thermodynamic study of (pb^2+) removal by adsorption onto modified magnetic graphene oxide with chitosan and cysteine

A new modified magnetic graphene oxide with chitosan and cysteine was synthesized for removing pb^2+ ions from aqueous solution. the properties of this adsorbent were characterized by field emission scanning electron microscopy (fesem), vibrating sample magnetometer (vsm) and energy dispersive analysis system of x-ray (edax). physicochemical parameters such as effect of ph, contact time, adsorbent dosage and initial concentration of pb ^2+ was also studied. the results showed that the maximum capacity of absorbent in lead ions adsorption (at equilibrium concentration of 120 ppm) occurred at phoptimum= 5.75, toptimum= 30 min and adsorbent 85.4 mg/g dosage=0.1 gr. maximum empirical adsorption capacity (qmax) was calculated 85.4 mg/g. the thermodynamic parameters (δh°, δg° and δs°) showed that the adsorption process of pb ^2+ on modified magnetic graphene oxide with chitosan and cysteine was endothermic and spontaneous. removal percentage was reduced to 15% after five stages of sorption/desorption studies. so, modified magnetic graphene oxide with chitosan and cysteine can be used as a complementary process for removal of pb^2+ ions from water and wastewater.