Crosslinked polyDADMAC gels as highly selective and reusable arsenate binding materials

[Display omitted] •Crosslinked DADMAC polymer gel is excellent sorbent for removal trace arsenic.•The arsenate removal is based on the ion exchange mechanism.•The arsenate exchange is highly selective over sulfate and chloride ions.•Equilibration with arsenate at pH 7 takes place within 10min.•The gels loaded can be recovered either by acidifying (0.1M) or treatment with brine. High porosity cationic hydrogels synthesized via crosslinking co-polymerization of diallyldimethylammonium chloride (DADMAC) with N,N′-tetraallylpiperaziniumdichloride (TAP) showed high affinity towards arsenate anions over a wide pH range within notably short periods. Batch tests indicated that poly(DADMAC) hydrogels removed 99% of the arsenate anions from aqueous solutions at pH 6–10 and exhibited a maximum arsenic removal capacity of 0.12g arsenic per gram of hydrogel. DADMAC hydrogels performed well at various pH levels after a short contact time (i.e., 10min). Evidence of the ion exchange mechanism was based on experiments with solutions containing competing chloride and sulfate ions. An “intra-particle diffusion model” was proposed for the kinetics of arsenic removal. This gel was determined to be a good candidate for use in practice due to its easy regeneration either by treating with a 8.24g/L of NaCl solution or by reducing the pH of the medium to below 1.0.