Ecofriendly removal of Lead, Cadmium and Arsenic along with turbidity from contaminated water using natural reservoir clay (NRC) and S. pasteurii derived urease

Abstract

Heavy metals (HMs: Pb, Cd, and As) are well-known inorganic pollutants due to their toxicity and persistence in environment. Present research mainly focused on the removal of HMs including turbidity of water using NRC (natural reservoir clay) and Sporosarcina pasteurii (S. pasteurii) derived urease. HMs removal efficiencies were optimized considering different initial HMs concentrations (20–1000 mg/l), absorbent concentration (0.01–0.7 g), and time (0-24 h), at neutral pH -7. In general, kaolinite and montmorillonite (X-ray fluorescence and X-ray powder diffraction) were the main components of NRC where the removal efficiency (%) was noticed in the order of Pb > Cd > As. Particularity, Pb removal efficiency (99 %) was noticed faster (within 10 s from 100 mg/l) than Cd (within 60 s from 80 mg/l Cd), at an absorbent dose 0.03 g. S. pasteurii derived-urease-dependent turbidity-reduction (NTU) was noticed in treated water. Moreover, overall, >99 % Pb and >94 % Cd along with the turbidity of water was removed by the simultaneous treatment of NRC (0.3 g) and S. pasteurii urease. The empirical constant (1 > n) and adsorption capacity indicated (Langmuir/Freundlich) an easy uptake with monolayer adsorption of Pb and Cd by NRC (best-fit second-order-rate-expression compared to first-order-kinetic-model). Green technologically, the HMs and turbidity from water can be removed by NRC and S. pasteurii.