Korean Journal of Chemical Engineering (v.30, #7)

Thin film solar cells composed of chalcopyrite Cu(In1−x Ga x )(Se1−y S y )2 (CIGSSe) absorbers have gained considerable attention in recent years in an effort to develop sustainable technologies for harnessing clean energy. Nonvacuum solution methods can reduce production costs by replacing vacuum-based deposition methods with large-scale, high-throughput processes. The efficient use of materials can reduce production costs. Non-vacuum processes generally rely on two sequential steps: solution-coating, followed by a post-annealing process. Depending on the point at which the CIGS phase evolves, non-vacuum processes can be categorized as nanoparticle (NP) approaches or molecular precursor approaches. These two types of liquid processes are believed to be compatible with a variety of applications, such as roll-to-roll coating for the production of flexible, portable devices. Additional thermal treatments using a gaseous chalcogen or oxygen can improve the absorber quality. This review describes the current status of chalcopyrite thin film solar cells fabrication methods via low-cost solution routes. An analysis of recently published reports describing liquid-based deposition methods is introduced, and the features of the development steps are compared. Finally, a discussion and future outlook are offered.
Keywords: CIGS; Thin Film Solar Cell; Non-vacuum Process; Solution Deposition; Nanoparticle; Molecular Precursor

Viruses as self-assembled nanocontainers for encapsulation of functional cargoes by Yuanzheng Wu; Hetong Yang; Hyun-Jae Shin (1359-1367).
Viruses naturally exhibit an incredible variety of sophisticated nanostructures, which makes them ideal biological building blocks for nanoengineered material research. By mimicking their spontaneous assembly process, tremendous advances have been made towards utilizing virus and virus-like particles (VLPs) as protein cages, scaffolds, and templates for nanomaterials in the last few years. This review outlines recent progress in the field of bionanotechnology in which viruses are introduced to encapsulate various functional cargoes in a precise and controlled fashion. The encapsulation mechanisms are summarized into three main strategies: electrostatic interaction, chemical conjugation, and covalent attachment by genetic manipulation. The combination with chemical modification and genetic engineering heralds a brilliant future for fabrication of functional nanomaterials. These well-defined architectures will find attractive applications in biosensing, drug delivery, enzyme confinement, light-harvesting system, and pharmaceutical therapy.
Keywords: Virus; Virus-like Particles (VLPs); Encapsulation; Nanomaterials; Drug Delivery

Integration of qualitative and quantitative risk assessment methods for gas refinery plants by Hyungjoon Yoon; Jaedeuk Park; Wonsub Lim; Kwanghee Lee; Nakki Choi; Chuljae Lee; Il Moon (1368-1374).
This paper focuses on the development of an integrated risk assessment system to increase the safety of gas refinery plants. This integration is important in managing the design and the operation of chemical plants and it requires significant time, effort and specialized expertise. We propose a systematic procedure to apply quantitative and qualitative hazard identification methods before constructing the refinery plants. Advantages of this assessment procedure are 1) systematic method in identifying most of the important hazards, 2) complete and rigorous analysis, and 3) reducing budget and time. The qualitative and quantitative assessment method consists of two and three steps, respectively. After these five steps, the risk of the same plant was calculated and analyzed. This method can identify risk and potential hazards from local gas refinery plants effectively and systematically. We applied the integrated qualitative and quantitative risk assessment method to remove the risk of a local gas refinery plant with 160 P&ID sheets. The result of this work confirmed that no residential population existed within the bounds of the 1×10−6 per annum risk contour. Therefore, the risk to the public from the gas refinery plants should be considered acceptable.
Keywords: Integrated Risk Assessment; Quantitative and Qualitative Methods; Potential Hazards; Annum Risk Contour

The effect of noncondensable gas on heat transfer in the preheater of the sewage sludge drying system by Young Cheol Park; Joeng-Geun Kim; Gyoung Tae Jin; Sang-Ho Lee; Jong-Ho Moon; Seung-Yong Lee; Sang-Il Choi (1375-1379).
We used a shell-and-tube type preheater to investigate the effect of noncondensable gas on heat transfer. In the preheater of the drying system, heat is exchanged between steam-air mixed gas which is dryer outlet gas and sewage sludge. To evaluate the performances of the preheater, water was first used in the tube-side material instead of sewage sludge and steam-air mixed gas in the shell-side material. The test variables were as follows: mixed gas inlet temperatures range from 95 to 120 °C; inlet air content, m air /m steam from 55 to 83%; tube-side water flow rate from 42 to 62 kg/h. The shell-side heat transfer coefficient varied from 150 to 550W/m2K, which corresponds to the amount of noncondensable gas in the steam-air mixed gas and the overall heat transfer coefficient varied from 60 to 210W/m2K. Using sewage sludge as a tube-side material the overall heat transfer coefficient varied from 60 to 130W/m2K and the outlet temperature of sewage sludge was above 90 °C, which is high enough for reducing energy consumption in the dryer by preheating the sewage sludge.
Keywords: Drying System; Preheater; Heat Transfer; Condensation; Noncondensable

Modeling volatile organic compounds sorption on dry building materials using double-exponential model by Baoqing Deng; Di Ge; Jiajia Li; Yuan Guo; Chang Nyung Kim (1380-1385).
A double-exponential surface sink model for VOCs sorption on building materials is presented. Here, the diffusion of VOCs in the material is neglected and the material is viewed as a surface sink. The VOCs concentration in the air adjacent to the material surface is introduced and assumed to always maintain equilibrium with the materialphase concentration. It is assumed that the sorption can be described by mass transfer between the room air and the air adjacent to the material surface. The mass transfer coefficient is evaluated from the empirical correlation, and the equilibrium constant can be obtained by linear fitting to the experimental data. The present model is validated through experiments in small and large test chambers. The predicted results accord well with the experimental data in both the adsorption stage and desorption stage. The model avoids the ambiguity of model constants found in other surface sink models and is easy to scale up.
Keywords: VOCs Sorption; Gas-phase Mass Transfer Coefficient; Building Materials

Concerns about the depletion and increasing price of natural gas are generating interest in the technology of synthetic natural gas (SNG) production. SNG can be produced by the methanation reaction of synthesis gas obtained from coal gasification; this methanation reaction is the crucial procedure for economical production of SNG. We investigated the effect of operating parameters such as the reaction temperature, pressure, and feed compositions (H2/CO and CO2/CO ratios) on the performance of the methanation reaction by equilibrium model calculations and dynamic numerical model simulations. The performance of the methanation reaction was estimated from the CO conversion, CO to CH4 conversion, and CH4 mole fraction in the product gas. In general, a lower temperature and/or higher pressure are favorable for the enhancement of the methanation reaction performance. However, the performance becomes poor at low temperatures below 300 °C and high pressures above 15 atm because of limitations in the reaction kinetics. The smaller the amount of CO2 in the feed, the better the performance, and an additional H2 supply is essential to increase the methanation reaction performance fully.
Keywords: Methanation; Methane; Synthetic Natural Gas; Operating Parameter

Production of biodiesel from soybean oil catalyzed by attapulgite loaded with C4H5O6KNa catalyst by Bin Ye; Yihuai Li; Fengxian Qiu; Chuanjia Sun; Zhenyu Zhao; Teng Ma; Dongya Yang (1395-1402).
Biodiesel is a green, safe, renewable alternative fuel, which is of great significance to solving the problem of energy shortage and environmental pollution. A series of solid base catalysts were prepared with the support of attapulgite (ATP), the load of C4H5O6KNa by impregnation method, and were used to catalyze transesterification of soybean oil with methanol to biodiesel. The activities of prepared catalysts were investigated compared to pure ATP. The optimal conditions for the catalyst preparation were investigated: molar ratio of Na: ATP was 1.7: 1 and calcination temperature was 400 °C. The prepared catalysts were characterized by several techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, N2 adsorption-desorption measurements, X-ray diffraction and the Hammett indicator method. The prepared solid base catalyst can be separated from reaction system effectively and easily. The effects of the molar ratio of methanol to oil, reaction temperature and amount of catalyst on the biodiesel yield were investigated. The experimental results showed that a 22: 1 molar ratio of methanol to oil, 10.0% of catalyst amount, 65 °C of reaction temperature and 3.0 h of reaction time gave the best results. The catalyst has longer lifetime and maintained sustained activity after being used for five cycles.
Keywords: Transesterification; Biodiesel; Attapulgite; Solid Base Catalyst

We fabricated eicosane/poly(vinylidene fluoride) (PVDF) core/shell nanofibers by melt coaxial electrospinning as potential heat-storage applications. Eicosane, a hydrocarbon with melting point near the human body temperature and high latent heat, was chosen as the core material. Melted eicosane and PVDF solutions were coaxially electrospun using a double spinneret, in which melted eicosane was fed at 0.090–0.210 mL/h while the feeding rate of PVDF solution was maintained constant at 1.500 mL/h. The applied voltage and working distance were maintained constant at 12 kV and 17 cm, respectively. Good core/shell structure of nanofibers was observed at core feed rates of 0.090–0.180mL/h by transmission electron microscopy. Differential scanning calorimetry and thermogravimetric analysis values indicated good thermal stability and high energy-storage capacity of the obtained nanofibers. The highest amount of eicosane encapsulated in the electrospun core/shell nanofibers reached 32.5 wt% at core feed rate 0.180 mL/h and had a latent heat of 77 J/g at melting point 39.2 °C. These shape-stabilized core/shell composite nanofibers showed good thermoregulating properties and had sufficiently high tensile strength for potential energy-storage applications, especially in smart textiles.
Keywords: Melt Electrospinning; Coaxial Electrospinning; Phase-change Material; Eicosane; Nanofiber; Energy Storage

Performance improvement of direct methanol fuel cells (DMFCs) was achieved via an anodic treatment technique. Previously, anodic treatment was performed using sulfuric acid as acidic media, but various organic acids including formic, acetic, oxalic, and citric acids were employed in this study to avoid the use of toxic sulfuric acid. By replacing sulfuric acid to organic acids, a potential damage to catalyst layers and other components such as polymer electrolyte membrane and bipolar plates are expected to be minimized. The anodic treatment was performed by applying 0.7 V (vs. reversible hydrogen electrode) at the anode of DMFCs flowing the organic acid solutions for 30min. After the anodic treatment, peak power densities of DMFCs were increased by +7, +32, +23, and −2.6% when formic, acetic, oxalic, and citric acid solutions were employed, respectively. The enhanced catalytic activity of the DMFCs in the acetic and oxalic acid solutions was confirmed by analyzing electrochemical impedance spectroscopy data.
Keywords: Direct Methanol Fuel Cell; Methanol Electro-oxidation; Electrocatalyst; Electrochemical Impedance Spectroscopy; PtRu

Removal of humic acid from water using adsorption coupled with electrochemical regeneration by Hafiz Muhammad Anwaar Asghar; Syed Nadir Hussain; Edward Pelham Lindfield Roberts; Nigel Willis Brown (1415-1422).
A novel and economic waste water treatment technology comprised of adsorption coupled with electrochemical regeneration was introduced at the University of Manchester in 2006. An electrically conducting adsorbent material called Nyex™ 1000 (Graphite intercalation based material) was developed for the said purpose. This adsorbent material delivered significantly lower adsorption capacity for the removal of a number of organic pollutants. With the aim to expand the scope of newly developed adsorbent material called Nyex™ 2000, we studied the adsorption of humic acid followed by electrochemical regeneration. Nyex™ 2000 is a highly electrically conducting material with an adsorption capacity almost twice that of Nyex™ 1000 (intercalation based graphite compound) for humic acid. The adsorption of humic acid onto both Nyex™ adsorbents was found to be fast enough keeping almost the same kinetics with approximately 50% of the adsorption capacity being achieved within the first twenty minutes. The parameters affecting the regeneration efficiency, including the treatment time, charge passed and current density, were investigated. The regeneration efficiency at around 100% for Nyex™ 1000 & 2000 adsorbents saturated with humic acid was obtained using the charge passed of 8 and 22 Cg−1 at a current density of 7mA cm−2 during a treatment time of 30minutes, respectively.
Keywords: Humic Substances; Nyex™ Materials; Adsorption; Electrochemical Regeneration; Electrical Conductivity

The photodegradation of hydrogen sulfide (H2S) was examined using a self-made microwave electrodeless discharge lamp (MEDL). The features of the MEDL had been tested. The results showed that the MEDL absorbed 18.3, 32.7 and 41.8W power at the microwave (MW) output power of 165, 330 and 660W, respectively. The intensity of the emitted light increased with increasing MW output power. The reactive oxygen species (ROS) generated by irradiated air and nitrogen were detected, respectively. It was illustrated that the irradiated air could generate a number of ROS, at least including 1O2 and ·OH. And the amount of ROS increased with increasing MW output power. In photodegradation of H2S process, the effects of MW output power and gas composition were investigated. The removal efficiency of H2S under nitrogen was obviously lower compared with that under air. The removal efficiency of H2S increased with increasing MW output power.
Keywords: Microwave Electrodeless Discharge Lamp (MEDL); Reactive Oxygen Species (ROS); Photodegradation; Hydrogen Sulfide

Inulin conversion to hydroxymethylfurfural by Brønsted acid in ionic liquid and its physicochemical characterization by Young-Byung Yi; Myoung-Gyu Ha; Jin-Woo Lee; Chung-Han Chung (1429-1435).
A simple conversion process of inulin polymer into hydroxymethylfurfural (HMF) was developed using Brønsted acid catalyst (HCl) in the presence of an ionic liquid, 1-octyl-3-methylimidazolium chloride ([OMIM]Cl). In addition, the physicochemical properties of inulin particle and its depolymerixation products were scrutinized. FESEM and XRD diffraction frequency showed that inulin particles are clustered in a granulated formation and their molecular structure is highly amorphous. FT-IR analysis identified five characteristic frequency regions: Region 1; 700–900, Region 2; 900–1,200, Region 3; 1,200–1,350; Region 4; 1,350–1,500, and Region 5; 1,530–1,800 cm−1. HPLC analysis confirmed that the major composition of inulin consists of fructose and glucose. The synthesis of HMF was significantly affected by the Brønsted catalyst and its concentration. Its highest yield (63.1±5.1 dwt%) was achieved at 0.3M HCl in the presence of [OMIM]Cl. No presence of the Brønsted catalyst exhibited negligible HMF yield (2.3±1.1 dwt%). Our results demonstrate that the Brønsted catalyst plays a pivotal role in the catalytic process of HMF synthesis from inulin polymer.
Keywords: Brønsted Acid; Hydroxymethylfurfural; Inulin Polymer; Ionic Liquid

Size-resolved aerosol monitoring for PM10, PM2.5, and PM1.0 was performed to qualify and quantify the elements and ions by using proton induced X-ray emission (PIXE), inductively coupled plasma optical emission spectrometry (ICP-OES), and ion chromatography (IC) analysis. Time-resolved aerosol samplings based on 2-hour and 14-hour intervals were carried out during daytime and nighttime, respectively. Physical and chemical properties of size-resolved aerosols were investigated to characterize air quality in the national park area of Gyeongju, Korea. The PIXE and ICPOES methods made elemental mass of Al, Si, S, K, Ca, Ti, Cr, Fe, Sr, and Pb. And ions of Na+, NH4 +, Ca2+, Cl, NO 3 , and SO 4 2− were analyzed by the IC method. The mass concentrations of Si, S, Ti, and Pb determined by PIXE showed relatively good correlation with those determined by ICP-OES. But Fe and Sr had worse correlations with an average R2 of 0.4703 and 0.4825, respectively. The PIXE method was a good alternative to measure chemical species of Al, Si, S, K, Ca, Ti, Cr, and Pb for size-resolved aerosols except Fe and Sr in this study. The average relative errors of sizeresolved elements for 2-hour and 14-hour interval collections were 10.1±5.7% (0.1–28.3%) and 9.9±7.7% (1.3–38.4%). Ammonium sulfates (AS), mineral dust (MD), and sea salt (SS) aerosols were reconstructed from the elements determined by PIXE and ICP-OES and ions obtained by IC. The mass concentration of MD was calculated with crustal elements of Al, Si, Ca, Ti, and Fe, which are associated with soil erosion. The average relative error of MD was the lowest value of 0.8% in the PM10 regime and the highest value of 10.0% in the PM1.0 regime. The average relative errors of AS for PM10, PM2.5, and PM1.0 determined by PIXE, ICP-OES, and IC showed relatively lower values of 0.8–5.7%, 1.7–5.9%, and 3.3–8.3%, respectively. The average mass concentrations of AS, MD, and SS of PM10, PM2.5, and PM1.0 except submicron SS determined by PIXE were comparable to those determined by ICP-OES and IC within the acceptable relative errors.
Keywords: PIXE; ICP-OES; Aerosol; Element

Expression characteristics of the maeA and maeB genes by extracellular malate and pyruvate in Escherichia coli by Irisappan Ganesh; Sambandam Ravikumar; Si Jae Park; Seung Hwan Lee; Soon Ho Hong (1443-1447).
The malate-pyruvate conversion pathway is catalyzed by two malic enzyme isomers, MaeA and MaeB. qRT-PCR was carried out under malate and pyruvate supplemented conditions to understand the dynamics of maeA and maeB gene expression. maeA expression was elevated by malate, and maeB expression was inhibited by levels of both malate and pyruvate higher than 0.1 mM. Green fluorescent protein (GFP) reporter plasmids were also constructed by integration of the maeA/maeB promoter with the gfp gene. We showed that maeA driven GFP expression was positively and negatively correlated with extracellular malate and pyruvate induction. In contrast, no significant changes in maeB driven GFP expression were observed under both malate and pyruvate supplemented conditions.
Keywords: Malate; Pyruvate; maeA ; maeB ; Green Fluorescent Protein; Escherichia coli

Enantioseparation of chiral ofloxacin using biomacromolecules by Wei Li; Yanli Li; Yan Fu; Jinli Zhang (1448-1453).
Natural biomacromolecules including bovine serum albumin (BSA), calf thymus DNA (ct-DNA) and fish sperm DNA (fs-DNA) were studied as the free chiral selectors to separate R- and S-ofloxacin enantiomers from racemic ofloxacin, combined with ultrafiltration and subsequent crystallization. First, the interactions between chiral ofloxacin and biomacromolecules including BSA, ct-DNA, and fs-DNA were investigated using circular dichroism and fluorescence spectroscopy. BSA exhibited stereoselective adsorption towards R-ofloxacin at pH 9.0 with an enantioselectivity of 1.23, while ct-DNA showed enantiospecific interaction with S-enantiomer with the selectivity of 1.70 at pH 5.0. One single-stage adsorption by BSA provides an enantiomeric excess in the permeate (e.e. p ) of 14% in S-enantiomer, and five-stage operations enhance the chiral resolution to reach the e.e.p value of 44%. R-enantiomer with an e.e. p of −26% can be obtained through one single-stage adsorption by using ct-DNA, and −85% can be reached by five-stage operations. Enantiomeric mixtures with the intial e.e. of 44% (S-) can be upgraded to 95% (S-) through subsequent crystallization. This programmable process of adsorption and desorption using BSA or ct-DNA as chiral selectors can be successfully applied to produce the enantiomers with highly optical purity.
Keywords: Enantioseparation Bovine Serum Albumin DNA Chiral Drug Ofloxacin

C9232 is a typical emulsifier of emulsion liquid membrane and its main component, bis-succinimide, has amine functional groups which react with carboxylic acids. The average numbers of secondary amine groups and isobutylene units in the bis-succinimide were determined through elemental analysis. Acetic acid was extracted by emulsion liquid membrane with use of C9232, and we verified that C9232 was suitable for its extractant in the emulsion liquid membrane systems. Equilibrium experiments for reactive extraction of acetic acid by C9232 were carried out by varying the overall acetic acid concentration and overall C9232 concentration in liquid-liquid extraction systems. Also, an equilibrium model for the reactive extraction of acetic acid was investigated for the purpose of analyzing the emulsion liquid membrane systems for separation of acetic acid from other carboxylic acids or sugars in the future. The calculated results from the equilibrium model were in good agreement with the experimental data.
Keywords: Acetic Acid; C9232; Bis-succinimide; Reactive Extraction; Equilibrium Model; Emulsion Liquid Membrane

Emulsion liquid membrane for selective extraction of bismuth from nitrate medium by Bahram Mokhtari; Kobra Pourabdollah (1458-1465).
The novelty of this work is the selective extraction of bismuth ions from nitrate medium by emulsion liquid membrane. Di(2-ethylhexyl)phosphoric acid was used as extractant of bismuth ions from nitrate medium by emulsion liquid membrane, and Triton X-100 was used as the biodegradable surfactant in n-pantanol n-pentanol bulk membrane. The extraction of bismuth ions was evaluated by the yield of extraction. The experimental parameters were evaluated and were optimized. They included the ratio of di(2-ethylhexyl)phosphoric acid concentration to the concentration of /Triton X-100 concentration (1.0: 0.5% w/w), nature of diluents (n-pentanol), nature and concentration of the stripping solution (sulfuric acid, 0.5M), stirring speed (1,800 rpm) and equilibrium time of extraction (20min), initial feed solution of bismuth (350 ppm) and the volume ratio of the internal stripping phase to the membrane phase (14 times). The experimental parameters of kinetic extraction revealed that the bismuth ions were extracted at 100% 97%.
Keywords: Nano-emulsion; Surfactant; n-Alcohol; Extraction

Supercritical carbon dioxide extraction of oil from Thunnus tonggol head by optimization of process parameters using response surface methodology by Sahena Ferdosh; Md Zaidul Islam Sarker; Nik Norulaini Nik Ab Rahman; Md Jahurul Haque Akand; Kashif Ghafoor; Mohamed Bin Awang; Mohd Omar Ab Kadir (1466-1472).
Total oil was extracted from ground fish head of Longtail tuna (Thunnus tonggol) using supercritical carbon dioxide (SC-CO2) at 20 to 40 MPa, 45 to 65 °C and 1 to 3 ml min−1. Response surface methodology (RSM) was employed to optimize the operating conditions of the SC-CO2 technique where the highest oil yield was obtained (35.6% on dry weight basis) at 40 MPa, 65 °C, and 3 ml min−1. The solubility of the oil in SC-CO2 increased from 2.9 to 14.2 g oil/100 g of CO2 with increasing pressure and temperature. The total saturated, monounsaturated and polyunsaturated fatty acids obtained were 41.6, 24.7 and 26.8%, respectively, where the omega-3 fatty acids were found to be 22.3%. A correlation was developed determining the coefficients of the second-order polynomial equation where the extraction parameters of SC-CO2 method to extract fish oil from fish sample were successfully optimized using response surface methodology.
Keywords: Fish Wastes; Thunnus tonggol Head Oil; Supercritical Fluid Extraction; Central Composite Rotatable Design, Correlations

A divided wall column (DWC) has widely been utilized as an energy-efficient distillation column. When it is applied to the offshore floating liquefied natural gas (FLNG) plant, its compactness can provide a favorable distillation system for the unconventional plant on top of its high energy efficiency. We investigated the design characteristic, cost evaluation and operation difficulty of the DWC at its utilization in the FLNG plant. The results from the HYSYS simulation of the DWC were compared with those of the conventional distillation system, and the following was found from the study. The DWC replacing the depropanizer and debutanizer of the conventional distillation system requires 12.5% less investment cost. While the saving of 25% in steam cost is expected from the DWC, the total utility cost including the refrigerant cost is reduced by 20.2% due to the lower cost reduction of refrigeration in the DWC.
Keywords: Divided Wall Column; Energy-efficient Distillation; Floating Liquefied Natural Gas Plant; Thermally-coupled Distillation

The direct deposition of polymeric films with a torch-type atmospheric pressure plasma using benzene, n-hexane and cyclohexane in Ar was performed on several substrates. The surface morphologies of the films deposited with n-hexane and cyclohexane were uniformly smooth for all deposition thicknesses, and the typical water contact angle on the films indicating the degree of hydrophobicity was about 85o. However, the films deposited using benzene had a micro-coarse surface morphology and showed a superhydrophobic property with a water contact angle exceeding 150°. Some trace of oxygen incorporation was shown in all films due to the plasma deposition process in an air ambient. The small amount of oxygenated species did not lead to a decrease of hydrophobicity of the films.
Keywords: Atmospheric Pressure Plasma; Surface Treatment; Hydrophobicity; Contact Angle; C6 Hydrocarbon

The purpose of this work is to apply Donnan dialysis coupled with the cation exchange membrane (CMX), the cation exchange grafted textile (CET) and the solvent impregnated resin (SIR) for recovery and enrichment of heavy metal ions from dilute solutions. The influence of some analytical parameters was investigated. The transport results show that the three barriers enhance the diffusion of silver, lead and copper, but the osmosis phenomenon is limited when the transport is carried out through CET and the SIR. The results of enrichments indicate that SIR and CET increase the enrichment factor of less hydrated ions. For instance, and for a volume ratio equal to 10, the values of silver enrichment factor obtained for (CMX/CMX/CMX), (CMX/CET/CMX) and (CMX/SIR/CMX) are equal to 2.5, 8.92 and 4.98, respectively. In addition, the use of SIR improves the enrichment of lead, whereas the CET improves the silver’s one.
Keywords: Heavy Metals; Enrichment; Donnan Dialysis; Hybrid System; Cation Exchange Grafted Textile; Solvent Impregnated Resin; Extractant; D2EHPA; TOPO; DPTU

Statistical optimization of mixture ratio and particle size for dry co-digestion of food waste and manure by response surface methodology by Si-Kyung Cho; Dong-Hoon Kim; Yeo-Myeong Yun; Kyung-Won Jung; Hang-Sik Shin; Sae-Eun Oh (1493-1496).
Response surface methodology has been widely applied to optimize the process. However, it was rarely applied to dry digestion. We used central composite design to optimize the anaerobic dry co-digestion of food waste and manure. Mixture ratio and particle size of food waste and manure were selected as independent variables, and target surface response was the methane production yield (MPY). BMP tests were conducted, and MPY was fitted by a secondorder polynomial quadratic model, which was found to be significant with higher coefficient (R2=0.98). As results of F-value analysis, the mixture ratio was found to be more important than particle size. Finally, the optimum conditions of mixture ratio (food waste:manure=5.79: 4.21) corresponding to 15.6 of C/N ratio and particle size 1.12 cm were determined. In addition, 313mL CH4/g VS added of MPY was anticipated under optimum conditions with 94.4% of desirability.
Keywords: Dry Co-digestion; Food Waste; Manure; Mixture Ratio; Response Surface Methodology (RSM)