A highly efﬁcient polyampholyte hydrogel sorbent based ﬁxed-bed process for heavy metal removal in actual industrial efﬂuent /Guiyin Zhou a , Jinming Luo b , Chengbin Liu a, * , Lin Chu a , Jianhong Ma c , Yanhong Tang d , Zebing Zeng a , Shenglian Luo a, ** - Zhou,Guiyin