Biosorption of heavy metal ions from aqueous effluents utilising snail shell dust as a biomaterial

The freshwater snail, Bellamya bengalensis is commonly utilised as food by humans and its shells are discarded as waste and considered a nuisance. However, it is impossible to exclude its potential as a biomaterial for detoxifying heavy metals from wastewater. The present study is an attempt to eliminate heavy metals like Copper, Nickel, and Lead from synthetically prepared relevant heavy metal solutions using snail shell dust as a biosorbent. The efficacy of freshwater snail shell dust was estimated by studying various factors, viz., contact time, adsorbent dosages, size of the adsorbent, pH of test solution, and initial heavy metals concentration. The present finding thus revealed the highest percentile removal of heavy metals as 93.64%, 97.24%, and 99.98% for Copper, Nickel, and Lead, respectively. The percentile removal of heavy metals declined with a raised initial concentration of relevant heavy metals. The data was also analysed using adsorption isotherms (Langmuir and Freundlich isotherms) and was observed to follow Langmuir isotherm with a maximum adsorptive capacity of 28.95 mg/g, 29.14 mg/g and 16.35 mg/g for Copper, Nickel, and Lead, respectively, thus reflecting the monolayer mode of the adsorption mechanism. The above results thus authenticate the use of snail shell dust as a low-cost, sustainable, and green biomaterial for the eradication of heavy metals.