Sutasinee Neramittagapong

Optimizing chemical oxygen demand removal from synthesized wastewater containing lignin by catalytic wet-air oxidation over CuO/Al2O3 catalysts

In this study, 10% CuO/Al2O3 catalyst was used in a catalytic wet-air oxidation process to remove chemical oxygen demand (COD) and color from experimentally designed wastewater containing lignin. The catalyst was prepared using an impregnation method and was characterized by X-ray diffraction (XRD), atomic absorption spectroscopy (AAS), and Brunauer-Emmett-Teller method (BET) for surface area before use. A series of Box-Behnken design (BBD) experiments were used to identify the conditions (temperature, pressure, reaction time, and catalysts) necessary for the COD removal process. The predicted model had R2 and R2adj correlation coefficients of 0.98 and 0.97, respectively. Pressure only and the interaction effect between temperature and pressure were found to have a significant effect on COD removal (both confidence interval [CI] 95%). Finally, response surface methodology (RSM)-optimized results suggested that 92% of COD could be removed in 1 L of experimental wastewater with a lignin concentration 350 g/L in 120 min under the following conditions: a reaction temperature of 185 °C, a pressure of 10 bars, and catalyst loading of 1 mg/L. The experiment, performed in triplicate, yielded a COD removal of 90 ± 2%. The results are believed to be of importance to pulp and paper industrial wastewater treatment and other similar applications. Implications: Catalytic wet-air oxidation (CWAO) has been used as an alternative to overcome problems related to the high temperatures and pressures required by the traditional wet-air oxidation. CWAO has been widely applied to treat various industrial wastewaters. To reduce the overall operational cost, it is necessary to identify the optimal condition required when designing wastewater treatment plant processes. In this work, the authors had successfully demonstrated the application of response surface methodology (RSM) with the Box-Behnken design (BBD) as a means of elucidating the complicated interaction effects between parameters.

Photocatalytic Degradation of Alachlor on Fe-TiO2-Immobilized on GAC under Black Light Irradiation Using Box-Behnken Design

The aim of this work was focused on the photocatalytic degradation of alachlor from aqueous solution using 10%wt Fe-TiO2, as 0.1%wt of Fe doped into TiO2 structure, immobilized on granular activated carbon (GAC) under black light irradiation. The extended photocatalytic conditions were studied as functions of catalyst loading, number of black light, and initial pH of solution using Response Surface Method (RSM) based on Box-Behnken design (BBD). Characterizations of the photocatalyst by TGA-DTA, and XRD were investigated. Photocatalyst was calcined at 400°C under nitrogen atmosphere. As a Result of calcinations, photocatalyst consisted of only graphite crystallite while the crystallite phases of TiO2 were not observed. The degradation results showed that the photocatalytic process gave the highest percent degradation comparing with adsorption and photolysis processes. The effects of three operating variables which are catalyst loading, number of black light, and initial pH of solution on the degradation efficiency of alachlor were examined. Photocatalyst loading was only significant parameter effecting for photocatalytic degradation of alachlor. The photocatalytic degradation slightly increased with increasing of number of black light while pH of solution did not affect photocatalytic degradation of alachlor. The photocatalytic process and adsorption process were affected from the initial alachlor concentrations as well.

Dimethyl Ether Synthesis via Methanol Dehydration over Diatomite Catalyst Modified Using Hydrochloric Acid

The synthesis of dimethyl ether via methanol dehydration has been carried out over untreated-diatomite catalyst (DM) and hydrochloric acid modified treatment on diatomite catalyst (DMHC). The reactions were carried out in a fixed-bed reactor. The effects of hydrochloric acid modifications of diatomite on its catalytic performance were studied. The characterization such as XRD, SEM, FT-IR and FT-Raman had no deformation after HCl-modified treatment on catalysts. DMHC catalyst apparently gave the higher methanol conversion rate than DM due to the acidity while the selectivity of dimethyl ether from 250 to 350°C was slightly changed. The acidity was depended upon Al(IV) ions; nevertheless, both Al(V) and Al(VI) were affected and hence increasing the basic active sites. Not only was the competitively catalytic methanol dehydrogenation preferred with basic condition but also methanol-blocking water molecule interaction was the unwanted reaction. In this investigation, the chemical-bond arrangements of silicon and aluminium ions were proposed with solid MAS/NMR. The DMHC catalyst exhibited better DME yield than the DM catalyst, and it could be used as a selective catalyst for DME synthesis from methanol.

Optimal Decolorization Efficiency of Reactive Red 3 by Fe-RH-MCM-41 Catalytic Wet Oxidation Coupled with Box-Behnken Design

The reactive red 3 was degraded by catalytic wet oxidation process over Fe-RH-MCM-41 prepared by Direct Hydrothermal Technique (DHT) at Si/Fe molar ratio of 10 using silica from rice husk. The extended reaction conditions were studied as a function of reaction temperatures, initial H2O2 concentrations and initial pH of solutions designed by Box-Behnken design (BBD) based on Response Surface Methodology (RSM) to achieve the optimal condition and interaction of independent variables. The characterizations of catalyst were studied by XRD, BET surface area and TEM to explain the morphology of surface and to confirm the hexagonal structure. The results showed the 2theta peak can be indexed to hexagonal lattice that also confirmed by TEM result and surface area about 650 m2/g. All of independent variables showed significant on the degradation of reactive red 3 except for initial H2O2 concentration.

Metal Adsorbent Prepared from Coir Pith as Agricultural Waste: Adsorption of Zn(II) and Pb(II) from Aqueous Solution

Adsorption of Zn(II) and Pb(II) from aqueous solution were studied by using modified coir pith as an adsorbent. The extended adsorption conditions were investigated as a function of calcination temperature, contact time, adsorbent size, initial pH of solution and initial Zn(II) and Pb(II) concentrations. The adsorption capacity increased rapidly in first 5 minute and reached equilibrium in 120 minutes for Zn(II) and 10 minutes for Pb(II). In case of Zn(II); the results showed that the calcination temperature of modified coir pith above 600oC gave the higher adsorption capacity. The sizes of modified coir pith have no effect on the adsorption capacity. The adsorption capacity increased with increasing initial solution pH value. In case of Pb(II); the calcination temperature of modified coir pith showed no effect on the adsorption capacity. The sizes of modified coir pith showed a little effect on the adsorption capacity. The adsorption capacity increased with increasing of initial solution pH value up to pH of 3 and then stable. The results also corresponded with the Langmuir and Freundlich isotherms and pseudo second order kinetic adsorption models. The modified coir pith gave a higher Zn(II) and Pb(II) adsorption capacity of 29.33 mg Zn(II)/g adsorbent and 36.50 mg Pb(II)/g adsorbent, respectively.

Methanol dehydration to dimethyl ether over strong-acid-modified diatomite catalysts

ABSTRACT Dimethyl ether synthesis via methanol dehydration over strong-acid-modified (with sulfuric, hydrochloric and nitric acid) diatomite (DM) catalysts was conducted in a fixed-bed reactor with elevated temperature reaction from 250 to 350°C. The modified DM catalysts were characterized by using X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, fourier transform Raman spectroscopy, temperature-programmed desorption of ammonia, temperature-programmed of carbon dioxide, thermal gravimetric analysis, and solid-state 27Aluminum magic angle spinning/nuclear magnetic resonance spectroscopy. It was found that sulfuric-acid-modified DM catalyst yielded the highest DME selectivity (~99%). It was also revealed that methanol conversion depended on Al ions. The methanol conversion increased with Al(IV) but decreased with Al(V) and Al(VI).

Catalytic Wet-Air Oxidation of Aniline Removal from Synthetic Wastewater

Wet-air oxidation (WAO) and catalytic wet-air oxidation (CWAO) over CuO/Al2O3 and NiO/Al2O3 catalysts for aniline removal were investigated. The oxidation reaction was carried out in a 1000-ml high-pressure batch reactor. The temperatures of 160, 200 and 260C and the pressures of 5 and 10 bars were generally applied for 120 min. CuO/Al2O3 and NiO/Al2O3 catalysts were prepared by impregnation method. It is found from the results that aniline was completely degraded at these conditions. However, aniline was converted into other organic carbons which remained in the solution. So COD was found in the solution after the reaction. It is seen from the results that 56% of COD was removed by WAO at 200C and 10 bars for 120 min. The CWAO over CuO/Al2O3 catalyst showed higher COD removal (76%) than NiO/Al2O3 catalyst (60%). The types of metal oxide had an effect to the activity of COD removal; that is, CuO showed higher COD removal than NiO. The WAO and CWAO of COD removal in aniline solution were the first-order kinetic with the constant reaction rate and activation energy for CuO/Al2O3 of 0.234 s-1 and 11.772 kJ/mol, respectively.

Dimethyl Ether Synthesis via Methanol Dehydration over BEA Zeolite from Bagasse Fly Ash with Zircronium- and Nickel-Ion Exchange

The synthesis of dimethyl ether via methanol dehydration has been carried out over Beta zeolite (BEA) and ion-exchanged Beta zeolite from bagasse fly ash using hydrothermal method. The reactions were taken place in a fixed-bed reactor. The effects of nickel and zirconium ion-exchanged of BEA were investigated. Ni-BEA zeolite exhibited high methanol conversion rate and DME-resultant upon the reaction temperature from 200 to 225°C with equilibrium-limiting condition over 225°C; Furthermore, the Ni-BEA zeolite presented the best stable activity at 225°C over 1,200 minute. The Ni-BEA zeolite has also been interesting as a zeolite which suited to be one role importance to improve the properties for methanol dehydration to dimethyl ether.

Effects of Electrolytes on Zinc Deposition onto a Nickel Foam

The electrodeposition of zinc on nickel foam was prepared to use as an anode. The effects of potassium hydroxide (KOH) or zinc sulfate (ZnSO4) on the deposition of Zn dendrite at different current density were investigated. The morphology characterization of Zn dendrite was performed using Scanning Electron Microscope (SEM). The Zn anode prepared at the current density of 0.8A and using ZnSO4 as electrolyte showed a good morphology called compact. It gave a specific discharge of 210 cycles for more than 5 hours.

Effect of Chromium Loading on Diatomite for the Synthesis of Dimethyl Ether from Methanol

This research investigates the results of catalytic methanol dehydration for synthesis of dimethyl ether using chromium on diatomite catalyst with different the metal loading. The reactions were performed in pack-bed reactor at temperature between 250 to 350°C. According to the experimental results, the conversion of methanol increased with the increase of chromium loading on diatomite catalyst. DME selectivity was up to 99 percent. The surface acidity increased due to chromium loading, whereas the surface areas decreased. It was found that metal oxide loading and surface acidity affected reaction rates more than the surface area of the catalyst. Finally, 15%Cr/DM catalyst give high methanol conversion at 91.7 percent and it has exhibited good stability during the 12 hour experiment. The catalyst has shown efficient synthesis of dimethyl ether from methanol.