This study focuses on development of a new adsorption technique by CO 2 -activated chitosan. Carbon dioxide was utilized to form the functional chemical groups of chitosan on the adsorptions of anionic dyes, Brilliant Blue FCF and Congo Red, in the aqueous solution. CO 2 -activated chitosan results in the dye adsorption significantly faster than that of chitosan in pure water. The adsorption capacities and removal efficiencies of the dye are increased by CO 2 -activated chitosan. Furthermore, the dye adsorptions on CO 2 -activated chitosan were investigated at various temperatures and initial dye concentrations in the aqueous solution. Interestingly, the high temperature adsorption provides the enhancement of adsorption capacities and removal efficiencies of the dye by the carbamate cross-linking of chitosan with CO 2 . CO 2 -activated chitosan was further characterized by Fourier transform infrared spectra, amino group ratio, zeta potential, and thermal gravimetric analysis. These characterizations can be used for understanding the unique adsorption of the dye on CO 2 -activated chitosan. Carbon dioxide-activated chitosan in this work will provide an effective operation and a clean process of dye adsorption in wastewater treatment.

Two subsequent separation processes are required to produce absolute ethanol (at least purity of 99.5% v/v),namely the distillation and adsorption processes. Thus, it is important to find the optimum operation conditionfor those following processes. The aims of the present study are to optimize the feed plate of distillation and thetemperature of feed adsorbent. This study is conducted using a continuous sieve tray distillation system with thenumber of 16 trays, the length-diameter ratio of 80.64, the reflux ratio of 3.5, and the feed with ethanol contentof 10 % v/v ethanol, which is produced via the fermentation process of molasses. To conduct the first aim of thisstudy, the feed enters the distillation column with several of variable feed plate, i.e. 12, 13, 14, and 15. This feedplate location is calculated from the top of the column. On the other hand, the second aim of this study, isconducted using the subsequent combination of distillation and adsorbent columns, where the distillate (purity ofethanol around 95% v/v) from the distillation column is then flowed into the adsorbent column with various feedadsorbent temperature, i.e. 80 °C, 90 °C, 100 °C, and 110 °C, to be purified as an absolute ethanol. Here theadsorbent column is designed as a fix bed adsorption column with a molecular sieve of 3A (zeolite) is used as anadsorbent for that purification process. Our results showed that the optimum feed plate is 14, because at thisplate the ethanol distillate has the highest content among those various variables. Meanwhile, the optimumtemperature of feed adsorbent is 90° C, which requires the least energy for the distillation - adsorption process,i.e. at 18691 kJ/kg absolute ethanol. This primary study is expected to be an alternative way to optimize theoperating condition of the sieve tray distillation-molecular sieve adsorption system by means of acquiring aminimum energy involving in the process to achieve the highest purity of ethanol.

Carbon dioxide is one of the greenhouse gases that cause climate change, thus the effort for reducing the concentration of CO2 necessary, for example through the conversion of CO2. The conversion of CO2 into methanol plays important role, because in addition to reducing greenhouse gas, it is also creating a future energy carrier needed in fuel cell technology. One of the CO2 conversion methods is the electrolysis method using MEA. The electrochemical CO2 conversion in this study used a Cu2O-ZnO/C composite catalyst made by milling methods at various milling times, as well as the effect of PCA utilization. The catalysts were characterized using Particle Size Analyzer (PSA), Brunauer-Emmett-Teller (BET), Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and SEM-EDX analysis. The results of PSA and BET characterization showed that the longer the milling time, the smaller the particle size and the higher the relative surface area. The use of PCA increased the unoxidized Cu content as indicated by the SEM-EDX results. Based on the results of CV analysis, the catalyst that has the largest ECSA (Electrochemical surface area) value is the catalyst milled using PCA and the milling time is three hours.