Korean Journal of Chemical Engineering (v.32, #9)
Integrated fabrication-conjugation approaches for biomolecular assembly and protein sensing with hybrid microparticle platforms and biofabrication - A focused minireview by Sukwon Jung; Hyunmin Yi (1713-1719).
Controlled manufacturing of polymeric hydrogel microparticles is crucial, yet challenging, for rapid and sensitive detection of biomacromolecules in biodiagnostics and biosensing applications. Our approach is an integrated fabrication-conjugation strategy utilizing a simple and robust micromolding technique and biofabrication with a potent aminopolysaccharide chitosan as an efficient conjugation handle for high-yield bioorthogonal conjugation reactions. We present a concise overview of our recent findings in the controlled fabrication of shape-encoded or core-shell structured microparticles consisting of poly(ethylene glycol) (PEG) and short single-stranded (ss) DNA or chitosan, and their utility in the covalent conjugation and nucleic acid hybridization-based assembly of target ssDNAs, proteins and viral nanotemplates. Particularly, two novel routes to achieve substantially improved protein conjugation capacity and kinetics are presented from our recent reports: tobacco mosaic virus (TMV) as a high capacity nanotubular template and polymerization-induced phase separation (PIPS) of pre-polymer droplets for controlled core-shell structure formation. We envision that our fabrication-conjugation approaches reported here, combined with our current and future endeavors in improved fabrication and design of controlled structures with chemical functionalities, should permit a range of manufacturing strategies for advanced functional microscale materials and platforms in a wide array of applications.
Keywords: Micromolding; Hydrogel Microparticles; Biofabrication; Biomolecular Conjugation; Biosensing
Microbial bioremediation processes for radioactive waste by Changhyun Roh; ChanKyu Kang; Jonathan R. Lloyd (1720-1726).
Microbial processes can affect the environmental behavior of priority radionuclides, and understanding these reactions is essential for the safe management of radioactive wastes and can contribute to the remediation of radionuclide-contaminated land. Underlying mechanisms that can control radionuclide solubility in biogeochemical systems can range from biosorption and biomineralization process, through direct (enzymatic) and indirect redox transformations. The mechanisms of enzyme-mediated reduction of problematic actinides, in principal, uranium (U), but including neptunium (Np), plutonium (Pu) and Americium (Am), are described in this review. In addition, the mechanisms by which the fission products technetium (Tc), cesium (Cs), and strontium (Sr) are removed from a solution by microorganisms are also described. The present review discusses the status of these microbiological processes, and the potential for cost-effective and scalable in situ remediation of radioactive waste.
Keywords: Bioremediation; Radioactive Waste; Actinides; Fission Product
Fe-aminoclay-entrapping electrospun polyacrylonitrile nanofibers (FeAC-PAN NFs) for environmental engineering applications by Jae-Young Lee; Saehae Choi; Dongsu Song; Seung Bin Park; Moon Il Kim; Go-Woon Lee; Hyun Uk Lee; Young-Chul Lee (1727-1732).
Electrospun polyacrylonitrile nanofibers (PAN NFs) with entrapped water-soluble Fe-aminoclay (FeAC) [FeAC-PAN NFs] were prepared. Slow dropwise addition of water-soluble FeAC into a PAN solution, less aggregated of FeAC into electrospun PAN NFs was one-pot evolved without FeAC post-decoration onto as-prepared PAN NFs. Taking into consideration both the Fe3+ source in FeAC and the improved surface hydrophilicity, the feasibility of Fentonlike reaction for decolorization of cationic model dye methylene blue (MB) under 6 hrs UV-light irradiation was established. In the case where FeAC-PAN NFs were enhanced by hydrogen peroxide (H2O2) injection, the apparent kinetic reaction rates were increased relative to those for the PAN NFs. Thus, our flexible FeAC-PAN NF mats can be effectively utilized in water/waste treatment and other environmental engineering applications.
Keywords: Fe-aminoclay (FeAC); Polyacrylonitrile Nanofibers (PAN NFs); One-pot Synthesis; Fenton-like Reaction; Water Treatment
A novel and computationally efficient algorithm for stability analysis of multi input-multi output process control systems by Hooman Fatoorehchi; Hossein Abolghasemi; Reza Zarghami; Randolph Rach; Sebastian von Freeden (1733-1743).
An efficient method based on the Faddeev-Leverrier algorithm combined with the Adomian decomposition method is devised to facilitate the stability analysis of multi-input multi-output control systems. In contrast to prior eigenvalue algorithms, our method affords all eigenvalues of the state matrix, either real or complex. Specifically, the calculation of the complex eigenvalues is made possible through special canonical forms, mainly involving square root operators, of the characteristic equation of the state matrix. Moreover, the proposed method does not require an initial guess, which is often a matter of concern since an inappropriate guess can cause failure in such available schemes. For the sake of illustration, a number of numerical examples, including chemical reaction processes, are also provided that demonstrate the efficiency of our new technique.
Keywords: Control System; Stability Analysis; State-space Model; Adomian Decomposition Method; Adomian Polynomials
Enhancement of CH4-water mass transfer using methyl-modified mesoporous silica nanoparticles by Sung-Yeob Lee; Kyo-Sung Mo; Jin-Ha Choi; Nam Hwi Hur; Young-Kee Kim; Byung-Keun Oh; Jinwon Lee (1744-1748).
Surface-modified mesoporous silica nanoparticle (MSN) with methyl groups was used to enhance the CH4-water volumetric mass transfer coefficient (k L a) and the solubility of CH4 in water. Two types of samples were tested: unmodified MSN and methyl-modified MSN. The mass transfer for each type of sample was measured every 20 s by gas chromatography. The results showed that the methyl-modified MSN, which have both hydrophobic and hydrophilic properties on the surface, exhibited higher CH4-water volumetric mass transfer coefficient and solubility in water. The dissolved concentrations of CH4 were enhanced by 10.7% and 27.8%, and the volumetric mass transfer coefficient were enhanced by 28.6% and 84.7%, respectively, by using unmodified MSN and methyl-modified MSN.
Keywords: Methane (CH4) Gas; Mass Transfer; Gas Fermentation; Mesoporous Silica Nanoparticle (MSN); Surface Modification
Instantaneous NO release from ellipsoidal particles during char combustion in a hot gas with fluctuating temperature by Jie Li; Jian Zhang (1749-1758).
We have established the instantaneous governing equations for NO release during char combustion of nonspherical particles theoretically. The instantaneous released NO mass variations, the instantaneous char oxidation reaction rates, and the instantaneous NO reduction reaction rates of char particles were computed numerically under different fluctuation amplitudes of gas temperature, kinetic parameters of char oxidation reaction and NO reduction reaction, and particle aspect ratios. The gas temperature fluctuation results in a faster NO release rate, a faster char oxidation reaction rate, and a faster NO reduction reaction rate during the whole char combustion processes. The activation energy of char oxidation reaction has obvious influence on the NO release and char combustion processes. The kinetic parameters of NO reduction reaction have no contribution to the conversion time. Under the same particle surface area, the conversion rate of char nitrogen to NO increases with the increase in the particle aspect ratio.
Keywords: Gas Temperature Fluctuation; Ellipsoidal Particle; Aspect Ratio; NO Release; Char Combustion
Fabrication of palladium nanoparticles immobilized on an amine-functionalized ceramic membrane support using a nanoparticulate colloidal impregnation method with enhanced catalytic properties by Yan Du; Rizhi Chen (1759-1765).
An efficient and reusable catalyst was developed by depositing palladium nanoparticles on an amine-functionalized ceramic membrane support using a nanoparticulate colloidal impregnation method. The as-prepared Pdloaded ceramic membrane support was characterized by XRD, SEM, EDS, TEM, XPS, ICP, and its catalytic properties were investigated in the liquid-phase p-nitrophenol hydrogenation. A comparative study was also made with the palladium nanoparticles deposited on an amine-functionalized ceramic membrane support by an impregnation-reduction method. The palladium nanoparticles could be homogeneously immobilized on the ceramic membrane support surface, and exhibited excellent catalytic performance in the p-nitrophenol hydrogenation. The catalytic activity of the Pdloaded ceramic membrane support prepared by the nanoparticulate colloidal impregnation method increased by 16.6% compared to that of impregnation-reduction method. In the nanoparticulate colloidal impregnation method, palladium nanoparticles were presynthesized, higher loading of Pd(0) could be obtained, resulting in better catalytic activity. The as-prepared Pd-loaded ceramic membrane support could be easily reused for several cycles without appreciable degradation of catalytic activity.
Keywords: Palladium Nanoparticles; Nanoparticulate Colloidal Impregnation Method; Ceramic Membranes; p-Nitrophenol Hydrogenation
High performance of manganese oxide octahedral molecular sieve adsorbents for removing sulfur compounds from fuel gas by Phuoc Hoang Ho; Seong Chan Lee; Jieun Kim; Doohwan Lee; Hee Chul Woo (1766-1773).
Properties of porous manganese oxide adsorbents for adsorptive removal of tert-butylmercaptan (TBM) from CH4 fuel gas were investigated at ambient temperature and atmospheric pressure. The adsorbents were prepared by oxidation reactions of Mn2+ with KMnO4 and via the sol-gel method by reduction of KMnO4 using fumaric acid as the reducing agent. The effects of preparation method, precursor, temperature, and time for the structure and desulfurization properties of the resulting adsorbents were studied. Cryptomelane octahedral manganese oxide molecular sieve (OMS-2) adsorbents exhibited high breakthrough TBM adsorption (1.3–2.5mmol g-1) with the properties varied by the synthesis condition. The OMS-2-Ac prepared by the oxidation reactions of manganese acetate resulted in smaller OMS-2 crystallites with higher surface area compared to those prepared from manganese sulfate and chloride precursors, and it exhibited an enhanced TBM adsorption uptake. TBM adsorption capacity of OMS-2 could be further enhanced by introducing Cu into the structure. This gave rise to a markedly high TBM breakthrough adsorption (7.4mmol g-1) for Cu-OMS-2 (7.8 wt% Cu doping), which is significantly greater than the values reported for activated carbon, zeolite, and other porous oxide based solid adsorbents at similar conditions in the literature.
Keywords: Adsorptive Desulfurization; Manganese Oxide Molecular Sieve; Tert-Butylmercaptan; Fuel Processing; Fuel Cell
Dimethyl carbonate synthesis via transesterification of propylene carbonate with methanol by ceria-zinc catalysts: Role of catalyst support and reaction parameters by Praveen Kumar; Vimal Chandra Srivastava; Indra Mani Mishra (1774-1783).
Ceria and zinc oxide catalyst were impregnated onto various oxide supports, namely Al2O3, TiO2 and SiO2, individually by deposition-coprecipitation method. The synthesized catalysts (CZA, CZS and CZT having supports Al2O3, TiO2 and SiO2, respectively) were characterized by X-ray diffraction (XRD), NH3- and CO2-temperature programmed desorption (TPD) and N2 adsorption. These catalysts were used for synthesis of dimethyl carbonate (DMC) from methanol and propylene carbonate in a batch reactor. CZS was found to have larger average grain size as compared to CZA and CZT. Composite oxides (catalysts) were found to contain individual phases of ZnO, CeO2 and some spinel forms of Zn, Ce along with their supports. CZS having highest basicity and surface area showed better catalytic activity as compared to CZA and CZT. Effect of reaction temperature and methanol/PC molar ratio on DMC yield was studied and a reaction mechanism has been discussed. Maximum DMC yield of 77% was observed with CZS catalyst at 170 °C with methanol/PC molar ratio of 10.
Keywords: DMC; Transesterification Catalysts; Propylene Carbonate; Methanol
Gasification of ash-free coal prepared with microwave method by Choong-Gon Lee; Won-Ki Kim; Duc-Luong Vu (1784-1788).
The production of ash-free coal as a clean fuel for high temperature fuel cell was investigated. The ash-free coal was made from a bituminous coal. It was prepared by solvent extraction using a microwave. The solvent-to-coal ratio and microwave irradiation time of raw coal were parameters for the extraction yield. The microwave method showed merits in terms of faster extraction and higher extraction yield than conventional heating methods. In addition, gasification behaviors of the ash-free coal were investigated by gas chromatography. Contrary to carbon, ash-free coal showed hydrogen as a dominant gas species in its gasification and did not require carbonate catalyst. The electrical conductivity of ash-free coal was found very low close to zero.
Keywords: Ash-free Coal; Solvent Extraction; Microwave; Molten Carbonate; Gasification
Hydrothermal carbonization of oil palm shell by Sabzoi Nizamuddin; Natesan Subramanian Jayakumar; Jaya Narayan Sahu; Poobalan Ganesan; Abdul Waheed Bhutto; Nabisab Mujawar Mubarak (1789-1797).
Palm shell is one of the most plentiful wastes of the palm oil mill industry. This study identifies the capability of hydrothermal carbonization process (HTC) to convert palm shell into high energy hydrochar. The influence of reaction time and reaction temperature of the HTC process was investigated. The process parameters selected were temperature 200 °C to 240 °C, time 10 to 60min, and water to biomass ratio was fixed at 10 : 1 by weight %. Fourier transform infrared (FTIR), elemental, proximate, Burner Emmett and Teller (BET), thermo-gravimetric (TGA) analyses were performed to characterize the product and the feed. The heating value (HHV) was increased from 12.24 MJ/ kg (raw palm shell) to 22.11 MJ/kg (hydrochar produced at 240 °C and 60 min). The hydrochar yield exhibited a higher degree inverse proportionality with temperature and reaction time. Elemental analysis revealed an increase in carbon percentage and a proportional decrease in hydrogen and oxygen contents which caused higher value of HHV. The dehydration and decarboxylation reactions take place at higher temperatures during HTC resulting in the increase of carbon and decrease in oxygen values of hydrochar. The FESEM results reveal that the structure of raw palm shell was decomposed by HTC process. The pores on the surface of hydrochar increased as compared to the raw palm shell.
Keywords: Hydrothermal Carbonization; Palm Shell; Hydrochar; Characterization; Renewable Energy
A two-dimensional analytical model of laminar flame in lycopodium dust particles by Alireza Rahbari; Ashkan Shakibi; Mehdi Bidabadi (1798-1803).
A two-dimensional analytical model is presented to determine the flame speed and temperature distribution of micro-sized lycopodium dust particles. This model is based on the assumptions that the particle burning rate in the flame front is controlled by the process of oxygen diffusion and the flame structure consists of preheat, reaction and post flame zones. In the first step, the energy conservation equations for fuel-lean condition are expressed in twodimensions, and then these differential equations are solved using the required boundary condition and matching the temperature and heat flux at the interfacial boundaries. Consequently, the obtained flame temperature and flame speed distributions in terms of different particle diameters and equivalence ratio for lean mixture are compared with the corresponding experimental data for lycopodium dust particles. Consequently, it is shown that this two-dimensional model demonstrates better agreement with the experimental results compared to the previous models.
Keywords: Lycopodium Dust Particles; Two-dimensional Analytical Model; Laminar Flame Speed; Flame Temperature Distribution
Removal of cadmium(II) from aqueous solution by adsorption onto modified algae and ash by Maria Harja; Gabriela Buema; Laura Bulgariu; Dumitru Bulgariu; Daniel Mircea Sutiman; Gabriela Ciobanu (1804-1811).
Pollution with cadmium ions has serious negative consequences on human health and environment. Adsorption of low-cost materials represents a viable option for the removal of cadmium ions from aqueous media. In this study are comparatively discussed the adsorption behaviour of cadmium(II) on two low-cost materials, one of biologic nature (marine algae) and other of inorganic nature (ash), after their treatment with alkaline solution. The influence of contact time and initial cadmium ions concentration was studied in batch system, for each type of adsorbent. In optimum experimental conditions (solution pH of 5.0; adsorbent dose of 8 g L−1 ) and an initial cadmium concentration of 360mg L−1, the obtained uptake capacities reach to 34.15mg g−1 for the modified algae and to 43.12mg g−1 for the modified ash, respectively. The uptake data were analyzed using two isotherm models (Langmuir and Freundlich) and the models’ parameters were evaluated. The results indicate that t heLangmuir model provides the best correlation of experimental data for both adsorbents, and the maximum adsorption capacities were 41.8mg g−1 for modified algae and 48.0 mg g−1 for modified ash, respectively. The kinetics of the cadmium uptake was modelled using the pseudofirst order, pseudo-second order and intra-particle diffusion model equations. It was shown that the pseudo-second order kinetic equation could best describe the adsorption kinetics of cadmium ions, whatever the nature of adsorbent.
Keywords: Cadmium; Adsorption; Modified Algae; Modified Ash
Enhancing biological treatment of dye wastewater with zero-valent iron by Younggyun Choi; Byungju Park; Daniel Kuhyon Cha (1812-1817).
Pretreatment of authentic industrial dye wastewater with zero-valent iron (ZVI) was evaluated using a bench-scale integrated anaerobic-aerobic (ZVI-AO) biological treatment system. Average ADMI (American Dye Manufacturers’ Institute) value of dye wastewater was reduced from 245 to 107 units with ZVI column pretreatment. Subsequent treatment of ZVI column effluent by a continuous AO process further reduced the ADMI values to 18-39, resulting in overall decolorization efficiency of 78-89%. A control AO system without ZVI pretreatment, which was operated in parallel, achieved just 44-69% of ADMI removal efficiency. In addition, the ZVI integrated system yielded effluents with much lower COD and BOD concentrations than the control system. The aerobic batch respiration tests confirmed that ZVI treatment transformed the recalcitrant dye compounds to slowly biodegradable fractions, thus enhancing the overall biodegradability of dye wastewater.
Keywords: Zero-valent Iron; Decolorization; ADMI Value; Anaerobic-aerobic Process; Biodegradability
Use of wheat straw for effective binding of metal ions via a novel modification by Faiza Farooq; Umar Farooq; Madeeha Batool; Makshoof Athar; Muhammad Salman; Qaiser Ahmed; Ayesha Ashraf (1818-1826).
An innovative biacetyl-modified Triticum aestivum (BMTA) was prepared and its biosorption efficiency was investigated for the removal of Pb(II) and Cr(III) ions from synthesized single and binary metal solutions. The characterization using infrared spectrum, surface area determination and potentiometric titrations indicated an increased acid content of the biomass, indicating BMTA as a potential choice for the binding of metal ions at a relatively low pH. The isoelectric point was found to be at pH 4.5. Various biosorption parameters were optimized. Langmuir model best fitted the experimental equilibrium data with q max 27.39mg/g for Pb(II) ions and 24.69mg/g for Cr(III) ions in single metal system and 24.21mg/g for Pb(II) and 12.97mg/g for Cr(III) ions in binary system, respectively. The kinetics was described by pseudo-second-order model both in single and binary metal system. The studies indicated relatively selective biosorption of Pb(II) ions by BMTA compared to other metal ions.
Keywords: Biacetyl; Wheat Straw; Lead; Chromium; Selective Biosorption
Preparation and electrochemical characterization of polyvinylchloride/FeTiO3-co-Fe3O4 nanoparticles mixed matrix ion exchange membranes: Investigation of concentration and pH effects by Sayedmohsen Hosseini; Alireza Hamidi; Abdolreza Moghadassi; Fahime Parvizian; Sayed Siavash Madaeni (1827-1834).
Polyvinyl chloride based/FeTiO3-co-Fe3O4 nanoparticles mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. The effect of using filler additives in casting solution and also electrolyte concentration and pH on electrochemical properties of membrane was studied. Membrane potential, transport number and selectivity were improved by using FeTiO3-co-Fe3O4 nanoparticles in membrane matrix. Utilizing FeTiO3/ Fe3O4 nanoparticles in membrane matrix also led to improvement of membrane ionic flux from 2.95*10−5 to 4.15*10−5 (mol/m2·s) obviously. Similar trend was also found for membrane electrical conductivity. Moreover, the transport number, selectivity and membrane electrical conductivity were enhanced by increase of electrolyte concentration. Prepared membranes exhibited higher transport number/selectivity at pH 7 compared to other pH values. Obtained results showed that the membrane electrical resistance decreased initially by increase of electrolyte pH sharply and then began to increase. Membranes exhibited lower selectivity for bivalent ions compared to monovalent type. Modified membranes containing FeTiO3-co-Fe3O4 nanoparticles showed more appropriate electrochemical properties compared to other prepared membranes.
Keywords: Cation Exchange Membrane; Mixed Matrix; FeTiO3-co-Fe3O4 Nanoparticle; Membrane Fabrication/Characterization; Electrolyte’s Concentration/pH
Synthesis of ordered mesoporous SBA-15 and its adsorption of methylene blue by Anaam Akram Sabri; Talib Mohammed Albayati; Raghad Adnan Alazawi (1835-1841).
The removal of methylene blue (MB) dye pollutant from synthetic wastewater onto mesoporous SBA-15 was studied in batch adsorption systems. The characterization for the prepared adsorbent such as: X-ray diffraction (XRD), scanning electron microscopy (SEM), BET surface area and Fourier transform infrared (FTIR) spectroscopy was achieved. The experiments were carried out to measure the adsorption capacity as a function of contact time, initial concentration (40-110 mg/L), pH (3-11) and adsorbent dose (0.1-2.3 g/L). The equilibrium of the process was achieved within 20 min. Adsorption isotherms were fitted with the Langmuir, Freundlich and Temkin models. The equilibrium data were better represented with Langmuir Isotherm model. The kinetics of the MB sorption on SBA-15 was examined by using pseudo-first and pseudo-second order kinetics models. The kinetics analysis showed that the overall adsorption process was successfully fitted with the pseudo-second-order kinetic model. Good linearization of the data was observed for the initial phase of the reaction in accordance with expected behavior of intraparticle diffusion as the rate-limiting and rate-controlled step. SBA-15 can be effectively recovered by calcinations and reused fourteen times in batch system without significant loss in removal of methylene blue from aqueous solution.
Keywords: Waste Water Treatment; Mesoporous SBA-15; Methylene Blue; Batch Adsorption; Organic Pollutants
Effect of light intensity on the correlation between cell mass concentration and optical density in high density culture of a filamentous microorganism by Jong Hyun Yoon; Jong-Hwan Shin; Joon Ho Park; Tai Hyun Park (1842-1846).
We investigated the effect of light intensity on the correlation between optical density (OD) and cell mass concentration in high cell density culture of Anabaena variabilis. When the light intensity was gradually increased to maintain specific irradiation rate above 10 mmol/s/g dry cell, the dry cell mass concentration to OD ratio changed when the cell density became higher than OD 10, while the correlation was linear when light intensity remained constant after 2.5 days. When the OD was below 10, the dry cell concentration to OD ratio in unicells was the same as that of filaments, indicating that filament length, unicell size, and unicell dry cell concentration did not affect the dry cell concentration to OD ratio. Scanning electron microscope pictures revealed the differences in morphological structures between filaments below and above OD 10. Therefore, we propose that the morphological structures of filaments affected the dry cell concentration to OD ratio.
Keywords: High Cell Density; Optical Density (OD); Dry Cell Mass Concentration; Cell Morphology; Filamentous Microorganism
Thermal stability and degradation kinetics of polyphenols and polyphenylenediamines enzymatically synthesized by horseradish peroxidase by Hansol Park; Oyul Kwon; Keungarp Ryu (1847-1852).
Various substituted phenols and phenylenediamines were enzymatically polymerized by horseradish peroxidase in 80% (v/v) organic solvents-aqueous buffer (100 mM sodium acetate, pH 5) mixtures with H2O2 as the oxidant. The thermal stability of the polymers was investigated by thermogravimetric analysis (TGA) and represented by the char yield (wt% of the initial polymer mass) after being heated at 800 °C. Poly(p-phenylphenol) had the highest thermal stability among the synthesized polymers with a char yield of 47 wt%. The polymers containing amino groups such as poly(p-aminophenol) and polyphenylenediamines were also shown to possess high thermal stabilities. The activation energies for the thermal degradation of the polymers determined by derivative thermogravimetric analysis (DTG) using Horowitz-Metzger’s pseudo-first-order kinetics were in the range between 23-65 kJ/mol and comparable to those of the chemically synthesized polymers. Dynamic structural changes of the enzymatically synthesized polymers upon heating were studied by differential scanning calorimetry (DSC). The DSC curves of poly(p-phenylphenol) showed a broad exothermic peaks between 150-250 °C, indicating that the polymer undergoes complex structural transitions in the temperature range. On the other hand, the DSC curves of the poly(p-aminophenol) and the poly(p-phenylenediamine) which contain amino groups showed strong sharp endothermic peaks near 150 °C, implying that these polymers possess homogeneous oriented structures which undergo a concerted structural disintegration upon heating.
Keywords: Peroxidase; Polydiamines; Polyphenols; Thermal Property
Improving water permeability and anti-fouling property of polyacrylonitrile-based hollow fiber ultrafiltration membranes by surface modification with polyacrylonitrile-g-poly(vinyl alcohol) graft copolymer by Noor Aina Mohd Nazri; Woei Jye Lau; Ahmad Fauzi Ismail (1853-1863).
The effect of polyacrylonitrile-g-poly (vinyl alcohol) (PAN-g-PVA) copolymer additive on the properties of PAN-based hollow fiber UF membranes was studied. The resulting hollow fiber membranes were characterized with respect to structural morphology, surface properties, and proteins rejection in order to investigate the impact of PAN-g- PVA copolymer composition (presented at different PAN: PAN-g-PVA ratio) in the UF membrane on the separation and antifouling properties. Results showed that the hollow fiber membrane prepared from the highest composition of PAN-g-PVA copolymer (PAN: PAN-g-PVA 80 : 20) was able to produce pure water flux as high as 297 L/m2·hr in comparison to 41 L/m2·hr reported in control PAN membrane when tested at 1 bar. Fouling experiments performed using bovine serum albumin (BSA), albumin from chicken egg (CE) and trypsin indicated that the blend membranes with higher surface coverage of hydrophilic PVA (34-60%) were more excellent in minimizing protein fouling, which might be correlated with the formation of hydrophilic PVA layer on their surface. Although increase in membrane hydrophilicity upon PAN-g-PVA copolymer incorporation might be the main reason contributing to improved membrane antifouling properties, the changes in membrane surface roughness and pore size could not be completely ruled out to influence membrane anti-fouling resistance during protein filtration.
Keywords: Amphiphilic Copolymer; Ultrafiltration; Polyacrylonitrile; Anti-fouling; Poly(vinyl alcohol); Protein
Two-stage batch sorber design and optimization of biosorption conditions by Taguchi methodology for the removal of acid red 25 onto magnetic biomass by Akeem Adeyemi Oladipo; Mustafa Gazi (1864-1878).
Biomagnetic material (MFC) was synthesized via simple co-precipitation and used as biosorbent for the removal of acid red 25 (AR25) under optimized conditions. The characteristics of MFC were studied using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), Boehm titration and scanning electron microscopy (SEM). Optimum removal of AR25 was achieved at pH=5.0. The equilibrium data were well described by the Sips and Freundlich models. Taguchi methodology was employed to optimize the biosorption experiments. 411.56 mg/g and 96.8% were obtained as the biosorption capacity and removal efficiency, respectively, at the optimum conditions of ionic strength (0.5 M), influent volume (300 L) and MFC dosage (4 g). The contact time for removal of 96% AR25 in two-stage batch system is 400.8 min which is lower than the single-stage treatment process (895 min).
Keywords: Biosorption Optimization; Ferula Communis; Taguchi Methodology; Two-stage Batch Sorber; Kinetics; Acidic Dyes
Evaluation of 2,4-D removal via activated carbon from pomegranate husk/polymer composite hydrogel: Optimization of process parameters through face centered composite design by Fulya Taktak; Zeynep İlbay; Selin Şahin (1879-1888).
A new type of polymer composite hydrogel was prepared by introducing activated carbons from pomegranate husk into poly ((2-dimethylamino) ethyl methacrylate) network. The removal of 2,4-dichlorophenoxyacetic acid (2,4-D) from aqueous solution was studied with respect to pH of the media, initial 2,4-D concentration and activated carbon content into the polymeric network. Face centered composite design (FCCD) through response surface methodology (RSM) was used for designing the experiments as well as for studying the effects of the process parameters. A quadratic model and a two factor interaction design model were developed for the removal of 2,4-D and adsorption capacity, respectively. The optimum pH of the pesticide solution, activated carbon content into the polymeric network and initial concentration of 2,4-D were found as 3, 2.5 wt% and 100mg/L. 63.245% and 68.805 (mg/g) for the removal of 2,4-D and adsorption capacity were obtained by using Simplex optimization method. Furthermore, the surface characteristics of the adsorbent prepared under optimized conditions were examined by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR).
Keywords: 2,4-Dichlorophenoxyacetic Acid; Pomegranate Husk; Polymer Composite Hydrogel; Optimization
Combined adsorption and reduction of Cr(VI) from aqueous solution on polyaniline/multiwalled carbon nanotubes composite by Jiahong Wang; Xiaolong Yin; Wei Tang; Hongrui Ma (1889-1895).
Polyaniline/multiwalled carbon nanotube (PANI-MWCNT) was prepared by bounding polyaniline on the surface of oxidized multiwalled carbon nanotube. The structure and surface properties of synthesized composites were characterized by Fourier transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscope (TEM), and its adsorption capability for aqueous Cr(VI) was also studied. Characterized results showed that polyaniline was successfully anchored on the surface of MWCNT. From adsorption experiments the maximum adsorption amount of Cr(VI) onto PANI-MWCNTs was 28.25, 31.75 and 36.76 mg·g‒1 at 15, 25 and 35 °C. Thermodynamic parameters showed that the Cr(VI) adsorption process was endothermic, spontaneous and feasible. Cr(VI) adsorption followed pseudo-second-order kinetics. Cr(VI) adsorption on the adsorbent decreases with increasing solution pH. The presence of anions in solution almost has no effect on Cr(VI) adsorption, indicating good selectivity. XPS analysis confirms that electrostatic interaction, reduction and chelation contribute to enhanced Cr(VI) removal. Cr(VI) loaded absorbent can be readily desorbed in 0.1 mol·L‒1 of NaOH solution, and the desorption rate was 84.12%.
Keywords: Polyaniline/Multiwalled Carbon Nanotube; Hexavalent Chromium; Adsorption; Desorption
Preparation of anion exchange membrane using polyvinyl chloride (PVC) for alkaline water electrolysis by Gab-Jin Hwang; Soo-Gon Lim; Soo-Yeon Bong; Cheol-Hwi Ryu; Ho-Sang Choi (1896-1901).
An anion exchange membrane was prepared by the chloromethylation and the amination of polyvinyl chloride (PVC), as the base polymer. The membrane properties of the prepared anion exchange membrane, including ionic conductivity, ion exchange capacity, and water content were measured. The ionic conductivity of the prepared anion exchange membrane was in the range of 0.098×10−2-7.0×10−2S cm−1. The ranges of ion exchange capacity and water content were 1.9-3.7meq./g-dry-membrane and 35.1-63.1%, respectively. The chemical stability of the prepared anion exchange membrane was tested by soaking in 30 wt% KOH solution to determine its availability as a separator in the alkaline water electrolysis. The ionic conductivity during the chemical stability test largely did not change.
Keywords: Hydrogen Production; Water Electrolysis; Alkaline Water Electrolysis; Separator; Anion Exchange Membrane
Fabrication of composite nanofiltration membranes with enhanced structural stability for concentrating oligomeric proanthocyanidins in ethanol aqueous solution by Yanyan Ma; Yanlei Su; Yafei Li; Zhongyi Jiang (1902-1909).
Composite nanofiltration (NF) membranes with enhanced structural stability were fabricated and used to concentrate oligomeric proanthocyanidins (OPC) in ethanol solution. The composite NF membranes were prepared by interfacial polymerization of piperazine (PIP) with trimesoyl chloride (TMC), upon the porous supports of polyethersulfone (PES) and polyvinyl formal (PVF) blend membranes. The active layers of composite NF membranes were covalently linked to porous supports owing to hydroxyl groups of PVF upon support surface, which could participate in the interfacial polymerization reaction. The pure water fluxes of the composite NF membranes reached 34.9 L/m2h, while the rejections of Na2SO4 and orange GII were 92.7% and 98.4%, respectively. The enhanced structural stability of the composite NF membranes were confirmed by long-term immersion experiment in ethanol. NF concentration process was considered as a potential alternative to conventional evaporation concentration process for OPC concentration in ethanol solution.
Keywords: Polyvinyl Formal (PVF); Composite Nanofiltration Membrane; Structural Stability; Oligomeric Proanthocyanidins (OPC); Concentration
Controlling the polymorphism of carbamazepine-saccharin cocrystals formed during antisolvent cocrystallization using kinetic parameters by Min-Jeong Lee; In-Chun Wang; Min-Ju Kim; Paul Kim; Keon-Hyoung Song; Nan-Hee Chun; Hwa-Gyoo Park; Guang Jin Choi (1910-1917).
The cocrystal approach has been extensively investigated over the last decade as one of the most promising methods toward modifying the dissolution behavior of insoluble drug substances. This study demonstrates that the polymorphism of pharmaceutical cocrystalline powders prepared via antisolvent methods can be controlled using kinetic parameters. A carbamazepine-saccharin (CBZ-SAC) cocrystal was selected as a model drug in this study. This crystal was manufactured through a scaled-up antisolvent process with a total solution volume of 4.5 L. CBZ-SAC cocrystal crystalline powders were synthesized by adding 3 L of water as the antisolvent into 1.5 L of CBZ and SAC in methanol, whereby the antisolvent addition rate and the agitation speed were varied as the principal kinetic parameters. To investigate how cocrystallization proceeds under each condition, periodical sampling was combined with off-line characterization and in-line near-infrared (NIR) measurements to monitor the progress of reaction over the 120-minute process. We found that the creation of form-I was preferred when the addition speed or agitation speed was increased, but a highly pure form-II resulted if kinetic conditions were reversed. These differences in polymorphism can be explained by changes in kinetic characteristics when the process is monitored by NIR. This study is directly applicable to the industrial synthesis of these types of materials, precisely when specific CBZ-SAC cocrystalline polymorphs must be manufactured on a large scale.
Keywords: Co-crystal; Carbamazepine; Anti-solvent; Scale-up; Near-infrared; In-line Monitoring; Kinetic Parameter
New α-Zn2V2O7/carbon nanotube nanocomposite for supercapacitors by Nulu Venugopal; Woo-Sik Kim (1918-1923).
This study synthesized α-Zn2V2O7 nanopowders using a hydrothermal approach followed by annealing treatment. The resulting powders were then mixed with multi-walled carbon nanotubes and electrochemically characterized as new nanocomposite electrodes for supercapacitors. The structure and surface morphology of the powders were characterized by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Plus, the capacitive behavior of the composite electrodes was evaluated by cyclic voltammetry and galvanostatic charge-discharge cycles in different molar aqueous KCl solutions. The α-Zn2V2O7/multi-walled carbon nanotube composite electrodes were prepared using three different ratios and screened for their use in supercapacitors. As a result, the α-Zn2V2O7/multi-walled carbon nanotube composite electrode with a 1 : 2 ratio was identified as the best electrode with a specific capacitance value of 44.8 F g−1 in 0.5M KCl. Notwithstanding, all the tested composite electrodes demonstrated an excellent cycle stability and showed a less than 4% change in their specific capacitance values when compared to the initial values.
Keywords: Nano Zinc Pyrovanadate; Carbon Nanotubes; Composite Electrode; Aqueous Electrolyte
Effect of ionic-strength adjusters on the detection of silver ion using ion-selective electrode by Seung Yeon Oh; Hwa Kyung Sung; Hyeon Ho Shin; Uiseok Jeong; Ig-chun Eom; Pil-je Kim; Younghun Kim (1924-1927).
Ion-selective electrodes (ISEs) are used in a wide variety of applications for determining the concentrations of various ions in aqueous solutions. When compared to many other analytical techniques, ISEs are relatively inexpensive, simple to use, and have an extremely wide range of applications and concentrations. In recent reports, cytotoxicity of silver nanoparticles (AgNPs) showed that AgNPs were ionized in the cells and led to causing cell-death. Thus, the measurement of silver ions in aqueous phase is important. In this work, several sodium and potassium salts were considered as ionic-strength adjusters (ISA) and were used in the calibration step to enhance sensitivity of detection the target ion. The result showed that potassium iodine (0.05M KI) acted as a very effective ISA, compared to conventional ISA (5M NaNO3).
Keywords: Ion Selective Electrode; Silver Ion; Silver Nanoparticles; Toxicity
Morphology study of nanofibers produced by extraction from polymer blend fibers using image processing by Neda Dehghan; Mohammad Ali Tavanaie; Pedram Payvandy (1928-1937).
The morphology of nanofibers extracted from the industrial-scale produced polypropylene/polybutylene terephthalate (PP/PBT) blend fibers was studied. To study the morphology and diameter measurements of the nanofibers, image processing method was used, and the results were compared with the results of a conventional visual method. Comparing these two methods indicated the good performance of image processing methods for the measuring of nanofiber diameter. Among the various applied image processing methods, the fuzzy c-means (FCM) method was determined as the best for image thresholding. Additionally, the distance transform method was determined as the best way for measuring nanofiber diameter. According to high regression coefficient (R=0.98) resulting between the draw ratio and nanofibers diameter, the high effectiveness of draw ratio to nanofiber diameter is concluded. The spherical (drop) shapes of the PBT dispersed phase particles were eventually deformed into very thin fibrils during the drawing process. The results of measuring the nanofiber diameters showed that the diameter means of nanofibers varied from 420 nm to 175 nm with the highest draw ratio. Good uniformity for diameter of nanofibers was observed, which had not been observed in previous works.
Keywords: Polymer Blend Fibers; Nanofibers; Morphology; Draw Ratio; Image Processing
Hydrodynamic characteristics of bubbles in bubbling fluidized bed with internals by Jong-Hun Lim; Jea-Ho Shin; Keon Bae; Joon-Hwan Kim; Dong-Ho Lee; Joo-Hee Han; Dong Hyun Lee (1938-1944).
The hydrodynamic characteristics of bubbles in bubbling fluidized beds with internals were investigated. The signal range of the optical fiber probe was calibrated from 0.5 V (the bubble phase) to 4.5 V (the emulsion phase). Data sampling involved an optical probe at a rate of 903Hz for 725 s. To obtain improved bubble data, the data were analyzed by three processes: threshold determination, bubble analysis, and erroneous bubble elimination. The data on the bubble rise velocity and bubble frequency were measured and compared to the bed height (0.2–0.7 m), superficial gas velocity (4–7 U mf ), radial position r/R (0.22–0.95), number of distributor nozzles (2, 3, and 7), and the use of the internals with different hydraulic diameters of 0.19, 0.17, and 0.15 m. The experimental data were compared with several reported empirical correlations. Both the bubble rise velocity and bubble frequency increased with decreasing number of distributor nozzles. Furthermore, in the presence of internals, the bubble rise velocity decreased, whereas the bubble frequency increased with decreasing hydraulic diameter of the cross-sectional area divided by internals. Moreover, bubble breaking occurred at a specific position of r/R=0.7, not at the edge of the internals.
Keywords: Bubble Rising Velocity; Optical Probe; Internal; Bubbling Fluidized Beds