methylene blue adsorption by magnesium oxide nanoparticles immobilized with chitosan (cs-mgonp): response surface methodology, isotherm, kinetics and thermodynamic studies

In this research, a chitosan-immobilized magnesium oxide nanoparticle (cs-mgonp) was synthesized to evaluate it as a prospective adsorbent for a cationic methylene blue (mb) dye. for the synthesized adsorbent, functional groups were analyzed through fourier transform infrared (ft-ir) spectroscopy. x-ray diffraction (xrd) and scanning electron microscopy (sem) were used to identify the structural and morphological observations. the evaluation of process parameters such as ph (5-9), cs-mgonp dosage (0.2-0.6g/l), initial mb concentration (10-30mg/l), and temperature (283-323k) on mb adsorption was done at an equilibrium agitation time of 70 min using central composite design (ccd) of response surface methodology (rsm). mb removal percentage of 94.51% (desirability=0.829) was obtained under the optimal conditions of ph=7.28, dosage=0.47g/l, initial mb concentration= 19.37mg/l and temperature =309.76k. the adsorption onto cs-mgonp fits well with pseudo-second-order kinetics equation and equilibrium data made the best fit with langmuir isotherm with maximum mb uptake capacity of 163.87mg/g.