Investigating the removal of Mn(II) from water and wastewater using low-cost bio-sorbents: orange peels and sugarcane bagasse

The high content of manganese (Mn) in potable water is a significant public health problem; therefore, it is necessary to lower it to an acceptable level that is mandated by regulatory agencies. This study was motivated by the need to evaluate the efficacy of low-cost and reusable bio-sorbents, namely orange peels (OPs) and sugarcane bagasse (SCB), for the attenuation of Mn(II) from simulated and real effluent. The solid:liquid ratio of 30 mg:100 mL was applied, and the results revealed that OPs removed 96.71% of Mn(II) at an optimum contact period of 120 min while SCB removed 94.74% of Mn(II) at an ideal contact period of 30 min. The pH study revealed the ideal removal efficiency (RE) at pH 5 for both OPs and SCB, while the optimum dosage was 100 mg for OPs and 50 mg for SCB. The study also found that SCB and OPs can be reused up to the third adsorption-desorption cycle without their RE changing significantly in those adsorption-desorption cycles. The bio-sorbents were characterized using Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) hyphenated to energy-dispersive X-ray spectroscopy (EDS), powder X-ray diffraction (PXRD), zeta potential analyzer, and thermogravimetric analysis (TGA). The characterization results revealed a noticeable difference between pure and water-reacted bio-sorbents. From the findings of this study, the use of OPs and SCB could yield the desired result in Mn(II) removal from water.