Negative rejection of acids and separation of ions by hyperfiltration

A loose charged membrane was prepared by crosslinking albumin in a collodion matrix. High water flow is obtained at relatively low pressures. Hyperfiltration of sulphuric acid and of hydrochloric acid in this membrane gives negative rejection (enrichment) in the concentration range from 10-3N to 10-1N; the negative rejection is higher and is observed in a wider range for sulphuric acid. Mixtures of copper sulphate and sulphuric acid and of copper chloride and hydrochloric acid were hyperfiltrated. Positive rejection of copper ions and negative rejection of hydrogen ions were obtained in these mixtures. Thus, a considerable separation was achieved.