Effect of MXenes, nZVI and Acacia-wood Biochar Treatments on Bioavailability Pb and Fractions in Calcareous-polluted Soils

Abstract

The remediation of contaminated soils with heavy metals is a critical environmental policy in both developing and industrialized countries. The various adsorbents utilization is an effective method for the immobilization of toxic metals in contaminated soils. The present research sought to evaluate lead (Pb) immobilization in contaminated calcareous soil impacted by the application of different amendments such as Acacia-wood biochar MXenes, and nZVI and their interaction during maize growth. The study employed three amendments, biochar MXenes, and nZVI at three concentrations (0, 2.5, and 5%) and various levels of Pb pollution (0, 50, and 100 mg/kg soil). An incubation time of 16 weeks was designated for homogenization of supplements in soil, and maize cultivated following standard procedures. After incubation, various fractions of Pb, such as residual, organic matter-bound, carbonate-bound, exchangeable, and manganese and iron-bound, were determined. Additionally, Pb was assessed using EDTA and DTPA techniques and 1000-grain weight of maize was recorded. The findings indicated that maximum concentration of Pb associated with organic matter was achieved in the 5% Acacia-wood biochar application, reaching 20 mg/kg. Maximum and minimum concentration of Pb extracted was DTPA were recorded in the control sample (95 mg/kg) and 5% biochar treatment (65 mg/kg). Findings indicated that enhancing quantities of biochar and MXenes supplements enhanced weight of 1000 grains of maize across all treatments. Results indicate that biochar and MXenes addition decreased level of Pb extracted using EDTA (129 mg/kg) and DTPA (79 mg/kg). Findings indicated that biochar and MXenes application decreased active Pb and Pb mobility in soil by enhancing carbonate and organic fractions. The biochar and MXenes addition in remediation of soil can improve their efficacy in decreasing the level and active Pb mobility. Biochar offers stable C matrix for more Pb immobilization, whereas MXenes enhance adsorption potential and facilitate ion-exchange ability.