Potential of NaOH pretreated Mangifera indica waste biomass for the mitigation of Ni(II) and Co(II) from aqueous solutions

• A comparison of effect of different chemical pretreatments on Mangifera indica phyto parts.
• Different phyto parts of M. indica were studied for Ni(II) and Co(II) removal.
• NaOH pretreated M. indica leaves biomass was found best with high uptake capacity.

Mangifera indica biomass was chemically pretreated to evaluate its Ni(II) and Co(II) uptake capacity from aqueous solutions. The adsorption characteristics of Ni(II) and Co(II) by M. indica were found dependent on pH, chemical pretreatments, initial concentrations of the metals and time. The M. indica biomass was pretreated using HCl, HNO3, H3PO4, NaOH, CH3COOH, C6H6, HCHO and H2O2. The maximum Ni(II) and Co(II) uptake was 131.5 mg/g at pH 6 and 114.6 mg/g at pH 5, respectively at 30°C with NaOH pretreated M. indica biomass. The equilibrium adsorption data was better fitted to Langmuir adsorption isotherm model and pseudo-second order model.