Corn husk biochar and chromium(VI) ions blended soil as fuel in soil microbial fuel cell

Chromium metal ion (Cr(VI)) is a highly mobile species which pollutes the entire biosphere originating from the discharge of point and nonpoint sources. Carcinogenic and mutagenic Cr(VI) is then remediated by adsorption process using a carbonaceous material. Biochars are biomass derived carbonaceous materials which effectively holds water in its micro pores there by facilitating the multiplication of microbial population with wide range of applications. Biochars are employed as adsorbent materials for contaminant removal. In the present work experiments were conducted to investigate the Cr(VI) removal efficiency of corn husk biochar (CHB) from aqueous synthetic K2Cr2O7 solution. However, the discharge of Cr(VI) loaded CHB in environment once again creates challenges in the form of nonpoint source pollution. Hence, it was further planned to add the Cr(VI) adsorbed CHB to soil which might renders the mixture as fuel in soil microbial fuel cell (SMFC) for power generation with Cr(VI) degradation. SMFC is a device which generates electrical power using soil as fuel in presence of pollutant. Soil microbes serve as catalyst, mediators, degraders, and exoelectrogens in SMFC. CHB was prepared by the method of slow pyrolysis at 450 degrees C. The prepared biochar's physicochemical properties and water holding capacity (WHC) measurements were done using standard protocols. CHB was then subjected as adsorbent material for Cr(VI) adsorption. The mode of adsorption was characterized by standard isotherm modeling, FTIR, SEM with EDS, and XRD studies. The propagation of secondary pollution after adsorption experimentation is prevented by mixing Cr(VI) loaded CHB with soil and utilized as fuel in SMFC. The study concluded that CHB belonged to class I biochar possessing alkaline nature. Nine percent addition of CHB to soil holds double the amount of water as compared to blank soil benefitting microbes. Cr(VI) was adsorbed onto CHB surface physically and had justification from FTIR, SEM with EDS, and XRD studies. The discharge of Cr(VI) loaded CHB in SMFC generated potential of 320 mV steadily for eight number of days. Thus, the present study explored CHB as adsorbent material for Cr(VI). CHB also possessed the character of holding water effectively in soil facilitating microbial population. Both the properties were thus coined into single roof as fuel in SMFC which delivered power from pollutant and aids in finding a viable solution for the control of primary and secondary pollution.