Removal of Direct Red 31 Dye from Aqueous Solutions Using Synthesized Nanocomposites Hydrogel

The aim of this study was to investigate the performance of nanocomposites hydrogel as adsorbents for removal of Direct Red 31 dye from aqueous solutions. Here, these nanocompsites were prepared from polyacrylamide (PAM) and polyacrylic acid (PAA) hydrogels in the presence of sodium montmorillonite as nanofiller. The resulting nanocomposites were well characterized by FTIR, TGA, XRD and SEM analysis. The effect of various operation factors such as nanocomposite dosage, solution pH, contact time and initial dye concentration on the adsorption process was studied. The results showed that the maximum adsorption capacity (qmax) of Direct Red 31 was obtained in acidic pH, contact time 90 min and adsorbent dosage 0.05 g which was 168.63, 108.22 and 128.9 mg/g in PAM, PAA and (PAM-co-PAA) nanocomposites respectively. The experimental data were fitted into Langmuir and Freundlich adsorption isotherms and it was found that data fitted well with Freundlich model. Kinetic studies showed that dye adsorption process followed the pseudo-second-order kinetic model.