Shrimp shells-derived biochar for efficient adsorption of Pb2+ in aqueous solutions

Oxidation modification is an important technique for the development of novel adsorbents and has attracted considerable interest in recent years. A new and efficient Pb(II) adsorbent was developed in this study using simple and cost-effective protocols. Shrimp shell biochar (SSC) was obtained by pyrolysis of abandoned shrimp shells and subsequently treated with mixed acid to obtain modified biochar (SSC-M). The structure and adsorption properties of SSC and SSC-M were investigated for Pb(II) adsorption using a variety of characterisation methods. Both SSC and SSC-M exhibited excellent aqueous Pb(II) adsorption capacities and achieved maximum adsorption capacities of 94.16 and 156.48 mg g(-1) at the optimal condition, respectively. The adsorption of lead ions by SSC and SSC-M followed a pseudo-second-order kinetics model and a monolayer adsorption process. Moreover, the prominent adsorption performance of SSC-M for Pb(II) was mainly attributed to electrostatic interactions and surface complexation. SSC-M can be a promising and affordable adsorbent for Pb(II) ions owing to its significant adsorption capacity.