Korean Journal of Chemical Engineering (v.29, #11)

This study was conducted to evaluate the presence, origination and classification of various hydrolyzing enzymes from malt and their specified hydrolyzing effects on various substrates for bioethanol production and to link these characteristics with the future prospects of bioethanol production. These enzymes are categorized as cell wall, starch, protein, lipid, polyphenol and thiol hydrolyzing enzymes based on their substrate specificity. Waste from beer fermentation broth (WBFB) has been evaluated as a rich source of malt derived hydrolyzing enzymes with significant self potential for bioethanol production. However, yeast cells cannot survive at the high temperature required for the saccharification activities of hydrolyzing enzymes during simultaneous saccharification and fermentation (SSF). This dilemma might be resolved by bioethanol production at elevated temperatures via cell-free fermentation systems in the presence of malt hydrolyzing enzymes. Moreover, emerging technologies such as genetic engineering in biomass and biotransformation in cell-free enzymatic systems will likely hasten bioethanol production in the near future. The present study adds new dimensions to eco-friendly bioethanol production from renewable and waste energy resources based on the specific hydrolyzing activities of malt enzymes.
Keywords: Hydrolyzing Enzymes; Waste from Beer Fermentation Broth; Bioethanol; Cell-free Fermentation; Genetic Engineering; Biotransformation

Photocatalytic reduction of carbon dioxide using Co3O4 nanoparticles under visible light irradiation by Joseph Albert Mendoza; Hye Kyoung Kim; Hoey Kyung Park; Kyun Young Park (1483-1486).
Photocatalytic reduction of carbon dioxide under visible light irradiation was carried out with Co3O4 powders suspended in water. A Pyrex glass batch reactor of 10mL in volume was used with a 21 W LED lamp of 510 to 620 nm in wave length as light source, and the reaction time was held at 4 h. The major products were formic acid and formaldehyde; the production rates were 4.53 μmol g−1h−1 and 0.62 μmol g−1h−1 for formic acid and formaldehyde, respectively. Carbon monoxide and methane were detected in trace amounts. The occurrence of the photo-reduction with Co3O4 is against the expectation from the valence band edge of Co3O4 in the literature. Possible causes for the contradictory result are discussed.
Keywords: Photocatalytic Reduction; Visible Light; Carbon Dioxide; Co3O4 ; Nanoparticles

We investigated the effects of ion exchange resins on the efficiency of crystallization with an increased surface area for the purification of vancomycin. As surface area-increasing materials, diverse types of ion exchange resin were used to increase the surface area per working volume (S/V). When the S/V was increased, in cation exchange resin Amberlite 200, Amberlite IR 120 (Na), and Amberlite IRC 50 and in anion exchange resin Amberlite IRA 400 (Cl) and Amberlite IRA 910 (Cl), vancomycin crystals were successfully generated. The yield of vancomycin increased (>97%), and the time necessary for crystallization was reduced dramatically (reduced from 24 hr to 12 hr). On the other hand, the purity of the vancomycin was approximately 95% and was not affected by increasing S/V. Use of an ion exchange resin also resulted in the production of smaller vancomycin crystals than in the absence of ion exchange resin.
Keywords: Vancomycin; Crystallization; Purification; Surface Area per Working Volume (S/V); Ion Exchange Resin

A computer simulation was performed using a commercial process simulator, Aspen Plus, for NMP (Nmethyl-2-pyrrolidone) extractive distillation process to separate 1,3-butadiene from the C4 hydrocarbon mixtures. The Redlich-Kwong equation of state and NRTL activity coefficient model were used to calculate thermodynamic properties in the simulation of the extractive distillation process. Binary parameters of the NRTL model not provided in the simulator were estimated using the UNIFAC method. The simulation results of the 1,3-butadiene recovery from the C4 mixtures were in good agreement with the plant operation data. The process simulation showed that the material balances in the extractive distillation were successfully predicted for various NMP solvent flow rates. The results obtained in this work provided the optimum solvent rate and the reflux ratio for the NMP extractive distillation process to separate 1,3-butadiene from the C4 mixtures.
Keywords: Extractive Distillation; NMP Solvent; Aspen Plus; 1,3-Butadiene

The alternative fuel, dimethyl ether (DME), which can be synthesized from natural gas, coal or biomass syngas, has been traditionally used as a diesel substitute or additive. DME purification processes with a conventional distillation sequence consume a large amount of energy. We used dividing wall columns (DWCs) to improve the energy efficiency and reduce the capital cost of the DME purification process. Various possible DWC arrangements were explored to find the potential benefits derived from thermally coupled distillations. The results show that utilizing DWCs can significantly reduce both the energy consumption and investment cost of the DME purification process. The lower energy consumption also results in the reduction of the CO2 emission.
Keywords: Distillation; Dimethyl Ether; DME; Dividing Wall Column; DWC; Thermally Coupled Distillation Column

We tested the thermal resistance of a carbon-fiber-reinforced fuel storage tank by using the simulations and the experiments. A model describing the one-dimensional heat transfer in a composite wall exposed to a flame was developed. As a moving boundary condition, the thickness recession is expressed by the one-step Arrhenius-type decomposition kinetics. The differential equations are solved by the Crank-Nicolson method, the algorithm of which is developed by us. For the experimental verification of the simulation, the well-controlled heat is added to one side of the square specimen taken from a carbon-fiber-wounded epoxy cylinder and the change in mass of the specimen is recorded as time passes. From the comparison of the results of two methodologies, it is hypothesized that the normalized thickness by the initial value should be always equal to the normalized mass by the initial value at a certain time. As a result, the surface recession data obtained by the simulations provide good predictions for those by the experiments.
Keywords: Carbon Fiber Reinforced Plastic (CFRP); Heat Transfer; Cone Calorimeter; Kinetics; Thermal Decomposition

The influence of cobalt particle size on catalyst performance in Fischer-Tropsch synthesis (FTS) has been investigated using functionalized carbon nanotube (CNT)-supported nano catalyst. The catalysts were synthesized by wet impregnation and special sol-gel technique. The catalysts were characterized by BET, XRD, H2 chemisorption, TPR, and TEM. According to TEM analysis, small Co particles (3–8 nm) synthesized by sol-gel technique have very narrow particle size distributions and are mostly confined inside the CNT. The deposition of cobalt nanoparticles synthesized by sol-gel technique on the functionalized CNT shifted the reduction peaks to a low temperature, indicating higher reducibility for uniform cobalt particles. The proposed sol-gel technique increased the FTS rate from 0.62 to 0.71 g HC/gcat./h, C 5 + selectivity increased 7% and CH4 selectivity decreased 4%, compared to that prepared by incipient wetness impregnation. This new catalyst preparation method may offer an attractive alternative for nanoparticles synthesis with uniform, and various size distributions.
Keywords: Fischer-Tropsch Synthesis; Carbon Nanotube; FTS Activity and Selectivity; Functionalization; Cobalt Particle Size

Catalytic steam reforming of biomass-derived tar for hydrogen production with K2CO3/NiO/γ-Al2O3 catalyst by Prapan Kuchonthara; Buppha Puttasawat; Pornpote Piumsomboon; Lursuang Mekasut; Tharapong Vitidsant (1525-1530).
A major problem of using Ni-based catalysts is deactivation during catalytic cracking and reforming, lowering catalytic performance of the catalysts. Modification of catalyst with alkali-loading was expected to help reduce coke formation, which is a cause of the deactivation. This paper investigated the effects of alkali-loading to aluminasupported Ni catalyst on catalytic performance in steam reforming of biomass-derived tar. Rice husk and K2CO3 were employed as the biomass feedstock and the alkali, respectively. The catalysts were prepared by a wet impregnation method with γ-Al2O3 as a support. A drop-tube fixed bed reactor was used to produce tar from biomass in a pyrolysis zone incorporated with a steam reforming zone. The result indicated that K2CO3/NiO/γ-Al2O3 is more efficient for steam reforming of tar released from rice husk than NiO/γ-Al2O3 in terms of carbon conversion and particularly hydrogen production. Effects of reaction temperature and steam concentration were examined. The optimum temperature was found to be approximately 1,073 K. An increase in steam concentration contributed to more tar reduction. In addition, the K2CO3-promoted NiO/γ-Al2O3 was found to have superior stability due to lower catalyst deactivation.
Keywords: Biomass Gasification; Tar Reforming; Alkali Metal; Ni-catalyst; K2CO3

Computational fluid dynamics modeling of hydrogen production in an autothermal reactor: Effect of different thermal conditions by Sayed Reza Shabanian; Masoud Rahimi; Amin Amiri; Shahram Sharifnia; Ammar Abdulaziz Alsairafi (1531-1540).
A numerical model was developed and validated to simulate and improve the reforming efficiency of methane to syngas (CO+H2) in an autothermal reactor. This work was undertaken in a 0.8 cm diameter and 30 cm length quartz tubular reactor. The exhaust gas from combustion at the bottom of reactor was passed over a Ru/γ-Al2O3 catalyst bed. The Eddy Dissipation Concept (EDC) model for turbulence-chemistry interaction in combination with a modified standard k-ɛ model for turbulence and a reaction mechanism with 23 species and 39 elementary reactions were considered in the combustion model. The pre-exponential factors and activation energy values for the catalyst (Ru) were obtained by using the experimental results. The percentage of difference between the predicted and measured mole fractions of the major species in the exhaust gas from combustion and catalyst bed zones was less than 5.02% and 7.73%, respectively. In addition, the results showed that the reforming efficiency, based on hydrogen yield, was increased with increase in catalyst bed’s thermal conductivity. Moreover, an enhancement of 4.34% in the reforming efficiency was obtained with increase in the catalyst bed wall heat flux from 0.5 to 2.0 kW/m2.
Keywords: CFD; Combustion; Hydrogen Production; Reforming Efficiency; Syngas

Effects of operation parameters on impedance responses are characterized to study electrochemical reactions of an anode-supported solid oxide fuel cell (SOFC) in an air blowing operation. The anode-supported SOFC, which consists of Ni-yttrium stabilized zirconia (YSZ) support/Ni-YSZ anode functional layer/YSZ electrolyte/gadolinium doped ceria (GDC) interlayer/La0.6Sr0.4Co0.2Fe0.8O3-δ -GDC cathode, is fabricated by a tape casting and co-firing process. To investigate the electrochemical response on impedances, an equivalent circuit is modeled with five elements and fitted by the complex nonlinear least square (CNLS) method. Based on the impedance spectra with the operation parameters, two among five elements are clarified to be concerned with anodic reactions and another two concerned with gas diffusion reactions in electrodes. It is difficult to clarify one among five elements with the results here. The clarified elements may be used to study the effects of materials and processes for SOFC with impedance responses, which will be helpful to improve the performance and reliability.
Keywords: Solid Oxide Fuel Cell; Impedance Spectra; Anode-supported Cell; Equivalent Circuit; Air Blowing

The impact of waste landfill on climate change was analyzed by comparing the amount of CH4 emission from landfill with the potential energy conversion. For this analysis, compulsive collection and surface emission amount of CH4 were used against Sudokwon Landfill Site 2nd Landfill, which is currently under operation in the Republic of Korea. As a result of the estimation, the total CH4 amount which can be collected from the Sudokwon Landfill Site 2nd Landfill during 2001–2035 is 3,068×106 N m3. During the same period, the total CH4 emission amount from the landfill slope, intermediate covering and final covering is 899×106 N m3. Especially, 95% (854×106 N m3) of the total surface emission is emitted during the landfill period 2001–2015. After final covering, in the period of 2016–2035, only 5.0% (45×106 N m3) is emitted. Additionally, as a result of analysis by comparing the surface emission amount from the route of the slope, intermediate covering and final covering, 92.8% (834×106 N m3) of CH4 is emitted from intermediate covering during landfill operation. The CH4 emission from the surface of Sudokwon Landfill Site 2nd Landfill during 2001–2035 can be converted to 32.9×106 Ton in CO2 bases. On the other hand, on CO2 bases, the reduction amount of global warming gas by converting compulsorily collected CH4 to energy source is about 19–33% of surface emitted CH4. It can be concluded that to improve the landfill method as a waste treatment methodology which can better adapt to the climate changes, various research and development on the intermediate covering system along with the fundamental enhancement on present landfill facility establishment standards and operating guidelines are required.
Keywords: CH4 ; Landfill Covering; Surface Emission; Fossil Fuel; Climate Change

Sorptive removal of Co, Sr and Cs from aqueous solution by SAMMS was investigated. The single-solute sorption data were well fitted by the Freundlich, Langmuir and Dubinin-Radushkevich models (R2>0.95). The maximum sorption capacities (q mL ) of the Langmuir model were in the order of Cs (1.14 mmol/g)>Co (0.20 mmol/g)≈Sr (0.195 mmol/g). The bi-solute competitive sorption of the metals was analyzed by the Langmuir, competitive Langmuir, modified extended Langmuir and P-factor models. The sorption of one metal was suppressed by the presence of competing metals. Sorptions of Co and Sr were strongly dependent on the initial solution pH but that of Cs was not. The calculated thermodynamic parameters such as ΔH0, ΔS0 and ΔG0 showed that sorption of Co onto SAMMS was endothermic, whereas those of Sr and Cs were exothermic. The negative ΔG0 values indicated all the sorption processes were spontaneous in nature.
Keywords: Cesium; Cobalt; Mesoporous Silica; Self-assembled Monolayers on Mesoporous Supports (SAMMS); Sorption; Strontium

Biosorption of hazardous textile dyes from aqueous solutions by hen feathers: Batch and column studies by Sagnik Chakraborty; Shamik Chowdhury; Papita Das Saha (1567-1576).
The biosorption potential of hen feathers (HFs) to remove hazardous textile dyes, namely congo red (CR) and crystal violet (CV), from their aqueous solutions was investigated in batch and dynamic flow modes of operation. The effect of biosorption process parameters such as solution pH, initial dye concentration, temperature, feed flow rate and bed height was studied. Biosorption equilibrium data were well described by the Langmuir isotherm model. Kinetic studies at different temperatures showed that the rate of biosorption followed the pseudo second-order kinetics well. A thermodynamic study showed that biosorption of both CR and CV was spontaneous and endothermic. Breakthrough time increased with increase in bed height but decreased with increase in flow rate. The Thomas model showed good agreement with the dynamic flow experimental data. Overall, the results suggest the applicability of HFs as an efficient biosorbent for removal of carcinogenic textile dyes from aqueous media.
Keywords: Biosorption; Hen Feathers; Congo Red; Crystal Violet; Thermodynamics; Breakthrough

The degradation of phenol was investigated in a continuous flow impinging streams system. In the first step, statistical experimental designs were used to optimize the process of phenol degradation in a photo-impinging streams reactor. The more important factors affecting phenol degradation (p<0.05) were screened by a two-level Plackett-Burman design. Four of the latter parameters, namely phenol concentration, catalyst loading, pH and slurry flow rate, were selected for final process optimization, applying central composite design (CCD). The predicted data showed that the maximum removal efficiency of phenol (99%) could be obtained under the optimum operating conditions (phenol concentration=50 mg l −1, catalyst loading=2.1 g l −1, pH 6.2 and slurry flow rate=550ml min−1). These predicted values were then verified by certain validating experiments. A good correlation was observed between the predicted data and those determined by the experimental study. This may confirm the validity of the statistical optimum strategy. Finally, continuous degradation of phenol was performed, and the results indicated a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.
Keywords: Phenol Degradation; Plackett-Burman Design; Central Composite Design; Photo-impinging Streams Reactor-Continuous Flow

This research has two parts: at first part electro coagulation (EC) method was used to remove the dye Direct Black 22 (DB22 (in aqueous media. All experiments were done in a 2 liter reactor with two electrodes made of steel (SS-304) as cathodes and one aluminum electrode as anode. Parameters affecting the process, such as anode material, electrolyte concentration, current density, initial pH of solution and the initial dye concentration, were investigated. Total amount of consumed energy was used for determination of optimal conditions. According to the results obtained for DB22 at optimized conditions, color and COD removal percentage were 92% and 85%, respectively. In addition, the current efficiency for aluminum anode in removal of DB22 was 90%. At the second part of the research work, color removal by EC for six different dyes was evaluated. The results showed that dye structure and anode type are very important factors on performance of the process.
Keywords: Direct Black 22; Electro Coagulation; Organic Dyes; Removal; Water Treatment

Effect of antioxidant in an acute lung injury animal model by Hyung-Sub Kang; Hye-Min Park; Hyeon-Kyu Go; Shang-Jin Kim; Jin-Shang Kim; Seong-Jong Kim; Gi-Beum Kim (1591-1596).
The objective of this study was to scrutinize the involvement of nitric oxide (NO) and the diagnosis of blood in ARDS in a rat model determined by the sequential exposure to lipopolysaccharide (LPS). Also, the present study was designed to evaluate the effects of taurine and dexamethasone on ARDS induced by LPS. Measurements of nitrite/nitrate were elevated in BAL of LPS challenged rats, indicative of an induction of the NO synthase. Taurine and dexamethasone abrogated the extent of endotoxin-induced ARDS, as evidenced by the decreases BAL nitrate/nitrite, BALF protein and lung pathology. T+L+D-group had higher PaO2 and lower PaCO2 values than L-group and T+Lgroup. But, ionized Ca2+ and Mg2+ both were not shown significant change. Also, T+L and T+L+D-group showed significant increase compared with L-group, but for the other side no significant difference was seen between T+L and T+L+D group. We suggest that taurine and dexamethasone may be a drug of choice for preventing ARDS.
Keywords: Acute Respiratory Distress Syndrome (ARDS); Lung Injury; Lipopolysaccharide (LPS); Taurine; Dexamethasone; Nitric Oxide (NO)

Effectiveness of antioxidant and membrane oxygenator in acute respiratory distress syndrome by endotoxin by Seong-Jong Kim; Kyung-Hwa Kim; Shang-Jin Kim; Hyung-Sub Kang; Jin-Shang Kim; Min-Ho Kim; Jung-Ku Jo; Jong-Beum Choi; Yeong-Seok Yang; Sung-Jun Kang; Gi-Beum Kim (1597-1603).
This study evaluated the effectiveness of antioxidants in animal models with damaged lungs such as inflammatory mediator-induced acute respiratory distress syndrome (ARDS) and established an ARDS therapy technique by suppressing active oxygen with membrane oxygenator. When inflammatory mediator that has an endotoxin, such as LPS, was injected directly into the airway, inflammatory pulmonary edema developed in the lung, and could induce ARDS. To treat such endotoxin-induced ARDS, the antioxidants such as taurine and dexamethasone were injected and their antioxidant effects were evaluated. They turned the blood pH to the normal condition, increased blood hemoglobin and hemocrit concentration and oxygen partial pressure (PO2), and improved survival. When a membrane oxygenator was used alone on the animal models with ARDS, similar antioxidant effects were identified. When a membrane oxygenator and antioxidants were used simultaneously, synergistic antioxidant effects were revealed. Therefore, the simultaneous use of antioxidants and membrane oxygenator is more effective than the use of either of them in treating the animal models with ARDS. This result indicates that bilateral use of antioxidants and membrane oxygenator may be useful as a potential therapy technique for the treatment of acute respiratory distress syndrome.
Keywords: ARDS; Membrane Oxygenator; Endotoxin; Antioxidant; Dexamethasone

Thermal stabilities of polyphenols and fatty acids in Laminaria japonica hydrolysates produced using subcritical water by Jung-Nam Park; Abdelkader Ali-Nehari; Hee-Chul Woo; Byung-Soo Chun (1604-1609).
We investigated the thermal stability of polyphenols and fatty acids from Laminaria japonica powder by subcritical water hydrolysis among the range of the experimental conditions. The experiment was carried out at temperatures and pressures ranging from 200 to 280 °C and 13 to 60 bar, respectively for 28 to 42 min. Polyphenol and fatty acids in hydrolysates obtained from different conditions were analyzed by GC and UV-spectrophotometer. The results were compared with those obtained from Laminaria japonica oils extracted by supercritical CO2. Polyphenol and several fatty acids in hydrolysates produced by subcritical water showed high thermal stability.
Keywords: Fatty Acid; Laminaria japonica ; Polyphenol; Subcritical Water Hydrolysis; Supercritical Carbon Dioxide; Thermal Stability

Butyl acetate synthesis in imidazolium ring-based ionic liquids (ILs) containing trifluoromethanesulfonate, [TfO] using Candida antarctica lipase B was demonstrated. Among the ILs tested, the highest butyl acetate production and its initial rate was achieved in [Bmim][TfO]. Compared with tert-butanol, which has been the conventional solvent for transesterification reactions, the initial reaction and conversion rate were approximately 1.4 and 1.1 times, respectively, higher. Some physicochemical parameters, such as viscosity, hydrophobicity, and partial charge of ILs were examined to find the relations which influence reaction rates. Although only weak correlations between each parameter and enzyme activity were found, it shed a light on understanding the generalization complexity of ILs for enzyme reaction.
Keywords: Ionic Liquids; Butyl Acetate; CALB; Viscosity; Hydrophobicity

Tie-line data for aqueous mixtures of butyric acid with isobutyl acetate at various temperatures by Hossein Ghanadzadeh; Sara Asgharzadeh; Nastran Dastmoozeh; Sina Shekarsaraee (1615-1621).
Experimental liquid-liquid equilibrium (LLE) data for the system of (water+butyric acid+iso-butyl acetate) were obtained at T=(298.2, 303.2, 308.2, and 313.2) K and atmospheric pressure. This ternary system exhibits type-1 behavior of LLE. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie-line data was determined by applying the Othmer-Tobias and Hand correlations. Distribution coefficients and separation factors were calculated over the immiscibility regions.
Keywords: Butyric Acid; LLE Data; Ternary Mixture; NRTL Model; UNIQUAC Model

A carrier-mediated separation of phenolic compounds from the dilute aqueous solution was studied with an emulsion liquid membrane, constituted by a solution of ionic liquid (Aliquat 336) in kerosene, sodium hydroxide as a stripping agent and Sorbitan monooleate as a surfactant. The effects on various operating parameters such as surfactant concentration, carrier concentration, emulsification time, strip agent concentration, stirring speed, phase volume ratio, external phase pH and treat ratio were experimentally investigated. Additionally, a stability test was performed under a static condition using Rose Bengal dye. The results showed that the stability of emulsion and extraction was enhanced on adding Aliquat 336 in membrane phase, and it has been verified by FT-IR spectra. By selecting appropriate conditions, the stability and life span of membrane was increased by six times and the percentage of removal of phenol increases upto 99.3% at the treat ratio of 3.
Keywords: Ionic Liquid; Aliquat 336; Phenolic Compounds; Surfactant; Emulsion Liquid Membrane

Modeling of P-ρ-T properties of ionic liquids using ISM equation of state: Application to pure component and binary mixtures by Mohammad Mehdi Papari; Sayed Mostafa Hosseini; Fatemeh Fadaei-Nobandegani; Jalil Moghadasi (1628-1637).
Ihm-Song-Mason (ISM) equation of state (EOS) has been previously employed for modeling the volumetric properties of ionic liquids (ILs). The novelty of the present work is in replacing the macroscopic scaling constants with microscopic ones. Three temperature-dependent parameters that appeared in the EOS, which are universal functions of the reduced temperature, were determined using these new microscopic scaling constants. These parameters are the effective hard-sphere diameter (σ) and the non-bonded interaction energy between two spheres (ɛ). The present EOS is evaluated by examination of 3997 experimental density data points for five classes of ILs. The average absolute deviation (AAD) of the calculated densities from literature values was found to be of the order of 0.38%. Our calculations involved a broad range of temperature from 293 K to 472 K and pressures from 0.1MPa up to 200MPa. Another aspect of the present study is the extension of the proposed EOS to predict density of binary mixtures involving IL+ water and IL+ IL. In the case of binary mixtures, 898 data points were taken to assess the capability of the EOS. The overall AAD of the calculated mixture densities from the literature ones was within 0.43%.
Keywords: Equation of State; Ionic Liquid; Binary Mixture

Extraction of copper by leaching of electrostatic precipitator dust and two step removal of arsenic from the leach liquor by N. K. Sahu; Barsha Dash; Suchismita Sahu; I. N. Bhattacharya; T. Subbaiah (1638-1642).
The paper deals with the extraction of copper from the deposited material of the liner of the electrostatic precipitator (ESP) of the copper smelter plant. These precipitates of ESP liner (ESP dust) generally contain mixed phases of copper and arsenic. An attempt is made to extract copper from ESP dust, subsequently removing arsenic from the leach liquor. The ESP dust containing paramelaconite (6CuO·Cu2O), α-domeykite (Cu3As), metadomeykite (Cu3As), enargite (Cu3AsS4) and (Cu,Fe) SO4·H2O is not a naturally occurring geological mineral; thus comparatively high acid concentration and temperature are required to break the matrix of this mixed material so as to liberate the content. The leaching efficiency of copper was 97% at 97 °C. The acid concentration of 1.5M and pulp density of 20% was found to be optimum. The removal of arsenic as ferric arsenate was carried out in two stages: increasing the pH and precipitation of arsenic by adjusting pH of the solution and by adding ferrous sulfate and hydrogen peroxide. The optimum removal of arsenic was 95% when pH was raised to 2.35 followed by precipitation. The key progression of the process is the recovery of copper from ESP dust as well as removal of arsenic from the leach liquor.
Keywords: ESP Dust; Copper Arsenide; Leaching; Arsenic; Ferric Arsenate

Two-step rapid synthesis of mesoporous silica for green tire by Askwar Hilonga; Jong-Kil Kim; Pradip Bhikaji Sarawade; Dang Viet Quang; Godlisten Namwel Shao; Gideon Elineema; Hee Taik Kim (1643-1646).
We report a two-step rapid route of synthesizing inexpensive mesoporous silica using the waste material (hexafluorosilicic acid, H2SiF6) of phosphate fertilizer industry and sodium silicate (Na2O·SiO2). The reaction was performed in a newly innovated manufacturing apparatus. This apparatus produces mesoporous silica with uniform properties through controlled mixing of source materials at predetermined equivalent ratio. The precursors are rapidly mixed within the nozzles to enable uniform control of physical properties of the final product. The obtained mesoporous silica was characterized using N2 physisorption studies, scanning electron microscope (SEM), and EDS. The final product was found to have superior properties that are suitable for green tire (environmentally friendly tire) as inorganic filler. The process reported in this study may significantly reduce the release of hazardous materials into the environment and it might confer economic benefits to the responsible industries. A project on innovative industrial application of our products for the tire industry is in progress.
Keywords: Mesoporous Silica; Hexafluorosilicic Acid; Sodium Silicate; Green Tire

Genipin cross-linked kappa-carrageenan/hydroxyethyl cellulose hydrogels were prepared and the effect of cross-linking on hydrogels characteristics was investigated. Swelling and transform mechanisms of both native and cross-linked gels in different pH were also studied. We found that the concentration of genipin affects the physical stability of gels. The optimum concentration that a cross-linked hydrogel molecular structure can be in its most stable form is also discussed. Native hydrogels exhibited more swelling in alkaline medium than acidic and neutral; however, by increasing the cross-linker concentration, the swelling ability in neutral medium increased so that genipin cross-linked hydrogels could swell in pH 7 more than in pH 1.2 and 12. Fourier transform infrared spectroscopy (FTIR) was applied to study the formation of new bonding due to genipin reactions and explain hydrogels’ stability in various concentrations. Differential scanning calorimetry (DSC) measurements reveal that by increasing genipin, the gel ability to hold water increases to some point and then decreases due to less structural stability. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) tests were performed to study the crystallinity changes and microstructure of hydrogels. Finally, the power law model was applied to study the transform mechanism of hydrogels.
Keywords: Swelling; Hydrogels Structural Stability; Genipin Cross-linking; Kappa-carrageenan/hydroxyethyl Cellulose; Characterization