Abstract:
Stringent discharge limits, high costs, and low removal efficiency of the conventional treatment methods are facing challenges to
handle industrial effluents containing heavy metals. The objective of this study was to use a recoverable magnetic zeolite to remove
Cr(VI) from aqueous solution. The study investigated the application of nanotechnology to improve surface properties,
recoverability, and adsorptive capacity of natural zeolite and the CCD-RSM-based optimization of adsorption process variables.
Natural zeolites coated with various fractions of magnetic nanoparticles (25%, 33.33%, 50%, and 75%) were investigated for
surface characters, adsorption capacity, removal efficiency, and recoverability. Natural zeolite coated with 33.33% (MZ33) was
found a better adsorbent in terms of surface characters, adsorption capacity, and removal efficiency. Thirty batch adsorption
experiments designed with CCD were carried out in order to optimize adsorption process variables using response surface
methodology (RSM). It was found that adsorbent dose = 2 g/L, contact time = 75 min, initial CrðVIÞ concentration = 10 mg/L,
and solution pH = 1:5 were the optimum conditions to achieve 93.57% Cr(VI) removal, which is very close to the experimental
result of 94.88%. The adsorption isotherm determined from the operating parameters revealed that experimental data fit to the
Langmuir isotherm model with R2 = 0:9966 and maximum adsorption capacity = 43:933 mg/g. This proved that the adsorption
of Cr(VI) on magnetic zeolite involved monolayer adsorption on the active sites. The separation factor, RL, value lies between
0 and 1 indicating that adsorption of Cr(VI) on the magnetic zeolite is favorable. The adsorption kinetics study follows
pseudo-first order in the removal of Cr(VI). FTIR analysis of magnetic zeolite revealed the presence of numerous functional
groups participating in Cr(VI) adsorption. The current study confirmed that magnetic zeolite is a cost-effective and favorable
material for the removal of Cr(VI) from aqueous solution.
