Facile One-Pot Synthesis of Sustainable Carboxymethyl Chitosan – Sewage Sludge Biochar for Effective Heavy Metal Chelation and Regeneration

[Display omitted] •Sustainable CMC-SSBC adsorbent was fabricated by facile one pot synthesis.•A shorter equilibrium time and a superior adsorption capacity was achieved for HMs.•CMC-SSBC was highly selective for HMs despite the presence of background electrolytes.•This effort is a typical strategy for controlling waste by waste. In this paper, sewage sludge, a solid waste from wastewater treatment plant, which eagerly requires proper treatment was reused as solid support in the form of sewage sludge biochar, then modified with carboxymethyl chitosan to form a bio-adsorbent. Further, carboxymethyl chitosan coating on sewage sludge biochar improved carboxymethyl chitosan’s stability in water. The prepared bio-adsorbent revealed a shorter equilibrium time (