Corn Stover, Orange Peel, and Pistachio Shell Biochars As a Filter Media for Removing Lead and Arsenic in Water.

The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. This study evaluated three different biochars pyrolyzed with locally-sourced feedstock materials in South Texas as a filter media for removing lead (Pb) and arsenic (As) in water. Biochar is a highly porous charcoal produced by the combustion of biomass with limited or no oxygen (pyrolysis). Although biochar has been used as a soil amendment for a long time, the idea of using other feedstocks (e.g. plant biomass, manure, biosolids) to make biochars for water treatment is relatively new. The objective of this study is to 1) produce biochar from locally sourced feedstocks, corn stover (CS), orange peel (OP), and pistachio shell (PS), and 2) evaluate the biochar’s physico-chemical properties (pH, surface area, electrical conductivity, elemental composition, Fourier transform infrared spectroscopy, and Scanning electron microscopy with energy dispersive X-ray spectroscopy). Feedstock materials were pyrolyzed under nitrogen conditions at temperature (300, 450, or 600°C). Our results showed that higher pyrolysis temperature resulted in higher surface areas for PS and CS biochars, which likely enhanced the adsorbent potential for lead (Pb). The optimal pH was found to be 6 for all biochar types in the solution pH range between 2 and 6 with percent Pb removal being 96% for CS, 95% for OP, and 19% for PS biochar. Biochars without surface modification was not effective in removing arsenic in water. Magnetized biochar was produced to evaluate its adsorbent properties for the arsenic removal in aqueous solution. Isotherm and pH studies were done to show the effectiveness of magnetic biochar in removing As (III) and As (V).