Clay and Magnetic Sand Biomass Based Composite for Methylene Blue Adsorption (Effects of Composition Ratios of Functional Materials and Synthesis Conditions)

Abstract

In recent times, iron oxide based magnetic nanoparticles (mainly magnetite (Fe₃O₄) or maghemite (γ-Fe₂O₃)) as well as clay and clay based composites, have become very important in the elimination of persistent organic compounds from waste water systems. This has been carried out by magnetic assisted chemical separation (MACS) process. The feasibility of using two locally sourced materials: magnetic black sand from down beach Limbe and clay from Bamessing Ndop for the removal of methylene blue (MB) dye from aqueous solution have been studied. The effects of contact time, pH, adsorbent dosage, temperature, grinding / length of grinding, composition ratios of the functional materials such as peel, pectin and starch, hydrothermal carbonization and concentration of dye solution were investigated. The test samples have exhibited great potentials for use in waste water purification for the removal of persistent organic compounds such as methylene blue dye. The results revealed that, varying various compositional ratios of the functional materials such as peel, pectin and starch to increase their affinity, selectivity, or degradation capacity towards targeted compounds influenced the activities of the adsorbents. The results also indicated that maximum performance was reached at pH value of 8 for Iron oxide (sand) based adsorbents and 12 for clay based adsorbents. Grinding / increase in grinding time have shown positive effects on the adsorbent properties of the composite from black sand and maximum grinding time varied depending on the compositional ratios of functional materials. Also within a certain threshold, hydrothermal carbonization improved on the adsorbent efficiency of the samples formulated with saccharides. The adsorption kinetic of methylene blue onto the adsorbents could be better fitted by the linear Langmuir isotherm and the pseudo-second-order model was a better model fitting the kinetics of the adsorption in this study.