A new class of oxyhalide photocatalysts
xBiOBr–(1−
x)BiOI prepared by a soft chemical method were characterized by X-ray diffraction and UV–Vis diffuse reflectance spectra. They are all ...visible-light-responsive materials with the bandgaps ranging from 1.92 to 2.91
eV. Methyl orange (MO) photocatalytic degradation experiments showed that BiOBr possessed a higher photocatalytic activity than P25 (TiO
2) under UV illumination and iodine-modified BiOBr exhibited high photocatlytic activities under visible-light irradiation. The high photocatalytic activity is in close relation with the deep valance band edge position and the internal electric fields between Bi
2O
2 slabs and halogen anionic slabs.
Materials with regulated nanoscale morphology provide capabilities to remove dangerous pollutants from wastewater, by adsorption. In this study, the chitosan-based composite fibrous adsorbent was ...fabricated and used as a novel and facile eliminator in the process of removing cationic methyl orange (MO) from the water medium. Different methods were applied to check the properties of the desired composite fibrous adsorbent. The removal value showed that the chitosan-embedded composite fibrous adsorbent has super characteristics and can be removed the organic dye from the water. The influence of pH, time, temperature, eliminator quantity, and MO content was explored. With increasing time and eliminator quantity, the adsorption efficiency increased. The composite fibrous adsorbent with the advantage of its high functionality and combined micro-nanomorphology features, has emerged as a very promising candidate for obtaining versatile and robust adsorbents. This work presents how the tunned synthesis of composite fibrous adsorbent tailored their nanoarchitecture giving rise to adsorption capacities toward cleaning aqueous samples polluted with MO dye. The composite fibrous adsorbent was prepared by the direct immobilization method, with normal aging temperature, in order to study the effect of synthesis conditions on the adsorption properties of MO dye. The solution acidity was exhibited as the key factor, and a suitable pH of 5.50 was selected based on the efficiency. The competing ions were not adversely affected in the dye adsorption as defined by the stable bonding mechanism. The adsorption data were highly fitted with the Langmuir adsorption model with monolayer coverage. The determined maximum adsorption was 175.45 mg/g, which was comparable with the other forms of materials. The adsorbed MO dye elution was evaluated using ethanol and then the composite fibrous adsorbent was ready to use for MO dye adsorption after washing with water without significant loss in its functionality. Therefore, we explored the tunned morphology of composite fibrous adsorbent for obtaining performant adsorbents for the elimination of refractory pollutants in wastewater.
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•Cotton fabric was modified with chitosan for toxic dye removal assessment.•The dye was highly removed with high adsorption capacity in the Langmuir adsorption model.•The composite fibrous adsorbent exhibited recyclability without significant deterioration.
Using simple solid state reaction route, the La and Fe doped SrTiO3 nanoparticle have been successfully synthesized. The effects of different dopant concentrations (1, 2, 3, 4 and 5 wt %) on the ...characteristics of the as-prepared samples were systematically investigated using various techniques. X-ray diffraction (XRD) investigation exhibit the formation of the cubic perovskite structure of all samples. Field emission scanning electron microscopy (FESEM) images have been confirmed the uniformity and particle size reduction of the samples with increasing of doping elements. Also, the increase of surface area from 9.7 m2/g for pure SrTiO3 to 64.2 m2/g for 5 wt% La-Fe doped SrTiO3 validated by Brunauer-Emmett-Teller (BET) studies. The UV–vis diffuse reflectance spectra (DRS) demonstrate the blue-shift of absorption tail for doped samples as well as reduction of band gap energies (from 3.2 eV to 2.72 eV) with the increase of the doped element. Photoluminescence (PL) analysis of the synthesis nanoparticle display defective states and decline in PL intensity as a result of the doping materials effect in SrTiO3. The 150 min of irradiation time, 0.6 g/L of catalyst dosage, and 5 ppm of initial MO concentration have been obtained as the optimum photocatalyst operating conditions. Also, the photocatalytic investigation reveals the enhancement of degradation rate of Methyl Orange (MO) under visible irradiation for the doped sample. The perfect photocatalytic activity at 4 wt% of Fe-La-doped SrTiO3 nanoparticles is around 19 times higher than that of pure SrTiO3 (96% compare to 5%). In the end, the photocatalytic performance mechanisms are deeply explained.
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•La and Fe doped SrTiO3 perovskite photocatalyst was successfully synthesized.•Effect doping elements on the characteristics of SrTiO3 was studied in detail.•Photocatalytic activity was enhanced almost 19 times with optimum doping.•Doped photocatalyst was stable and efficient through cyclic degradation experiment.
Industrial use of heavy metals and dyes critically depends on the effective handling of industrial effluents. Effective remediation of industrial effluents using various adsorbent materials has thus ...become critical. In this paper, we study two-dimensional MXenes as an adsorbent for removing Cr(VI) and methyl orange (MO) in waters. The physico-chemical performance of MXenes was studied using X-ray diffraction, Fourier transform infrared spectroscopy, Brunauer−Emmett−Teller, scanning electron microscopy, high resolution-transmission electron microscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy techniques. The adsorption system, including influence of contact time, pH of solutions, co-ions, and desorption experiments were performed for effective Cr(VI) and MO removal. The Cr(VI) and MO removal rate of the MXenes was very fast, and the kinetic system was driven by pseudo-second-order kinetics. The sorption isotherm closely well-tailored with the Langmuir isotherm, and the maximum removal efficiencies were 104 and 94.8 mg/g for Cr(VI) and MO, respectively. The MXenes was successfully regenerated by 0.1 M NaOH aqueous solution and can be repeatedly recycled. The uptake of Cr(VI) and MO by the MXenes was mainly due to chemical adsorption, namely electrostatic adsorption, complexation, surface interactions, and ion exchange mechanisms. This investigation demonstrates the selectivity and feasibility of the MXenes as a real adsorbent for eliminating Cr(VI) and MO from the aqueous environment.
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NiFe layered double hydroxides nanoflakes decorated montmorillonite (MMT@NiFe LDH) was successfully prepared by a one-pot hydrothermal method. The 2D-2D growth MMT@NiFe LDH was ...utilized as an effective adsorbent for removal of anionic dye of methyl orange (MO) and cationic dye of methylene blue (MB). The mole ratio of Ni2+/Fe3+ could quite influence the interlayer spacing, surface area per unit charge and the ultrathin hexagonal laminated morphology of NiFe LDH decorated on the surface of MMT. Various characterization techniques were conducted to identify it, such as XRD, FT-IR, TG-DTA, BET, XPS and SEM. Under the optimal conditions, the Langmuir-fitted maximum adsorption capacities for MO and MB are 108.80 mg g−1 and 99.18 mg g−1, respectively. Adsorption kinetics for MO and MB are both verified to be fit in with pseudo-second-order model. This work suggests a facile pathway to synthesize desirable bifunctional adsorbent for cationic and anionic dyes, which provides the potential application for the actual wastewater purification.
The integrated high-efficiency treatment technology for dye industry wastewater is one of the current research hot topic in industrial wastewater treatment area. This article reports a new fluidized ...three-dimensional electrochemical treatment process integrating activated carbon adsorption, direct electro-oxidation and ·OH oxidation. In the process, activated carbon is polarized in a fluidized bed electrochemical reactor to enhance the direct electro-oxidation and ·OH oxidation, and there is a synergistic effect of effective adsorption and electrochemical oxidation to strengthen the treatment efficiency. When 200 mg/L methyl orange is processed, its removal rate reaches 99.9% in 30min, and the synergistic efficiency is 57.3%. After 8 cycles of activated carbon reusage in the process, the removal rate of methyl orange still kept at 89.2%. It is also founded that the activated carbon maintains 64.5% of its original adsorption capacity during the cycle. These results shows its interesting application potential in the fields of high-efficiency, low-cost and green treatment of various industrial organic wastewaters. Further improvements should focus on the development of continuous operation model and the improvement of the activated carbon electro-catalytic performance and the practical regeneration ways of the activated carbon particle electrodes.
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•Study on three-dimensional electrode integrated process of fluidized activated carbon.•The synergistic effect of adsorption and electrochemical oxidation was observed.•It can remove 99.9% of 200 mg/L methyl orange, obtain 57.3% synergistic efficiency.•Activated carbon can maintain 64.5% adsorption capacity in 10 cycles.•Polarized activated carbon improve the direct electro-oxidation and ·OH oxidation.
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•Novel nanophotocatalysts of ZSM-5/ZnO/Ag were synthesized and characterized.•Photocatalytic degradation of methyl orange was investigated.•Ag nanoparticles were improved the ...photocatalytic activity of ZSM-5/ZnO.
In this study, ZSM-5/ZnO/Ag nanocomposite was synthesized with different amounts of silver and used for photocatalytic degradation of methyl orange aqueous solution. ZnO nanoparticles were initially precipitated on the surface of ZSM-5 zeolite, and the obtained ZSM-5/ZnO nanocomposite was modified by silver nanoparticles to increase the photocatalytic efficiency of the nanocomposite. The synthesized nanocomposites were characterized by FESEM, EDX, FTIR, XRD, UV–vis and TGA analyses. Furthermore, the effect of various parameters affecting the dye degradation as the initial dye concentration (2–20 mg/L), the photocatalyst amount (0.01-0.07 g) and initial pH (3–11) were studied. The band gap investigations showed that ZSM-5/ZnO modification with silver nanoparticles increases the photocatalytic activity of the resulting nanocomposite. The highest value of dye decomposition was obtained about 90% with an initial concentration of 5 ppm, pH = 11, 0.07 g photocatalyst under UV exposure for 2 h. Increasing photocatalyst amount in the solution and increasing silver amount in the photocatalyst structure (ZSM-5/ZnO/Ag ratio equal to 3:3:1, 3:3:5 and 3:3:10) increased the dye removal from the solution. Additionally, dye degradation of dye in alkaline conditions (pH values of 7–11) was more than that of the acidic conditions (pH values of 3–7). Investigation of different dye removal kinetic models showed the conformance of the pseudo-second-order model to the process of methyl orange dye degradation with R2>0.99 by synthetic nanocomposites.
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•A novel pH-sensitive CD/CA-g-PDMAEMA adsorbent was synthesized.•CD/CA-g-PDMAEMA could simultaneously adsorb dyes and BPA.•BPA was entrapped by cavities while dyes were attracted by ...surface groups.•CD/CA-g-PDMAEMA could selectively remove MO at pH 4.0 and MB at pH 11.0.•BPA adsorption was largely unaffected by pH in the range of 2.0–10.0.
The coexistence of anionic dye, cationic dye and endocrine-disrupting chemicals (EDCs) in dyeing wastewater has highlighted a great necessity to develop new and effective approaches for their simultaneous removal. In this study, a novel amphoteric adsorbent was successfully synthesized using a two-step strategy, starting with the preparation of citric acid (CA) crosslinked β-cyclodextrin (CD) polymer (CD/CA) through esterification reactions, followed by the grafting of 2-dimethylamino ethyl methacrylate monomer (PDMAEMA) through polymerization reaction. Adsorption performance of the synthesized material (CD/CA-g-PDMAEMA) toward EDCs (bisphenol A, BPA), cationic dye (methylene blue, MB) and anionic dye (methyl orange, MO) in the monocomponent and multicomponent systems were evaluated. The adsorbent showed a maximum adsorption capacity (qmax) of 79.0 mg/g for BPA at pH 6.5, 165.8 mg/g for MO at pH 4.0 and 335.5 mg/g for MB at pH 11.0, respectively. By altering the solution pH, zeta-potential of the adsorbent could be changed, endowing the material with selective adsorption properties toward anionic or cationic dyes, while BPA adsorption efficiency was vastly insusceptible to the changes in solution pH from 2.0 to 10.0. These characteristics are beneficial for the application of CD/CA-g-PDMAEMA in real wastewaters treatment. In addition, the pseudo-second-order model fitted well with the experimental data in both monocomponent and multicomponent systems, and the adsorption mechanisms were proposed: BPA could form inclusion complex with β-cyclodextrin cavities, while MB and MO molecules could interact with the carboxyl and tertiary amino groups on CD/CA-g-PDMAEMA through electrostatic attractions.
