Poly(diallyldimethylammonium-MoS4) based amorphous molybdenum sulphide composite for selectively mercury uptake from wastewater across a large pH region.

Amorphous molybdenum sulphide materials are attracting more attention in heterogeneous catalysis, gas adsorption and water remediation fields. Herein, a new type of amorphous molybdenum sulphide composite (poly(diallyldimethylammonium-MoS4), shorten as PDADMA-MoS4) was synthesized via a facile precipitation reaction. Metal adsorption tests of prepared PDADMA-MoS4 composite shows that Hg2+ and Pb2+ concentrations in solution can decrease from 10 ppm to <0.5 ppb level much lower than the drinking water requirement (<2 ppb) in 10 min. The metal adsorption isotherms suggest that maximum metal-uptake capacities are 1460.0 mg/g for Hg (pH = 5) and 433.7 mg/g for Hg (pH = 1), indicating that this sorbent works over a wide pH range (1.0-7.0) to effectively remove Hg from aqueous solution. More importantly, at very low pH = 1, this sorbent material exhibits extraordinarily high selectivity of Hg over Pb and Cu (separation factors βHg/Cu=4.5×104 and βHg/Pb=3.6×104). The excellent Hg capacity and selectivity at low pH region (pH < 2) has shed light on the new generation of adsorbent materials for acidic wastewater treatment.