Efficient removal of Hg(II) from dental effluents by thio-functionalized biochar derived from cape gooseberry (Physalis peruviana L.) leaves

Mercury is well known to be highly toxic to humans and aquatic life. Wastewater discharges from dental clinics are the predominant source of mercury species in the environment. Innovative biochar was fabricated by the thio-functionalization of cape gooseberry (Physalis peruviana L.) leaves to produce thio-modified biochar for the sequestration of Hg (II) ions. The removal Hg(II) efficiency for the native and thio-functionalized cape gooseberry biochars were compared. Sulfur impregnation improved the affinity of biochar for Hg(II) uptake via –SH exchange and complexation mechanisms by 54%. The applicability of the novel thio-modified biochars for Hg(II) removal from dental effluents below five ppb levels was tested. The Hg(II) removal efficiency was 96.4% for 3BHS at pH = 5.0 and 25 min of contact time. The results of the present study indicated that thio-modified biochar from cape gooseberry could be a potential low-cost material for the sequestration of Hg(II) ions from acidic wastewater.