Showing papers in "Journal of The Taiwan Institute of Chemical Engineers in 2016"
TL;DR: In this paper, the authors provide a brief review of researches on nanofluid flow and heat transfer via semi-analytical and numerical methods and show that the Nusselt number is an increasing function of nanoparticle volume fraction.
Abstract: The use of additives in the base fluid like water or ethylene glycol is one of the techniques applied to augment the heat transfer. Newly an innovative nanometer sized particles have been dispersed in the base fluid in heat transfer fluids. The fluids containing the solid nanometer size particle dispersion are called ‘nanofluids’. Two main categories were discussed in detail as the single-phase modeling which the combination of nanoparticle and base fluid is considered as a single-phase mixture with steady properties and the two-phase modeling in which the nanoparticle properties and behaviors are considered separately from the base fluid properties and behaviors. Both single phase and two phase models have been presented in this paper. This paper intends to provide a brief review of researches on nanofluid flow and heat transfer via semi analytical and numerical methods. It was also found that Nusselt number is an increasing function of nanoparticle volume fraction, Rayleigh number and Reynolds number, while it is a decreasing function of Hartmann number.
TL;DR: In this article, the potential of citrus limetta peel (CLP) as a low cost adsorbent for the removal of Methylene blue (MB) dye was investigated.
Abstract: In the present work, the potential of citrus limetta peel (CLP) as a low cost adsorbent for the removal of Methylene blue (MB) dye was investigated. Batch adsorption studies were conducted to find out how adsorption was affected by various factors like contact time, initial dye concentration, adsorbent dosage, pH and temperature. The experimental data was analysed in the light of Langmuir, Freundlich and Temkin isotherm models. The data was found to be best represented by Langmuir adsorption isotherm with maximum adsorption capacity for monolayer coverage was found to be 227.3 mg/g. The data were analysed in the light of different available kinetic models and was observed to be best followed pseudo-second order kinetics. Desorption of MB-loaded CLP was studied with various desorbing agents and HCl was found to be most effective desorbing agent among HCl, NaOH, NaCl, CH3COOH and deionised doubly distilled water (DDDW). Results suggest that CLP is a very effective low cost adsorbent for the removal of dyes from wastewater.
TL;DR: Amino acids are biologically important organic compounds in the human body which contain two important functional groups namely: NH2 (amine) and COOH (carboxylic acid) in their structures as mentioned in this paper.
Abstract: Amino acids are biologically important organic compounds in the human body which contain two important functional groups namely: –NH2 (amine) and –COOH (carboxylic acid) in their structures. In the present work, corrosion inhibitive performance amino acids such alanine (Ala), methionine (Met), aspartate (Asp), asparagine (Asn), lysine (Lys), arginine (Arg) and histidine (His) were investigated. All quantum chemical calculations related to these amino acids at the B3LYP/6-31G++(d, p) HF/6-31G++(d,p) methods were performed. Corrosion inhibition effects of the subject amino acids were discussed not only in the gas phase but also in the water phase, acetic acid and formic acid. Furthermore, molecular dynamic simulations employing Monte Carlo sampling approach were applied to search for the most stable configuration and adsorption energies for the interaction of the amino acid corrosion inhibitors on Cu (111)/50 H2O interface. A good correlation between theoretical data and experimental data has been obtained. Moreover, arginine that is a basic amino acid the best corrosion inhibitor among amino acids, considered in this study.
TL;DR: In this paper, the chitosan/TiO 2 composite nanofibrous adsorbents were developed by two techniques including TiO 2 nanoparticles coated chitosa-nibers (coating method) and electrospinning of chitosi-nigram solutions (entrapped method) for the removal of Pb (II) and Cu(II) ions in a batch system.
Abstract: The chitosan/TiO 2 composite nanofibrous adsorbents were developed by two techniques including TiO 2 nanoparticles coated chitosan nanofibers (coating method) and electrospinning of chitosan/TiO 2 solutions (entrapped method). The potential of prepared nanofibers was investigated for the removal of Pb (II) and Cu (II) ions in a batch system. The nanofibers were characterized by SEM, FTIR and BET analysis. Kinetic and equilibrium studies showed that the experimental data of Pb (II) and Cu (II) ions were best described by pseudo-first-order and Redlich–Peterson isotherm models using the both chitosan/TiO 2 nanofibers. The maximum adsorption capacities of Cu (II) and Pb (II) ions using entrapped and coating methods were found to be 710.3, 579.1 and 526.5, 475.5 mg/g at equilibrium time of 30 min and 45 ° C, respectively. The reusability studies indicated that the chitosan/TiO 2 nanofibers prepared by entrapped method could be reused frequently without significant loss in adsorption performance after five adsorption/desorption cycles. Whereas, lower than 60% of total adsorption in first cycle took place for metal ions sorption using nanofibers prepared by coating method. The sorption studies of metal ions in a binary system revealed that the selectivity of metal sorption using chitosan/TiO 2 nanofibrous adsorbent was in order of Cu (II) > Pb (II).
TL;DR: In this paper, the adsorption of crystal violet (CV) dye from aqueous solution using magnetic nanoparticles (MNPs) modified with sodium dodecyl sulphate (SDS) was investigated.
Abstract: The adsorption studies of crystal violet (CV) dye from aqueous solution using magnetic nanoparticles (MNPs) modified with sodium dodecyl sulphate (SDS) was investigated. The synthesized MNPs were characterized by TEM, EDAX and XRD. In batch optimization studies, the maximum removal efficiency of 80.4% was obtained at the optimum levels of pH 6, contact time 10 min, adsorbent dosage 0.25 g/L and initial dye concentration 10 ppm. The adsorption data was best fitted with Freundlich isotherm ( R 2 = 0.957) and maximum adsorption capacity of 166.67 mg/g was determined from Langmuir isotherm. The adsorption of CV by SDS coated MNPs follows the pseudo-second order kinetic model. The results of this study showed that the SDS coated MNPs were found to be cost effective and easily separable nanoadsorbent for efficient removal of crystal violet dye.
TL;DR: In this article, the results revealed the presence of carboxyl, hydroxyl, and carbonyl groups, which are likely responsible for the adsorption of Pb(II) ions.
Abstract: In this study sugar cane biochar (SC-BC) and orange peel biochar (OP-BC) were used to remove Pb(II) ions from aqueous solutions. To achieve this goal, biochars were produced by the pyrolysis of biomasses at temperature less than 500 °C by using a small-scale biochar producing plant. Furthermore, batch adsorption studies have been performed, and the effects of several factors, i.e ., pH, contact time, initial Pb(II) ions concentration and temperature were investigated on Pb(II) ions sorption mechanism and optimizing the removal efficiency of Pb. Boehm titration method and Fourier transform infrared (FTIR) spectroscopy were employed to quantitatively describe the major function groups on the surface of biochars. The obtained results revealed the presence of carboxyl, hydroxyl, and carbonyl groups, which are likely responsible for the adsorption of Pb(II) ions. Given the same chemical structure, SC-BC was more effective in removing Pb(II) ions than OP-BC, with the removal capacities of 86.96 mg/g, much higher than those of OP-BC (27.86 mg/g). The equilibrium data were well fitted with Langmuir model and the adsorption process was well fitted by pseudo-second-order model. We suggested the major adsorption mechanisms of Pb(II) ions through a specific ion-exchange mechanism, and surface precipitation. Results indicated that not only the chemical composition but also the morphological structure plays an important role in the sorption nature of biochar.
TL;DR: In this article, the adsorption and corrosion inhibition properties of three piperidine derivatives, namely, (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl)-piperidine 4-yl), (1.5-5-dimethoxybenzenesulfonamide (FMPPDBS) and FMPPNBS, on the corrosion of iron were investigated by performing quantum chemical calculations and molecular dynamics simulations.
Abstract: The adsorption and corrosion inhibition properties of three piperidine derivatives namely, (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine-4-yl)-2,5-dimethoxybenzenesulfonamide (FMPPDBS), (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine-4-yl)-4-nitrobenzenesulfonamide (FMPPNBS), (1-(5-fluoro-2-(methylthio) pyrimidine-4-yl) piperidine-4-yl)-3-methoxybenzenesulfonamide (FMPPMBS) on the corrosion of iron were investigated by performing quantum chemical calculations and molecular dynamics simulations. Global reactivity parameters such as E HOMO , E LUMO , HOMO–LUMO energy gap (∆ E ), chemical hardness, softness, electronegativity, proton affinity, electrophilicity and nucleophilicity have been calculated and discussed. The adsorption behaviors of these piperidine derivatives on Fe(110), Fe(100) and Fe(111) surfaces were investigated using molecular dynamics simulation. The binding energies on metal surface of studied compounds followed the order: FMPPDBS > FMPPMBS> FMPPNBS and this ranking obtained is consistent with the experimental data.
TL;DR: Due to sterically-hindered adsorption of some thiophenic sulfur compounds (S-compounds) such as thiophene, dibenzothiophene and their derivatives on catalyst surface, hydrodesulfurization (HDS) is not effective to remove such S-compound in fuel oils as mentioned in this paper.
Abstract: Due to sterically-hindered adsorption of some thiophenic sulfur compounds (S-compounds) such as thiophene, dibenzothiophene and their derivatives on catalyst surface, hydrodesulfurization (HDS) is not effective to remove such thiophenic S-compounds in fuel oils. To produce clean fuel oils with lower S-content (e.g., S
TL;DR: In this paper, the authors investigated the entropy generation due to conjugate natural convection-conduction heat transfer in a square domain under steady-state condition, and the results showed that both the average Nusselt number and entropy generation are increasing functions of K ro while they are maxima at some critical values of D.
Abstract: Entropy generation due to conjugate natural convection–conduction heat transfer in a square domain is numerically investigated under steady-state condition. The domain composed of porous cavity heated by a triangular solid wall and saturated with a CuO–water nanofluid. Equations governing the heat transfer in the triangular solid together with the heat and nanofluid flow in the nanofluid-saturated porous medium are solved numerically using the over-successive relaxation finite-difference method. A temperature dependent thermal conductivity and modified expression for the thermal expansion of nanofluid are adopted. A new criterion for assessment of the thermal performance is proposed. The investigated parameters are the nanoparticles volume fraction φ (0–0.05), modified Rayleigh number Ra (10–1000), solid wall to base-fluid saturated porous medium thermal conductivity ratio K ro (0.44, 1, 23.8), and the triangular solid thickness D (0.1–1). The results show that both the average Nusselt number and the entropy generation are increasing functions of K ro , while they are maxima at some critical values of D . It is also found that the addition of nanoparticles increases the entropy generation. According to the new proposed criterion, the results show that the largest solid thickness ( D = 1.0) and the lower wall thermal conductivity ratio manifest better thermal performance.
TL;DR: In this paper, a numerical investigation is performed on the unsteady natural convection of water-based nanofluid within a wavy-walled cavity under the influence of a uniform inclined magnetic field using the mathematical nano-fluid model proposed by Buongiorno.
Abstract: A numerical investigation is performed on the unsteady natural convection of water based nanofluid within a wavy-walled cavity under the influence of a uniform inclined magnetic field using the mathematical nanofluid model proposed by Buongiorno. The left vertical wavy and right vertical flat walls of the cavity are kept at constant but different temperatures whereas the top and bottom horizontal walls are adiabatic. All boundaries are assumed to be impermeable to the base fluid and nanoparticles. The mathematical model formulated in dimensionless stream function, vorticity and temperature variables is solved using implicit finite difference schemes of the second order. The governing parameters are the Hartmann number, undulation number, wavy contraction ratio, inclination angle of the magnetic field relative to the gravity vector and dimensionless time. The effects of these parameters on the average Nusselt number along the hot wavy wall, as well as on the streamlines, isotherms and isoconcentrations are analyzed.
TL;DR: In this article, the authors used morus alba pendula leaves extract (MAPLE) as a new green corrosion inhibitor for carbon steel in 1-M HCl solution at different concentrations (0.1-0.4 g/L) and temperatures (25-60 °C).
Abstract: Recently the researchers' attention has been directed toward using environmentally friendly corrosion inhibitors extracted from plant leaves for corrosion protection of steel structures against acidic environments. The objective of this study is using morus alba pendula leaves extract (MAPLE) as a new green corrosion inhibitor for carbon steel in 1 M HCl solution at different concentrations(0.1–0.4 g/L) and temperatures (25–60 °C). In addition, the effect of addition of potassium iodide (KI) to the MAPLE was studied. Electrochemical investigations were performed by electrochemical impedance spectroscopy (EIS) and polarization test. Also, surface characterizations were done on the steel panels exposed to 1 M HCl solutions containing MAPLE by atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR). The inhibitor adsorption/desorption behaviors in the 1 M solution was studied by UV–visible analysis. Results obtained from electrochemical measurements revealed that a high inhibition efficiency value of 93% was achieved in the presence of 0.4 g/L MAPLE at room temperature (25 °C). A synergistic effect was observed between KI and MAPLE with optimum concentration of 0.4 g/L MAPLE+ 10 mM KI. Adsorption of extract on the steel surface in the presence of KI resulted in an inhibition efficiency of 96%. The presence of flavonoids such as morusin, kuwanonC and kuwanonG, phenolic acids and pyrrole alkaloids in the MAPLE is responsible for its high inhibition efficiency in 1 M HCl solution on the steel surface. It was found that MAPLE acted as a mixed type corrosion inhibitor and the inhibition efficiency was increased by increasing the inhibitor concentration obeying a Langmuir adsorption isotherm.
TL;DR: In this paper, the effect of mild steel corrosion in 1M HCl solution by some alkylimidazolium-based ionic liquids (ILs) was investigated using electrochemical, spectroscopic, surface morphology, quantum chemical calculations, quantitative structure activity relationship (QSAR) and Monte Carlo simulation methods.
Abstract: Inhibition of mild steel corrosion in 1 M HCl solution by some alkylimidazolium-based ionic liquids (ILs) namely 1-ethyl-3-methylimidazolium ethylsulfate [EMIM]+[EtSO4]−, 1-ethyl-3-methylimidazolium acetate [EMIM]+[Ac]−, 1-butyl-3-methylimidazolium thiocyanate [BMIM]+[SCN]−, 1-butyl-3-methylimidazolium acetate [BMIM]+[Ac]− and 1-butyl-3-methylimidazolium dicyanamide [BMIM]+[DCA]− was investigated using electrochemical, spectroscopic, surface morphology, quantum chemical calculations, quantitative structure activity relationship (QSAR) and Monte Carlo simulation methods The studied ILs showed appreciable inhibition efficiencies within the range of concentrations considered Polarization measurements showed that the studied ILs are mixed-type inhibitors, that is, they inhibit both the anodic mild steel dissolution and cathodic hydrogen evolution reactions The adsorption of the ILs on mild steel affords competitive physisorption and chemisorption processes and obeyed the Langmuir adsorption isotherm Spectroscopic studies confirmed chemical interactions between the ILs and mild steel, while the scanning electron microscopy (SEM) images revealed the formation of protective film of the inhibitors on mild steel surface Theoretical quantum chemical calculations, QSAR analyses and Monte Carlo simulations studies were used to correlate experimental results The best fit QSAR equations are functions of molecular weight, fraction of electrons transferred from the inhibitor to the metal and dipole moment of the ILs
TL;DR: In this article, the influence of treatment conditions on the waste tire-derived activated carbon for adsorptive desulfurization was reported on the surface properties of the rubber compounds.
Abstract: This work reports on the influence of treatment conditions on the waste tire-derived activated carbon for adsorptive desulfurization. The rubber tires were carbonized and activated. The obtained activated carbon (AC) was treated with HNO3 or NaOH at a temperature range of 30–90 °C. The morphology and surface properties of AC were characterized by surface pH, Boehm's titration, N2 adsorption–desorption isotherms, Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscope. The AC sample, treated with HNO3 at 90 °C, possess the highest surface oxygen containing functional groups (2.39 mmol/g), surface area (473.35 m2/g) and pore volume (0.70 cm3/g) and the more adsorption capacity to the refractory sulfur compounds. The Boehm's titration experiments indicated that the amount of surface oxygen containing functional groups on the surface of the acid-treated AC increases with treatment temperatures. Acid-treated AC at 90 °C proves to be optimum for adsorptive desulfurization with the order of dibenzothiophene > benzothiophene > thiophene.
TL;DR: In this paper, Mg-Fe layered double hydroxide (MgFe-LDH) particles were incorporated into wheat-straw biochar by liquid-phase deposition.
Abstract: Mg–Fe layered double hydroxide (MgFe-LDH) particles were incorporated into wheat-straw biochar by liquid-phase deposition. The obtained biochar/MgFe-LDH composite was used to remove nitrate from aqueous solutions. X-ray diffraction patterns demonstrated that LDH particles were successfully deposited onto the carbon surface within the biochar matrix. Adsorption kinetic and isotherm studies and the effects of co-existing anions and adsorbents dosages were investigated using laboratory batch sorption experiments. The biochar/MgFe-LDH composite showed a strong sorption ability to nitrate in aqueous solutions with the Langmuir maximum adsorption capacity of 24.8 mg/g. A high selectivity for nitrate of the biochar/MgFe-LDH composite was also observed irrespective of the co-existence of sulfate and phosphate. The biochar/MgFe-LDH composite can thus be potentially used as an alternative adsorbent for the treatment of nitrate-contaminated waters as well as a soil amendment for the reduction of soil nitrate leaching.
TL;DR: In this article, the authors investigated batch adsorption experiments for the Cephalexin (CFX) antibiotic on walnut shell activated carbon (AC), where the adsorbent was prepared by chemical activation method in the presence of ZnCl 2.
Abstract: The batch adsorption experiments were investigated for the adsorption of cephalexin (CFX) antibiotic on walnut shell activated carbon (AC). The adsorbent was prepared by chemical activation method in the presence of ZnCl 2 . Several adsorption parameters including the adsorbent dosage, the initial CFX concentration, contact time, temperature, and pH were studied. The adsorption isotherm was analyzed by different isotherm models. It was found that the Freundlich and Toth models provided the best fit for the experimental data for two and three parameter models, respectively. The maximum adsorption capacity was obtained 233.1 mg/g based on the Langmuir model. The kinetic data were well represented by pseudo-second order model. Thermodynamics analysis showed endothermic nature of CFX adsorption on walnut shell AC under examined conditions.
TL;DR: In this article, the removal of crystal violet dye from aqueous solution by ultrasound assisted adsorption using zinc oxide nanorods loaded on activate carbon as an adsorbent was discussed.
Abstract: The present work discusses the removal of crystal violet dye from aqueous solution by ultrasound assisted adsorption using zinc oxide nanorods loaded on activate carbon as an adsorbent The said adsorbent was prepared and characterized using field emission scanning electron microscopy, X-ray diffraction and Fourier transform infrared analysis The important process parameters, such as initial crystal violet concentration (8–24 mg/L), solution pH (30–70), adsorbent doses (0005–0025 g), and sonication time (2–6 min) were optimized using design of experiments The optimum removal efficiency of crystal violet onto adsorbent was determined as 9982% at pH 70, 0025 g adsorbent dosage, 24 mg/L initial crystal violet concentration and 50 min sonication time Analysis of variance showed a high coefficient of determination ( R 2 = 0992) The present analysis suggests that the predicted values are in good agreement with experimental data Also, the artificial neural network model was used for predicting removal (%) of crystal violet dye based on experimental data Equilibrium data was fitted well with the Langmuir model having maximum adsorption capacity of 11364 mg/g The adsorption of crystal violet followed the pseudo-second order kinetic model This study clearly showed that response surface methodology was one of the appropriate methods to optimize the operating conditions
TL;DR: A comprehensive review of the recent development on FBF process application to industrial wastewater treatment is presented in this paper, where the authors have shown the potential applicability of FBF technology to reduce the levels of recalcitrant organic contaminants in wastewater effluents.
Abstract: The manufacture of products for the growing population results in large volume of wastewater that needs treatment. Advanced oxidation processes (AOPs) are popular for low cost, high efficiency and being eco-friendly in the degradation of toxic pollutants in the wastewater using the generated non-selective hydroxyl radical (•OH) for oxidation. Among the many AOPs, the Fenton process has been proven to be effective for treating recalcitrant organic compounds by using Fe2+ and H2O2 to produce the •OH. One disadvantage is the production of a large amount of sludge that needs further treatment and disposal. The fluidized-bed Fenton (FBF) process uses carriers that reduce the production of sludge by crystallizing the target pollutant onto the carrier surface. This paper is a comprehensive review of the recent development on FBF process application to industrial wastewater treatment. FBF process was used to treat industrial wastewaters like thin film transistor liquid crystal display manufacturing effluents, pharmaceutical products, textile, phenol and phenol derivatives-containing wastewater and other refractory organics in wastewater. This review highlights the advantages of FBF process over other technologies that are based on Fenton oxidation in terms of performance, operating conditions and factors affecting the removal efficiency. Included in this review are the reaction kinetics and mechanism involved and the carriers that were used. Finally, full-scale applications are collected and described. This review has shown the potential applicability of FBF technology to reduce the levels of recalcitrant organic contaminants in wastewater effluents.
TL;DR: In this article, the structural characteristics, surface area, and thermal analysis of the synthesized MIL-53 (Fe) was carried out using XRD, TGA, TEM, and BET methods.
Abstract: In this paper, MIL-53 (Fe), was synthesized and the adsorption interaction between this MOF and methyl red (MR) in an aqueous solution was studied. The structural characteristics, surface area, and thermal analysis of the synthesized MIL-53 (Fe) was carried out using XRD, TGA, TEM, and BET methods. The effects of the parameters such as initial concentration, contact time, adsorbent dosage, and temperature on the adsorption capacity were investigated for the determination of the best fit adsorption isotherm, adsorption kinetics, adsorption thermodynamics, and equilibrium time. It was found that the adsorption kinetics obeyed the pseudo-second-order kinetic model and an intraparticle diffusion model was also applied to understand the adsorption mechanism. The Langmuir and Freundlich adsorption isotherm models were also investigated. The results of the adsorption thermodynamics revealed that the adsorption of MR by selected MOF was a spontaneous and exothermic process. MIL-53 (Fe) opens its pores only in the presence of guest molecules. Its flexible structure leads to high adsorption capacities for MR.
TL;DR: In this paper, a methanol extract of Ligularia fischeri was studied for its inhibitive effect on the corrosion of mild steel in a 1-M hydrochloric acid medium, using the metrics of weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS).
Abstract: A methanol extract of Ligularia fischeri was studied for its inhibitive effect on the corrosion of mild steel in a 1 M hydrochloric acid medium, using the metrics of weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The corrosion rate of mild steel and Ligularia fischeri's inhibition efficiencies were calculated. The inhibition efficiency [ η (%)] was observed to increase with increasing concentrations of Ligularia fischeri . A maximum inhibition efficiency of 92% was achieved using 500 ppm of the inhibitor. The weight loss experiments were performed at different temperatures to understand the thermodynamic mechanism of inhibition. A mixed inhibition mechanism was proposed for the effects of Ligularia fischeri extract, as revealed by the potentiodynamic polarization technique. A solution analysis by atomic absorption spectroscopy (AAS) for mild steel showed decreased dissolution of iron in the presence of Ligularia fischeri . The adsorption mechanism and surface morphology of the mild steel, both with and without the inhibitor, were studied using UV–visible, Fourier transform infrared (FT-IR), Raman, wide-angle X-ray diffraction (WAXD), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM-EDS), and atomic force microscopy (AFM).
TL;DR: In this article, the corrosion inhibition performance of three pyridazine derivatives, MPYO, PPYO and PPYS, for mild steel in 1-M HCl solution were studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques.
Abstract: The corrosion inhibition performances of three pyridazine derivatives, 6-methyl-4,5-dihydro-2H-pyridazine-3-one (MPYO), 6-phenyl-2H-pyridazine-3-one (PPYO) and 6-phenyl-2H-pyridazine-3-thione (PPYS) for mild steel in 1 M HCl solution were studied by gravimetric, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. Some thermodynamic parameters were calculated and discussed. The effect of molecular structure on the inhibition efficiency was theoretically studied by density functional theory (DFT). Experimental and theoretical studies agreed well and confirmed that PPYS is the best corrosion inhibitor among the studied organic compounds which was related to the presence of a more favorable adsorption center of S atom in its molecular structure.
TL;DR: In this article, a numerical model is developed to study the effects of chemical reaction and heat source on MHD heat and mass transfer of an electrically conducting Jeffrey fluid over a stretching sheet in the presence of power law form of temperature and concentration.
Abstract: A numerical model is developed to study the effects of chemical reaction and heat source on MHD heat and mass transfer of an electrically conducting Jeffrey fluid over a stretching sheet in the presence of power law form of temperature and concentration. Similarity transformations are used to convert the governing partial differential equations to a set of coupled non-linear ordinary differential equations. The resulting equations are then solved numerically by shooting method with Runge–Kutta fourth order scheme. The influence of various dimensionless parameters on the velocity, temperature and concentration distributions are analyzed and discussed through graphs and tables. It is observed that the Deborah number ( β ) and ratio of relaxation and retardation times parameter ( λ ) have opposite effects on the skin friction coefficient. However, the effects of β and Pr on the Nusselt number profiles are similar. Subsequently the present results are in very good agreement with the results obtained for a viscous fluid.
TL;DR: Magnetic biochar prepared with Astragalus membranaceus residue according to the Fe2+/Fe3+ co-precipitation method was used as an adsorbent for Cr(VI) in aqueous solutions during batch experiments as mentioned in this paper.
Abstract: Magnetic biochar prepared with Astragalus membranaceus residue according to the Fe2+/Fe3+ co-precipitation method was used as an adsorbent for Cr(VI) in aqueous solutions during batch experiments. Scanning electron microscopy and energy dispersive spectroscopy results proved that the adsorbent contained substantial amounts of iron oxide and confirmed that magnetic biochar was prepared. The surface area decreased from 111.48 to 59.34 m2/g after the adsorbent became magnetic. X-ray diffraction analysis and X-ray photoelectron spectroscopy studies further demonstrated the existence of iron oxide in the magnetic biochar and showed that oxygen-containing groups decreased after adsorption. The maximum Cr(VI) adsorption occurred at pH 2 (23.85 ± 0.23 mg/g). The adsorption data were described well by a pseudo-second-order model and the Langmuir isotherm model (R2 = 0.994 and R2 = 0.993, respectively). The intraparticle diffusion model results indicated that intraparticle diffusion is not the only rate-limiting step. Together, these results proved that magnetic biochar could be separated easily from water with external magnetic fields and that such a material could be used as a cost-effective adsorbent in heavy metal removal applications.
TL;DR: In this paper, a semi-interpenetrating polymer networks (semi-IPNs) hydrogel with slow-release fertilizers of nitrogen and phosphorus was prepared by the method of solution polymerization.
Abstract: A novel wheat straw based semi-interpenetrating polymer networks (semi-IPNs) hydrogel with slow-release fertilizers of nitrogen and phosphorus was prepared by the method of solution polymerization. The influences of particle sizes, salt solutions, ionic strength and pH changes on the swelling and fertilizer releasing properties of the product were investigated. Effect of cations on both swelling and fertilizer release properties were observed in the order of Na+ > K+ > Ca2+. The product could hold more water in the pH range of 6–9. The swelling behaviors of the product in various salt solutions, ionic strength and pHs conditions were evaluated by Schott's second-order swelling kinetics model. The fertilizers diffusion parameters of the product could be assessed by a cubic form perfectly according to the diffusion coefficients in the kinetic equation.
TL;DR: In this paper, zero-valent iron particles supported on reduced graphene oxides (NZVI/rGOs) from spent graphene oxide (GO)-bound iron ions were developed by using a plasma reduction method to improve the reactivity and stability of NZVI.
Abstract: Nanoscale zero-valent iron particles supported on reduced graphene oxides (NZVI/rGOs) from spent graphene oxide (GO)-bound iron ions were developed by using a plasma reduction method to improve the reactivity and stability of NZVI. The specific surface area (SSA) of NZVI/rGOs was 117.97 m2 g−1, while the SSA of NZVI particles was 59.59 m2 g−1. The adsorption kinetics was quite fast, which could be completed within 50 min. The adsorption capacity of NZVI/rGOs toward Cd(II) was 425.72 mg g−1, which was higher than other adsorbent materials. Moreover, the NZVI/rGOs could be regenerated by the plasma reduction technique and maintained high removal performance after four cycles. NZVI/rGOs also showed high removal capability toward Cd(II) in the simulated Cd(II)-bearing effluent. The above experimental results show that the NZVI/rGO can be efficient materials for the purification of Cd(II)-contaminated water in the environmental pollution management.
TL;DR: In this paper, a thermal and flow analysis of an unsteady squeezing nanofluid flow and heat transfer using Brinkman model in presence of variable magnetic field is presented.
Abstract: This paper presents a thermal and flow analysis of an unsteady squeezing nanofluid flow and heat transfer using nanofluid based on Brinkman model in presence of variable magnetic field. Galerkin Method (GM) is used to solve the nonlinear differential equations governing the problem. Squeezing flow between parallel plates are very applicable in the many industries and it means that one or both of the parallel plates have vacillation. The effects of active parameters such as the Hartman number, squeeze number and heat source parameter are discussed. Results for temperature distribution and velocity profile, Nusselt number and skin friction coefficient by Galerkin Method (GM) are presented. As can be seen in results, the values of Nusselt number and skin friction coefficient for CuO is better than Al 2 O 3 ’s. Also, according to figures, as nanofluid volume fraction increases, Nusselt number increases and skin friction coefficient decreases, increase in the Hartman number results in an increase in velocity and temperature profiles and an increase in squeeze number can be associated with the decrease in the velocity.
TL;DR: In this paper, a commercial coffee waste was treated using cationic surfactants cetyltrimethyl ammonium bromide (CTAB) or Cetylpyridinium chloride (CPC) to enhance its adsorption capacity for the removal of methyl orange dye from aqueous solutions.
Abstract: In this present work, a commercial coffee waste was treated using cationic surfactants cetyltrimethyl ammonium bromide (CTAB) or cetylpyridinium chloride (CPC) to enhance its adsorption capacity for the removal of methyl orange dye (MO, anionic dye) from aqueous solutions. A series of experiments were undertaken in an agitated batch to assess the effect of key parameters such as pH, contact time, adsorbent dose and ionic strength. Maximum methyl orange dye adsorption onto modified commercial coffee waste (MCWs) was observed at pH 3.5 with 0.1 g/50 ml of adsorbent dose. Modeling study shows that pseudo-second-order kinetic model and Langmuir adsorption isotherm model provide better fitness to the experimental data. The maximum adsorption capacity (62.5 mg/g at 25 °C) was obtained with CPC modified commercial coffee waste. Calculated thermodynamic parameters ∆ G 0 , ∆ H 0 and ∆ S 0 showed that adsorption is spontaneous and exothermic. The FT-IR analysis showed that possible mechanisms controlling MO adsorption on the MCWs included electrostatic interactions and hydrophobic interaction.
TL;DR: A selective adsorbent for Hg(II) was prepared by coating Fe 3 O 4 nanoparticles with SiO 2 which was further functionalized with thiol (−SH) group.
Abstract: A selective adsorbent for Hg(II) was prepared by coating Fe 3 O 4 nanoparticles with SiO 2 which was further functionalized with thiol (–SH) group. The new adsorbent (Fe 3 O 4 @SiO 2 -SH) was shown to adsorb aqueous Hg(II) species in a wide range of pH (1.0–8.0) conditions. The Hg(II) adsorption capacity q e was more than 90.0 mg g −1 at pH > 3.0, and was slightly decreased to 84.6 mg g −1 under strong acidic conditions due to the electrostatic repulsion. The Langmuir isotherm model fitted the adsorption data better than the Freundlich, Temkin, and Dubinin-Radushkevich isotherms models. The maximum adsorption capacity of Fe 3 O 4 @SiO 2 -SH for Hg(II) was 132.0 mg g −1 . The adsorption kinetics were shown to follow the pseudo-second-order kinetic model, and the kinetic constant k 2 was 2.4 × 10 −3 g mg −1 min −1 . The magnetic retrieve of the newly-developed adsorbent was easily carried out via an external magnetic field, enabling both excellent adsorbent utilization and adsorption efficiency at high Hg(II) concentrations.
TL;DR: In this paper, a facile and novel method has been developed for surface modification of multiwalled carbon nanotubes (CNT) with carboxymethyl chitosan via combination of mussel inspired chemistry and Michael addition reaction.
Abstract: The adsorption removal of heavy metal ions from aqueous solution using polymer nanocomposites has attracted great interest because of their advantages from both nanomaterials and polymers In this work, a facile and novel method has been developed for surface modification of multiwalled carbon nanotubes (CNT) with carboxymethyl chitosan via combination of mussel inspired chemistry and Michael addition reaction To obtain resultant CNT based chitosan nanocomposites (CNT-PDA-CS), pristine CNT were first coated with polydopamine (PDA) thin films through self polymerization of dopamine under alkaline aqueous solution Then PDA modified CNT were further functionalized with carboxymethyl chitosan (CS) via Michael addition reaction The successful preparation of CNT-PDA-CS nanocomposites was ascertained by a series of characterization techniques including transmission electron microscopy, Fourier transform infrared spectroscopy, thermal gravimetric analysis and X-ray photoelectron spectrometry The utilization of the resultant CNT-PDA-CS for removal of Cu2+ from aqueous solution was also examined in this work The results showed that CNT-PDA-CS exhibited obviously enhanced Cu2+ removal capability as compared with the unmodified CNT Considered the versatility of mussel inspired chemistry, the method described in this work should be a general route for fabricating highly efficient adsorbents, which should be of great interest for environmental applications
TL;DR: In this paper, the adsorption potential of a low cost adsorbent Hibiscus Cannabinus kenaf was investigated for Cr(VI) removal from water using batch and continuous mode experiments.
Abstract: Adsorption is one of the excellent ways for heavy metal removal from aqueous solution because of advantages like the low cost, availability, profitability, ease of operation and efficiency. In this study, adsorption potential of a low cost adsorbent Hibiscus Cannabinus kenaf was investigated for Cr(VI) removal from water using batch and continuous mode experiments. Optimum removal of Cr(VI) ions was occurred at pH 7. The kinetic results showed that the Cr(VI) removal followed intraparticle diffusion kinetics with a correlation coefficient greater than 0.94. The adsorption isotherms of Cr(VI) could be described very well by both the Langmuir and Freundlich equations (R2=0.997). The maximum Cr(VI) uptake was found to be 582 µg/g in Langmuir model. Column studies have been carried out to compare these with batch capacities. The Yoon–Nelson and Thomas models were found appropriate for description of the breakthrough curve, whereas the Bohart–Adams model was not match very well. The recovery of Cr(VI) and chemical regeneration of the spent kenaf have also been studied. The high Cr(VI) adsorption capacity and regeneration efficiency of kenaf suggests it as a promising alternative for heavy metal removal specially at near circumneutral pH.
TL;DR: In this paper, in-situ hybrid nanoparticles of Cu-Zn (50:50) alloy were synthesized and the stability of the hybrid nanofluids was carried out using photo capturing method and DLS method.
Abstract: The trend toward renewable lubricant technology is now irreversible; an eco-friendly cutting fluid will go along with machining to achieve relative sustainability. Eco-friendly nanofluids are developed in this work and compared with traditional cutting fluids used for heat transfer. In this work, in-situ novel hybrid nanoparticles of Cu–Zn (50:50) alloy were synthesized. The stability of the hybrid nanofluids was carried out using photo capturing method and DLS method. The flash point was measured using Pensky–Martens open cup apparatus as per ASTM D6450. The thermal conductivity and rheological studies were carried out using KD-2 Pro and Rheometer. The results illustrate that the hybrid nanofluids exhibited stability for 72 h and then the agglomeration of particles starts and by 168 h almost all the particles tend to settle down. Nanofluids with vegetable oil as basefluid showed better increment in flash point, thermal conductivity and showed marginal less stability. Vegetable oil behaved as Newtonian fluid and the change in viscosity with application of shear was less noticed compared with other two fluids. On the basis of integrated study of thermal conductivity and viscosity, in the point of cost and higher relative thermal conductivity to relative viscosity for effective heat transfer vegetable oil based nanofluid showed better results.