Synthesis, characterization, and swelling behavior evaluation of hydrogels based on Gum ghatti and acrylamide for selective absorption of saline from different petroleum fraction-saline emulsions

In this research article, the synthesis of Gum ghatti and acrylamide based superabsorbents under pressure with N,N′-methylene bisacrylamide as a crosslinker and an ascorbic acid-potassium persulfate redox pair as an initiator is reported. To study the impact of the different reaction variables on the water absorbance of the candidate polymer, different reaction parameters, including the reaction time, amount of solvent, pH of the medium, initiator ratio, pressure, and monomer and crosslinker concentrations, were optimized. The candidate polymer was characterized with different techniques, including Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis, differential thermogravimetry, and X-ray diffraction. The crosslinked product was found to be thermally more stable than the initial backbone. The swelling capacity of the synthesized polymer was investigated in deionized water as a function of time, temperature, and pH of the swelling medium. Moreover, the effects of the ionic strengths of different cations on the swelling capacity of the candidate polymer were studied with different salt solutions. The tendency of absorbency for these hydrogels in salt solutions was found to be in the following order: Na ⁺ > Ba ²⁺ > Fe ³⁺ > Sn ⁴⁺ for NaCl, BaCl ₂, FeCl ₃, and SnCl ₄ salt solutions. Further, the candidate polymer was used for the selective absorption of saline water from different petroleum fraction-saline emulsions. The results showed that the saline absorption capacities of the hydrogels were 667, 610, 646, and 680% in kerosene-saline, diesel-saline, petrol-saline, and petroleum ether-saline emulsions, respectively.