Nanoarchitectonics with self-healing hydrogel for hierarchical porous carbons and its application in cadmium-arsenic complex pollution

Abstract

A cheap and green method for porous carbons (CAC-1) with high surface area (409.41 mg/g) is constructed benefiting from self-healing properties of calcium alginate hydrogel under atmospheric drying. Layered double hydroxides modified CAC-1 (CAC-LDH-1) is applied in cadmium-arsenic complex pollution. The adsorption capacities of the CAC-LDH-1 on Cd(II) and As(V) are 331.03 mg/g and 33.48 mg/g in single system, and 79.87 mg/g and 150.59 mg/g in binary system. In binary system, the synergistic action of Cd(II) ions greatly improve the adsorption capacity and adsorption rate of As(V) ions. The adsorption process of cadmium-arsenic by CAC-LDH-1 mainly follows the second-order kinetic model and Freundlich model, and the adsorption process is endothermic and spontaneous. XPS, FTIR, XRD, SEM-EDS mapping and pore size distribution are carried out to explore the structure and adsorption mechanism of CAC-LDH-1. After treatment with 1 % CAC-LDH-1 for 30 days, the proportions of E1-Cd, F1-As, and F2-As that can be utilized by plants decrease from 46.32 % to 33.15 %, 10.08–2.15 %, and 43.06–35.23 %. Compared with CK group, Cd/As contents in the above/under-ground part of red cherry radish seedlings decrease by 31.41∼59.09 %. CAC-LDH-1 inhibits little effect on the microbial diversity of soil, but change the dominant bacterial colonies.