Ferrofluid mediated chitosan@mesoporous carbon nanohybrid for green adsorption/preconcentration of toxic Cd(II): Modeling, kinetic and isotherm study

In this research an efficient ionic liquid based ferrofluid system was developed for efficient adsorption/preconcentration of cadmium using magnetic mesoporous carbon - chitosan nanohybrid. Mesoporous CMK - 3 was synthesized using MCM - 48 as ordered template. Then magnetic CMK was combined with chitosan through reaction with epichlorohydrin. The nanohybrid was characterized with FESEM, TEM, XRD, SEM mapping, FTIR, BET and VSM techniques. Effective parameters on cadmium adsorption was optimized with response surface methodology (RSM) using Box - Behnken design. Solution pH, contact time, adsorbent dosage and ionic strength were four studied variables on cadmium adsorption. Results showed that all studied variables are significant on cadmium adsorption. Isotherm study was performed at optimum conditions (pH = 8, time 3 min, adsorbent dosage 13 mg and ionic strength of 0.15%) based four isotherm models and results showed that cadmium adsorption followed the order of Redlich-Peterson > Freundlich > Langmuir > Dubinin-Radushkevich with maximum adsorption capacity of 251.9 mg g− 1. Results for kinetic study confirmed that pseudo second order model can better describe cadmium adsorption. Regeneration of the sorbent was performed with HNO3 solution (1.0 mol L− 1). Finally developed adsorption process was employed for cadmium preconcentration from real samples.