http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Aftab Aslam Parwaz Khan,Abdullah M. Asiri,Anish Khan,Naved Azum,Malik Abdul Rub,Mohammed M. Rahman,Sher Bahadar Khan,K. S. Siddiqi,Khalid A. Alamry 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
The reactions of Cefuroxime (CFA) by hexacyanoferrate (III) (HCF(III)) in alkaline medium at a constant ionic strength has been studied spectrophotometrically. It is a first order reaction, but fractional order in both CFA and alkali. Decrease in dielectric constant of the medium decreases the rate of reaction. The effect of added products and ionic strength has also been investigated. A mechanism involving free radicals is proposed. In a composite equilibrium step, CFA binds to HCF(III) to form a complex that subsequently decomposes to the products. The main two products were separated and identified by column chromatography, TLC and FT-IR. There is good agreement between the observed and calculated rate constants under different experimental conditions. The reaction was studied at different temperatures and activation parameters were computed with respect to the slow step of the proposed mechanism.
Aftab Aslam Parwaz Khan,Pardeep Singh,Pankaj Raizada,Abdullah M. Asiri 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-
In this work, a dual Z-scheme Ag3PO4/CdS/Fe-g-C3N4 (AP/CdS/FeCN) photocatalyst was prepared byprecipitation- deposition method. AP/CdS/FeCN photocatalyst was converted into the heterogenousphoto-Fenton system with the addition of H2O2. The synergistic coupling between AP/CdS/FeCN andH2O2 resulted in enhanced for phenol degradation, with a rate constant of constant 6.2 10 4 s-1, which is1.31 and 1.61 times than that of AP/CdS/FeCN and Fe2O3/H2O2. The enhancement in photodegradationwas attributed to (i) more regeneration of Fe2+ ions, (ii) enhanced visible light absorption, (iii) elevatedredox potential due to more hydroxyl radical’s formation, and (iv) low Fe leaching in the reactionsolution. As indicated by EIS, PL, and trapping experiments, photoinduced CB electrons of g-C3N4 and CdSwere transferred entirely to Fe3+ to regenerate Fe2+ ions to accelerate the Fenton cycle. In comparison tothe conventional Fe2O3/H2O2 Fenton process, Fe ion leaching in AP/CdS/FeCN/H2O2 catalytic system wasalmost negligible. It confirmed strong chemical interaction of Fe3+ with g-C3N4. AP/CdS/FeCN/H2O2displayed significant catalytic efficacy andfirmness forfive successive catalytic cycles. Moreover, the AP/CdS/FeCN/H2O2 nanocomposite exhibited substantial mineralization perfomance for other phenolicpollutants. The results demonstrate that AP/CdS/FeCN/H2O2 catalytic system has the potential for waterpurification.
Aftab Ahmad Khan,김종오 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.96 No.-
This study aimed to prepare a membrane by engineering a “slippery” surface on a polyethersulfone (PES)membrane for long-term, direct-contact membrane distillation (DCMD). Membrane surfaces andwettability were analyzed usingfield-emission scanning electron microscopy, atomic force microscopy,and attenuated total reflection–Fourier-transform infrared spectroscopy. Contact angles and liquid entrypressures also were measured. The wetting and fouling-resistance competence of the modified PESmembrane (PES-M) in DCMD was assessed using two hypersaline feed solutions, i.e., multiple salts(2000 mg L 1 [CaSO4 + CaCO3 + CaCl2 2H2O + NaCl]) + 20 mg L 1 humic acid (MSHA-F) and Busan seawaterfeed. The effectiveness of the PES-M membrane against the MSHA-F solution was evaluated over multiplecycles. The membrane was cleaned after each 50-h cycle and successfully reused for three consecutivecycles after cleaning with a clean-in-place method. The PES-M membrane displayed robust performanceagainst both feeds, particularly against MSHA-F for 150 h, during which it lost only 20%flux and showed afinal conductivity of 68.8 mS/cm. The PES-M membrane is a resilient candidate that can resist fouling andwetting.
Khan, Aftab Ahmad,Khan, Imtiaz Afzal,Siyal, Muhammad Irfan,Lee, Chang-Kyu,Kim, Jong-Oh Elsevier 2019 Environmental research Vol.170 No.-
<P><B>Abstract</B></P> <P>The goal of this study was to prepare a robust anti-wetting and anti-fouling polyethersulfone (PES) membrane for the rejection of a highly saline (NaCl and CaCl<SUB>2</SUB>·2H<SUB>2</SUB>O) feed solution containing humic acid (HA) in direct contact membrane distillation (DCMD). Response surface methodology (RSM) was used to determine the optimum formulation of the used materials. The variable factors selected were polydimethyl siloxane (PDMS) and silica (SiO<SUB>2</SUB>); liquid entry pressure (LEP) and contact angle (CA) were selected as responses. Scanning electron microscopy (SEM) analysis confirmed the SiO<SUB>2</SUB> deposition and Fourier-transform infrared spectroscopy (FTIR) test evidenced the new functional groups i.e., Si–OH, siloxane, and C–F bond vibrations at 3446, 1099 cm<SUP>−1</SUP>, and 1150–1240 cm<SUP>−1</SUP> respectively on the membrane surface. The average roughness (Ra) was increased four times for the coated membranes (0.202–0.242 µm) as compared to that for pristine PES membrane (0.053 µm). The optimum PES-13 membrane exhibited consistent flux of 12 LMH and salt rejection (> 99%) with anti-fouling characteristic in DCMD using the feed solution of 3.5 wt% NaCl + 10 mM CaCl<SUB>2</SUB>·2H<SUB>2</SUB>O + 10 mg L<SUP>−1</SUP> HA. The PES-13 membrane may therefore be a key membrane for application in DCMD against CaCl<SUB>2</SUB>·2H<SUB>2</SUB>O-containing salty solutions with HA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PES membrane was prepared for application in DCMD using silica nanoparticles. </LI> <LI> Response surface methodology was employed to optimize the coating formulation. </LI> <LI> Modified membranes were resistant to fouling against calcium-humic acid feed. </LI> <LI> The high fluxes for PES-13 membrane were recorded with all three feed solutions. </LI> </UL> </P>
Aftab Aslam Parwaz Khan,Anish Khan,Abdullah M. Asiri,Malik Abdul Rub 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5
In this paper provides the mechanistic investigation of Mn(II)-catalyzed oxidative of biotin (BTN) has been studied by peroxomonosulphate (PMS) in alkaline medium at 293–308 K with a constant ionic strength. Such studies are much helpful in gaining an insight into the interaction of metal ions through the study of the mechanistic pathway of biotin in redox reactions. The stoichiometry of the reaction is 1:1 in the presence of catalyst. The reaction shows polymerization in the presence of acrylonitrile under the experimental conditions employed. Influence of dielectric constant and ionic strength of the medium on the reaction rate have been done. Manganese peroxide was proposed as the intermediate to explain the experimental observations. Temperature effect is noticeable in all these reactions and activation parameters have been determined. The effect of temperature was evaluated by Arrhenius equation and transition state theory, a mechanism was proposed based on the observation of the experimental results. It involves the formation of an activated complex, which decomposes to give the product. It is identified with the help of FTIR and TLC.
Khan, Aftab Ahmad,Siyal, Muhammad Irfan,Lee, Chang-Kyu,Park, Chansoo,Kim, Jong-Oh Elsevier 2019 Separation and purification technology Vol.210 No.-
<P><B>Abstract</B></P> <P>In this study, hybrid organic-inorganic functionalized polyethersulfone (PES) membrane was prepared for treating hyper-saline feed solutions containing humic acid (HA) foulant. The membrane modification was carried out by dip-coating with silica nanoparticles, followed by vacuum filtration coating with 1H,1H,2H,2H-perfluorodecyl triethoxysilane and polydimethylsiloxane. The membranes were characterized by field emission scanning electron microscope, atomic force microscope, Fourier transform infrared, and thermal gravimetric analyses. The evaluation of membranes with water contact angle, liquid entry pressure, direct contact membrane distillation (DCDM), and stability tests, proved the durable amphiphobic nature of the modified PES membrane (PDMS-FAS/SiNPs). The membrane performance was respectively better from that of commercial polypropylene (PP) and polyvinylidene fluoride (PVDF) membranes. In the DCMD of a feed solution of 1 M NaCl and 10 mg L<SUP>−1</SUP> HA, the flux of the PDMS-FAS/SiNPs membrane remained consistent (17 LMH), with a permeate conductivity of 33.96 µS cm<SUP>−1</SUP>. The optimized modified membrane showed better performance in terms of permeate flux, salt rejection, and anti-fouling behavior in DCMD. These wonderful results of functionalized PDMS-FAS/SiNPs PES membrane are attributed to the step-wise simple, and inexpensive dip-coating followed by vacuum filtration coating using efficient hybrid organic-inorganic material combination.</P> <P><B>Highlights</B></P> <P> <UL> <LI> PES membrane functionalization using hybrid organic-inorganic material. </LI> <LI> Dip and vacuum filtration coating methods were used for membrane modification. </LI> <LI> Consistent rejection of hyper-saline feed solution containing humic acid. </LI> <LI> Functionalized PES membrane performance compared with other membranes. </LI> <LI> Modified PES membrane was more durable than commercially available PP and PVDF. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Khan, Aftab A.,Al-Kheraif, Abdulaziz A.,Al-Shehri, Abdullah M.,Sä,ilynoja, Eija,Vallittu, Pekka K. Elsevier 2018 Journal of the mechanical behavior of biomedical m Vol.78 No.-
<P><B>Abstract</B></P> <P>This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, <I>i.e.</I>, two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as “stage 1–5”. To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (P<0.001). The regression coefficient suggests nanohardness increased on average by 0.039GPa for every storage group. The increased nanohardness values in the core region of 6-months and 2-years stored prepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC.</P>