Polyethersulfone membrane coated with Dragon blood resin: Effect of input parameters and optimization using response surface methodology

This study investigates the effectiveness of dragon blood resin (DBR) as a hydrophilic additive to prevent fouling on membrane surfaces. The input parameters, including DBR, Fe³⁺, NMP concentration, and coating time were studied to understand their correlation with response variables, such as permeability, selectivity, and fouling recovery. A central composite design (CCD) to analyze the twenty-one sets of experimental designs. The selected membrane was characterized for hydrophilicity, functional group, morphology, and mechanical properties. The ANOVA result indicates that the p-value for all response models is significant, except for humic acid rejection. The study found that a higher concentration of DBR and NMP, as well as a longer coating time, result in lower permeability, greater humic acid rejection, and higher contact angle, while Fe³⁺ concentration does not have a significant effect. The membrane's surface characteristics did not change significantly after coating, such as chemical function and morphology, while the tensile strength decreased with increasing DBR concentration, NMP, and coating time. The membranes demonstrated good selectivity and antifouling properties, with the optimal condition being 0.223 mg/L DBR, 5 min coating time, 1.65 mg/L Fe³⁺, and 46.19% NMP, resulting in 30.34 L/m².h.bar of humic acid permeability and 119.6% of fouling recovery.