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Futalan, Cybelle M.,Huang, Yu-Shen,Chen, Jheng-Hong,Wan, Meng-Wei IWA Publishing 2018 Water Science & Technology Vol.78 No.3
<P>In the present work, the removal efficiency of As(V) from aqueous solution using chitosan-coated bentonite (CCB), chitosan-coated kaolinite (CCK) and chitosan-coated sand (CCS) was evaluated. The chitosan-based adsorbents were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, the Brunauer–Emmett–Teller method and thermogravimetric analysis. Kinetic studies revealed that As(V) uptake using CCB, CCK and CCS fitted well with the pseudo-second order equation (<I>R<SUP>2</SUP></I> ≥ 0.9847; <I>RMSE</I> ≤ 9.1833). Equilibrium data show good correlation with the Langmuir model (<I>R<SUP>2</SUP></I> ≥ 0.9753; <I>RMSE</I> ≤ 8.5123; <I>SSE</I> ≤ 16.2651) for all adsorbents, which implies monolayer coverage onto homogenous energy sites. The Langmuir adsorption capacity for As(V) at pH 7.0 was determined to be 67.11, 64.85, and 16.78 mg/g for CCB, CCK and CCS, respectively. Thermodynamic studies show that As(V) uptake is exothermic in nature using CCK and endothermic using CCB and CCS. Moreover, adsorption of As(V) was feasible and spontaneous for CCB and CCS at 298 to 328 K. Results show that CCB is the most effective adsorbent in the removal of As(V) from water due to its high surface area and large pore diameter.</P>
Ligaray, Mayzonee,Futalan, Cybelle M.,de Luna, Mark Daniel,Wan, Meng-Wei Elsevier 2018 Journal of cleaner production Vol.175 No.-
<P><B>Abstract</B></P> <P>In this study, real thin-film transistor liquid-crystal display wastewater with an initial chemical oxygen demand (COD) concentration of 1348.00 ppm was treated using chitosan-coated bentonite (CCB). Characterization analysis of the CCB adsorbent was performed using Brunauer-Emmett-Teller surface area analysis, scanning electron microscopy, and Fourier-transform infrared spectrometer. The effect of parameters such as contact time, CCB dosage, pH and temperature on the COD removal was examined. Results show that increasing the contact time and CCB dosage increases COD removal efficiency while no considerable change was observed in removal efficiency with varying temperature and pH. Adsorption experiments showed that the removal of COD using CCB best fits the Langmuir isotherm (<I>R</I> <SUP> <I>2</I> </SUP> ≥ 0.9821) while kinetic data was best described by the pseudo-second order equation (<I>R</I> <SUP> <I>2</I> </SUP> ≥ 0.9980), which implies that chemisorption is the rate-determining step. Thermodynamic studies revealed that adsorption of COD onto CCB was spontaneous, exothermic (ΔH° = 5.95 kJ/mol) and decreased randomness in the system (ΔS° = -0.88 J/mol·K). Optimization studies using response surface methodology with central composite design was performed to determine the operating parameters that would yield the maximum COD removal. It was determined that the optimum conditions of 20.32 h, 0.8 g CCB, pH 4.0, and 30 °C would yield a maximum removal of COD of 73.34%.</P> <P><B>Highlights</B></P> <P> <UL> <LI> COD removal using CCB is spontaneous, exothermic and results to low disorder. </LI> <LI> Maximum COD removal of 73.34% from TFT-LCD wastewater using CCB is attained. </LI> <LI> CCB mass is the most significant factor affecting COD removal from wastewater. </LI> </UL> </P>
Choi Angelo Earvin Sy,Futalan Cybelle Concepcion Morales,이정재 한국원자력학회 2020 Nuclear Engineering and Technology Vol.52 No.7
This research presents a case study on the remediation of a radioactive waste (uranium: U) utilizing a multi-objective fuzzy optimization in an electrocoagulation process for the iron-stainless steel and aluminum-stainless steel anode/cathode systems. The incorporation of the cumulative uncertainty of result, operational cost and energy consumption are essential key elements in determining the feasibility of the developed model equations in satisfying specific maximum contaminant level (MCL) required by stringent environmental regulations worldwide. Pareto-optimal solutions showed that the iron system (0 mg/L U: 492 USD/g-U) outperformed the aluminum system (96 mg/L U: 747 USD/g-U) in terms of the retained uranium concentration and energy consumption. Thus, the iron system was further carried out in a multi-objective analysis due to its feasibility in satisfying various uranium standard regulatory limits. Based on the 30 mg/L MCL, the decision-making process via fuzzy logic showed an overall satisfaction of 6.1% at a treatment time and current density of 101.6 min and 59.9 mA/cm2 , respectively. The fuzzy optimal solution reveals the following: uranium concentration e 5 mg/L, cumulative uncertainty e 25 mg/ L, energy consumption e 461.7 kWh/g-U and operational cost based on electricity cost in the United States e 60.0 USD/g-U, South Korea e 55.4 USD/g-U and Finland e 78.5 USD/g-U.
de Luna, Mark Daniel G.,Futalan, Cybelle M.,Dayrit, Raymond A.,Choi, Angelo Earvin S.,Wan, Meng-Wei Elsevier 2018 Journal of Cleaner Production Vol.203 No.-
<P><B>Abstract</B></P> <P>In this study, oxidative-adsorptive desulfurization technology was applied to raw diesel containing 1480.4 ppm sulfur. For oxidative desulfurization, the oxidant and catalyst were hydrogen peroxide and phosphotungstic acid, respectively. Two types of continuously mixed reactors: (1) continuous stirred tank reactor (CSTR) and (2) in-line mixer were evaluated under varying reaction temperature, mixing speed and diesel flow rate. For the in-line mixer system, the mixer speed and the flow rates for diesel and oxidant were modeled and optimized using Box-Behnken design of the response surface methodology. Optimization of process parameters resulted in sulfur removal of 85.90% at 18,000 rpm mixer speed, 500 mL min<SUP>−1</SUP> diesel flow rate and 300 mL min<SUP>−1</SUP> H<SUB>2</SUB>O<SUB>2</SUB> flow rate. In the subsequent adsorptive desulfurization experiments, continuous fixed-bed adsorption using alumina removed 92.81% sulfur from treated diesel fuel thereby producing low-sulfur diesel that is within the allowable limit of Euro IV standard.</P> <P><B>Highlights</B></P> <P> <UL> <LI> In-line mixer has better removal efficiency of sulfur from diesel over CSTR. </LI> <LI> Oxidative-adsorptive desulfurization achieved 92.81% sulfur removal. </LI> <LI> Oxidative-adsorptive desulfurization achieved residual sulfur of 30 ppm. </LI> </UL> </P>
de Luna, Mark Daniel G.,Wan, Meng-Wei,Golosinda, Lucille R.,Futalan, Cybelle M.,Lu, Ming-Chun ACS AMERICAN CHEMICAL SOCIETY 2017 ENERGY AND FUELS Vol.31 No.9
<P>Mixing-assisted oxidative desulfurization (MAOD) of model fuel that contains dibenzothiophene (DBT) using phosphotungstic acid (HPW) as a catalyst and hydrogen peroxide (H2O2) as an oxidant was evaluated. Characterization analysis of HPW shows that the average crystallite size is 82.39 nm, with a disintegrated structure and morphology. The effect of operating parameters, such as mixer speed (5000-10 000 rpm), tetraoctylammoniurn bromide [phase-transfer agent (PTA)]/HPW ratio (0.5:1-5:1), and temperature (25-60 degrees C), on the sulfur conversion of DBT was examined. Results show that the sulfur conversion increases with an increasing temperature and mixer speed and a lower amount of PTA. The highest sulfur removal and rate constant of 100.0% and 0.1528 min(-1), respectively, were attained under the following conditions: 1:1 ratio, 40 degrees C, and 10 000 rpm. The pseudo-first-order equation and Arrhenius equation were applied to determine the kinetic rate constant and activation energy of HPW in the oxidation of DBT in a MAOD system. High correlation coefficient values (R-2 >= 0.93) indicate that the pseudo-first-order equation has the goodness of fit in describing the experimental kinetic data. Moreover, the activation energy of HPW derived from the Arrhenius equation was 42.60 kJ/mol.</P>