Purification of natural bentonite,Na~+-modified(Na~+ ion exchange) process and the preparation of Cu~(2+)-bentonite were studied in this experiment,and compared the influence of different Na~+-modified agent on the content of montmorillonite and capacity of ion exchange.The content of pure montmorillonite of natural bentonite raised after purified,Na~+-modified process by the ion exchange of sodium pyrophosphate was best.When the concentration of acid or alkali in the suspension system is moderate(pH=4~11),...