Preparation and Characterization of Biochar and Activated Carbon Derived from Cashew Bagasse Waste

Abstract

Biochar and Activated carbon derived from cashew bagasse waste are veritable materials produced from agro-waste. They are currently under-utilized owing to paucity of information in their recycling methods which reduces agricultural waste from the environment. This study investigates the use of under-utilized cashew bagasse waste in the production of biochar and activated carbon using pyrolysis and chemical activation methods, respectively. Cashew bagasse waste was pyrolysed at 4000C for 20mins at a heating rate of 100C per mins. The biochar produced was allowed to cool at room temperature for 30 mins. It was further reduced to smaller size particles using euro premium grinder and later sieved with 10 mesh sieve size prior to its application. The biochar was chemically activated using 0.3M Orthophosphoric acid (H3PO4) as activating agent at an impregnation ratio of 1:2.36(w/w). It was heated at 1000C to form a paste and later placed in muffle furnace at 5000C for 30 mins. This was allowed to cool and washed with distilled water until a neutral pH was obtained and later oven dried at 1050C for 24 hours to a constant weight to produce activated carbon. The produced activated carbon was kept in air tight containers prior to analysis. Characterization of pH, bulk density, moisture content, dry matter, volatile matter, and fixed carbon were determined for biochar and activated carbon. Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) analysis was performed to determine the functional groups and surface morphology of biochar and activated carbon, respectively. The Data obtained were analyzed using descriptive statistics and ANOVA at P value < 0.05. The results showed that significant differences (p<0.05) were observed in the characterized parameters determined. The biochar and activated carbon has pH: (7.68±0.06 and 6.13±0.03); Bulk density :( 0.18±0.01 and 0.20±0.01) %; Moisture content: (6.67±0.33 and 16.00±0.58)%; Dry matter (93.33±0.33 and 84.00±0.58) %; Volatile matter (68.67±3.18 and 29.67±5.21) %; Fixed carbon (30.24±3.20 and 69.32±5.16) %, respectively. FTIR Analysis showed that biochar and activated carbon were more polar and also contained specific bonds. SEM analysis also indicated that biochar and activated carbon have porous structures. This study, therefore, revealed that chemically activated carbon had better characteristics than biochar produced through pyrolysis method. Keywords: Activated carbon, Biochar, Cashew bagasse waste, Characterization, Pyrolysis, Chemical activation