The aim of this study was to investigate the effect of pyrolysis temperature on the biochar yield and properties via slow pyrolysis of coconut flesh waste. The temperature used in the slow pyrolysis experiment was varied between 350°C to 600°C at a constant heating rate of 5°C/min. The results indicated that higher pyrolysis temperature could reduce the percentage of biochar yield. The increment of pyrolysis temperature from 350°C to 600°C would reduce the biochar yield from 23.54 wt.% to 13.97 wt.%. The effect of pyrolysis temperature was also significant on the composition and physical properties of biochar yield. The physicochemical properties of biochar were identified by proximate, elemental, heating value, SEM images and BET surface area analyses. The increment of pyrolysis temperature from 350°C to 600°C increased the ash content of biochar from 4.63 wt.% to 8.19 wt.%, the fixed carbon content from 45.20 wt.% to 79.09 wt.% and carbon content from 72.70 wt.% to 83.25 wt.%. Meanwhile the volatile matter and oxygen content of biochar were decreased from 50.17 wt.% to 12.71 wt.% and 13.86 wt.% to 10.99 wt.%, respectively as the pyrolysis temperature was increased from 350°C to 600°C. The increment of pyrolysis temperature from 350°C to 600°C increased the surface area of biochar by 8 fold from 0.3971 m2/g to 3.4486 m2/g. Meanwhile, the higher heating value of biochar was decreased from 33.95 MJ/kg to 27.49 MJ/kg as the pyrolysis temperature was increased from 350°C to 600°C.

Production of biochar from slow pyrolysis of biomass is a promising carbon negative procedure since it removes the net carbon dioxide in the atmosphere and produce recalcitrant carbon suitable for sequestration in soil. Biochar production can vary significantly with the pyrolysis parameter. This study investigated the impact of temperature and heating rate on the yield and properties of biochar derived from cassava plantations residues which are cassava stem (CS) and cassava rhizome (CR). The pyrolysis temperatures ranged from 400 C to 600 C while the heating rate parameter was varied from 5 C/min to 25 C/min. The experiment was conducted using the lab scale slow pyrolysis system. The increment of temperature and heating rate of slow pyrolysis for both cassava wastes had raised the fixed carbon content of the biochar but decreased the biochar yield. More biochar was produced at lower temperature and lower heating rate. Temperature gave more influence on the biochar yield as compared to the heating rate parameter. The highest biochar yield of more than 35 mf wt. % can be obtained from both CS and CR at 400 C and heating rate of 5 C/min. From the proximate analysis, the results showed that cassava wastes contain high percentage of volatile matter which is more than 80 mf wt. %. Meanwhile, the biochar produced from cassava wastes contain high percentage of fixed carbon which is about 5 8 times higher than their raw samples. This suggested that, it is a good step to convert CS and CR into high carbon biochar via slow pyrolysis process that can substantially yield more biochar, up to 37 mf wt. % in this study. Since the fixed carbon content for both CS and CR biochar produced in any studied parameter were found to be more than 75 mf wt. %, it is suggested that biochar from cassava wastes is suitable for carbon sequestration.

The aim of this study is to investigate the potential of coconut frond as a feedstock for biochar production via slow pyrolysis process.  Proximate, elemental and thermogravimetric analysis were performed to evaluate the chemical and thermal properties of the coconut frond.  The percentage of its lignocellulosic component and high heating value were determined. Surface morphology of coconut frond was examined using field emission scanning electron microscope (FESEM). Coconut frond (CF) contains 78.03±3.91 d.b. wt% of volatile matter, 4.96±0.07 d.b. wt% of ash content and 17.01±3.86 d.b. wt% of fixed carbon. Elemental analysis revealed a sulfur content of 0.94±0.12 %, while the percentage of nitrogen is 0.46±0.33%. The composition of carbon and hydrogen are 34.0±6.22 % and 7.71±0.34 % respectively. The high heating value of CF is 17.77±0.40 MJ/kg. CF consists of 43.91±1.80 % cellulose, 31.58±1.20 % hemicellulose, and 18.15±0.60 % lignin. From thermogravimetric (TG) analysis, it is apparent that the weight loss of CF occurred prominently in the temperature range 200°C - 400°C.  The peaks of the DTG curve at 281.75±0.35 °C and 334.08±0.35°C indicate the weight loss of coconut frond sample due to the degradation of hemicellulose and cellulose, respectively. The FESEM images of CF show its fibrous strands are compact with a few large pores with diameters around 42.5 - 48.1 μm large pores in the center of the CF sample. The results of the analysis show that CF has a potential as a feedstock for biochar production via slow pyrolysis. CF also can be used in other application such as syngas and bio-oil production due to the low lignin percentage and high volatile percentage.

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