(691f) Biomass Residue Characterization for Their Potential Application As Biofuels

Physico– and thermo– chemical characteristics of four types of walnut shells (PSW, TSW, MSW and HSW) have been investigation in the present work. From the proximate analysis (wt% on dry ash free basis), the highest moisture, volatile matter, ash and fixed carbon contents is observed in PSW (9.26), HSW (79.8), MSW (5.84) and TSW (26.1), respectively. It is found that TSW have lowest moisture (8.08) and volatile matter (73.9) and HSW has lowest ash (2.0) and fixed carbon (20.2) contents. From the ultimate analysis it is found that the H/C and O/C ratios are almost 1.6 and 0.8, respectively, for all types of walnut shells. Heating values are observed in the range of 13.8–18.4 MJ/kg, which is comparable to the wood waste and lignite coal. The cellulose, hemicellulose, lignin and extractives in walnut shell are found to vary from 32.3-34.5, 21-27, 39-43 and 1.4-1.7%, respectively. From the thermogravimetric analysis (TGA), it is observed that the complete moisture removal is below 152 ^oC. The highest and lowest moisture losses of 9 and 5% have been observed at a heating rate of 5 ˚C/min for MSW and TSW, respectively. The degradation of lignocellulosic biomass is occurred between 330 to 510 ˚C. For all walnut shell samples the most prominent FTIR band peak have been found at wavenumbers of 3400, 2931, 1420 and 1050 cm^–1, which is due to the stretching vibrations of –OH, CH–, aromatic C=C, and aliphatic ether and alcohol groups, respectively in cellulose, hemicellulose and lignin. Scanning electron microscopy (SEM) analysis indicated the rough texture and heterogeneous structures of biomass. Further, the x-ray diffraction (XRD) analysis showed the crystalline structure, which is due to the presence of cellulose. From the observations made in the present work, it can be concluded that the walnut shell is a potential candidate for energy generation through thermo-chemical conversion.

Keywords: Walnut shell, Proximate and Ultimate Analysis, Higher heating values, Compositional analysis