(662e) Adsorptive Removal of Lead from Aqueous Solution Using Biochar

Heavy metal pollution in aqueous solution is a worldwide problem because of its toxicity and non-biodegradable properties. Lead is one of the major heavy metal contaminants, which can cause disastrous consequences on human health, such as kidney damage and neurobehavioral deficiency. Along with that, lead is harmful to the environment with its toxic characteristics. Lead can enter into aqueous solution from different sources such as household plumbing system, acid battery, metal finishing process and so on. Allowable limit of lead in drinking water is up to 0.015 mg/L according to the United States Environmental Protection Agency. Due to stringent environmental regulations of potable water, it is imperative to develop cost-effective and environmental-friendly technologies for removing lead from aqueous solution. Adsorption is one of the most cost-effective methods to remove heavy metals from aqueous media. In recent years, biochar as an adsorbent has received significant attention because of its distinctive characteristics. Biochar is produced by the carbonization of biomass, and it is rich in carbon. Different types of waste biomass have been used to produce biochar, which can be used as an adsorbent to remove contaminants from water. Adsorption capacities of biochars depend on its physical and chemical properties on the basis of type and pyrolysis temperature of feedstock materials.

Therefore, this study focuses on the removal of lead from aqueous solution by batch adsorption experiments using biochar derived from wood chips (spruce, pine, and fir). Adsorption characteristics of lead onto biochar were evaluated as a function of biochar dosages and contact time using batch adsorption experiments. At the end of each batch test, samples were collected and analyzed to determine the residual lead concentration using an Inductively Coupled Plasma Mass Spectrometry. Results demonstrated that the percentages of lead removal increased with the increase of biochar dosages. The percentages of lead removal were 12.8%, 36.8%, 85.4% and 99% with biochar dosages of 1 g/L, 2 g/L, 4 g/L and 6 g/L, respectively for an initial lead concentration of 100 mg/L in 24 hours. The pH values of the solution were not controlled during the tests. It was observed that the pH values were 4.6, 4.8, 5.9 and 6.7 for 12.8%, 36.8%, 85.4% and 99% of lead removal, respectively at the end of the test. About 73% of lead was removed within first 3 hours. Lead adsorption capacity of biochar was about 16.5 mg/g. This study indicated that biochar can remove lead from aqueous solution very effectively. Further experiments are in progress to investigate the optimum parameters (dose of biochar, initial lead concentration, pH and contact time), adsorption kinetics, adsorption isotherm, and removal mechanisms of lead onto biochar.