A bowl-shaped structure-controllable hydrothermal carbon experiment design combined with DFT simulation: Efficient adsorption of Cd and Pb in coal gangue accumulation areas

Abstract

As industrial mining develops, massive cadmium (Cd) and lead (Pb) have migrated and polluted the soil in large mining areas, which seriously threatens human health and ecology. Here, a bowl-shaped structure-controllable hydrothermal carbon (HC) was prepared with D-ribose as biomass raw material and sodium oleate (SO) and PEO-PPO-PEO (P123) as template agents for passivating Cd and Pb in soil. The binding energies of functional groups and matched pore size between HC and pollutants were simulated by Density Function Theory (DFT) and Materials Studio (MS). The results showed that –COOH-Cd and –OH-Pb have the largest binding energies (0.261 ev and 0.271 ev), with bond lengths of 2.27 Å and 2.21 Å respectively. A pore diameter of 3–6 nm of HC is more suitable for adsorbing Cd and Pb pollutants. Furtherly, acidic D-ribose HC (PDHC) and alkaline D-ribose HC (NDHC) have more oxygen-containing functional groups and a larger specific surface area, the specific surface area of NDHC can reach 178.459 m2·g−1. The OM content of soil was increased by 98 %, 113 % and 120 % after remediation with DHC, PDHC and NDHC, respectively. Comparatively, PDHC is excellent for reducing the TCLP-Cd content by 86 %, and NDHC decrease the TCLP-Pb content by 79 % in the remediated soil. This work offers a specific instructive method to developing high-performance HC for remediating Cd and Pb polluted sites.