Adsorption Characteristics of Lead by Biochar from Mouth Rinse Residue

Abstract Biochars were prepared from mouth rinse residue between 200°C and 600°C.The effects of different pH, adsorbent dosage, adsorption time, and initial concentration of solution on Pb 2+ adsorption were investigated. The results showed that the Pb 2+ adsorption amount of the biochar increased with the increasing pH. At 200°Cand 300°C, the optimum pH was 6.0, and the optimum pH was 7.0 between 400°C and 600°C. The optimal adsorbent dosage was 0.02 g. Pb 2+ adsorption amount indicated that biochar prepared at lower temperature was better. The Pb 2+ adsorption process of biochars could be well fitted by the quasi-second-order kinetic equation. Fitting five kinds of biochar with Langmuir and Freundlich model showed that the biochars fitted the Langmuir model whose maximum adsorption capacities were 188.68, 185.19, 135.14, 109.89 and 86.21 mg/g respectively. Accordingly, biochar can be a effective way to expand the resource utilization of residue.