Removal of Methyl Violet from aqueous solutions using poly (acrylic acid-co-acrylamide)/attapulgite composite

The adsorption of Methyl Violet (MV) cationic dye from aqueous solution was carried out by using crosslinked poly (acrylic acid-co-acrylamide)/attapulgite (Poly(AA-co-AM)/ATP) composite as adsorbent. The factors influencing adsorption capacity of the composite such as pH, concentration of the dye, temperature, contact time, adsorbent dosage, ionic strength and surfactant were systematically investigated. The equilibrium data fitted very well to the Langmuir isotherm and the maximum adsorption capacity reached 1194 mg/g at 30°C. The thermodynamic parameters including ΔG0, ΔH0 and ΔS0 for the adsorption processes of MV on the composite were also calculated, and the negative ΔH0 and ΔG0 confirmed that the adsorption process was exothermic and spontaneous. The kinetic studies showed that the adsorption process was consistent with the pseudo second-order kinetic model and the desorption studies revealed that the regeneration of the composite adsorbent can be easily achieved.