Removal of methyl orange from aqueous solutions with poly(acrylic acid-co-acrylamide) superabsorbent resin

Poly(acrylic acid-co-acrylamide) (P(AA-co-AM) superabsorbent resin was prepared by solution polymerization of acrylic acid (AA) and acrylamide (AM) using ammonium persulfate (APS) as an initiator and N,N′-methylenebisacrylamide (MBA) as a cross linker. P(AA-co-AM) was used for the removal methyl orange (MO) from aqueous solutions. Factors influencing the adsorption capacity, such as adsorption time, initial concentration of MO, dosage of the superabsorbent resin, pH value and ionic strength, were investigated in detail. It was found that P(AA-co-AM) was effective to remove MO from its aqueous solutions. The equilibrium adsorption capacity was 394.6 mg/g at room temperature as the initial concentration of MO was 3000 mg/L. The mechanism of the adsorption process was also speculated. Study on the equilibrium adsorption isotherms showed that the adsorption was in accordance with both Langmuir and Freundlich model. Further study of the adsorption kinetics showed that the adsorption process was consistent with the Pseudo second-order kinetic model.