Efficient scavenging of Cr(VI) via radiation preparation of amino-functionalized agricultural waste loofah: Behavior and mechanism insight

The excessive discharge of Cr(VI) not only causes severe environmental pollution but also poses significant ecological risks. Thus, it is an urgent human demand and scientific challenge to use renewable biomass to prepare adsorbent in an eco-friendly and efficient way, effectively remove Cr(VI) pollutants, and achieve sustainable development. Herein, loofah, a cheap, strong toughness and 3D network structure, was selected as the substrate. Glycidyl methacrylate (GMA) was grafted onto the surface of loofah via electron beam radiation. Subsequently, two aminated loofah-based adsorbents, PLGD and PLGP, were synthesized through a ring-opening reaction with diethylenetriamine (DETA) and polyethyleneimine (PEI), respectively, followed by protonation. At 318.15 K, the maximum adsorption capacities of PLGD and PLGP for Cr(VI) were determined to be 162.04 and 94.12 mg/g, respectively. The adsorption behavior of Cr(VI) by PLGD and PLGP followed the Langmuir isotherm model and pseudo-second-order (PSO) kinetic model. The pHpzc values of PLGD and PLGP were 6.5 and 9.7, respectively. The potential mechanisms for Cr(VI) removal included electrostatic interactions, ion exchange, surface functional group complexation and reduction. This study provided a strategic approach for utilizing agricultural and forestry waste to develop functional adsorbents for the efficient removal of Cr(VI), and further enhanced the application potential of low-toxicity and cost-effective biosorbents in the elimination of heavy metal pollutants.