Geopolymer as a Portland cement substitute had been synthesized from alkaline activation of co-combustion residuals of bamboo and kaolin. Types of used alkaline activators were NaOH solution, KOH solution, a mixture of NaOH solution-water glass, and a mixture of KOH solution-water glass. Geopolymer with NaOH solution as activator had a compressive strength which was higher compared to geopolymer with KOH solution as an activator. However, geopolymer with NaOH solution-water glass as activator had a compressive strength which was lower compared to geopolymer with KOH solution-water glass as activator either at room temperature curing or at a curing temperature of 60 °C. The use of water glass with NaOH or KOH solution as activator could increase the compressive strength of geopolymer and yielded geopolymer having more dense and more homogeneous microstructure seen from SEM images. XRD patterns revealed the presence of sodium aluminosilicate hydrate in geopolymer with NaOH solution and NaOH solution-water glass as activators, and potassium aluminosilicate hydrate in geopolymer with KOH solution and KOH solution-water glass as activators. Furthermore, FTIR spectra indicated asymmetrical vibration of Si(Al)-O at around 1008 cm-1 related to geopolymer product.

ZnO nanoparticles are multi-purposes materials that can be synthesized by several methods, including physical and chemical routes. A novel synthesis method of ZnO nanoparticles is the biological method using plant extracts as reducing and capping agents, such as the fruit extract of Averrhoa bilimbi. Plant extracts are superior agents for synthesizing nanoparticles because it provides essential phytochemical substances as reductor, capping agents, and free from toxicants. In this study, the effects of precursor concentrations and the amount of plant extract on the formation and morphology of nanoparticles were investigated. The characteristics of ZnO particles were studied by UV-Vis spectroscopy, XRD, FTIR, TEM, and DLS. The study showed that the formation of ZnO nanoparticles occurred after five hours reaction at 70°C, as indicated by color change of the solution. ZnO nanoparticle formation was confirmed by the maximum absorption at the wavelength of 372 nm and XRD analysis. FTIR analysis showed that the as-synthesized ZnO contained significant organic compounds on its surface, especially compared to commercial ZnO. Reduction reactions using A.bilimbi produce nanoparticles in the size from 35.4 to 59.5 nm with round shape and some agglomeration that were observed by TEM. The ZnO antibacterial property was tested against planktonic and biofilm Escherichia coli. The result showed that as-synthesized ZnO have comparable antibacterial antibiofilm property as the commercial ZnO nanoparticles at low concentration. Interestingly, this property was diminished when as-synthesized ZnO nanoparticles were used at high concentrations.

Bamboo has been widely used in Indonesia for construction, handicrafts, furniture and other uses. However, the use of bamboo as a biomass for renewable energy source has not been extensively explored. This paper describes the thermal and ash characterization of three bamboo species found in Indonesia, i.e. Gigantochloa apus, Gigantochloa levis and Gigantochloa atroviolacea. Characterization of bamboo properties as a solid fuel includes proximate and ultimate analyses, calorific value measurement and thermogravimetric analysis. Ash characterization includes oxide composition analysis and phase analysis by X-Ray diffraction. The selected bamboo species have calorific value comparable with wood with low nitrogen and sulphur contents, indicating that they can be used as renewable energy sources. Bamboo ash contains high silicon so that bamboo ash has potential to be used further as building materials or engineering purposes. Ash composition analysis also indicates high alkali that can cause ash sintering and slag formation in combustion process. This implies that the combustion of bamboo requires the use of additives to reduce the risk of ash sintering and slag formation.

The global shift of petroleum refinery towards heavier crude oils means an increasing demand of hydrocracking catalysts. This work studies the conversion of a kaolin originating from the Bangka island in Indonesia into a hydrocracking catalyst support consisting of zeolite-Y and amorphous alumina-silica phases. After a beneficiation process combining controlled settling and adsorption of the kaolin suspension in water with the addition of 125 ppm of 0.01% polyacrylamide solution as flocculant and 156 ppm of 0.1% calcium chloride solution as the adsorbent, the kaolinite phase content is increased from 63.6 to 74.3 %-mass. After spray drying, the kaolin is calcined at three temperatures for 2 hours each, producing calcined kaolin phases K700Cat 700 °C, K1013at 1013 °C, and K1050Cat 1050 °C. Temperatures of calcination for obtaining calcined kaolin phases is determined based on result of DSC/TGA. Synthesis of zeolite-Y is done by mixing varying proportions of these three calcined kaolin products, and zeolite-Y crystal seeds. These mixtures are aged at room temperature for 11 hours prior to reaction in a hydrothermal condition at 93 °C for 15-21 hours. The best calcined kaolin composition is found to be K700C: K1013C: K1050C= 10:85:5 (%-mass), resulting in a zeolite NaY purity of 86-88 % as characterized by X-ray diffraction (XRD), average ratio of SiO2/ Al2O3of 5.35, mean pore diameter of 23.1 Å, specific surface area of 186 m2/g, and a total pore volume of 0.107 mL/g as measured by N2adsorption. In a parallel manner, a series of amorphous silica-alumina (ASA) synthesis experiments is done to identify the best metakaolin calcination temperature and metakaoline activation pH. These are found to be 527 °C and 8.0, respectively, producing an ASA product with a 65 %-mass amorphous phase content as estimated by XRD data processing. To prepare the hydrocracking catalyst support, the zeolite NaY is added into the ASA-forming metakaolin sol at a pH of 8.0, aged for 8 hours at 50 °C. An initial morphological characterization of the obtained zeolite-ASA composite catalyst support suggests a good dispersion of the smaller zeolite NaY particles in the ASA microspheres.

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