) removal

Toxic Cr(VI) residual in water has triggered constant worries for human health. To tackle this issue, mussel-inspired chelate resins with designable structure and abundant functional groups are emerging to purify the pollutant. Herein, the poly(hydroquinone-tetraethylenepentamine/polyethyleneimine) (PHTA-m%PEI_t) cross-linked resin had been firstly tailored as a representative adsorbent with respect to rapidly remove Cr(VI), originated from “self-assembly to polymerization”. Various characterizations had been performed to identify its microstructure and structure–activity relationship, including SEM, FT-IR, XPS, TGA, etc. Effects of PEI modification, solution volume, initial concentration, pH, adsorbent dosage, contact time, etc, on the removal of Cr(VI) were investigated systematically. Adsorption kinetics, isotherm, and thermodynamics had been explored to understand the uptake mechanism. Factually, the culminating impressive performance (q_m = 819.67 mg g⁻¹) was ascertained in PHTA-5%PEI₃₆ candidate, due to the stronger affinity of the protonated -NH₂/-NH- groups to Cr(VI) confirmed by density functional theory (DFT) and XPS investigations. A favorable monolayer chemisorption of Cr(VI) occurred on the homogeneous surface of PHTA-5%PEI₃₆, and the adsorption rate underwent a rate-limiting step. The toxic Cr(VI) reduced to Cr(III) accompanied the adsorption procedure. Accordingly, the creditable PHTA-5%PEI₃₆ with the strong anti-interference ability, has potential as a as a promising option for wastewater treatment.