Screening and optimization through response surface methodology for synthesis of pH, temperature and salt-sensitive Aloe vera-acrylic acid-based biodegradable hydrogel: Its evaluation as dye adsorbent

A pH-, temperature-, and salt-sensitive hydrogel was synthesized using acrylic acid (AA) as monomer, natural polysaccharide Aloe vera as backbone, ammonium persulfate-N,N-methylene-bis-acrylamide as an initiator-crosslinker system via free-radical grafting method. Different parameters such as treatment time, temperature, amount of solvent, pH, concentration of initiator, crosslinker and monomer were screened using Plackett-Burman design (PBD). The PBD showed that pH, monomer, and crosslinker were taken as the most important variables, which highly impact the swelling behavior of the synthesized hydrogel as compared to the rest of the variables. The half normality plot was used to find the significant parameters regarding the swelling capacity of the hydrogel. The center composite design was used for further optimizing the important variables like pH, monomer, and crosslinker. The pH and monomer interaction on percentage swelling (Ps) was studied through the analysis of variance model. Synthesized hydrogel Av-cl-poly(AA) was characterized by different techniques such as Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, and scanning electron microscopy (SEM). The effect of different chloride salt solutions like KCl, NaCl, BaCl2, FeCl3, and CoCl3 center dot 6H(2)O on Ps of synthesized Av-cl-poly(AA)-based hydrogel was also studied. Biodegradation studies of the synthesized polymer were also carried out using soil burial and vermicompositing methods. Biodegradation of semi interpenetrating polymer network (SIPN) was confirmed by SEM and FTIR techniques. Synthesized SIPN was also used as a device for the removal of dye and was found very effective as an adsorbent. POLYM. ENG. SCI., 2019. (c) 2019 Society of Plastics Engineers