Neutral Salt
Aqueous reference solutions composed of dihydrogen phosphate and hydrogen phosphate salts maintain stable hydrogen ion concentrations near neutral pH. Laboratory testing and chemical application rely on phosphate buffer solutions to stabilize pH near 7.0 during enzyme treatments and fastness testing on textile goods. Stable buffering capacity prevents pH fluctuations caused by acid or alkali carryover from preceding wet processing steps.
Proton Exchange
Reversible proton exchange between monobasic and dibasic phosphate species buffers against incoming hydrogen or hydroxyl ions. Maximum buffer capacity occurs at pH 6.8, corresponding to the second dissociation constant of phosphoric acid at room temperature.
Enzyme Stabilization
Enzymatic biopolishing and desizing operations on cellulosic fabrics require strict pH control within the optimal activity range of cellulase and amylase enzymes. Incorporating a phosphate buffer system into the enzyme liquor prevents pH drift during long continuous bath treatments, preserving enzyme activity and preventing fabric strength loss. Laboratories conducting colorfastness to perspiration tests utilize standardized phosphate buffer formulations to simulate human sweat conditions on test swatches.
Mill technicians verify buffer concentrations to ensure consistent enzyme performance across bulk production batches.
Effluent Limit
High phosphate concentrations in wastewater effluent contribute to environmental eutrophication, triggering strict discharge limits in textile industrial zones. Incompatibilities occur when phosphate ions react with divalent cations like calcium or magnesium, forming insoluble precipitates that spot fabrics. Buffer capacity drops rapidly when working pH strays more than one unit away from the central pKa value.
