The document discusses optimization and production of polyethersulfone ultrafiltration flat sheet membranes using lithium chloride as an additive. Polyethersulfone membranes were prepared using various concentrations of lithium chloride (1-5wt%) in the casting solution. Membranes produced with 2wt% lithium chloride had the lowest molecular weight cutoff. Higher lithium chloride concentrations beyond 2wt% resulted in increased molecular weight cutoff. Pure water permeability was highest for membranes with 5wt% lithium chloride due to lithium chloride's nucleophilic properties in the solvent.