Method for preparing polymeric aluminum sulfate by using aluminum foil pickling waste liquid

The invention discloses a method for preparing polyaluminum ferric sulfate (PAFS) by using an aluminum foil pickling waste liquid. The preparation method comprises the processes of acid dissolving, alkalization, and hydrolysis curing. The preparation method concretely comprises the following steps: carrying out ultrasonic cavitation on the aluminum foil pickling waste liquid used as a raw material, using waste sulfuric acid to adjust the acidity of the waste liquid in order to carry out an acid dissolving reaction, adding an alkalizing agent, carrying out an alkalization reaction, adding a stabilizer and deionized water, and carrying out a hydrolysis cuing reaction to obtain the polyaluminum ferric sulfate liquid product. The method effectively improves the content of total iron and aluminum oxide in the product, realizes the utilization of the aluminum foil pickling waste liquid and parts of aluminum resources, and has a better COD removal rate and a shorter settling time than existing polyaluminum chloride