Experimental study on removal of chromium using nano-silica coated pyrolysed biochar in batch, fixed bed and fluidized bed reactor: Synthesis, characterization, experimentation and mechanism

Abstract

Nowadays Nano technology is used as one of the alternative for removal of pollutants. In this study, raw sawdust was used as biomass and was pyrolyzed at high temperature in an inert environment. The synthesized char was finally coated with nano-silica in a Teflon coated hydrothermal reactor. The characterization of the synthesized composite was performed. Nano silica coated (AcSi) activated carbon was further used to reduce Cr+6 in three type of reactors (batch, fixed bed and fluidized bed reactor). With increased in concentration of Cr+6, the fluidization behaviour in case of Fluidized reactor and the breakthrough time in case of fixed bed reactor was decreasing. Reaction time and availability of the active surface group played an important role in both fixed and fluidised bed reactor and observed that biochar coated with nano-silica was capable to remove pollutants efficiently using all the reactor. The batch study suggested monolayer adsorption and exothermic reaction and maximum adsorption capacity was observed as 88.2 mg/g and removal was 99.8% after 120 min. Regeneration study suggested that the composite can be regenerated with alkali solution and upto 5 cycles this composite can be used.

Keywords

• Fluidized bed reactor
• Biochar
• Nano-silica
• Chromium
• Fixed bed reactor