Synthesis and characterization of collagen-based hydrogel nanocomposites for adsorption of Cd2+, Pb2+, methylene green and crystal violet

Collagen-based hydrogel nanocomposites, as adsorbent systems in wastewater treatment, were prepared by graft copolymerization of acrylamide and maleic anhydride onto hydrolyzed collagen using ammonium persulfate as an initiator and sodium montmorillonite as a nanoclay. The properties of synthesized adsorbents were characterized by Fourier transform infrared spectroscopy, X-ray diffraction patterns, and thermogravimetric analysis method. The morphology of the optimized product was examined by scanning electron microscopy. Batch adsorption experiments were conducted as a function of contact time, initial pollutant concentration, pH and comonomer ratios to achieve maximum adsorption capacity. The hydrogel nanocomposites showed high adsorption of ~120 mg/g for Pb 2+ and Cd 2+ metal ions over the feed concentration of 100 mg/L. The dye adsorption of the prepared nanocomposites was 652 mg crystal violet/g at the initial concentration of 800 mg/L and 179 mg methylene green/g in 400 mg/L dye in water, respectively. The experimental data also showed that more than 90 % of the maximum adsorption capacity of the optimized sample for both metal ions and the dyes was achieved within the initial 10 min. Four non-linear isotherm models were performed to describe the adsorption capacity. The results fitted better to the Redlich–Peterson model. The adsorption kinetic data conformed well to a pseudo-second-order model.