Influence of pyrolysis method and nano sizing technique toward properties of ZnO/CNS composite from rice husk for remediation of contaminated Earth crust

Pesticide contamination is one of earth crust problems, especially for agriculture soil. Addition of nanocarbon into liquid fertilizer is solution to remediate the polluted paddy field by adsorption and natural microbial degradation. Nano size of the carbon was conditionized by formation of dispersion system. The colloid system is needed to guarantee that the carbon can be used as part of fertilizer liquid to spray easily in the paddy field. Modification of nanocarbon using catalyst ZnO can improve catalytic degradation reaction of pesticide in agriculture soil. In this research, the nanocarbon was prepared from rice husk using hydrothermal - microwave and reflux - microwave. Purpose of this research is to study influence of both pyrolisis methods toward physical and chemical properties of nanocarbon. The pyrolisis process was performed by hydrothermal process (200°C, 5 h) or reflux process (200°C, 6 h) and followed by microwave process (800 W, 40 minutes). Weight ratio of the rice husk (> 60 mesh) and ZnCl2 as carbon activator is 50:1. No removal of ZnO after pyrolisis so that the products were ZnO - carbon composites. Nano size of the products were conditionized by formation of colloid system using each blending and stirring technique for 1 h. Chemical analysis of the rice husk was conducted by public analysis service in Department of Chemistry Brawijaya University. Result of the research showed that the rice husk contains in sequence of celulose>hemicellulose>lignin. The hydrothermal - microwave pyrolisis provided the darker product than the reflux - microwave method. FTIR spectra of the products showed that the pyrolized biomass had less both -OH and aliphatic -CH functional groups than the biomass. The double pyrolisis methods have produced the nanocarbons which have lower content of -OH and aliphatic -CH functional groups, but more M-O than the individual method. X-ray diffractograms of the composites had the patterns similar to CNT and nanocellulose difrractograms. The celulose crystalinity indexes of the composites are lower than of the biomass, indicating structure transformation of cellulose to the carbon structure. SEM images showed that the nanocomposite prepared by hydrothermal - microwave method has smaller particles than the reflux - microwave. Colloid system of the nanocomposite was more effectively formed by blending than stirring technique. UV - Vis spectra showed that the colloid of nanocarbon synthesized by hydrothermal - microwave meth