Water and ammonium adsorption characteristics of water retaining agent in different solutions of ammonium salt

In order to investigate the interaction between water retaining agents (WRAs）and NH4+, polyacrylate (PAA) and poly acrylate-co-acrylamide (P(AA-AM)) were selected as the tested WRAs to study the characteristics of water and NH4+ adsorption in a series of solutions of NH4+Cl, NH4+Cl-KCl and NH4+Cl-CaCl2 respectively. The results showed that NH4+ could obviously reduce the water absorbency of the WARs. The water absorbency was markedly decreased with the NH4+ concentration increase. The relationship between relative water absorbency and NH4+ concentration could be described by the minus power function. For NH4+, K+, Ca2+ individual solution and NH4+-K+, NH4+-Ca2+ coexistent solution, the influence of WRAs on water absorbency followed the order NH4+-K+< NH4+、K+