山竹壳合成贝壳粉负载纳米铁催化降解铬黑T

以山竹壳提取液和贝壳粉制备了贝壳粉负载的纳米零价铁（MS-NZVI/SP），探究其催化铬黑T的类芬顿降解效果。采用SEM、XRD、FTIR等手段对制备的材料进行表征。结果表明，MS-NZVI/SP被成功制备，且呈均匀球状颗粒，表面覆盖了有机物多酚，具有较好的稳定性和重复使用性。通过单因素实验优化了MS-NZVI/S对铬黑T降解性能，得到优化条件为：贝壳粉与纳米零价铁负载质量比1∶1，温度35℃，溶液pH为3，投加4 mL过氧化氢，100 mg合成的材料。在优化条件下，铬黑T的降解效率可达到93.01%，其降解过程符合准二级动力学模型。     

Effect of magnesium ferrite doping with lanthanide ions on dark-, visible- and UV-driven methylene blue degradation on heterogeneous Fenton-like catalysts

The catalytic behavior of magnesium ferrites doped with lanthanide ions (La³⁺, Ce³⁺, Sm³⁺, Gd³⁺, and Dy³⁺) on Methylene Blue (MB) degradation using Fenton process was studied. A slow increase in cubic Fd3m crystalline structure parameters and increase in crystallite size of doped samples magnesium ferrites were observed. A dramatic decrease in catalytic activity of catalysts obtained at 600 °C as compared to catalysts obtained at 300 °C was explicitly observed and this was grossly attributed to the elimination of surface hydroxyl groups as ascertained by FT-IR analysis. The initial magnesium ferrite demonstrated the highest catalytic activity under dark- (kˈ 0.0555 min⁻¹) and visible-light (kˈ 0.1029 min⁻¹) conditions. Catalytic efficiency of the lanthanides doped catalysts under UV-irradiation in accordance with the maximum appearance rate constant kˈ decreased in the following order Ce³⁺ > Dy³⁺ > La³⁺ ≈ MgFe₂O₄ > Sm³⁺ > Gd³⁺. The most active ferrites provided up to 99% of MB degradation in 60 and 20 min for visible- and UV-driven Fenton processes. Findings obtained from this study were observed to be competitive with other heterogeneous Fenton catalysts.     

Molecule assembly of heterostructured TiO2@BiOCl via fenton-like reaction for enhanced solar energy conversion

In this work, we applied the fenton-like reaction to fabricate TiO₂ nanocrystalline, and employed molecular self-assembly with TiO₂ and BiOCl to form composite photocatalyst with cookie-like nano-heterostructure for enhanced solar energy to hydrogen. The TiO₂@BiOCl photocatalyst with cookie-like nano-heterostructure exhibited excellent photocatalytic performance for the photocatalytic hydrogen evolution under sunlight irradiation compared to the single TiO₂ or BiOCl. Besides, the TiO₂@BiOCl photocatalyst displayed outstanding reusability and stability in the photocatalytic reaction. Meanwhile, the possible mechanisms of cookie-like nano-heterostructure formation and photocatalytic redox reaction have been proposed. What's more, this work demonstrated a new perspective for the design and mass preparation of TiO₂-based composite photocatalytic materials at atmospheric condition, which demonstrated that this method has enormous potential to achieve mass preparation of efficient photocatalyst for photocatalytic application.     

Decolorization of textile dye Rifafix Red 3BN by natural hematite and a comparative study on different types of Fenton process

Abstract

This work shows the decolorization of mono-azo dye Rifafix Red 3BN by environmentally friendly advanced oxidation processes using natural hematite. Our main focus is on the utilization of naturally occurring hematite for the treatment of wastewater. The experimental variables were initial concentration of dye, catalyst concentration, oxidant concentration, and reaction temperature. The optimum conditions were obtained as follows: catalyst dose 2?g/L, H₂O₂ concentration 20?mM, pH 3 and temperature 25?°C at a reaction time of 60?min. The % decolorization was increased from 55.91% to 93.89% using optimum conditions with initial 100?ppm dye. To assess the competence of different types of AOPs, the organic mono-azo dye was subjected to oxidize using various photochemical processes.     

Green synthesis of bentonite-supported iron nanoparticles as a heterogeneous Fenton-like catalyst: Kinetics of decolorization of reactive blue 238 dye

This study aimed to synthesize green tea nano zero-valent iron (GT-NZVI) and bentonite-supported green tea nano zero-valent iron (B-GT-NZVI) nanoparticles using green tea extracts in an environmentally sustainable way. Bentonite was used as a support material because it disperses and stabilizes GT-NZVI, and it helps to reduce the cost, increase the adsorption capacity of GT-NZVI, and decrease the optimum amount of GT-NZVI used in Fenton-like oxidation. A scanning electron microscope, an atomic force microscope, and a Fourier transform infrared spectroscope were used to characterize GT-NZVI and B-GT-NZVI, while the zeta potential was measured to evaluate the stability of iron nanoparticles. The decolorization kinetics of reactive blue 238 (RB 238) dye in the aqueous phase in the Fenton-like oxidation process were investigated as well. The effects of various experimental conditions such as reaction time, dosages of catalysts, concentration of H₂O₂, temperature, addition of inorganic salts, and other parameters were investigated. The results show that the oxidative degradation efficiencies of RB 238 dye catalyzed by GT-NZVI and B-GT-NZVI were 93.5% and 96.2%, respectively, at the optimum reaction conditions as follows: c(H₂O₂) = 5 mmol/L, ρ(GT-NZVI) = 0.5 g/L or ρ(B-GT-NZVI) = 0.5 g/L, c(RB 238 dye) = 0.05 mmol/L, and pH = 2.5 at 180 min. The best catalytic performance was exhibited when B-GT-NZVI was used. Three kinetic models were employed, and the second-order model was found to be the best model representing the experimental kinetic data of RB 238 dye. The value of activation energy decreased from 38.22 kJ/mol for GT-NZVI to 14.13 kJ/mol for B-GT-NZVI. This indicates that the effect of B-GT-NZVI in decreasing the energy barrier is more pronounced than that of the GT-NZVI catalyst, leading to improved Fenton-like oxidation processes.     

Fe supported on ceria as effective catalyst for the heterogeneous photo-oxidation of basic orange 2 in aqueous solution with sunlight

Fe^III supported on ceria as an effective catalyst for oxidation was prepared and used for the degradation of basic orange 2 azo textile dye (BO2). BO2 was chosen as a model pollutant and the catalytic oxidation was carried out in a batch reactor using hydrogen peroxide as the oxidant at pH 3. The influent factors on BO2 oxidation, such as catalyst dosage, H₂O₂ concentration, and BO2 concentration were studied by considering the BO2 conversion and chemical oxygen demand (COD) removal. The Fe^III-ceria catalyst showed a high catalytic activity for the oxidation of BO2 in aqueous solution. It was observed that the solution became colorless after 5 h of oxidation and over 90% COD removal was achieved with all the Fe^III-ceria catalysts used under dark conditions in the catalytic oxidation system. The catalytic removal of BO2 during BO2 oxidation was improved under solar radiation, which notably increased the BO2 degradation rate. Consecutive BO2 oxidation cycles carried out with the same Fe^III-ceria catalyst and untreated fresh dyestuff solution showed that the catalyst had good stability and good degradation performance, thus evidencing the possibility of being used in continuous processes. This study showed that the Fe^III-ceria catalytic oxidation process is an efficient method for the treatment of BO2 aqueous solutions.     

黄铁矿烧渣催化H_2O_2氧化废水中难降解污染物

传统Fenton氧化是以Fe2+离子为催化剂进行催化H2O2氧化,以含铁矿物为催化剂的非均相类Fenton反应最近受到重视。以酸性红B染料、苯酚等污染物以及实际工业废水为处理对象,研究了黄铁矿烧渣为催化剂的非均相类Fenton反应。考察了催化剂、H2O2投加量、初始pH、反应时间、催化剂回收重复利用等因素的影响和优化。在烧渣投加量为10g.L-1,双氧水投加量为20ml.L-1,体系pH在1～11范围内,反应6h后,酸性红B染料、苯酚的去除率接近100%,工业废水处理后脱色效果明显,而且BOD5/COD比值能大幅提高。研究表明:黄铁矿烧渣对催化H2O2氧化具有很强的催化活性,是有效的类Fenton反应催化剂,而且相比于单一含铁矿物具有更好的催化性能,反应受pH影响很小,解决了传统Fenton反应需要调节pH的难题。催化剂易于沉淀分离,能回收重复利用。     

Adsorption and oxidation of PCP on the surface of magnetite: Kinetic experiments and spectroscopic investigations

The oxidation of pentachlorophenol (PCP) on the surface of magnetite used as heterogeneous catalyst has been investigated under various experimental conditions (initial substrate concentration, H₂O₂ dose, solid loading and temperature) at neutral pH and correlated with the adsorption behavior. The surface reactivity of magnetite was evaluated by conducting the kinetic study of both H₂O₂ decomposition and PCP oxidation experiments. The occurrence of the optimum values of H₂O₂ and magnetite concentrations for the effective degradation of PCP could be explained by the scavenging reactions with H₂O₂ or iron oxide surface. The surface interactions with PCP in the absence and the presence of oxidant can be well described by Langmuir and Langmuir–Hinshelwood models, respectively. All batch experiments indicate that Fenton-like oxidation of PCP was controlled by surface mechanism reaction and the species compete with each other for adsorption on a fixed number of surface active sites. The apparent degradation rate was dominated by the rate of intrinsic chemical reactions on the oxide surface rather than the rate of mass transfer. Raman analysis suggested that the sorbed PCP was removed form magnetite surface at the first stage of oxidation reaction. The mineralization determined by TOC abatement was completed after 7 d, while total dechlorination was achieved at 4 d treatment time. The first reaction of PCP oxidation should be the dechlorination since 90% of chloride was formed at the first 30 h corresponding to the total disappearance of parent compound. All X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Mössbauer spectroscopy and chemical analyses showed that the magnetite catalyst exhibited low iron leaching, good structural stability and no loss of performance in second reaction cycle.     

Hydroxyl radical involvement in the decomposition of hydrogen peroxide by ferrous and ferric-nitrilotriacetate complexes at neutral pH

The relative rates of degradation of three hydroxyl radical probe compounds (atrazine, fenuron and parachlorobenzoic acid (pCBA)) by Fe^III/H₂O₂ (pH = 2.85), Fe^IIINTA/H₂O₂ (neutral pH), Fe^II/O₂, Fe^IINTA/O₂, Fe^II/H₂O₂ and Fe^IINTA/H₂O₂ (neutral pH) have been investigated using the competitive kinetic method. Experiments were carried out in batch and in semi-batch reactors, in the dark, at 25 °C. The data showed that the three probe compounds could be degraded by all the systems studied, and in particular by Fe^IINTA/H₂O₂ and Fe^IIINTA/H₂O₂ at neutral pH. The relative rate constants of degradation of the three probe compounds obtained for all the systems tested were identical and equal to 1.45 ± 0.03 and 0.47 ± 0.02 for k_Atrazine/k_pCBA and k_Fenuron/k_pCBA, respectively. These values as well as the decrease of the rates of degradation of the probe compounds upon the addition of hydroxyl radical scavengers (tert-butanol, bicarbonate ions) suggest that the degradation of atrazine, fenuron and pCBA by Fe^IINTA/O₂, Fe^IINTA/H₂O₂ and Fe^IIINTA/H₂O₂ is initiated by hydroxyl radicals.     

Fe~0/H_2O_2类Fenton体系降解水中对氯硝基苯

为解决传统Fenton过程中Fe3＋返回Fe2＋速率慢致使反应过程中铁离子循环受阻的瓶颈问题,对Fe0/H2O2-类Fenton降解对氯硝基苯（pCNB）的效果与机理进行研究.考察H2O2和铁的投加量、初始pH值等因素对pCNB降解效果的影响,对体系TOC和Cl-、NO3-浓度以及一些中间产物进行鉴定和分析.当pH值为...