4 sulfophthalic acid spa

Plastic bottle wastes were taken as sources of polyethylene terephthalate (PET) and used to prepare GO. Aniline monomer, ammonium persulfate (APS), hydrochloric acid (HCl), acetone, benzimidazole 98%, PVA (MW 1,300,000), and IC were purchased from Sigma-Aldrich Co. Glutaraldehyde (GA) (Alfa Aesar, Haverhill, MA, USA, 50 wt.% in H₂O) and 4-sulfophthalic acid (SPA) (Sigma-Aldrich, St. Louis, MO, USA, 99.9 wt.% in H₂O) were used as covalent and ionic cross-linkers, respectively, and nonwoven polyester fabric was purchased from R.P. Industries, Gujarat, India.

PEO (MW: 900,000 g mol-1, Acros Organics, (Fair Lawn, NJ, USA)) and PVA (99% hydrolysis and medium MW, USA). Glutaraldehyde (GA) (Alfa Aesar (Haverhill, MA, USA), 25 wt% in H₂O) and 4-sulfophthalic acid (SPA) (Sigma-Aldrich (St. Louis, MO, USA), 99.9 wt% in H₂O) were used as covalent and ionic cross-linkers respectively. Titanium (IV) oxide rutile (TiO2, <5 µm, ≥99.9%, Sigma-Aldrich) and H₃PO₄ (Fisher Chemical (Pittsburgh, PA, USA), 85 wt%).

Ten grams of PVA (99% hydrolysis and medium mW, USA) was dissolved in 100 mL of deionized H₂O at 90 °C for 2 h. Two grams of IC (type V) was dissolved in 100 mL of deionized H₂O at 80 °C for 1 h. PVA: IC (95:5) wt.% was blended. Then, the polymer blend was crosslinked, using 5 g of glutaraldehyde (GA) (Alfa Aesar; 50 wt.% in H₂O) as a covalent crosslinker, and 5 g of 4-sulfophthalic acid (SPA) (Sigma-Aldrich; 99.9 wt.% in H₂O) as an ionic crosslinker and sulfonating agent for PVA [24 ,26 (link)]. Then, the inorganic–organic nanocomposite was prepared by incorporating 1, 2.5, 5, and 7.5 wt.% of SO₄ZrO₂ into the polymeric matrix. Figure S1, in Supplementary Materials, explains the S-PVA/IC/SO₄ZrO₂ membrane structure, within which PVA and IC are ionically crosslinked through the esterification reaction between the carboxylic groups of the sulfophthalic acid and the hydroxyl groups of the polymers. In addition, the acetal reactions between the hydroxyl groups of the polymers and the aldehyde groups of the glutaraldehyde led to the covalent crosslinking of the two polymers. Furthermore, there was the formation of hydrogen bonds between the oxygen-containing SO₄ZrO₂ groups and the –OH groups of the PVA and IC [33 (link)], respectively.