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Photocatalytic coupling technologies have emerged as popular strategies to increase the treatment efficiency of dye-containing wastewater. Herein, the Z-scheme Co3O4/BiOBr heterojunction (Z-CBH) was constructed and developed as a photocatalytic peroxydisulfate (PDS) activator for the degradation of high-concentration Rhodamine B (RhB). Multiple testing techniques were employed to confirm the formation of Z-CBHs. When 0.1 g·L-1 of Z-CBH20 and 1.0 mmol·L-1 of PDS were added simultaneously under simulated sunlight irradiation, the RhB degradation efficiency could approach 91.3%. Its reaction rate constant (0.01231 min-1) was much beyond the sum of those in the Z-CBH20/light system (0.00436 min-1) and the PDS/light system (0.0062 min-1). h+, â¢OH, â¢O2-, SO4â¢-, and 1O2 were detected as the dominant reactive species for RhB degradation. The potential mechanism of photocatalytic PDS oxidation was proposed. The possible intermediates were determined by high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry assisted with density functional theory and Fukui theory. The possible degradation pathways of RhB degradation were put forward. The toxicological properties of RhB and its intermediates were evaluated by quantitative structure-activity relationship prediction. This work will not only provide a reference for developing photocatalytic persulfate activators but also gain an insight into the degradation pathways of RhB and the toxicity of its intermediates.
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It is a challenging task to design a piezoelectric photocatalyst with excellent performance under mechanical agitation instead of ultrasonic irradiation. Integrating vacancy defects into a heterojunction seems to be an effective strategy for synergistically increasing its piezo-photocatalytic performance. For this goal, a two-step hydrothermal method was adopted to architect a type-I oxygen-vacancy-rich BaTiO3/BiOBr heterojunction to surge the degradation of Rhodamine B (RhB) under the combined action of simulated sunlight irradiation and mechanical agitation. Various instrumental techniques demonstrated the formation of a BaTiO3/BiOBr heterojunction with high crystallinity. The existence of surface oxygen vacancies was confirmed by XPS and EPR tests. PFM results manifested that this heterojunction had excellent piezoelectric properties, with a piezoelectric response value of 30.31 pm V-1. Comparative experiments indicated that RhB degradation efficiency under piezo-photocatalysis over this heterojunction largely exceeded the total sum of those under piezocatalysis and photocatalysis. h+, ·O2-, and 1O2 were the dominant reactive species for RhB degradation. The improved separation efficiency of photogenerated charges was verified by electrochemical measurements. DFT calculations indicated that the polarization of BaTiO3 could affect the electronic band structure of BiOBr. This work will provide comprehensive insights into piezo-photocatalytic mechanism at a microcosmic level and help to develop new-styled piezoelectric photocatalysts.
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Bismuth oxyhalides (BiOXs, X = Cl, Br and I) are emerging photocatalytic materials with unique layered structure, flexible band structure and superior photocatalytic activity. The purpose of this study was to develop a facile alcoholysis route to prepare BiOClxI1-x nanosheet solid solutions at room temperature. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence emission spectroscopy (PL) and Brunauer-Emmett-Teller (BET) surface area analyzer were used to characterize the as-prepared photocatalysts. These results revealed that two-dimension BiOClxI1-x nanosheet solid solutions could be obtained with high percentage of {001} crystal facets exposed. Moreover, the formation of solid solution could regularly change the optical absorption thresholds and band gaps of BiOClxI1-x photocatalysts. The photocatalytic experiments indicated that BiOCl0.75I0.25 exhibited the highest photocatalytic performance for the degradation of Rhodamine B (RhB) under simulated sunlight irradiation and the photocatalytic process followed a pseudo-first-order kinetic equation. A possible mechanism of RhB photodegradation over BiOClxI1-x solid solutions was proposed based on the structural properties of BiOClxI1-x solid solutions and RhB photosensitization.
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Luz , Agua , Catálisis , RodaminasRESUMEN
The development of a catalyst with high catalytic activity was one of the most important issues for the heterogeneous Fenton-like process. In this study, nanocomposites of Fe3O4 anchored onto reduced graphene oxide (RGO) were prepared by a moderate alkaline-thermal precipitation method and developed as highly efficient heterogeneous Fenton-like catalysts. The characterization results indicated that Fe3O4 nanoparticles (NPs) were tightly anchored onto few-layer RGO sheets via a strong interaction. Contrast experiments showed that Fe3O4/RGO nanocomposites had much better Fenton-like catalytic activity than Fe3O4 NPs. The process optimization of methyl orange (MO) discoloration in Fe3O4/RGO-H2O2 system was accomplished by central composite design under response surface methodology. A second-order polynomial model was established to predict the optimal values of MO discoloration and its significance was evaluated by analysis of variance. Three-dimensional response surfaces for the interaction between two variables were constructed. Based on the model prediction, the optimum conditions for MO discoloration in Fe3O4/RGO-H2O2 system were 2.9 for solution pH, 16.5 mM H2O2 concentration, 2.5 g/L catalyst dosage and 33.5 min of reaction time, with the maximum predicted value for MO discoloration ratio of 99.98%.
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Compuestos Azo/química , Grafito/química , Modelos Químicos , Nanopartículas/química , Contaminantes Químicos del Agua/química , Catálisis , Color , Peróxido de Hidrógeno/química , Concentración de Iones de Hidrógeno , Hierro/química , Microscopía Electrónica de Transmisión , Óxidos/química , Espectrometría Raman , Difracción de Rayos XRESUMEN
Due to the difficult separation of superfine schorl powder (SSP) from solution after being used, millimetre-scale porous schorl ceramisite (PSC) was obtained through solid-phase sintering method and used as a heterogeneous catalyst for Fenton-like discoloration of organic dyes. SSP and PSC were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and field emission scanning electron microscopy. The results demonstrated that both SSP and PSC were mainly composed of schorl and there existed large amounts of micropores on the surface of PSC. A series of control experiments indicated that PSC exhibited higher Fenton-like catalytic activity than SSP. Methylene blue (MB) discoloration in both PSC-H2O2 and SSP-H2O2 systems followed pseudo-first-order kinetics and the reaction rate constant k1 obtained in PSC-H2O2 system was 3.23 times as large as the one in SSP-H2O2 system. Then, the process optimization of MB discoloration in heterogeneous Fenton-like reaction catalyzed by PSC was operated by central composite design under response surface methodology. Based on the model prediction, the optimum conditions for MB discoloration in this system were determined.
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Colorantes/química , Peróxido de Hidrógeno/química , Azul de Metileno/química , Silicatos/química , Contaminantes Químicos del Agua/química , Catálisis , Cinética , Porosidad , Purificación del Agua/métodos , Difracción de Rayos XRESUMEN
In the past decades, the amount of biomass waste has continuously increased in human living environments, and it has attracted more and more attention. Biomass is regarded as the most high-quality and cost-effective precursor material for the preparation carbon of adsorbents and catalysts. The application of biomass carbon has extensively explored. The efficient application of biomass carbon in organic wastewater purification were reviewed. With briefly introducing biomass types, the latest progress of Machine learning in guiding the preparation and application of biomass carbon was emphasized. The key factors in constructing efficient biomass carbon for adsorption and catalytic applications were discussed. Based on the functional groups, rich pore structure and active site of biomass carbon, it exhibits high efficiency in water purification performance in the fields of adsorption and catalysis. In addition, out of a firm belief in the enormous potential of biomass carbon, the remaining challenges and future research directions were discussed.
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Biomasa , Carbono , Aprendizaje Automático , Aguas Residuales , Purificación del Agua , Aguas Residuales/química , Carbono/química , Adsorción , Purificación del Agua/métodos , Eliminación de Residuos Líquidos/métodos , Catálisis , Contaminantes Químicos del Agua/análisisRESUMEN
Herein, using an electrophoretic deposition strategy, a S-scheme CdS (cubic)/BiVO4 (monoclinic) heterostructured photocatalyst is fabricated. The as-synthesized photocatalysts exhibit high carrier separation efficiency, prominent hydrogen evolution ability and high stability. The results of the detailed density functional theory (DFT) prove that the photogenerated electrons and holes are located in BiVO4 and CdS components, respectively. Besides, an explicit solvent model based on the electron-enriched region in CdS/BiVO4 heterojunction is designed deliberately to investigate the solid/liquid interface issues. Intriguing findings demonstrate that the surface hydrogen diffusing rate in CdS/BiVO4/H2O is faster than that of BiVO4/H2O and is highly associated with the electron-enrich effect, which has a greater capacity to promote water decomposition, the possibility of proton collision and photocatalytic hydrogen evolution. Notably, the H p orbital can participate in the electron-enrich effect during solvation, thus reforming the orbital energy level and activating the HER of the BiVO4 component in the CdS/BiVO4 system.
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Phototherapy, including photothermal and photodynamic therapy, has gained extensive attention in the tumor treatment field recently, while synergistic therapy can significantly improve curative effects. However, a complicated photo-responsive nanosystem, different excitation wavelengths, and low tissue depth hindered its actual application. Herein, single near-infrared responsive PEGylated defective MoO2 nanocrystals were fabricated by a green hydrothermal method. The photothermal and photodynamic performances of the samples were presented in detail under a safe power of 1064 nm (NIR-II, 1.0 W cm-2). Interestingly, the photodynamic properties were prompted by the localized surface plasmon resonance (LSPR) photothermal effect obviously, and the collaborative enhancement mechanism was explored in depth. Subsequently, the in vitro cytotoxicity was evaluated on the 4T1 cancer cells under NIR-II irradiation. This work may provide guidance for the facile fabrication of TMOs for NIR-II responsive and enhanced dual-modal phototherapy.
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Nanopartículas , Neoplasias , Fotoquimioterapia , Humanos , Resonancia por Plasmón de Superficie , Fototerapia/métodos , Fotoquimioterapia/métodos , Nanopartículas/química , Neoplasias/tratamiento farmacológico , Polietilenglicoles/química , Línea Celular TumoralRESUMEN
As a clean and efficient technology for the degradation of organic contaminants, sulfate radical based advanced oxidation processes (SR-AOPs) have attracted more and more attention in the past decades. Cobalt is regarded as the most reactive and efficient non-noble metal catalyst for the activation of persulfate including peroxymonosulfate (PMS) and peroxydisulfate (PDS) to produce sulfate radicals. Due to the limitations of homogeneous catalytic systems, the heterogeneous cobalt-containing catalysts have been emerged and rapidly developed. Various strategies have been schemed to further enhance the activation ability of persulfate by heterogeneous cobalt-containing catalysts. This paper provides an overview on the recent progress in enhancement strategies for the highly efficient activation of persulfate by heterogeneous cobalt-containing catalysts. With a brief introduction on the chemistry and feature of sulfate radical reactions catalyzed by homogeneous Co2+/Co3+ species, the main strategies for enhancing persulfate activation by heterogeneous cobalt-containing catalysts are summarized, such as surface and morphology design, multiple reactive centers design, organic-inorganic hybrids and heterostructure composites. Future perspectives of heterogeneous SR-AOPs systems catalyzed by cobalt-containing catalysts are outlined.
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Cobalto , Metales , Catálisis , Oxidación-ReducciónRESUMEN
Multi-component sorption studies were carried out for attenuation of divalent heavy metal cations (Pb2+, Cu2+ and Zn2+) by a low-cost mineral adsorbent from the aqueous solution. Kinetic and equilibrium batch-type sorption experiments were conducted under variable conditions for multi-component using low-grade (<12%P2O5) phosphate rock. Percentage of multiple heavy metal species removal increases with decreasing initial metals concentration and particle size. The equilibrium data were well described to a lesser extent by Freundlich model but Langmuir model seemed to be more appropriate with the fixation capacity obtained at room temperature for Pb2+, Cu2+ and Zn2+ was 227.2, 769.2 and 666.6 micromol g(-1), respectively. Two simple kinetic models were tested to investigate the adsorption mechanism. Rate constants have been found nearly constant at all metal concentrations for first order. The comparison of adsorption capacity of low-grade phosphate rock decreases in multi-component system as compared to single component due to ionic interactions. X-ray powder diffraction (XRPD) technique was used to ascertain the formation of new metal phases followed by surface complexation. Used adsorbents have been converted into a value added product by utilizing innovative Zero-waste concept to solve the used adsorbents disposal problem and thus protecting the environment.
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Cobre/química , Plomo/química , Fosfatos/química , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/química , Zinc/química , Adsorción , Concentración de Iones de Hidrógeno , Intercambio Iónico , Cinética , Tamaño de la PartículaRESUMEN
Developing a catalyst with high efficiency and recyclability is an important issue for the heterogeneous Fenton-like systems. In this study, magnetic Fe3O4 and reduced graphene oxide (RGO) nanocomposites were prepared by a facile alkaline-thermal precipitation method and employed as a highly effective heterogeneous Fenton-like catalyst for methyl orange (MO) degradation. Characterization of these nanocomposites by XRD, FTIR, Raman, FESEM and TEM revealed that nanoparticles (NPs) of Fe3O4 were tightly anchored on the few-layer RGO sheets. The anchoring of Fe3O4 NPs and the reduction of GO were achieved in one pot without adding any other reducing agents. Based on the measurements of GO surface Zeta potentials, a possible anchoring mechanism of Fe3O4 NPs onto RGO sheets was given. The Fe3O4/RGO nanocomposites exhibited much higher Fenton-like catalytic efficiency for MO degradation than pure Fe3O4 NPs. This degradation process followed the first-order kinetics model, where k1 and T complied with the Arrhenius equation with Ea of 12.79â¯kJ/mol and A of 8.20â¯s-1. Magnetic measurements revealed that Fe3O4/RGO nanocomposites were ferromagnetic as indicated by the presence of magnetic hysteresis loops. The Fe3O4/RGO nanocomposites showed good stability and recyclability. Hydroxyl radicals, OH were determined as the dominant oxidative species in Fe3O4/RGO-H2O2 system and the Fenton-like mechanism for MO degradation in water was proposed and discussed.
RESUMEN
The catalyst of CuOx/Al2O3 was prepared by the dipping-sedimentation method using gamma-Al2O3 as a supporter. CuO and Cu2O were loaded on the surface of Al2O3, characterized by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). In the presence of CuOx/Al2O3, the microwave-induced chlorine dioxide (ClO2) catalytic oxidation process was conducted for the treatment of synthetic wastewater containing 100 mg/L phenol. The factors influencing phenol removal were investigated and the results showed that microwave-induced ClO2-CuOx/Al2O3 process could effectively degrade contaminants in a short reaction time with a low oxidant dosage, extensive pH range. Under a given condition (ClO2 concentration 80 mg/L, microwave power 50 W, contact time 5 min, catalyst dosage 50 g/L, pH 9), phenol removal percentage approached 92.24%, corresponding to 79.13% of COD(Cr) removal. The removal of phenol by microwave-induced ClO2-CuOx/Al2O3 catalytic oxidation process was a complicated non-homogeneous solid/water reaction, which fitted pseudo-first-order by kinetics. Compared with traditional C1O2 oxidation, ClO2 catalytic oxidation and microwave-induced ClO2 oxidation, microwave-induced ClO2 catalytic oxidation system could significantly enhance the degradation efficiency. It provides an effective technology for the removal of phenol wastewater.
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Compuestos de Cloro/química , Microondas , Óxidos/química , Fenol/química , Fenol/efectos de la radiación , Contaminantes Químicos del Agua/química , Contaminantes Químicos del Agua/efectos de la radiación , Óxido de Aluminio/química , Catálisis , Cobre/química , Concentración de Iones de Hidrógeno , Residuos Industriales , Oxidación-Reducción , Temperatura , Eliminación de Residuos Líquidos/métodosRESUMEN
Graphitic carbon nitride (g-C3N4) used in this work was obtained by heating dicyandiamide and melamine, respectively, at different temperatures. The differences of g-C3N4 derived from different precursors in phase composition, functional group, surface morphology, microstructure, surface property, band gap and specific surface area were investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-visible diffuse reflection spectroscopy and BET surface area analyzer, respectively. The photocatalytic discoloration of an active cationic dye, Methylene Blue (MB) under visible-light irradiation indicated that g-C3N4 derived from melamine at 500°C (CN-M500) had higher adsorption capacity and better photocatalytic activity than that from dicyandiamide at 500°C (CN-D500), which was attributed to the larger surface area of CN-M500. MB discoloration ratio over CN-M500 was affected by initial MB concentration and photocatalyst dosage. After 120 min reaction time, the blue color of MB solution disappeared completely. Subsequently, based on the measurement of the surface Zeta potentials of CN-M500 at different pHs, an active anionic dye, Methyl Orange (MO) was selected as the contrastive target pollutant with MB to reveal the synergic effect between adsorption and photocatalysis. Finally, the photocatalytic mechanism was discussed.
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Contaminantes Ambientales/aislamiento & purificación , Grafito/química , Azul de Metileno/aislamiento & purificación , Nitrilos/química , Fotólisis , Adsorción , Catálisis , Guanidinas/química , Triazinas/químicaRESUMEN
The CO(2-)3-substituted apatite solid solutions were prepared through different methods. The FTIR and XRD measurements were applied to investigate its crystal chemistry properties. The results indicated that the CO(2-)3-substituted sites in the carbonate hydroxyapatite(CHAP) prepared through homogeneous precipitation method are type-B in which [CO3.OH] tetrahedral-coordinations are substituted for [PO4] tetrahedral-coordinations; the ones in the CHAP prepared through solid phase ions exchange method are type-A in which [CO3] triangle-coordinations are substituted for [OH] in column sites; the ones in the carbonate fluorapatite(CFAP) prepared through solid phase reaction method are type-B in which [CO3.F] tetrahedral-coordinations are substituted for [PO4] tetrahedral-coordinations; the ones in the CHAP prepared through sol-gel method are AB mixed-type. The vibrational band psi 3 is splitted into psi 3-1, psi 3-4 and psi 3F. The psi 3F is combined by psi 3-2 (type-A) and psi 3-3 (type-B) in Gaussian function fitting. When Wco(2-)3 < 3.34%, substitution value of type-A increases with the increasing of CO(2-)3 contents. When Wco(2-)3 = 3.34%, substitution value of type-A has maximum. When 3.34% < Wco(2-)3 < 7.52%, substitution value of type-B increases with the increasing of CO(2-)3 contents. When Wco(2-)3 = 7.52%, substitution value of type-B has maximum.
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Apatitas/química , Carbonatos/química , Cristalización , Estructura Molecular , Soluciones , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
The anatase/schorl composites were prepared and employed for the photocatalytic discoloration of an azo dye, Methyl Orange (MO). X-ray diffraction results indicated that TiO2 existed in the form of anatase phase and no diffraction peaks of schorl could be observed for all the composite samples. Scanning electron micrographs showed that the particles of anatase were well deposited and dispersed on the surface of schorl. Photocatalytic experiments revealed that the anatase/schorl composites exhibited higher photocatalytic activity for MO discoloration than pure TiO2 and more than 90% discoloration ratio could be obtained within 60 min UV irradiation when the sample containing 3 wt.% of schorl as TiO2 support was used. Then, the central composite design (CCD) under the response surface methodology (RSM) was employed for the experiment design and process optimization. The significance of a second-order polynomial model for predicting the optimal values of MO discoloration was evaluated by the analysis of variance (ANOVA) and 3D response surface plots for the interactions between two variables were constructed. Based on the model prediction, the optimum conditions for the photocatalytic discoloration of MO by TiO2/schorl composite were determined to be 15 × 10(-3) mM MO initial concentration, 2.7 g/l photocatalyst dosage, solution pH 6.6 and 43 min reaction time, with a maximum MO discoloration ratio of 98.6%. Finally, a discoloration ratio of 94.3% was achieved for the real sample under the optimum conditions, which was very close to the predicted value, implying that RSM is a powerful and satisfactory strategy for the process optimization.
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Compuestos Azo/química , Colorantes/química , Procesos Fotoquímicos , Silicatos/química , Titanio/química , Contaminantes Químicos del Agua/química , Compuestos Azo/análisis , Catálisis , Colorantes/análisis , Industria Textil , Eliminación de Residuos Líquidos/métodos , Contaminantes Químicos del Agua/análisis , Difracción de Rayos XRESUMEN
A cationic dye, Rhodamine B (RhB), could be efficiently discolored by heterogeneous Fenton-like reaction catalyzed by natural schorl. In this work, with the main goal of the optimization for RhB discoloration, central composite design under the response surface methodology (RSM) was employed for the experiment design and process optimization. The significance of a second-order polynomial model for predicting the optimal values of RhB discoloration was evaluated by the analysis of variance and 3D response surface and counter plots for the interactions between two variables were constructed. The Pareto graphic analysis of the discoloration process indicated that, among all the variables, solution pH (X 3, 47.95 %) and H2O2 concentration (X 1, 24.39 %) had the largest influences on the heterogeneous Fenton-like discoloration of RhB. Based on the model prediction, the optimum conditions for RhB discoloration were determined to be 45 mM H2O2 concentration, 2.5 g/L schorl dosage, solution pH 2, and 110 min reaction time, with the maximum RhB discoloration ratio of 98.86 %. The corresponding experimental value of RhB discoloration ratio under the optimum conditions was determined as 99.31 %, which is very close to the optimized one, implying that RSM is a powerful and satisfactory strategy for the process optimization.
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Colorantes/química , Peróxido de Hidrógeno/química , Oxidantes/química , Rodaminas/química , Silicatos/química , Contaminantes Químicos del Agua/química , Catálisis , Color , Concentración de Iones de Hidrógeno , Modelos Químicos , Análisis de Regresión , Factores de Tiempo , Eliminación de Residuos Líquidos/métodosRESUMEN
The existence of 'electrostatic poles' on the schorl surface encouraged us to apply schorl for a TiO(2) support. TiO(2)/schorl composite photocatalyst was prepared and characterized by XRD, SEM and UV/DRS, and their photocatalytic activity was evaluated by discoloration of acid fuchsine (AF). The results indicated that TiO(2) existed in the form of anatase and was well deposited and enwrapped on the schorl surface. The absorption edge of TiO(2)/schorl exhibited a slight red shift in the UV/DRS spectra, compared with that of pure TiO(2). The photocatalytic activity of TiO(2)/schorl for AF discoloration was higher than that of pure TiO(2). The AF discoloration ratio approached 100% after irradiation time of 12h. The optimum photocatalyst was found to be that containing 4.76 wt.% of schorl and sintered at 550 degrees C. The reaction followed pseudo-first-order kinetics, discussed by the Langmuir-Hinshelwood model. Hypotheses were proposed to interpret the mechanism for the enhanced photocatalytic activity of TiO(2)/schorl.
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Bencenosulfonatos/química , Fotoquímica/métodos , Silicatos/química , Contaminantes Químicos del Agua/aislamiento & purificación , Purificación del Agua/métodos , Absorción , Catálisis , Concentración de Iones de Hidrógeno , Cinética , Microscopía Electrónica de Rastreo , Electricidad Estática , Temperatura , Factores de Tiempo , Rayos Ultravioleta , Contaminantes Químicos del Agua/química , Difracción de Rayos XRESUMEN
Mineral-catalyzed Fenton-like system has been found to be effective for the discoloration of dyeing wastewater. In our present study, schorl has been successfully developed as a novel heterogeneous catalyst for discoloration of an active commercial dye, Argazol blue (BF-BR), in an aqueous solution. Through a number of batch discoloration experiments under various conditions, it was found that the reactivity of the system increased by, respectively, increasing schorl dosage, temperature, hydrogen peroxide starting concentration and by decreasing the pH. At the condition of pH 2, T=55 degrees C, [BF-BR](0)=200mg/L, [H(2)O(2)](0)=48.5 mmol/L and schorl dosage=10 g/L, 100% of discoloration ratio can be achieved in less than 4 min, and 72% of total organic carbon (TOC) can be removed in less than 200 min. The reaction kinetics analysis shows that the discoloration of BF-BR follows the first-order kinetics. The schorl samples after BF-BR discoloration was tested by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and Scanning electron microscope (SEM) and the results rule out the possibility of formation of new solid phases during BF-BR discoloration. The content of Fe ion leaching in the solution was also measured using inductively coupling plasma-atomic emission spectra (ICP-AES). A mechanism proposed herein indicates adsorption and Fenton-like reaction (heterogeneous and homogeneous) are responsible for the discoloration of BF-BR.
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Colorantes/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Catálisis , Peróxido de Hidrógeno , Concentración de Iones de Hidrógeno , Residuos Industriales/prevención & control , Hierro , Cinética , Minerales , TemperaturaRESUMEN
The sorption of aqueous lead on carbonate-hydroxyapatite (CHAp) is a complicated non-homogeneous solid/water reaction, which from the kinetic point of view has two stages. In the first stage, the reaction rate is so fast and the kinetic pathway so intricate that further research is required. In the second stage, the reaction rate slows down and the reaction process follows that of a first-order kinetic equation. Experimental results show that the relationship between the reaction rate constant k(1) and temperature T agrees with the Arrhenius equation, and that the activation energy of sorption (E(a)) is 11.93 kJ/mol and the frequency factor (A) is 2.51/s. The reaction rate constant k(1) increases with the Pb(2+) initial concentration and decreasing pH, but with increasing CHAp dosage. X-ray diffraction (XRD), scanning electron microscopy with energy dispersion spectrum (SEM-EDS) and toxicity characteristic leaching procedure (TCLP) tests indicate that the main sorption mechanism is dissolution-precipitation, in conjunction with surface sorption.