关键词: 聚羧酸减水剂, 吸附, 水泥

Abstract: A series of polycarboxylate superplasticizers were prepared and the effects of mole ratio of different monomers on the adsorption were studied.The experimental results showed that the product was the best when mole ratio of acrylic polyether，2-acrylamide-2-methyl propane sulfonic acid sodium，acrylic acid，and maleic anhydride was 1∶0.14∶3.6∶2.6.Adsorption kinetics and thermodynamics of the best product on cement particle surfaces at different temperatures and concentrations were studied by TOC analysis.The kinetic results showed that the adsorption process followed Lagergren adsorption rate equation.Adsorption rate constant k and activation energy Ea were 0.01594 min-1(30℃)and 17.9647 kJ·mol-1，respectively.Thermodynamic results showed that the adsorption capacity of PC increased with temperature.The thermodynamic parameters obtained are as follows：ΔHad=-24.788 kJ·mol-1，ΔSad=0.050 kJ·mol-1·K-1，ΔGad=-39.886 kJ·mol-1(30℃)，indicating that the adsorption is a spontaneous exothermic process.In theory，higher temperature is not beneficial to adsorption process，but as temperature increases，more PC adsorbs at cement particle surfaces，resulting in larger adsorption capacity.The reason is that the heat released will promote hydration of cement，so that it is easier for PC to dope with hydration products.

Key words: polycarboxylate superplasticizer, adsorption, cement