Adsorption Capacity and its Dynamic Behavior of the Hydrogen Storage on Carbon Nanotubes

The potential of carbon nanotubes (CNTs) produced in our laboratory to be used for hydrogen storage was tested in this study. The test includes the determination of the hydrogen gas adsorption capacity and the dynamics of the adsorption and desorption of hydrogen on CNTs at isothermal temperature of 25oC and pressures of 0–1,000 psia. A similar test was also conducted on commercial CNTs obtained from the Chinese Academy of Sciences for comparison. The results showed that the hydrogen adsorption capacity of the local CNTs is lower than that of commercial CNTs. At pressures around 960 psia, the adsorption capacities of local and commercial CNTs are 0.09% and 0.13% weight, respectively. In general, the hydrogen adsorption data of both the adsorbents can be represented well by the Langmuir model, with less than 3% absolute average deviation (AAD). The dynamics of adsorption and desorption can be represented well by the Gasem and Robinson model with less than 2% AAD. The adsorption and desorption processes on both local and commercial CNTs occurred very quickly. At the highest pressure (960 psia), the adsorption and desorption equilibriums on the local CNTs were reached in approximately 30 s, while on commercial CNTs, they were reached in 2 s. The rates of the adsorption equilibriums on both local and commercial CNTs increase at a higher pressure. In the desorption process, while the equilibrium time is reached slightly faster at a higher pressure on commercial CNTs, the time is almost similar at all pressures for local CNTs

Optimasi Penggunaan Koagulan pada Pengolahan Air Limbah Batubara

Coagulation Test for coal wastewater was conducted with jar test methode. This research was performed by comparing coagulant activity with pH and dosage variation. Coagulant used in this research were FeCl3, Al2(SO4)3, PAC, dan Nalco 8100. Optimum condition was identified by varying acidity on pH of 5, 6, 7, and 8 with dosage variation on each pH. Optimum dosage range for each coagulant was defined from pre eliminary test. The parameter tested are turbidity, pH, TSS, and disolved Fe, Mn, and Al. Laboratory test result showed that the most effective coagulant to reduce contaminant substances is Nalco 8100. Optimum condition was reached at pH of 8 and 1 ppm. Keyword: Coagulant, Jar test, Coal, Wast

Mathematical Model Controlled Potassium Chloride Release Systems from Chitosan Microspheres

Chitosan can be prepared in the form of microspheres that serve as a depot for bioactive compounds released in a controlled way to diseased organs. In this study, a mathematical model of potassium chloride release from chitosan microspheres was developed. The model was validated using experimental data. The potassium chloride-loading percentages of 10.01%, 20.84%, and 20.57% were prepared using a cross-linking method. The potassium chloride loading was kept constant at about 20% when the potassium chloride mass in the preparation stage was above 5.024 mg/mL. Experiments and a model calculation of potassium chloride release from the microspheres with a loading of 10.01% and 20.57% were performed. In general, the model reproduces the experimental data. The experiments and the calculation show that during the same period, microspheres containing more potassium chloride release a higher percentage of potassium chloride than do microspheres containing less potassium chloride

Synthesis of carbon nanotube using ferrocene as carbon source and catalyst in a vertical structured catalyst reactor

Development of nano-carbon technology in the world has recently occurred due to its excellent electric, thermal, and mechanical properties and it diverse of applications such as electronics, biology, and material. Fixed bed reactor run into blocked due to carbon deposition on the catalyst that cause pressure drop enhancement. Whereas, application of fluidized bed reactor as an alternative of prior reactor have some trouble for complicated of feed flow control that can cause change of catalyst particle size during reaction since agglomeration and adhesion of nanoparticles transpire. Synthesis of carbon nanotube material used a vertical structured catalyst gauze reactor with double furnace system to maintain the catalyst and carbon source in the form of gas phase. This will lead growth of CNT on the surface of the substrate proved by SEM and XRD characterization. Furnace 1 used to ferrocene vaporizer at 400°C and furnace 2 provide substrate placement for CNT growth at 850°C. CNTs characterization confirmed yield and CNT diameter 29.33% and 11.38 nm respectively. Characterization of SEM show that CNT grows on stainless steel type 316 substrate preferable with oxidative heat treatment. Nevertheless, CNTs product still contain many of impurities such as Fe3O4, Fe2O3, Fe3C, hexagonal graphite, and amorphous carbon