Effect of a Passivator Synthesized by Wastes of Iron Tailings and Biomass on the Leachability of Cd/Pb and Safety of Pak Choi (Brassica chinensis L.) in Contaminated Soil

Abstract

Cadmium (Cd) and lead (Pb) carry a high heavy-metal-toxic risk for both animals and plants in soil. In this study, iron-based biochar (T-BC) was prepared by co-pyrolysis using wastes of iron tailings and biomass with urea as the functioning agents. Field-emission scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and toxicity-characteristic leaching procedure (TCLP) methods were employed to analyze the physicochemical characteristics of T-BC. Additionally, a pot trial was conducted to examine the effects of T-BC on the physiological characteristics of pak choi (Brassica campestris L.), the availability of heavy metals, and enzyme activities in the soils. The results show that toxic metals have been volatilized by the roasting process and immobilized within T-BC via the formation of stable metal-compounds during the co-pyrolysis process, which satisfies the requirements of a soil passivator. Incubation experiments showed that the DTPA-extractable Cd and Pb in contaminated soils decreased with an increasing amendment rate. Moreover, in the pot experiments, by adding 1% (w/w) T-BC into soils, the soils benefited from its large adsorption, complex precipitation, and immobilization capacity. Approximately 36% Cd and 29% Pb concentrations of edible parts in pak choi were reduced. The amendment proved promising for the stabilization of Cd and Pb in contaminated soils, while providing a strategy for solving the residual waste of tailings and biomass.

Review on the Impact of Iron Tailings on the Environment and Its Prevention and Control Strategies

“…They also found that amaranth, as a dominant species, can effectively remove heavy metals from tailings. In another study by Zhou and Li [69] the preparation of ironbased biochar (T-BC) was explored as a means of soil remediation. They used iron tailings waste and biomass as raw materials and found that T-BC could adsorb and immobilize heavy metals in contaminated soil [70].…”

Facile Synthesis of Zinc‐Containing Mesoporous Silicate from Iron Tailings and Enhanced Fire Retardancy of Rigid Polyurethane Foam

“…The preparation of iron‐based biochar by co‐pyrolysis of ITS and biomass improves soil pH, mineral nutrients and soil enzyme activity. [ 17 ] Cobalt ferrite nanoparticles were co‐precipitated from ITS and successfully applied in photo/sono‐catalytic degradation of Congo red. [ 18 ] A novel mesoporous silica material from ITS exhibited high absorbance capability for methylene blue because of the porous structure.…”