The functionalization of Multi-walled Carbon Nanotubes (MWCNTs) is addressed to improve its interaction capability with other materials for further applications. The oxidation of MWCNTs by nitric acid is one of the promising methods for its surface modifications. In this research, MWCNTs functionalization was carried out in several steps such as oxidation, filtration, washing, and drying. The optimization of reaction time for MWCNTs functionalization was conducted to achieve the optimum condition which efficiently functionalizes MWCNTs surface. The sample characterizations were investigated by Boehm titration, Fourier Transform Infrared (FTIR) Spectroscopy, Thermo Gravimetric Analysis (TGA), and dispersion test. As a result, carboxyl groups were successfully attached onto the MWCNTs surface and stable dispersion of MWCNTs was obtained after 12 hours. Oxidation with nitric acid for 12 hours at room temperature is the optimum treatment time for surface modification.

Multi-walled carbon nanotubes (MWCNTs) are known as efficient drug carriers. To improve their interaction with other materials, surface modification of MWCNTs is necessary. In this work, MWCNTs were functionalized with acid and polysaccharides (chitosan and gelatin). The functionalization process was done via modification with acid solutions of nitric acid, sulfuric acid, and a mixture of nitric acid-sulfuric acid first, followed by functionalization with chitosan and gelatin. To achieve the optimum condition of MWCNTs functionalization, the reaction time, temperature, and acid ratio were varied. Furthermore, the effect of chitosan and gelatin addition into MWCNTs was studied at various mass ratios. The synthesized materials were characterized by Fourier transform infrared spectrophotometer, Boehm titration, and dispersion test. The Boehm titration results showed that the acid functional groups had been attached successfully to MWCNTs surface. The amount of acid functional groups increased along with reaction time. The highest amount of acidic group obtained from the data was 2.33 mmol/g. It was achieved when MWCNTs reacted with nitric acid for 24 hours. Temperature and acid ratio variations on the MWCNTs functionalization did not provide significant results. From the FTIR data, sharp peaks at 3480 cm-1 and 1040 cm-1 indicates a -CONH bond, which shows that chitosan and gelatin have been successfully grafted onto MWCNTs surface via an amide linkage. Moreover, the dispersion test showed that the functionalized materials were stable for 48 hours.

Scaffold, a template resemble an extracellular matrix, contributes a necessary part in tissue engineering to accommodate the growth of cells. In the development of scaffold made from organic materials such as chitosan and gelatin, researchers have done various ways to modify its properties and one of them is by incorporate it with inorganic materials. This research explored the potential of silica derived from geothermal power plant waste as a biocomposite material for scaffold. Biocomposites with two-dimensional (2-D) film form were prepared by simple drying process at room temperature and ambient pressure, while three-dimensional (3-D) scaffold form were fabricated by freeze-drying. The obtained biocomposites were characterized by Fourier Transform Infra-Red (FTIR) spectroscopy and Scanning Electron Microscopy (SEM). In addition, swelling and degradation tests were also performed on the films and scaffolds. The results showed that there are interactions between each component in chitosan/gelatin/geothermal silica biocomposites and the addition of geothermal silica decreases the swelling and degradation rates of the biocomposites. These results indicate that geothermal silica has a high potential to be used as an additive for controlling the physical properties of chitosan/gelatin scaffolds.

The potential effect of synthetic textile dyes towards human health and environment is much severe. Currently available dye in national and global market is dominated by synthetic commercial dye from various producers. Meanwhile, Indonesia demand for textile dye is increasing, but is not followed by production rate of textile dye. Producing environmentally friendly natural dye, which can compete in the global market, may solve those problems. A potential natural dye may be produced from tannin which is extracted from Mangrove bark. It has high yield with purity of 95% tannin (w/w) with solvent extraction method under moderate temperature condition. Mangrove tree bark is obtained from the side product of wood chips production. There are four species of Mangrove available for wood logging and chips producing activities namely Rhizophora Apiculata, Bruguiera Gymnorrhiza, B., Bruguiera Parviflora, and Ceriops Tagal. Mangrove can spread out the seed through the sea water naturally, making this wood reproduces widely and quickly. With proper treatment and logging management, considering the growth rate of mangrove, the sustainability of raw material is assured. The production of tannin will take place nearby the wood chips production. From 540 tonnes/month of mangrove bark as raw material, a 67 tonnes/month product could be extracted. The process will be carried out in small scale plant on empty land with area of 3.6 Ha. This plant has three units: raw material preparation, synthesis, and product purification. The product has desired purity and specification, and can be sold commercially. It also has the expected cash flow, and the profitability analysis result is also stunning. With Capital Expenditure (CAPEX) of Rp 141,896,000,000.- and operational Expenditure (OPEX) of Rp 28,842,000,000.-, the plant has Return on Investment of 27%. It has pay out time of 2.77 year, 19.08% DCFRR, Break Even Point at 40.85%, Shutdown Point at 10.25 %, IRR of 9.90%, and Net Present Value at Rp7,601,000,000.-. This investment also proves that at 5% change of raw material and products cost, the plant still overcomes the change and defend its profit state, making this investment feasible.