Sodium alginate-cl-poly (N,N-dimethyl acryl amide-co-2-acrylamino-2-methyl-1-propane sulphonic acid/titanium dioxide nanocomposite hydrogel: An efficient dye-removing agent

Sodium alginate (SAG) crosslinked poly (N,N-dimethyl Acrylamide-co-2 acrylamino-2-methyl-1-propane sulfonic acid)/Titanium dioxide [SAG-cl-poly(N,N-DMA-co-AMPS)/TiO2] nanocomposite hydrogel (NCHG) was prepared by in situ crosslinked free radical polymerization technique using SAG, a mixture of DMA and AMPS and titanium isopropoxide in presence of methylene-bis-acrylamide as a cross linking agent. Different characterization techniques are used to characterize NCHG. Water swelling behavior of NCHG together with swelling kinetics is evaluated. Maximum swelling (35% at 30 min) is observed at pH 8. NCHG is used for the removal of one cationic dye methylene blue (MB) and one anionic dye carmosine-A (CR-A) from their aqueous solution. Adsorption dynamics, kinetics and isotherms are evaluated. Maximum dye adsorption occurs at pH 8 and 2, at time 50 min for both the cases, at temperature 60 degrees C, 40 degrees C for MB and CR-A respectively. Pseudo-second order kinetics and Langmuir isotherm model are followed for all the two cases with Q(max) 403.22 mg.g(-1), 106.26 mg.g(-1) and the R-2 value 0.9987 and 0.9950 for MB and CR-A respectively. Evaluation of thermodynamic parameters of the adsorption indicates that the adsorption is spontaneous in nature for the two dyes.

Automated summary

In this study, a novel nanocomposite hydrogel material was prepared by in situ crosslinked free radical polymerization technique, and its characterization was conducted. The experimental results demonstrate that the hydrogel exhibits excellent swelling properties and efficient dye adsorption capacity.