Preparation of mixed matrix self-cleaning membrane incorporated by Z-scheme heterostructure via robust engineering in terms of dimension for decreasing cake fouling in a cross-flow reactor

Reducing irreversible fouling in polymer membranes by integrating photocatalytic and membrane processes as the self-cleaning photocatalytic membrane is a promising candidate for improving membrane filtration performance. In this study, mixed matrix photocatalytic membranes were prepared from the combination of different morphologies ZnO-g-C3N4 heterostructure in the polymer matrix by the phase-separation method. To investigate the self-cleaning and performance properties of mixed matrix photocatalytic membranes prepared from different morphologies heterostructures, the photocatalytic membrane reactor with a visible-light source was applied. Nanoflower/nanosheet (NF/NS) ZnO-g-C3N4 photocatalytic membrane showed good self-cleaning performance owing to the high photocatalytic performance of NF/NS ZnO-g-C3N4 heterostructure by the reduction of irreversible membrane fouling, thus improving the antifouling and filtration performance of the membrane. Also, the morphology and the uniform distribution of the NF/NS ZnO-g-C3N4 heterostructure in the membrane matrix caused good hydrophilic properties, high porosity, and a more symmetrical structure in the (NF/NS) ZnO-g-C3N4 photocatalytic membrane (F4). For the F4 membrane, the permeability and rejection values increased from 40.35 L m-2 h-1 and 90.9% in the dark environment to 84.37 L m-2 h-1 and 97.4% under visible-light for dye pollutants. Accordingly, F4 had the best filtration and self-cleaning performance, which can be used as a promising visible-light photocatalytic membrane in wastewater treatment processes.

Preparation of high-crystalline and non-metal modified g-C3N4 for improving ultrasound-accelerated white-LED-light-driven photocatalytic performances

As a non-metallic organic semiconductor, graphitic carbon nitride (g-C3N4) has received much attention due to its unique physicochemical properties. However, the photocatalytic activity of this semiconductor faces challenges due to factors such as low electronic conductivity and limited active sites provided on its surface. The morphology and structure of g-C3N4, including macro/micro morphology, crystal structure and electronic structure can affect its catalytic activity. Non-metallic heteroatom doping is considered as an effective method to tune the optical, electronic and other physicochemical properties of g-C3N4. Here, we synthesized non-metal-doped highly crystalline g-C3N4 by one-pot calcination method, which enhanced the photocatalytic activity of g-C3N4 such as mesoporous nature, reduced band gap, wide-range photousability, improved charge carrier recombination, and the electrical conductivity was improved. Hence, the use of low-power white-LED-light illumination (λ ≥ 420 nm) and ultrasound (US) irradiation synergistically engendered the Methylene Blue (MB) mineralization efficiency elevated to 100% within 120 min by following the pseudo-first-order mechanism under the following condition (i.e., pH 11, 0.75 g L-1 of O-doped g-C3N4 and S-doped g-C3N4, 20 mg L-1 MB, 0.25 ml s-1 O2, and spontaneous raising temperature). In addition, the rapid removal of MB by sonophotocatalysis was 4 times higher than that of primary photocatalysis. And radical scavenging experiments showed that the maximum distribution of active species corresponds to superoxide radical [Formula: see text]. More importantly, the sonophotocatalytic degradation ability of O-doped g-C3N4 and S-doped g-C3N4 was remarkably sustained even after the sixth consecutive run.

Applying in-situ visible photopolymerization for fabrication of electrospun nanofibrous carrier for meloxicam delivery

Despite meloxicam's many benefits, it will cause many drawbacks if the meloxicam release rate is not controlled. Accordingly, we introduced a technique based on the electrospinning process to control the release rate and also to reduce side effects. For this purpose, different nanofibers were used as drug couriers. Nanofibers were prepared using polyurethane, polyethylene glycol, and light curable poly (ethylene glycol) diacrylate (PEGDA) by electrospinning. In fact, light curable poly (ethylene glycol) diacrylate (PEGDA) was synthesized as a hydrophilic functional group. Next, PEGDA and polyurethane were used simultaneously to fabricate the drug carrier nanofiber in a single processing step, and the electrospinning apparatus was equipped with a blue light source for in-situ photopolymerization during the electrospinning process. The molecular structures of nanofibers and PEGDA were investigated by FT-IR, 1H NMR, 13C NMR, SEM, TEM, XRD, and DSC analyses. Finally, we reduced in vitro drug release to 44% within ten hours, while the minimum release of meloxicam from the tablet was 98%.

Volatile organic compounds (VOCs) removal by photocatalysts: A review

Amplified anthropogenic release of volatile organic compounds (VOCs) gets worse air quality and human health. Photocatalytic degradation of VOCs is the practical strategy due to its low cost, simplicity, high efficiency, and environmental sustainability. Different types of photocatalyst activated by UV and visible lights are applied for VOC degradation. This review tries to investigate the state-of-art of recently published papers on this subject with a focus on the high-efficiency photocatalyst. The novel photocatalysts are introduced and enhancing photocatalytic activity strategies such as the hybrid of two/three photocatalyst, impurity doping, and heterojunctions with narrow bandgap semiconductors have been explained. The procedures of visible light activation of the photocatalysts are discussed with attention to current problems and future challenges. In addition, effective operational parameters in the photocatalytic degradation of VOCs have been reviewed with their advantages and drawbacks. A series of strategies are developed for the efficient utilization of visible light photocatalysts and improving new materials or design structures to degrade produced toxic intermediates/by-products during photocatalytic degradation of VOCs. This review shows that there are significant challenges in the applications of photocatalysts in the selective removal of VOCs. Several approaches should be combined to produce synergistic effects, which may lead to much higher photocatalytic performance than individual strategies. Another challenge is to develop efficient photocatalysts to meet real problems on an industrial scale.

Integrating graphene oxide into layers of PVDF/PVDF@cross-linked sodium alginate/polyamide membrane for efficiently enhancing desalination performances

The membrane modules of the water treatment system are faced costly damages; thereby executing pre-desalination units based on Nanofiltration (NF) could prevent these suffers, and improve the permeated water flux (PWF) and salt rejection (SR). Hence, we focused on the construction of a novel ternary-layer NF membrane through “electrospinning Polyvinylidene Fluoride (PVDF) (as bottom layer)”, “generating middle layer by electrospinning PVDF along with, the implementation cross-linking after electrospraying Sodium Alginate”, and “synthesizing Polyamide (as top layer) through interfacial polymerization”. More importantly, it anticipated that the Taguchi statistical method can expeditiously optimize the effects of Graphene Oxide nano-sheets (GOns) on water-dependent properties, such as PWF and SR. Astonishingly, the desalination capabilities significantly improved, when the top, middle, and bottom layers simultaneously had 1, 0.1, and 0.1 wt.% of GOns, respectively. Overall, comparing the performances between the optimized sample containing low-dosage and without GOns demonstrated the PWF ameliorated from 6.68 to 20.36 L/m² h; also, the SR ability remained on an incremental basis as NaCl < MgCl₂ < MgSO₄ under 6 bar pressure. Manifestly, these authentic results denoted promising, innovative, and large-scaling insights when effectual PWF and SR be necessary.

Improvement of microwave absorption properties of polyester coatings using NiFe2O4, X-doped g-C3N4 (X = S, P, and O), and MTiO3 (M = Fe, Mg, and Zn) nanofillers

In recent decades, to reduce electromagnetic pollution, scientists focus on finding new microwave absorbers with effective performance, thin thickness, and broad bandwidth. In this work, the nanoparticles of NiFe₂O₄, X-doped g-C₃N₄ (M = S, P, and O), and MTiO₃ (M = Fe, Mg, and Zn) were successfully synthesized using co-precipitation, specific heat program, and semi-wet sol–gel methods, respectively. The synthesized nanoparticles were utilized as absorption agents and polyester resin as the matrix. Morphology, particle size, crystal structure, and chemical composition of the prepared nanocomposites were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and energy dispersive X-Ray analysis (EDX), respectively. The microwave absorption performance of the coatings was also investigated by a vector network analyzer (VNA). Moreover, the effect of different parameters on the performance of absorbent coatings was studied by the Taguchi method and optimized to achieve an optimal absorbent. The results showed that the optimal nanocomposite has the reflectance loss (RL) less than − 30 dB (equal to absorption > 99%) at a high-frequency range (8–12 GHz) and 1 mm thickness. Furthermore, the addition of such novel nanoparticles to absorbents resulted in high values of attenuation constant (more than 200 dB/m) at the X-band. Therefore, the polyester coating filled with ZnTiO₃, O-doped g-C₃N₄, and NiFe₂O₄ nanofillers can be considered a high-efficiency and low-density absorber.

The role of MnO2/polyaniline/Y-type barium hexaferrite (Al2Y, Mg2Y, and Ni2Y) nanoparticles in the improvement of the microwave absorption properties of polyester coatings

The prepared nanocomposite can be suggested as a promising microwave absorbent with the highest effective absorption at the lowest thickness.

Enhanced sonocatalytic performance of ZnTi nano-layered double hydroxide by substitution of Cu (II) cations

In this research, a series of CuZnTi-LDHs with different Cu²⁺/Zn²⁺ molar ratio were synthesized by co-precipitation method with the purpose of improving the sonocatalytic performance of ZnTi-LDH. All the LDH samples were synthesized by a facile co-precipitation process. The as-prepared LDHs were characterized by Powder X-ray diffraction (XRD), Field emission-scanning electron microscopy (FESEM), Transition electron microscopy (TEM), Brunauer-Emmelt-Teller (BET) analysis, and UV-visible diffuse reflectance spectroscopy (DRS) analysis. The results showed that Cu²⁺ substitution can significantly enhance the sonocatalytic properties of ZnTi-LDH. The Methylene blue degradation percentage over ZnTi-LDH reached 30% in 90 min, whilst this percentage reaches 71% over CuZnTi-LDH (1:1). The role of the Cu²⁺ incorporation on the observed enhancement in sonocatalytic performance was revealed by investigating the effect of radical scavengers on degradation efficiency and DRS spectra of ZnTi-LDH and CuZnTi-LDH (1:1). Benzoquinone (BQ), ammonium oxalate and tert-Bu lead to 22.5%, 53.5% and 74.6% decrease in degradation percentage by CuZnTi-LDH (1:1). However, the degradation efficiency showed 16.6%, 3.3% and 63.3% reduction in the presence of BQ, ammonium oxalate and tert-Bu respectively, in dye degradation by ZnTi-LDH. DRS spectra demonstrated that the band gap of the LDH decreases by Cu²⁺ substitution. The effect of operational parameters on sonodegradation was investigated as well. The kinetics of sonodegradation reaction obeyed the first order reaction kinetics with R² of 0.95.

Starch-based polyurethane/CuO nanocomposite foam: Antibacterial effects for infection control

In the present study, a new method for the synthesis of the open cell flexible polyurethane foams (PUFs) was developed by using starch powder and the modification of closed cell foam formulation. Starch is the second largest polymeric carbohydrate as a macromolecule on this planet with a large number of glucose units. Copper oxide nanoparticles (CuO NPs) were synthesized by thermal degradation method at different temperatures of 400, 600 and 800 °C as antimicrobial agents. The antimicrobial activity of CuO NPs and commercial CuO powder against the main causes of hospital infections were tested. CuO₆₀₀ was the most effective antimicrobial agent and enhanced polymer matrix tensile strength with starch powder as new polyurethane foams (PUFs) cell opener with high tensile strength. The effects of parameters on tensile strength were optimized using response surface methodology (RSM). CuO NPs and PUF had optimal conditions and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Foam synthesized at the optimal conditions had an open cell structure with high tensile strength and efficient antimicrobial activity that made them suitable to be used as an antimicrobial hospital mattress to control hospital infections.

Adsorption of cefixime from aqueous solutions using modified hardened paste of Portland cement by perlite; optimization by Taguchi method

In the present study, we have used a simple and cost-effective removal technique by a commercially available Fe-Al-SiO2 containing complex material (hardened paste of Portland cement (HPPC)). The adsorbing performance of HPPC and modified HPPC with perlite for removal of cefixime from aqueous solutions was investigated comparatively by using batch adsorption studies. HPPC has been selected because of the main advantages such as high efficiency, simple separation of sludge, low-cost and abundant availability. A Taguchi orthogonal array experimental design with an OA16 (4(5)) matrix was employed to optimize the affecting factors of adsorbate concentration, adsorbent dosage, type of adsorbent, contact time and pH. On the basis of equilibrium adsorption data, Langmuir, Freundlich and Temkin adsorption isotherm models were also confirmed. The results showed that HPPC and modified HPPC were both efficient adsorbents for cefixime removal.

Photo-assisted hetero-fenton decolorization of azo dye from contaminated water by Fe-Si mixed oxide nanocomposite

An aerogel of silica gel dopeyd with 2.86 wt% Fe was prepared by an alkoxide sol-gel method and using tetraethyl orthosilicate as a precursor material. The synthesized aerogel was calcined at 500 degress C to produce nanoparticle solids, and was characterized by XRD, FT-IR and SEM. The nanosized iron-silica gel mixed oxide was tested in the photooxidation of the azo dye Acid Red 14 (AR 14) using 30% aqueous hydrogen peroxide as oxidant and UV light. The 2.86 wt% Fe-loaded SiO2 showed very good efficiency in the decolorization of AR 14. The effects of various parameters including solution pH, catalyst, oxidant and initial dye concentrations on photodegradation were investigated and the optimum conditions were determined. The catalyst was resistant to leaching and could be recycled several times without appreciable loss of activity.

Removal of C.I. Basic Yellow 2 from aqueous solution by low-cost adsorbent: hardened paste of Portland cement

The adsorption of C.I. Basic Yellow 2 (BY2) from aqueous solutions on to hardened paste of Portland cement (HPPC) as a low-cost adsorbent and its adsorption kinetics at different conditions were studied. The adsorption process was followed by an online spectrophotometric analysis system, which consisted of a UV-Vis spectrophotometer, a designed spectrophotometric cell, a peristaltic pump and a glass reactor. The effect of experimental parameters, including initial dye concentration, mass of HPPC, initial pH and temperature, on adsorption was studied over a 30 miin adsorption period. For the kinetic study, the obtained data were treated according to various kinetic models. The results revealed that the experimental data were better fitted to the first-order kinetics model than to the second-order and intraparticle diffusion models. Equilibrium isotherms for the adsorption of BY2 on HPPC were analysed by Freundlich and Langmuir isotherms equations using the linear correlation coefficient. The Freundlich isotherm gave the best correlation of adsorption.

The photo-oxidative destruction of C.I. Basic Yellow 2 using UV/S(2)O(8)(2-) process in an annular photoreactor

The photo-oxidative decolorization of C. I. Basic Yellow 2 (BY2), was investigated using UV radiation in the presence of peroxydisulfate (S(2)O(8)(2-)) in an annular photoreactor at different conditions. S(2)O(8)(2-) and UV-light showed negligible effect when they were used independently. Removal efficiency of BY2 was sensitive to the operational parameters such as initial concentrations of S(2)O(8)(2-), BY2 and pH. The conversion ratios of BY2 at the volumetric flow rates of 330, 500 and 650 mLmin(- 1) were 84%, 78%, 69% in 1 h, respectively. The results showed that in the presence of S(2)O(8)(2-), the photooxidation quantum yield obtained higher than direct photolysis quantum yield, suggesting that photodecay of BY2 was dominated by photooxidation. The electrical energy per order (EE/O) values for decolorization of BY2 solution was calculated. Results show that applying an optimum peroxydisulfate concentration can reduce the EE/O.

Decolorization of C.I. Acid Yellow 23 solution by electrocoagulation process: investigation of operational parameters and evaluation of specific electrical energy consumption (SEEC)

This study investigates the evaluation of specific electrical energy consumption (SEEC) and the influence of operating parameters on the color removal efficiency of a dye solution containing C.I. Acid Yellow 23 by electrocoagulation process. Firstly, the operational parameters including current density, initial dye concentration, initial pH and time of electrolysis were optimized. Then the effects of the conductivity, the interelectrode distance and the area of cross-section of the electrodes on specific electrical energy consumption (SEEC) were studied under the optimum conditions. Our results indicated that for a solution of 50mg/l C.I. Acid Yellow 23, almost 98% color and 69% chemical oxygen demand (COD) were removed, when the pH was about 6, the time of electrolysis was 5min and the current density was approximately 112.5A/m(2). In addition, the results of our study revealed that when the conductivity and area of cross-section of the electrodes increased and interelectrode distance decreased, the cell voltage and specific electrical energy consumption would be decreased.

Biodegradation of dye solution containing Malachite Green: optimization of effective parameters using Taguchi method

In this paper, optimization of biological decolorization of synthetic dye solution containing Malachite Green was investigated. The effect of temperature, initial pH of the solution, type of algae, dye concentration and time of the reaction was studied and optimized using Taguchi method. Sixteen experiments were required to study the effect of parameters on biodegradation of the dye. Each of experiments was repeated three times to calculate signal/noise (S/N). Our results showed that initial pH of the solution was the most effective parameter in comparison with others and the basic pH was favorable. In this study, we also optimized the experimental parameters and chose the best condition by determination effective factors. Based on the S/N ratio, the optimized conditions for dye removal were temperature 25 degrees C, initial pH 10, dye concentration 5 ppm, algae type Chlorella and time 2.5h. The stability and efficiency of Chlorella sp. in long-term repetitive operations were also examined.

Removal of C.I. Acid Orange 7 from aqueous solution by UV irradiation in the presence of ZnO nanopowder

The removal of C.I. Acid Orange 7 (AO7) from aqueous solution under UV irradiation in the presence of ZnO nanopowder has been studied. The average crystallite size of ZnO powder was determined from XRD pattern using the Scherrer equation in the range of 33 nm. The experiments showed that ZnO nanopowder and UV light had a negligible effect when they were used on their own. The effects of some operational parameters such as pH, the amount of ZnO nanopowder and initial dye concentration were also examined. The photodegradation of AO7 was enhanced by the addition of proper amount of hydrogen peroxide, but it was inhibited by ethanol. From the inhibitive effect of ethanol, it was deducted that hydroxyl radicals played a significant role in the photodegradation of the dye. The kinetic of the removal of AO7 can be explained in terms of the Langmuir-Hinshelwood model. The values of the adsorption equilibrium constant, K(AO7), and the kinetic rate constant of surface reaction, k(c), were 0.354(mg l(-1))(-1) and 1.99 mg l(-1)min(-1), respectively. The electrical energy consumption per order of magnitude for photocatalytic degradation of AO7 was lower in the UV/ZnO/H(2)O(2) process than that in the UV/ZnO process. Accordingly, it could be stated that the complete removal of color, after selecting desired operational parameters could be achieved in a relatively short time, about 60 min.

Immobilization of TiO2 nanopowder on glass beads for the photocatalytic decolorization of an azo dye C.I. Direct Red 23

TiO2 supported on glass beads was prepared and its photocatalytic activity was determined by photooxidation of the commercial textile dye, C.I. Direct Red 23, in aqueous solution illuminated by a UV-C lamp (30 W). The progress of photocatalytic decolorization of the C.I. Direct Red 23 was studied by measuring the absorbance at lambda(max) = 507 nm by UV Vis spectrophotometer. The experiments indicated that both UV light and TiO2 were needed for the effective destruction of the dye. The effect of pH on the rate of decolorization efficiency was followed in the pH range 2-12. Acidic pH range was found to favor the decolorization rate. The addition of a proper amount of hydrogen peroxide improved the decolorization, whereas the excess hydrogen peroxide quenched the formation of hydroxyl radicals (*OH). The electrical energy consumption per order of magnitude for photocatalytic decolorization of the dye was lower in the UV/TiO2/H2O2 process than that in the UV/TiO2 process. In the real wastewater sample the efficiency of the method was determined by measuring the changes in the absorption spectra of the dye solution during photodegradation. Our results indicated that during the photooxidation process, the decolorization efficiency was more than 80% at irradiation time of 3 h.