Adsorptive removal of reactive green 5 (RG-5) and direct yellow 50 (DY-50) from simulated wastewater by Mangifera indica seed shell and its magnetic composite: Batch and Column study

Abstract

Removal of reactive green (RG-5) and direct yellow (DY-50) dyes was carried out by native Mangifera indica (mango) seed shell biomass and its magnetic composites. After synthesis of adsorbents, surface properties of mango seed shell biomass (BN) and magnetic composites (BMc) were determined by TGA, FTIR and SEM In batch experimentation mode optimum conditions for RG-5 and DY-50 uptake were found as: contact time, 120 min and temperature 35°C, pH 7 and 2, for DY-50 uptake with both adsorbents BN and BMc respectively, in case of RG-5 the optimum temperatures were 60 and 25°C for BN and BMc respectively, optimum pH and contact time were same as DY-50. Effects of surfactants, metals and salts concentration on the biosorption capacity were also investigated. Kinetic studies showed the best fitness of pseudo-second-order kinetic model on experimental data. Langmuir showed best fitness for BMc as well as BN (RG-5) and BM for DY-50, while Temkin isotherm best fitted on BN data for DR-50, conversely Freundlich only supports the adsorption mechanism for RG-5 with BN. Thermodynamic study for RG and DY revealed the endothermic and stable biosorption onto BN and BMc. Column study parameters such as effect of bed height and concentration were investigated at constant flow rate. Kinetic models BDST (bed depth service time) and Thomas were applied on column experimental data. Outcome of this research work showed that the magnetic bio-composites prepared by mango seed shell biomass has a great potential to remove RG and DY dyes from wastewater.