Sustainable biochar derived from waste lotus seedpod for efficient adsorption of residual carbamate pesticides

The pollution of carbamate pesticides (CMs) has seriously threatened human health. Here, a sustainable biochar derived from lotus seedpod (LSP) was prepared to remove residual CMs. Among various raw materials, lotus seedpod-derived biochar (LSPB) showed better surface morphology, high porosity and more surface functional groups to mediate the best adsorption performance of CMs. When the LSP/H3PO4 ratio, carbonization temperature and time was defined as 1:5, 700 °C and 60 min, respectively, LSPB obtained the highest adsorption capacity and good yield. The SEM micrographs, XRD and FTIR showed that LSPB was of porous and amorphous carbon structure, and increased functional groups for more surface adsorption sites. The adsorption efficiency of LSPB was considerably higher for adsorbent dosage of 0.5 g/L, solution temperature of 20 °C, initial CMs concentration of 10 μg/mL, and adsorption time of 30 min. The Elovich adsorption kinetic model indicated the potential heterogeneous surface adsorption mechanism of LSPB. Adsorption thermodynamic showed that the CMs adsorption on LSPB was spontaneous and endothermic. LSPB displayed favorable recovery performance, and can be effectively used for five cycles. LSPB showed potential adsorption performance in different CMs-residual waters, and is even superior to that of some commercial adsorption products. Based on its favorable adsorption performance and low-cost, this sustainable LSPB may be a promising CMs residues adsorbent for removal of it from water.