Cadmium Removal from aqueous solution by magnetized and polydopamine surface functionalized single-walled carbon nanotubes

Abstract

Pollution of water by heavy metals such as cadmium is becoming a serious ecological and public health hazard due to their toxic effects even at very low concentrations. Thus, the removal of heavy metals from wastewater is very important for controlling environmental pollution. The purpose of this study was removal of cadmium from aqueous solution by polydopamine surface functionalized and magnetized single-walled carbon nanotubes (SWCNTs/Fe3 O4 @PDA). In present study, the effects of experimental parameters such as adsorbent dosage, initial metal ion concentration and pH of solution on adsorption Cd (II) in batch system were fully studied. Also, to characterize the adsorbent, SEM and FT[1]IR analyses were utilized. The results showed that with increasing adsorbent dose and pH the adsorption percentage of cadmium increased and the optimum pH for cadmium removal was determined as pH=7. The results of fitting the data to the isotherm models showed that the Langmuir (R2 =0.99), Freundlich (R2 =0.97), Temkin (R2 =0.97) and Dubinin-Radushkevich (R2 =0.96) models logically described the data. The maximum adsorption capacity (qm) was obtained by Langmuir model as 186.48 mg/g which indicates a good absorption capacity of this adsorbent. The obtained experimental adsorption capacity (qe exp.) 120.72 mg/g was close to qe2 obtained by pseudo-second-order (PSO) kinetic model (121.95 mg/g). Therefore, it can be concluded that SWCNTs/Fe3 O4 @PDA adsorbent can be used as a new adsorbent in optimum conditions for removal of cadmium ions from aqueous solutions.