Showing papers in "Journal of The Taiwan Institute of Chemical Engineers in 2018"
TL;DR: In this paper, the performance of LHTESS was improved by adding CuO nanoparticles in to pure PCM, which has low thermal conductivity, and it can be concluded that highest rate of solidification is obtained for dp = 40nm.
Abstract: In order to saving thermal energy, latent heat thermal energy storage systems (LHTESS) can be utilized. Common phase change material (PCM) has low thermal conductivity. In this paper, CuO nanoparticles have been used to enhance the performance of LHTESS. CuO–water nanofluid properties are estimated by means of KKL. This unsteady process has been simulated by Finite element method. Results prove that solidification process is accelerated by adding CuO nanoparticles in to pure PCM. As number of undulations increases average temperature and total energy profiles reduce while solid fraction profile increases. Also, it can be concluded that highest rate of solidification is obtained for dp = 40 nm.
326 citations
TL;DR: In this paper, the corrosion inhibition performance of three triazine derivatives namely 4-((2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)-N,N-dimethylaniline (HT-1), 3-(2-(4 methoxybenzylIDene) hydrazine), 5,6diphensyl- 1, 2, 4-triazine (HTH-2) and 2-(2-5, 6-dipphenyl
Abstract: The corrosion inhibition performance of three triazine derivatives namely 4-((2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)-N,N-dimethylaniline (HT-1), 3-(2-(4 methoxybenzylidene) hydrazineyl)-5,6-diphenyl-1,2,4-triazine (HT-2) and 2-(2-(5,6-diphenyl-1,2,4-triazin-3-yl)hydrazineylidene)methyl)phenol (HT-3)on mild steel corrosion in1MHCl has been studied using gravimetric method, electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, scanning electron microscopy (SEM), Density functional theory (DFT) and molecular dynamics simulation. The corrosion inhibition efficiencies at optimum concentration (80 mg L-1) are 98.6% (HT-1), 97.1%(HT-2) and 94.3% (HT-3) respectively at 308 K. The corrosion inhibition efficiency increases with increase in concentration and decreases with increase in temperature. The adsorption of HTs on the surface of mild steel obeyed Langmuir isotherm. Potentiodynamic polarization study confirmed that inhibitors are mixed type with cathodic predominance. SEM analysis confirmed that metal surface is smooth in presence of inhibitors. Quantum chemical calculation and Molecular dynamics simulation further support the experimental findings.
206 citations
TL;DR: In this article, the importance of identifying the type of medium suitable for microalgae cultivation is highlighted along with descriptions and comparison of the medium types that include freshwater, saltwater and wastewater.
Abstract: As the world's natural fuel sources continue to deplete, the search for alternative fuel sources intensifies. A promising fuel source alternative is biofuels from microalgae, due to it being a renewable source, its wide availability, and also its high production rate. This paper reviews recent developments in microalgae culture medium, cultivation systems and growth modes. The importance of identifying the type of medium suitable for microalgae cultivation is highlighted along with descriptions and comparison of the medium types that include freshwater, saltwater and wastewater. The different cultivation systems such as open system, closed system, dark system and offshore cultivation used for cultivating microalgae are discussed, along with a study on the impact of large scale cultivation using these systems. Besides that, various growth modes for microalgae cultivation like phototrophic, heterotrophic, mixotrophic, photoheterotophic modes are reviewed.
159 citations
TL;DR: In this article, a citric acid-crosslinked β-cyclodextrin polymer (CA-β-CD) was applied for simultaneous adsorption of bisphenol A (BPA), methylene blue (MB) and Cu2+, typical pollutants of EDCs, dyes and heavy metals, respectively.
Abstract: The increasing worldwide pollution of nature waters with endocrine disrupting chemicals (EDCs), heavy metals and dyes has highlighted the need for versatile and effective removal approaches. In this study, a citric acid-crosslinked β-cyclodextrin polymer (CA-β-CD) was applied for simultaneous adsorption of bisphenol A (BPA), methylene blue (MB) and Cu2+, typical pollutants of EDCs, dyes and heavy metals, respectively. In a monocomponent system, the adsorption behaviors exhibited a monolayer maximum adsorption capacity (qm) of 0.3636 mmol/g for BPA, and a heterogeneous qm of 0.9229 and 0.9155 mmol/g for MB and Cu2+, respectively. The multicomponent experiment indicated that BPA and MB adsorptions onto CA-β-CD were independent from each other, whereas MB and Cu2+ competed over the same sites. An adsorption mechanism was proposed: each component of CA-β-CD played an essential role, the cyclodextrin cavities contributed to entrapment of non-polar BPA, and the surface carboxyl groups provided binding sites for polar MB and Cu2+. Adsorption performance of the polymer was unaffected by humic acid, a major component of natural organic matter. Overall, due to its green synthetic procedure, versatile and good adsorption performance, excellent recyclability and anti-jamming capacity, CA-β-CD has great potentials for practical applications in water purification.
157 citations
TL;DR: In this article, the MgAl-layered double hydroxide (LDH) was modified with polyethylene polyamine (PP) and tannic acid (TA) to improve the adsorption property of heavy metal ions.
Abstract: The MgAl-layered double hydroxide (LDH) was modified with polyethylene polyamine (PP) and tannic acid (TA) to improve the adsorption property of heavy metal ions. The PP@TA encapsulated LDH (denoted as LDH-PP@TA) was prepared via the combination of catechol chemistry and Michael addition and/or Schiff base reaction and characterized through TEM, FT-IR, SEM, TGA, and XPS. The adsorption performance was investigated by using LDH-PP@TA as adsorbent to adsorb the copper (II) ions from aqueous solution. The effect of contact time, solution pH, initial copper (II) ions concentration and temperature were investigated. The LDH-PP@TA exhibited high adsorption capacity of 41.56 mg/g, which is almost double that by LDH (23.39 mg/g). Equilibrium data for adsorption of copper (II) ions on adsorbents could be well fitted by the pseudo-second-order and Langmuir equations. Thermodynamic studies show the adsorption process is spontaneous and endothermic. Electrostatic adhesion and formation of copper complex are the major mechanisms for the copper (II) ions removal by LDH-PP@TA. These results reveal the great potential of LDH-PP@TA in the application of heavy metal ions removal.
155 citations
TL;DR: In this article, a polyacrylamide immobilized molybdenum disulfide (MoS2@PDA@PAM) composites were synthesized via the mussel-inspired chemistry and surface initiated atom transfer radical polymerization (SI-ATRP).
Abstract: In present work, novel polyacrylamide immobilized molybdenum disulfide (MoS2@PDA@PAM) composites were synthesized via the mussel-inspired chemistry and surface initiated atom transfer radical polymerization (SI-ATRP). The as-prepared MoS2@PDA@PAM composites were characterized by energy dispersive X-ray spectroscopy (EDX), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). Characterization results provide sufficient evidences for the successful functionalization of MoS2 with PAM. The products were used as adsorbents for removing of copper (II) ions. Results show the introduction of PAM onto MoS2 could enhance the adsorption capacity of MoS2@PDA@PAM towards copper (II) ions. The amount of adsorbed copper (II) ions by MoS2@PDA@PAM composites is 2.5 times that of pristine MoS2. The effects of various experimental factors on the adsorption process, including contact time, initial copper (II) ion concentrations, solution pH and temperature, were also studied in this work. The batch experiments show that the adsorption of copper (II) ions onto MoS2@PDA@PAM is dependent on time, pH and temperature. The optimum solution pH is observed at pH 7 and the increase of temperature is favorable for the adsorption of MoS2@PDA@PAM towards copper (II). Based on the experiment data, the adsorption kinetics, isotherms and thermodynamics were also investigated. The kinetics and isotherm studies show that pseudo-second-order kinetic and Freundlich isotherm models could well fit with the adsorption data. The thermodynamic results show that the adsorption of copper (II) ions on MoS2@PDA@PAM is a spontaneous and endothermic process. The adsorption process is mainly governed by the chemisorption involving the electrostatic interaction and/or chemical chelation between copper (II) ions and amino groups on the surface of MoS2@PDA@PAM. Taken together, it is proven that the PAM can be immobilized onto the MoS2 nanosheets via the mussel-inspired chemistry and SI-ATRP, and it can enhance the adsorption performance of MoS2@PDA@PAM composites, which might be used as adsorbents to remove heavy metal ions in real environment treatment.
146 citations
TL;DR: In this paper, a modified Hummers method was used to make the graphene oxide (GO) and carboxylated to GO COOH in a mixture of a strong basic pH from mixing in the chloroacetic acid with NaOH.
Abstract: In this study, the graphene oxide (GO) was made from graphite powder via a modified Hummers method, then carboxylated to GO COOH in a mixture of a strong basic pH from mixing in the chloroacetic acid with NaOH. The GO and GO COOH were characterized by means of the HR-TEM, FTIR, XRD and zeta potential. On this basis, the Cu(II) was adsorbed onto the GO and GO COOH in aqueous solutions using the simple batch-adsorption mode. The amount of thus-removed Cu(II) was successfully varied, depending on the pH values, initial copper concentration, reaction time and reaction temperature. Under the ambient temperature at pH 6 over 60-min adsorption time, the highest removal efficiency of Cu2+ are 97 and 99.4%, respectively. The experimental data agree well with the Langmuir isotherm in both cases, and the maximum adsorption capacities of GO and GO COOH are 277.77 and 357.14 (mg/g), respectively. The metal adsorption of the GO COOH is better than other carbonaceous adsorbents, and is exothermic and spontaneous from the calculations of chemical thermodynamics. The effect of competing cations on adsorption of Cu(II) ions on GO and GO COOH was evaluated by mono and divalent metals. The reusability of GO and GO COOH were estimated and it was found that both adsorbents have good regeneration properties.
130 citations
TL;DR: In this paper, a simulated-solar light driven photocatalytic Fenton-like process with using a novel biomimetic photocatalyst hemin-Bi2WO6 induced by H2O2 was investigated to degrade organic pollutants.
Abstract: Highly-efficient technologies are urgently needed to remove environmental organic pollutants. Photocatalytic degradation and Fenton (-like) process are often used to remove organic pollutants. But simplex photocatalysis is a rather slow process, while Fenton-like process is often limited by low pH levels. Introducing photocatalysis into Fenton-like process to form photocatalytic Fenton-like system is a promising method to overcome these drawbacks. This work investigated a simulated-solar light (SSL) driven photocatalytic Fenton-like process with using a novel biomimetic photocatalyst hemin-Bi2WO6 induced by H2O2 (SSL/H-Bi2WO6/H2O2 process) to degrade organic pollutants. H-Bi2WO6 possesses lower fluorescence intensity and faster electron transport than pristine Bi2WO6. Additionally, combined experimental and theoretical investigations indicated that SSL/H-Bi2WO6/H2O2 process revealed a high catalytic activity with enhanced pH tolerance. Furthermore, trapping experiments and electron spin resonance tests were used to explore the reaction mechanism of photodegradation. Presumably, the degradation of organic pollutants over SSL/H-Bi2WO6/H2O2 process was ascribed to ·OH, h+, and ·O2− radical species, and Fe(IV) O active species generated from the interaction of H2O2 with the variable valence state of iron on H-Bi2WO6. Overall, this work puts forward a new possibility for aqueous organic pollutants removal via SSL/H-Bi2WO6/H2O2 process, which may promote the application of photocatalytic Fenton-like process and biomimetic catalysis.
126 citations
TL;DR: In this paper, a simple and efficient method for the surface modification of MoS2 nanosheets with copolymers was achieved through the combination of mussel inspired chemistry and single-electron transfer living radical polymerization (SET-LRP) using 2-methacryloyloxyethyl phosphorylcholine (MPC) and itaconic acid (IA) as the monomers.
Abstract: Mussel inspired chemistry is a promising surface modification tool, which has attracted great research attention for different applications owing to its universality and interest properties. In this work, a rather simple and efficient method for the surface modification of MoS2 nanosheets with copolymers was achieved through the combination of mussel inspired chemistry and single-electron transfer living radical polymerization (SET-LRP) using 2-methacryloyloxyethyl phosphorylcholine (MPC) and itaconic acid (IA) as the monomers. The obtained MoS2-PDA-poly(MPC-IA) nanocomposites were ascertained by a series of characterization techniques, such as nuclear magnetic resonance spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. Moreover, the MoS2-PDA-poly(MPC-IA) nanocomposites showed enhanced dispersbility and great biocompatibility. The results implied that the MoS2-PDA-poly(MPC-IA) nanocomposites showed great potential in the field of biomedical science. In this work, the drug loading capability and controlled drug release behavior towards CDDP have been investigated. The drug loading in MoS2-PDA-poly(MPC-IA) composites is as high as 55.26%. All of these above results suggested that the combination of mussel inspired chemistry and SET-LRP is a facile and efficient strategy for fabrication of MoS2 based polymer nanocomposites with great potential application in biomedical fields.
122 citations
TL;DR: In this article, an efficient, surfactant-free, novel and facile green method for the immobilization of Cu NPs on the surface of the graphene oxide/manganese dioxide (GO/MnO2) nanocomposite using Cuscuta reflexa leaf extract was reported.
Abstract: The present study reports an efficient, surfactant-free, novel and facile green method for the immobilization of Cu NPs on the surface of the graphene oxide/manganese dioxide (GO/MnO2) nanocomposite using Cuscuta reflexa leaf extract. In fact the phytochemical content of the plant extract are responsible to biosynthesis of Cu nanoparticles (NPs) and their stabilization by functionalizing the surface of graphene. The Cu NPs were characterized by Fourier transformed infrared spectroscopy (FT-IR) and UV–visible spectroscopy. MnO2 NPs and GO/MnO2 nanocomposite were prepared by using a simple one-step hydrothermal method without using any toxic solvent. The synthesized GO/MnO2 and Cu/GO/MnO2 nanocomposites were characterized using X-ray diffraction analysis (XRD), field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM) images, Brunauer–Emmett–Teller (BET), Thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDS), elemental mapping and FT-IR spectroscopy. The synthesized Cu/GO/MnO2 nanocomposite was then successfully used as a reusable catalyst for the reduction of 2,4-dinitrophenilhydrazine (2,4-DNPH), 4-nitrophenol (4-NP), Rhodamine B (RhB), Congo red (CR), methyl orange (MO) and methylene blue (MB) using NaBH4 in water at ambient temperature. This method is clean and environmentally friendly without using any toxic reducing agents.
119 citations
Abstract: Natural layered magnesium silicate mineral (serpentine) was investigated as an adsorbent material for three common water pollutants (methylene blue dye, Congo red dye, and Cr(VI) metal ions). The adsorption properties of serpentine were explored as a function of contact time, serpentine dosage, initial concentrations and the initial pH value. The kinetic studies uncovered that the equilibrium time for the adsorption of Congo dye, methylene blue dye, and Cr(VI) ions was acquired after 180 min, 240 min, and 480 min, respectively. The uptake process of all the examined pollutants is chemical adsorption and represented by pseudo-second-order kinetic model instead of by Intra-particle diffusion and Elovich kinetic models. The adsorption equilibrium modeling of methylene blue and Cr(VI) was described as a monolayer adsorption and fitted well with Langmuir model rather than with Freundlich or Temkin isotherm models. The adsorption of Congo red dye occurred in a multilayer form and fitted well with Freundlich isotherm than the other studied models. The adsorption of the three pollutants controlled for the most part by the pH value. The basic media is promising for the removal of methylene blue, while the acidic conditions are favored for the adsorption of Congo red dye and Cr(VI) metal ions. The thermodynamic parameters revealed that the adsorption of methylene blue dye is endothermic reaction while the adsorption of Congo red dye and Cr(VI) metal ions is an exothermic reaction. Modifying the serpentine surface through acid and thermal activation improve the removal of the contemplated pollutants to a high degree. Acid leached serpentine utilizing HCl acid of 15%concentration and thermally activated serpentine at 200 °C are the best- modified products for maximum removal of Congo red dye, methylene blue dye, and Cr(VI) metal ions. Fixed bed Colum study gives the best results at bed thickness 3 cm, flow rate 5 mL/min and initial concentration 25 mg/L
TL;DR: In this paper, a novel approach for depositing carbon dots (CDs) and BiOI nanoparticles onto the surface of graphitic carbon nitride (g-C3N4) nanosheets (gCN-NS) was developed.
Abstract: In this study, we have developed a novel approach for depositing carbon dots (CDs) and BiOI nanoparticles onto the surface of graphitic carbon nitride (g-C3N4) nanosheets (gCN-NS). The synthesized materials were subsequently characterized by means of XRD, EDX, SEM, HRTEM, UV–vis DRS, FT-IR, TGA, XPS, PL, and BET instruments. The photocatalytic performance of the synthesized nanocomposites was evaluated by degradations of Rhodamine B (RhB), methylene blue (MB), methyl orange (MO), and Fuchsine under visible-light illumination. The obtained results revealed that the ternary gCN-NS/CDs/BiOI nanocomposites exhibited much better photocatalytic performance compared to the bare and binary photocatalysts due to the enhanced visible light absorption and improved charge separation. The gCN-NS/CDs/BiOI (30%) nanocomposite displayed superior photocatalytic performance for the removal of RhB, MB, MO, and fuchsine, which is about 29.5, 17.7, 10.9, and 16.5 times higher than that of the gCN. A good recyclability was also observed for the ternary nanocomposite after five cycles. Based on the obtained results, possible mechanism for the substantial enhancement of the photocatalytic performance via depositing the CDs and BiOI nanoparticles onto the surface of gCN-NS was discussed.
TL;DR: In this paper, a novel Z-Scheme CdS/Bi3O4Cl-50 heterostructure was fabricated by a facile surfactant-free method, and the visible-light-driven photocatalytic activity was investigated for degradation of ciprofloxacin (CIP) and tetracycline (TC).
Abstract: A novel Z-Scheme CdS/Bi3O4Cl heterostructure photocatalysts are fabricated by a facile surfactant-free method, and the visible-light-driven photocatalytic activity has been investigated for degradation of ciprofloxacin (CIP) and tetracycline (TC). For degradation of CIP, the Z-Scheme CdS/Bi3O4Cl-50 heterostructure displays the optimal rate constant (kapp = 0.0151 min−1), which is about 10.63 and 1.97 times higher than that of pure Bi3O4Cl (kapp = 0.00142 min−1) and CdS (kapp = 0.00764 min−1), respectively. Meanwhile, as expected, the rate constant of Z-Scheme CdS/Bi3O4Cl-50 heterostructure also displays the highest (0.0643 min−1) for degradation of TC, which is 2.14 times and 4.34 times as high as those of the bare CdS (0.0301 min−1) and Bi3O4Cl (0.0148 min−1), respectively. The enhancement of phototcatalytic activity is ascribed to the significant improved transfer and separation of charge carriers, which are proved by photocurrent and electrochemical impedance spectra (EIS) measurements. The possible degradation pathway for CIP and TC are proposed based on the HPLC-MS analysis. Compared with pure CdS nanospheres and Bi3O4Cl nanosheets, the Z-Scheme CdS/Bi3O4Cl heterostructures exhibit the excellent mineralization ability towards the CIP and TC molecules degradation through the analysis of the total organic carbon (TOC) tests. Moreover, the photocatalytic mechanism over Z-Scheme CdS/Bi3O4Cl heterostructure under visible light irradiation is investigated by active species trapping experiments and ESR technology. The present work provides a new approach to construct Z-Scheme heterojunction photocatalysts and a deeper insight for the mineralization activity, possible degradation pathways and photocatalytic mechanism.
TL;DR: In this article, a modified (fGO) and unmodified-graphene oxide nanosheets (GO) were introduced into the PU matrix to enhance the mentioned weaknesses.
Abstract: Polyurethane (PU) has been commonly used in a wide range of applications due to its high flexibility and good UV resistance. Attempts have been extensively carried out to improve the corrosion resistance and mechanical properties of this coating through inclusion of nanomaterials. In this study the graphene oxide nanosheets, covalently functionalized by (3-glycidyloxypropyl) trimethoxysilane, were introduced into the PU matrix to enhance the mentioned weaknesses. The modified (fGO) and unmodified-graphene oxide nanosheets (GO) were characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) analysis, field emission-scanning electron microscopy (FE-SEM), UV–vis and thermal gravimetric analysis (TGA). The physical–mechanical properties of the PU coatings reinforced with GO and fGO nanosheets were characterized by dynamic mechanical thermal analysis (DMTA) and tensile test. The influence of GO and fGO nanosheets on the fractured surface morphology of the PU coating after tensile test was studied by SEM analysis. In addition, the corrosion protection properties of the mild steel panels coated with PU coatings were characterized by salt spray test and electrochemical impedance spectroscopy (EIS). The results affirmed the physical–mechanical and anti-corrosion properties enhancement of the PU coating after incorporation of fGO nanosheets. The tensile stress, energy at break, loss factor and storage modulus values were significantly increased by addition of fGO nanosheets. The fGO stability and dispersion in the PU matrix was improved after modification with (3-glycidyloxypropyl) trimethoxysilane. The interfacial bonds between the polyurethane coating-fGO nanosheets were significantly enhanced. Besides the experiments, theoretical quantum mechanics approaches were utilized to examine the interactions of trimethoxysilane with polyurethane and GO surface.
TL;DR: In this article, the as-synthesized magnetic graphene oxide (mGO) nanocomposite was grafted with amine groups, namely the first and second generation of polyamidoamine dendrimer with different oxidation levels and shown to be effective in removing Cd, Pb, and Cu (II) ions from aqueous solution in batch system.
Abstract: In this study, the as-synthesized magnetic graphene oxide (mGO) nanocomposite was grafted with amine groups, namely the first and second generation of polyamidoamine dendrimer (mGO1st- and mGO2nd-PAMAM) with different oxidation levels and shown to be effective in removing Cd (II), Pb (II) and Cu (II) ions from aqueous solution in batch system. Raman spectroscopy, atomic force microscopy (AFM), Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) were used to identify the structural characteristics of amine functionalized nanocomposites. The pHZPC value of the sorbent was estimated to be 7.2 by titration methods. The different amine functionalization of the mGO stage of the two adsorbents and the differences in the behavior of the three metal ions under magnetic strength were found to be important in order to consider the performance of the adsorption systems. The adsorption capacities of metal ions were 435.85, 326.729 and 353.59 mg g−1 for Cd (II), Pb (II) and Cu (II), respectively. The obtained data were successfully fitted with the pseudo-second-order kinetic model. The adsorption capacity was dependent on the temperature and increased with the increase of temperature. Also, the equilibrium data were evaluated using the Freundlich, Langmuir, and Redlich–Peterson (R–P) isotherm models, suggesting the obtained data were fitted to the Freundlich isotherm model and the adsorption mechanism is heterogeneous. According to thermodynamic analysis, the adsorption process was found to be endothermic and spontaneous in nature. Moreover, the adsorbent was regenerated after a five time adsorption–desorption cycle without significant loss in adsorption capacity. The results from this study support that the as-synthesized adsorbent proves excellent removal ability of the metal ion from water and wastewater.
TL;DR: In this article, EuVO4 (EV) nanoparticles were dispersed over fluorine doped graphene sheets (FG24) to synthesize EV/FG24 nanocomposite.
Abstract: In present work, EuVO4 (EV) nanoparticles were dispersed over fluorine doped graphene sheets (FG24) to synthesize EV/FG24 nanocomposite Few layered fluorine doped graphene sheets were prepared by sonochemical exfoliation method using NaF as fluorine source FG24 and EV/FG24 composites were successfully characterized by FESEM, TEM, RAMAN, XRD, TGA, XPS, BET isotherm, FTIR, photoluminescence and UV–visible spectral techniques AFM and RAMAN analysis confirmed the formation of fluorine doped graphene sheets The high dispersion of EV/FG24 in water was ascertained by zeta potential measurement and Tyndall scattering experiment The photocatalytic activity of EV/FG24 was tested for the degradation of phenolic compounds and bacterial disinfection under visible light As compared to conventional slurry photocatalytic system, no magnetic stirring was used during degradation experiments The photodegradation rate was substantially influenced by adsorption of 2, 4-dinitrophenol (DNP) and phenol onto EV/FG24 The DNP and phenol were completely mineralized in 10 h The selected bacteria were inactivated by EV/FG24 in 3 h The effect of various radical scavengers revealed the pivotal role of hydroxyl radicals during disinfection mechanism EV/FG24 exhibited significant recycle efficiency during photocatalytic process EV/FG24 was used as a stable photocatalyst to depollute contaminated water
TL;DR: In this paper, direct transesterification with a combination of methanol and a cosolvent was demonstrated to be promising for the production of biodiesel from black soldier fly larvae (BSFL) biomass.
Abstract: In this study, direct transesterification with a combination of methanol and a cosolvent was demonstrated to be promising for the production of biodiesel from black soldier fly larvae (BSFL) biomass. Of the solvents tested, n-hexane was identified as the most effective cosolvent for the reaction, resulting in a 14.5-fold increase in the biodiesel yield, compared with the reaction without a cosolvent. The direct transesterification using n-hexane as a cosolvent was then optimized to maximize the biodiesel yield. The highest biodiesel yield of 94.14% was achieved at an n-hexane:methanol volume ratio of 1:2 (v/v), a solvent dosage of 12 mL, a catalyst loading of 1.2 mL, a temperature of 120 °C, and a reaction time of 90 min. The properties of the BSFL biodiesel were also tested, and most—such as the biodiesel's density (875 kg/m3), water content (0.03 mg/kg), ester content (98.3%), acid value ( °C), and cetane index (50)—met the specifications of the European standard EN 14214. This study suggested that direct transesterification using n-hexane as a cosolvent could be a promising method for biodiesel production from BSFL and decrease production costs.
TL;DR: In this article, the magnetic Fe3O4/activated carbon nanocomposites with high surface area were synthetized as recoverable adsorbents by chemical binding of the particles on activated carbon (AC) powders.
Abstract: The magnetic Fe3O4/activated carbon nanocomposites with high surface area were synthetized as recoverable adsorbents by chemical binding of Fe3O4 nanoparticles on activated carbon (AC) powders. The component AC and Fe3O4 in this nanocomposite possesses amorphous non-graphitic structure and cubic crystal structure, respectively. All composite samples presented superparamagnetic properties. The saturation magnetization of Fe3O4/AC nanocomposites was significantly lower than that of bare Fe3O4 particles, indicating that Fe3O4 particles were truly attached on AC surface. The microstructure image indicated that the Fe3O4 particles were uniformly dispersed on AC surface and thus maintained high specific surface area. The adsorption capacity of methyl orange (MO) at 30 °C slightly decreased from 384 mg/g on AC powders to 324 mg/g on Fe3O4/AC nanocomposites, which was reduced by 15% after magnetic fabrication. It was found that MO adsorption on Fe3O4/AC nanocomposites followed the pseudo-second order kinetic model and the isotherms could be described by the Langmuir model. The easy recovery of magnetic adsorbents from aqueous solution demonstrated their application potential to remove toxic pollutants in water and wastewater treatment.
TL;DR: In this paper, the types of semiconductors, modification methods of semiconductor for band gap engineering, and the application of SINR for photocatalytic reactions are summarized, with the aim to provide directions in improving the efficiency and flexibility of SINCs in design and application for different reactions.
Abstract: The utilization of solar energy is promising in chemical and environmental engineering. Photocatalytic process is applicable for some thermodynamically forbidden reaction such as water splitting and provides a potential approach for efficient solar energy utilization since it could store the abundant solar energy as chemical energy. The study on photocatalysts thrived from the 70s of last century. Among the several types of photocatalysts, semiconductor is one of the most widely studied categories and possesses the potential to be applied industrially. In this review, the types of semiconductors, the modification methods of semiconductors for band gap engineering, and the application of semiconductors for photocatalytic reactions will be summarized, and the challenges and the prospect of semiconductors are proposed, with the aim to provide directions in improving the efficiency and flexibility of semiconductor photocatalysts in design and application for different reactions.
TL;DR: In this paper, a thermal non-equilibrium model of the porous medium was used to investigate the thermal convection of a micropolar nanofluid inside a porous enclosure.
Abstract: The present paper deals with numerical investigation of natural convection of a micropolar nanofluid inside a porous enclosure using thermal non-equilibrium model. Rates of the heat transfer and micropolar nanofluid flow are widely considered by presenting contours of nanofluid flow, isotherms of fluid and solid phases, and contours of micro-rotation. Numerical results have been validated with previous references and good concordance has been observed. The results confirm that the thermal non-equilibrium model of the porous medium approaches the thermal equilibrium one by increasing thermal conductivity ratio parameter as well as the heat transfer interface parameter. The strength of convection inside pores of porous medium arises from augmenting H that can result in micro-rotations amplification. The characteristic equations of a micropolar fluid flow are transformed into classic Navier–Stokes equations by increasing porosity and the dimension of pores. Results indicate that the reduction of the thermal resistance of the fluid phase due to an increment of Kr can enhance the heat transfer rate through porous media. Finally, the permeability is important and influences the Nusselt numbers of both the solid matrix and the nanofluid when the nanofluid particles rotate around the center of their gravity.
TL;DR: In this paper, a magnetic reed biochar (MRBC) was synthesized through chemical co-precipitation firstly and subsequently pyrolysis, and the FF adsorption was characterized by SEM, XRD, FTIR and VSM.
Abstract: A magnetic reed biochar (MRBC) was synthesized through chemical co-precipitation firstly and subsequently pyrolysis. The MRBC and reed biochar (RBC) were characterized by SEM, XRD, FTIR and VSM and were used for the adsorption of florfenicol (FF). Batch experiment results showed that the FF adsorption on MRBC exhibited a pronounced pH-dependent pattern and presented a bell curve. However, the FF adsorption on RBC decreased gradually with the increasing pH values. Ionic strength initially inhibited and then promoted the FF adsorption and the multivalent co-existing anions significantly increased the FF adsorption on MRBC. The FF adsorption was non-spontaneous, exothermic and entropy-decreasing on MRBC and was of a non-spontaneous, endothermic and entropy-increasing nature on RBC. The pseudo second-order model presented better fittings for the FF adsorption kinetic data. Langmuir and Freundlich models can well describe FF adsorption on MRBC and RBC, respectively. The FF adsorption on RBC may be controlled by pore-filling effect and π–π EDA interaction, while hydrogen bonding, pore-filling effect and π–π EDA interaction contributed to the FF adsorption on MRBC. The adsorption–regeneration cycles confirmed that the MRBC was a highly efficient and reusable adsorbent for the removal of FF from aqueous solution.
TL;DR: In this article, modified electrolytic manganese residue (MEMR) was used as a high-efficiency adsorbent for the removal of methylene blue (MB) was synthesized via hydrothermal method.
Abstract: Electrolytic manganese residue (EMR) is a solid waste found in filters after sulphuric acid leaching of manganese carbonate ore. In this work, modified electrolytic manganese residue (MEMR) as a high-efficiency adsorbent for the removal of methylene blue (MB) was synthesized via hydrothermal method. The characterizations of MEMR were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption/desorption isotherms, and scanning electron microscope. The results showed that with the BET specific surface area of 500.8 m2/g the MEMR reached the maximum adsorption capacity (548.15 m2/g) within 50 min when the pH of initial solution was 6.05 and the initial concentration of MB was 1600 mg/L. The adsorption kinetics and equilibrium isotherms were accurately described by the pseudo-second-order model and Langmuir isotherm, respectively. The FTIR spectra indicated that electrostatic attraction and stacking interaction were the main adsorption mechanisms. Thermodynamic analyses showed that the adsorption of MB on MEMR was a spontaneous and exothermic physisorption process. This study revealed that MEMR can be used as a low cost and eco-friendly potential adsorbent for removing MB from wastewater.
TL;DR: In this paper, a biochar-supported sulfide-modified nZVI (S-nZVI/BC) was synthesized and characterized using X-ray diffraction, Xray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscope.
Abstract: Nano scale zerovalent iron (nZVI) used in waste water treatment can be more effective when modified with sulfur. In this study, we synthesized biochar-supported sulfide-modified nZVI (S-nZVI/BC) and characterized it using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. Our results reveal that sulfidation resulted in the formation of FeS on the surface of S-nZVI/BC. The Cr(VI) removal efficiency and capacity of the above composite were investigated as a function of initial solution pH/Cr(VI) concentration, reaction time, and presence of background ions (Ca2+and SO42–). Batch experiments revealed that solution pH had a significant impact on Cr(VI) removal capacities, with the maximum observed at pH 2.5. From a kinetic viewpoint, Cr(VI) removal was best described by a pseudo-second-order model. Importantly, the scavenger reaction was significantly promoted in the presence of SO42–, being slightly inhibited by Ca2+ and dissolved oxygen. Thus, the sulfidised nanohybrids exhibited excellent Cr(VI) removal performance, being well suited to the remediation of Cr(VI)-polluted water.
TL;DR: In this paper, the effect of solution pH, agitating time, initial concentration and coexisting Ca(II) ions on Pb-II binding were examined for rice straw (RS) biochar and MnOx-coated RS biochar.
Abstract: MnOx-coated rice straw biochar was simply synthesized through the reaction of rice straw biochar with KMnO4 in aqueous solution. SEM-EDS analysis confirmed the successful coating of Mn on the surface of the biochar. XPS and FTIR analyses were carried out to study the possible mechanism of Pb(II) binding onto rice straw (RS) biochar and MnOx-coated RS biochar. The work focused mainly on the evaluation of the sorbents for Pb(II) binding. Effect of solution pH, agitating time, Pb(II) initial concentration and co-existing Ca(II) ions on Pb(II) binding were examined. Both for RS biochar and MnOx-coated RS biochar, sorption kinetic data closely follow the pseudo-second-order model. Langmuir isotherm fits well with the experimental data, and the maximum sorption capacity for Pb(II) calculated from Langmuir model were 0.5782 and 1.4732 mmol g−1 for RS biochar and MnOx-coated RS biochar, respectively. This study suggested that KMnO4 modification is a simple and effective method to increase the sorption capacity of RS biochar.
TL;DR: In this paper, the authors investigated the thermal conductivity of nanofluid flow and heat transfer between two contracting and rotating disks by using the fourth-order Runge-Kutta method and showed that Nusselt number is a decreasing function of expansion ratio while it is increasing function of other parameters such as nanoparticle volume fraction, rotational Reynolds number, and injection Reynolds number.
Abstract: In this study, nanofluid flow and heat transfer between two contracting and rotating disks are investigated. Brownian motion is considered to simulate viscosity of nanofluid and Patel model is used to predict the behavior of thermal conductivity of nanofluid. The governing equations are solved via the fourthorder Runge–Kutta method. Different kinds of nanoparticles are examined. Effects of active parameters such as nanoparticle volume fraction, rotational Reynolds number, injection Reynolds number, and expansion ratio are considered. Results indicate that Nusselt number is a decreasing function of expansion ratio while it is increasing function of other parameters such as nanoparticle volume fraction, rotational Reynolds number, and injection Reynolds number. Also, it can be found that maximum value of heat transfer enhancement is obtained by selecting the silver (Ag) as nanoparticle.
TL;DR: In this paper, the performance of the magnetic SBA-15 based Chitosan composite modified with amine groups (Fe2O3@SBA15+CS+CS−APTMS) for copper and zinc removal from aqueous solution was studied in a batch system using response surface methodology (RSM) design of experiment.
Abstract: In order to develop new technologies in adsorption-based water treatment systems, the main objective of this research is the removal of copper and zinc heavy metals from aqueous solution using modified biocompatible silica magnetic nanoadsorbents. In this regard, the magnetic SBA-15 based Chitosan composite modified with amine groups (Fe2O3@SBA-15 − CS − APTMS), with different weight percentages, were synthesized and further characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and nitrogen adsorption/desorption analysis. The adsorption performance of Fe2O3@SBA-15 − CS − APTMS (3 mL) for copper and zinc removal from aqueous solution was studied in a batch system using response surface methodology (RSM) design of experiment. All the prepared adsorbents were tested under the obtained optimum operational parameters and their adsorptive behavior was compared. In order to investigate the adsorption rate and maximum adsorption capacity, the experimental data were fitted to Langmuir, Freundlich, Temkin, Redlich–Peterson and Sips isotherms and pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models. In addition, analysis of adsorption efficiency at different temperatures revealed the thermodynamic aspects of adsorption such as the variations in Gibbs free energy (ΔG0), standard enthalpy (ΔH0) and standard entropy (ΔS0). The obtained maximum adsorption capacities of Fe2O3@SBA-15 − CS − APTMS (6 mL) at 313 K for copper and zinc were 107.30 mg/g and 100.47 mg/g, respectively.
TL;DR: In this paper, a urea-functionalized magnetic biochar (MBCU) was prepared, characterized and evaluated for removal of lead (II) from aqueous solution, and the results of SEM, BET, XPS, FTIR, VSM and Zeta-potential exhibited a successful fabrication of MBCU.
Abstract: A novel urea-functionalized magnetic biochar (MBCU) was prepared, characterized and evaluated for removal of lead (II) from aqueous solution. The results of SEM, BET, XPS, FTIR, VSM and Zeta-potential exhibited a successful fabrication of MBCU. The magnetism magnitude of magnetic biochar could simultaneously affect the adsorption and recovery efficiency of lead (II) on magnetic biochar. Hence, the optimum mass ratio range of MBCU was determined to be 1.7:1–2.3:1, which could guarantee high removal (> 73.14%) and recovery (> 78.35%) efficiency. The experimental results indicated that the adsorption isotherm and kinetics were well described by the Sips model and pseudo-second-order model, respectively. The maximum adsorption capacity of lead (II) on MBCU was 188.18 mg/g at 323 K. Five-cycle reusability tests demonstrated MBCU could be effectively recovered and repeatedly used with a small adsorption loss (
TL;DR: A neuro-heuristic technique by incorporating artificial neural network models (NNMs) optimized with sequential quadratic programming (SQP) is proposed to solve the dynamics of nanofluidics system based on magneto-hydrodynamic Jeffery–Hamel problem involving nano-meterials.
Abstract: In this paper, a neuro-heuristic technique by incorporating artificial neural network models (NNMs) optimized with sequential quadratic programming (SQP) is proposed to solve the dynamics of nanofluidics system based on magneto-hydrodynamic (MHD) Jeffery–Hamel (JHF) problem involving nano-meterials. Original partial differential equations associated with MHD–JHF are transformed into third order ordinary differential equations based model. Furthermore, the transformed system has been implemented by the differential equation NNMs (DE-NNMs) which are constructed by a defined error function using log-sigmoid, radial basis and tan-sigmoid windowing kernels. The parameters of DE-NNM of nanofluidics system are optimized with SQP algorithm. To illustrate the performance of the proposed system, MHD–JHF models with base-fluid water mixed with alumina, silver and copper nanoparticles for different Hartman numbers, Reynolds numbers, angles of the channel and volume fractions with three different proposed DE-NNMs are designed to evaluate. For comparison purpose, the proposed results with reference numerical solutions of Adams solver illustrate their worth. Statistical inferences through different performance indices are given to demostrate the accuracy, stability and robustness of the stochastic solvers.
TL;DR: In this paper, the authors investigated the effect of different parameters such as Rayleigh number, the solid volume fraction of the nanoparticles, the U-shaped cavity's aspect ratio and heating obstacle's height on the flow field and heat transfer in the enclosure.
Abstract: Research on nanofluid for heat transfer enhancement of thermal systems has received great attention owing to the lack of energy sources. In this study, fluid flow and natural convection heat transfer of Al2O3–Water or TiO2–water nanofluid inside a U-shaped cavity consist of a hot obstacle has been investigated numerically by lattice Boltzmann method (LBM). In this paper, different parameters are investigated such as Rayleigh number, the solid volume fraction of the nanoparticles, the U-shaped cavity's aspect ratio and heating obstacle's height on the flow field and heat transfer in the enclosure. The results showed that the Rayleigh number (Ra), cavity aspect ratio (AR) and obstacle's height can be affected on isotherms, streamlines and local and average Nusselt number. The average Nusselt number of the obstacle sides increased by increasing the Ra number and solid volume fraction of nanoparticles (ϕ) regardless the AR. In addition, by increasing the AR, the average Nusselt number increased. At low Ra, the effect of nanoparticles on increment of heat transfer for narrow cavities was more than wide ones.
TL;DR: In this paper, a 3D graphene oxide (GO)-based porous composites with strong compressive mechanical properties were prepared by self-assembly of corn zein and GO through a facile hydrothermal process, which were used for the adsorption of rare earth elements (REEs) from aqueous solutions.
Abstract: Three-dimensional (3D) graphene oxide (GO)-based porous composites with strong compressive mechanical properties were prepared by self-assembly of corn zein (CZ) and GO through a facile hydrothermal process, which were used for the adsorption of rare earth elements (REEs) from aqueous solutions. The adsorption equilibrium for REEs by GO CZ composites could be achieved within 200 min. And the maximum adsorption capacities of GO CZ9:1 for yttrium (Y), lanthanum (La), erbium (Er), ytterbium (Yb) and neodymium (Nd) were 14.2, 17.29, 11.72, 10.08 and 9.68 mg g−1, respectively. The relatively high desorption rate (85–95%) of 3D GO CZ9:1 composite represents a higher reproducibility. Moreover, the 3D GO CZ composites obtained with a mass ratio of 3:1, 5:1 and 9:1 for GO and CZ could be compressed to 60% of their original volumes and gradually restored to their original morphologies under the corresponding stresses of 18, 16 and 11 KPa, respectively. The adsorption mechanism was also proposed.