Water treatment using activated carbon is widely accepted, despite its high production cost. Therefore, this study was aimed to investigate the potential of cassava stem in activated carbon form for methylene blue (MB) dye uptake from water. Raw cassava stem (RCS) was also utilized to evaluate the difference between cassava stem in its raw form and after being converted to the activated carbon (ACS). The MB adsorption from water using the RCS and ACS was done in this study. The batch adsorption study showed fast MB uptake by ACS at 60 min contact time, while higher adsorbent dosage and higher pH contributed to higher adsorption percentage. The thermodynamic study showed positive values of ∆H° of ACS, indicating that the adsorption process of MB was endothermic. Meanwhile, the negative value of ∆G° showed that the adsorption processes of MB were spontaneous. The thermodynamic study showed higher fitting to Langmuir isotherm, with data from the kinetic study showing better pseudo-second-order equation fitting, which suggests the chemisorption process had happened. The highest adsorption recorded by ACS was 384.61 mg/g, indicating the possibility of cassava stem as the lower cost raw material for activated carbon production with excellent adsorption characteristics.

Heavy metal contamination in water is happening worldwide. Adsorption using activated carbon is a common choice for cleaning the wastewater. The drawback of activated carbon is the higher cost of production due to the need for high heat in the process. This work investigated on activated carbon produced from the abundantly available Leucaena leucocephala biomass in order to reduce the cost of raw material. The biomass was chemically activated at different activation temperatures. The produced activated carbon was characterized using SEM, FT-IR, surface analyzer, and TGA. Isothermic and thermodynamic studies were done to evaluate the adsorption properties of the activated carbon. It was found out that higher surface area can be obtained using the higher activation temperature. Higher NaOH to carbonized sample ratios also resulted in higher surface area for all activation temperatures, which are 662 m²g^-1 for 700 °C activation temperature, 735 m²g^-1 for 750 °C, and 776 m²g⁻¹ for 800 °C. Isothermic studies showed that all of the activated carbon that is produced from Leucaena leucocephala biomass are fit to the Langmuir isotherm, regardless of any activation temperature. Lastly, the thermodynamic study found out the adsorption process is endothermic, reflected by the positive value of ΔH^o. It can be concluded that Leucaena leucocephala is a promising alternative material for producing activated carbon.

Today’s wood protection technology adopts copper-based chemical substances as the widely utilized material. Besides the adverse effect on human health, it also showed negative impact on organisms. To prevent this, a new method using of nano-sized chemical substances in wood preservation was being investigated. In this work, the effects of nano-clay and nano-sized particles of zinc oxide (ZnO), titanium oxide (TiO₂), aluminum oxide (Al₂O₃), and magnesium oxide (MgO) impregnation on the wood samples were investigated. Samples from Scots pine wood were impregnated with the nanoparticles. Besides that, samples with second impregnation of 10% polymethylmethacrylate (PMMA) were also prepared to investigate the improvement in wood properties. The physical and thermal properties of the samples were tested as well as biodegradation against the brown-rot fungus Coniophora puteana. Impregnation of nanoparticles slightly affect the water absorption properties, but second impregnation with 10% PMMA reduced the water absorption up to 20%. The lowest water absorption and the highest water repellencies after 336 h in water were determined on the samples treated with 10% nano-clay-PMMA and MgO-PMMA treatments. Water repellent efficiency and anti-swelling efficiency were also increased by addition of 10% PMMA with little decrement after longer soaking time. The highest ASE was found on the samples treated with 15% of nano-clay and zinc oxide nanoparticles (ZnO) with PMMA. Results also showed that impregnation of nanoparticles provides good protection against the tested fungi with the highest degradation was only 3.88% for Al₂O₃, compared to control sample with 20.26% weight loss. In conclusion, the applied nanoparticles are suitable substances to increase the durability of pine wood.

Evaluation of the Properties of Particleboard Made Using Oil Palm Starch Modified with Epichlorohydrin