Utilization of Mendong Plants-Activated Charcoal as H2S and NO2 Gas Adsorbent: Preliminary Study

The study of exhaust H2S and NO2 gases using activated carbon has been conducted. In this study, activated carbon was prepared from mendong plant (Frimbistylis umbellaris), which was activated using zinc chloride (ZnCl2) with concentrations of 2.5; 5; 7.5; and 10 % w/v to determine the efficiency of H2S adsorption. Mendong charcoal was obtained from the process of using a modified tool. Activation was done by maceration using ZnCl2 activator (w/v) for 24 hours. The adsorption of H2S and NO2 was analyzed using UV-Vis spectrophotometry. Determinations of H2S gas carried out using the blue methylene’s method for 1 hour showed the highest effectiveness of mendong activated carbon was of that at the concentration of 2.5 % ZnCl2 w/v with 80% of H2S removal. Further, the mendong activated carbon with the concentration of 2.5% ZnCl2 w/v was used for NO2 adsorption. The adsorption of NO2 gas was conducted for 1 hour using Griess Saltzman’s method. The result showed that the largest concentration of NO2 gas was adsorbed when the HNO3 concentration was 1.5 M (0.057 µg/mL). The percentage of NO2 efficiency adsorbed was at 28%.

Optimization and Kinetics of Zirconium Oxychloride (ZOC) Dissolution Using HNO3

The design of chemical reactor can not be separated from the optimization data and reaction kinetics obtained from the experimental measurement. Through the idea of making the dissolution reactor design, the purpose of this research is to obtain optimization data and dissolution kinetics of Zirconium Oxide Chloride (ZOC) using HNO3. The design of the solvent reactor is required to make the feedstock in the liquid-liquid extraction process continuously. The extraction process is a mini-pilot plant unit as a nuclear-grade zirconia manufacture. The dissolution optimization was carried out by dissolving ZOC solids of zircon sand processed products using HNO3 in a container with some variation of contact time, HNO3 concentration and temperature. While the kinetics data was gained by extracting from the optimization data obtained based on the formula of reaction orders. The investigation result with 6 gr of ZOC and 6M HNO3 concentration obtained the best contact optimum time of 2 minutes and the conversion number (α) of 0.96. The dissolution reaction mechanism was estimated in accordance with the reaction of order 1 with the k value of 1.5879 minutes-1. It was predicted that the reaction mechanism of ZOC dissolution in HNO3 begins with diffuse control and is followed by chemical reaction control. With increasing conversion temperature, the conversion will increase to 0.98, while the reaction also follows the reaction order 1. The optimum temperature at 60 °C, and the correlation between temperature (T) with the calculated reaction rate constant (k) according to the Arrhenius formula yielded an equation of ln k = - 4191,6 / T + 13,903 or k = 13,903.e- 4191,6 / T, with the frequency factor A = 1091430 and the activation energy E = 34,848 kJ / mole.

Potassium Gluconate Inhibition of α-Brass Corrosion in 1 M HNO3

Potassium gluconate inhibition effects of α-brass corrosion immersed in 1 M HNO3 were studied at room temperature (25°C). Gravimetric and potentiodynamic polarization measurement techniques were used separately for the experimental investigation. A Digi-Ivy potentiostat, connected to computer for data acquisition and analyses was used for the potentiodynamic polarization experiments. The observed potassium gluconate’s corrosion inhibition increased as the inhibitor concentration increased up to 3.5g/200ml HNO3 where a 0.7224g weight loss was recorded in comparison with the experiment without added inhibitor which had a 3.582g weight loss at 312 hours. The corresponding corrosion rate at 3.5g/200ml HNO3 concentration was 4.93 mm/yr while the uninhibited (control) experiment recorded a 20.33 mm/yr at 288 hrs. Corrosion inhibition efficiency values for the 1.5, 3, 3.5 and 4g/200ml HNO3 concentrations are respectively 16.99, 41.77, 79.86 and 64.53%. Other parameters recorded include: polarization resistance, Ω (3.20E+01); corrosion rate (19.15 mm/yr) and current density, 1.01E-03 Acm-2 for the 3.5g/200ml HNO3 concentration in HNO3 test medium were also achieved. A mixed type inhibitor was indicated with the recorded results of ba and bc. Adsorption isotherm showed that inhibitor protection mechanism followed both the Frumkin and the Freundlich models more than the Langmuir isotherm model.

Selective Uptake of Palladium From High-Level Liquid Wastes by Hybrid Microcapsules Enclosed With Insoluble Ferrocyanides

Fine crystalline powders of KCuFC were immobilized with alginate gel polymers by sol-gel methods. The uptake properties of KCuFC-microcapsules (KCuFC-MC) were examined by batch and column methods. The size of KCuFC-MC particle was estimated to be about 1 mm in diameter, and KCuFC powders were uniformly dispersed in KCuFC-MC particles. The uptake rate of Pd2+ for KCuFC-MC was attained within 3 d, and the uptake of Pd2+ was found to be independent of the temperature and coexisting HNO3 concentration. As for the breakthrough properties of Pd2+ through a column packed with KCuFC-MC, a breakpoint of 5% breakthrough was enhanced with lowering of flow rate and independent of coexisting HNO3 concentration. The Pd2+ ions were selectively adsorbed in the KCuFC crystal phase, while other metal ions such as Ru(NO)3+ and ZrO2+ were absorbed in the alginate phase. High uptake percentage of 98.6% was obtained by using the dissolved solutions of spent fuel from FBR-JOYO (119 GWd/t, JAEA). The alginate film enclosing KZnFC was further prepared by using the support of cellulose filter paper, where the Pd2+ ions were selectively adsorbed on the KZnFC-MC film. The alginate film enclosing insoluble ferrocyanides are predicted for the selective separation of Pd2+ as an ion-exchange filter. Thus, the microcapsules enclosing insoluble ferrocyanides are effective for the selective separation of Pd2+ from high-level liquid waste (HLLW).

Extraction model of low methoxyl pectin from apple pomace effects of acid concentration and time on the process and the product

In Brazil, one of the top apple producing countries in the world, apple processing is an increasing activity, with pomace as the main by-product. To extract pectin from pomace, factors affecting process and product should be studied for optimization. A model to produce LMP directly from dried apple pomace was established observing the effects of HNO3 concentration and the time of reaction at 97ºC, analyzed from a statistical and practical point of view. The model for gravimetric yield (R² =0.9834) predicts the highest value of 20.07 g/100 g (126 mM; 14.07 min) of a pectin with a degree of esterification of 48.49%. The model for degree of esterification of extracted pectin (R²= 0.9797) predicts the lowest value of 43.73% (200 mM; 10.07 min) with a yield of 16.77g/100 g. The results using the central coordinates (100 mM; 10 min) for gravimetric yield were 19.01 g/100 g and for the degree of esterification, 50.79%.