A green synthesis route of metal oxide has been developed to synthesize the V2O5 nanoparticles. V2O5 was synthesized using Foeniculum vulgare stems extract (FSE) and ammonium monovanadate as precursors. The role of secondary metabolite compounds affect the particle size of V2O5. The crystalline phase and crystallite size of V2O5 were investigated by X-Ray Diffraction (XRD) with the orthorhombic crystalline phase and the average crystallite size around 78.6 nm. The presence of functional groups was evaluated by Fourier Transform Infrared (FT-IR). The morphology, particle size, and chemical composition of V2O5 were analyzed by Scanning Electron Microscopy (SEM), Tunneling Electron Microscopy (TEM) and Energy Dispersive X-Ray (EDX). V2O5 nanoparticles show a good catalytic activity for the reduction of methylene blue (MB).

Rice husk and coconut shell waste is potential biomass found in Palembang that has not been utilized properly. Besides being used for primary purposes, biomass can be used for energy sources like renewable energy. Biomass residues can be obtained from the pyrolysis process with thermal cracking units (UTC) and used as bio-briquettes. Bio-briquette is prepared from a mixture of pyrolysis residues of coconut shell and rice husk with a mass ratio of 2:1 using a combination of adhesive mucilage (mango sap) and paste (starch). The adhesive is prepared by dissolving the starch in water, then mixing it into melted mango sap. The mass ratio of the sap and starch is 1:1 (w/w), while the ratio of the mixture of adhesive and water is 1:10. Based on the ATR-FTIR characterization, it showed that the C = C strain group and the C-H bending group appeared at 2800 cm−1, which was confirmed by its appearance at 800 cm−1 in the fingerprint area. Then, appears peak in the area of 1300 cm−1, indicating the presence of a nitro group, which is assumed to have come from mango sap. Measurements of the briquette physicochemical properties such as moisture content, ash content volatile matter, and fixed carbon were measured using the proximate analysis method. Furthermore, the addition of coconut shells in producing bio briquettes from rice husks increased the calorific value by 7.305 MJ kg−1. So that, bio-briquette is an effective as an alternative energy source to replace fossil fuel for household purposes.

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One of the heavy metals contained in the textile industry wastewater is chromium (Cr). Chromium hexavalent ions (Cr6+) are highly toxic and its accumulation in the human body will cause various negative impacts. This study aimed to determine the characteristics of silica synthesized by the sol-gel method to gain homogeneity and high purity. Synthesized silica was calcined at 700°C for 4 hours and its performance to adsorb Cr(VI) ions  in textile wastewater was investigated. The presence of -OH group from silanol (–Si-OH) was appeared at wavenumber 3367.70 cm-1, meanwhile siloxane functional groups were recorded at 1056.99 cm-1 and 784.38 cm-1 due to the O-Si-O asymmetric stretching and Si-O bending vibration. Optimum conditions of silica to adsorb Cr(VI) ions took place at pH 2 and contact time of 90 minutes by adsorption efficiency of 75,65% and followed the Freundlich isotherm.