In Situ Construction of Dye-Sensitized BiOCl/Rutile-TiO2 Nanorod Heterojunctions with Highly Enhanced Photocatalytic Activity for Treating Persistent Organic Pollutants.

The construction of efficient and stable heterojunction photocatalysts with a controllable close contact interface and visible-light response is a challenging research topic in the field of photocatalysis. Herein, a series of BiOCl/rutile-TiO2 (R-TiO2) nanorod heterojunctions were constructed using R-TiO2 nanorods as supporting frameworks followed by selective adsorption of Cl- on R-TiO2(110) facets and in situ growth of BiOCl on the surface of TiO2 nanorods. The strong affinity of rhodamine B (RhB) as a photosensitizer for BiOCl allowed the prepared BiOCl/R-TiO2 heterojunctions to work efficiently under visible-light irradiation. The dye-sensitized BiOCl/R-TiO2 nanorod heterojunctions displayed promising photocatalytic performance for simultaneously treating RhB and the persistent organic pollutant 2-sec-butyl-4,6-dinitrophenol (DNBP). The highly enhanced photodegradation activity of the BiOCl/R-TiO2 system was mainly attributed to the efficient RhB-photosensitization effect, the enhanced heterojunction effect, and the suitable conduction band match between BiOCl and R-TiO2, which facilitated electron transfer from the excited RhB to the catalyst surface and charge separation across the BiOCl/R-TiO2 interface, thus promoting the formation of •O2- and h+ as dominant active species in the reaction system for degradation of pollutants. The results demonstrate that the construction of a dye-sensitized BiOCl/R-TiO2 heterojunction system is an effective strategy for improving the photocatalytic potential.

Facile synthesis of rGO-supported AgI-TiO2 mesocrystals with enhanced visible light photocatalytic activity.

Facile synthesis of novel rGO-supported AgI decorated TiO2 mesocrystals (AgI-TMCs-rGO) and their photocatalytic activity under visible light irradiation are reported. The catalysts were prepared by combining the hydrothermal reaction process and in situ deposition-precipitation method. The structural features and chemical compositions of the prepared catalysts were investigated by HRTEM (high resolution transmission electron microscopy), XRD (x-ray powder diffraction), Raman spectra, XPS (x-ray photoelectron spectroscopy), UV-vis DRS (UV-vis diffuse reflectance spectra), PLS (photoluminescence spectra), and N2 physisorption measurements. The AgI-TMCs-rGO catalysts featured a large surface area, high adsorption capacity, enhanced photo-induced charge separation and strong absorbance of visible light. The intimate contact of various components and the fast transfer of charge carriers effectively suppresses photolysis of AgI and favors the structural stability of AgI-TMCs-rGO. The photocatalytic activity of the catalysts was evaluated by degrading Rhodamine B (RhB) in an aqueous solution under visible light irradiation. The highest photocatalytic activity was observed in the sample 20%Ag-TMCs-rGO, attributed to the synergistic effects of a lower band gap and a lowerrecombination rate of the charge carriers, along with the larger surface area of the fabricated sample.

In-situ synthesis of novel dual S-scheme AgI/Ag6Mo7O24/g-C3N4 heterojunctions with tandem structure for photocatalytic degradation of organic pollutants.

The controllable design of multivariate heterojunction with sequential structures is of significant relevance for breaking the performance limit of binary composite photocatalysts. In this work, the novel dual S-scheme ternary-component AgI/Ag6Mo7O24/exfoliated g-C3N4 (ECN) composite was prepared by a two-step in-situ synthetic strategy. The energy band bending at the heterointerface and the formation of dual built-in electric field could be observed due to distinct work functions of different components in the ternary composite. Benefiting from the sequential heterojunction structure, the AgI/Ag6Mo7O24/ECN composite achieved 98.7% removal efficiency of 2-nitrophenol (2-NP) within 70 min under visible light irradiation, and AgI/Ag6Mo7O24/ECN also showed higher degradation efficiency for a variety of organic pollutants such as methylene blue (MB), rhodamine B (RhB), methyl orange (MO), 4-nitrophenol (4-NP), 2-sec-butyl-4,6-dinitrophenol (DNBP) and tetracycline (TC). Notably, •OH and •O2- played dominant roles in the AgI/Ag6Mo7O24/ECN set up, which was consistent with the dual S-scheme charge transfer mechanism. In-depth insights for the photodegradation of 2-NP were presented based on a combined DFT study and GC-MS analysis. Additionally, the photoreduction of Ag+ in AgI/Ag6Mo7O24/ECN was also evaded by the fast transfer of photogenerated electrons through the dual S-scheme pathway, achieving the effect of killing two birds with one stone.

Photocatalytic degradation of 2,4-dinitrophenol (DNP) by multi-walled carbon nanotubes (MWCNTs)/TiO2 composite in aqueous solution under solar irradiation.

Nanosized multi-walled carbon nanotubes (MWCNTs)/TiO2 composite and neat TiO2 photocatalysts were synthesized by sol-gel technique using tetrabutyl titanate as a precursor. The as prepared photocatalysts were characterized using XRD, SEM, FTIR and UV-vis spectra. The samples were evaluated for their photocatalytic activity towards the degradation of 2,4-dinitrophenol (DNP) under solar irradiation. The results indicated that the addition of an appropriate amount of MWCNTs could remarkably improve the photocatalytic activity of TiO2. An optimal MWCNTs:TiO2 ratio of 0.05% (w/w) was found to achieve the maximum rate of DNP degradation. The effects of pH, irradiation time, catalyst concentration, DNP concentration, etc. on the photocatalytic activity were studied and the results obtained were fitted to the Langmuir-Hinshelwood model to study the degradation kinetics. The optimal conditions were an initial DNP concentration of 38.8 mg/L at pH 6.0 with catalyst concentration of 8 g/L under solar irradiation for 150 min with good recyclisation of catalyst. The degree of photocatalytic degradation of DNP increased with an increase in temperature. The MWCNTs/TiO2 composite was found to be very effective in the decolorization and COD reduction of real wastewater from DNP manufacturing. Thus, this study showed the feasible and potential use of MWCNTs/TiO2 composite in degradation of various toxic organic contaminants and industrial effluents.

Facile fabrication of hydrophilic PAA-Ti/TiO2 nanocomposite for selective enrichment and detection of phosphopeptides from complex biological samples.

Highly selective enrichment of trace phosphorylated proteins or peptides from complex biological samples is of profound significance for the discovery of disease biomarkers in biological systems. In this study, a novel affinity material has been synthesized to improve the enrichment specificity for phosphopeptides by using PAAS as coupling molecule. In the resulting materials, highly abundant titanium is available for selective enrichment of phosphopeptides, with plenty of carboxylate groups that can inhibit nonspecific adsorption. The enrichment results demonstrated that the hydrophilic PAA-Ti/TiO2 composite possesses excellent selectivity for phosphopeptides even at a very low molar ratio of phosphopeptides/non-phosphopeptides (1:1000), extreme sensitivity (the detection limit was at the fmol level), and high recovery of phosphopeptides (as high as 78%). Moreover, the as-prepared nanocomposite provides effective enrichment of phosphopeptides from real samples (mouse liver), showing great potential in the detection of low-abundance phosphopeptides in biological samples.

Study on the treatment of 2-sec-butyl-4,6-dinitrophenol (DNBP) wastewater by ClO2 in the presence of aluminum oxide as catalyst.

The chlorine dioxide (ClO(2)) oxidative degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) in aqueous solution was studied in detail using Al(2)O(3) as a heterogeneous catalyst. The operating parameters such as the ClO(2) concentration, catalyst dosage, initial DNBP concentration, reaction time and pH were evaluated. Compared with the conventional ClO(2) oxidation process without the catalyst, the ClO(2) catalytic oxidation system could significantly enhance the degradation efficiency. Under the optimal condition (DNBP concentration 39 mg L(-1), ClO(2) concentration 0.355 g L(-1), reaction time 60 min, catalyst dosage 10.7 g L(-1) and pH 4.66), degradation efficiency approached 99.1%. The catalyst was used at least 8 cycles without any appreciable loss of activity. The kinetic studies revealed that the ClO(2) catalytic oxidation degradation of DNBP followed pseudo-first-order kinetics with respect to DNBP concentration. The ClO(2) catalytic oxidation process was found to be very effective in the decolorization and COD(Cr) reduction of real wastewater from DNBP manufacturing. Thus, this study showed potential application of ClO(2) catalytic oxidation process in degradation of organic contaminants and industrial effluents.

Oxidative degradation of dinitro butyl phenol (DNBP) utilizing hydrogen peroxide and solar light over a Al2O3-supported Fe(III)-5-sulfosalicylic acid (ssal) catalyst.

A novel and efficient photo-Fenton catalyst of Fe(III)-5-sulfosalicylic acid (ssal) supported on Al(2)O(3) was prepared and characterized by FT-IR and TEM-EDX technique. A detailed investigation of photocatalytic degradation of 2-sec-butyl-4,6-dinitrophenol (DNBP) using this catalyst and H(2)O(2) under solar light irradiation was carried out. The effects of reaction parameters on photodegradation performance were investigated by examining H(2)O(2) dosage, catalyst loading, solution pH, initial DNBP concentration and temperature. The optimal conditions were an initial DNBP concentration of 40 mg L(-1) at pH 2.5 and temperature 30 degrees C with catalyst loading of 1.0 g L(-1) and H(2)O(2) concentration of 5 mmol L(-1) under solar light irradiation for 100 min. Almost complete degradation of DNBP was observed with [Fe(III)-ssal]-Al(2)O(3)/H(2)O(2) process under the optimal conditions. The degradation of DNBP by photo-Fenton-type process can be divided into the initiation phase and the fast phase. The kinetics of Fenton oxidation is complex and the degradation of DNBP in the two phases both can be described by a pseudo-first-order kinetic model. No obvious decline in efficiency of the [Fe(III)-ssal]-Al(2)O(3) catalyst was observed after 5 repeated cycles indicating this catalyst is stable and reusable. A possible reaction mechanism was proposed on the basis of all the information obtained under various experimental conditions.

Solar photocatalytic degradation of 2,6-dinitro-p-cresol (DNPC) using multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts.

Multi-walled carbon nanotubes (MWCNTs)-TiO(2) composite photocatalysts with excellent activity were prepared by sol-gel method in order to investigate its photocatalytic activity under solar irradiation for the degradation of 2,6-dinitro-p-cresol (DNPC) in aqueous solution. The prepared composite were analyzed by XRD, FTIR, SEM, TEM, TG-DTA and UV-vis absorption spectra techniques. The results showed that the composite can cause an obvious red shift of UV-vis spectra compared with pure TiO(2). The degradation of DNPC by MWCNTs-TiO(2) composite photocatalysts under solar irradiation was systematically studied by varying the experimental parameters such as pH value, irradiation time, the initial substrate concentration, reaction temperature, catalyst concentration, etc. The optimal conditions were a DNPC concentration of 33.4 mgL(-1) at pH 6.0 with MWCNTs-TiO(2) concentration of 6.0gL(-1) under solar irradiation for the illumination of 150 min. The presence of MWCNTs can enhance the photoefficiency of TiO(2). The highest efficiency on photodegradation of DNPC can be achieved with an optimal MWCNTs/TiO(2) mass ratio of 0.05%. The photocatalytic degradation of DNPC obeys a pseudo-first-order behavior according to the Langmuir-Hinshelwood model, and possible decomposing mechanisms are also discussed. The photocatalyst was used for five cycles with photocatalytic degradation efficiency still higher than 96%. The results of the study showed the feasible and potential use of MWCNTs-TiO(2) composite in degradation of toxic organic pollutants.

Preparation and application of sustained release microcapsules of potassium ferrate(VI) for dinitro butyl phenol (DNBP) wastewater treatment.

The encapsulated potassium ferrate(VI) (K(2)FeO(4)) samples were successfully prepared by phase separation method in organic solvents. The ethyl cellulose and paraffin were selected for the microcapsule wall materials (WM). The as prepared microcapsules were characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). The stability can be enhanced greatly when ferrate(VI) was encapsulated in the microcapsules with a mass ratio of Fe(VI):WM in the range of 1:1-1:3 for the same conserved time in air compared for pure K(2)FeO(4). The sustained release behavior of the microcapsules with different Fe(VI):WM mass ratios in 8.0M KOH solution was also investigated. The results indicated that the Fe(VI) release was reduced with increase of Fe(VI):WM mass ratios from 1:1 to 1:3. The release kinetics of the microcapsules is found to obey Ritger-Peppas equation. The prepared Fe(VI) microcapsules has been used for the removal of a typical alkyl dinitro phenol compound, 2-sec-butyl-4,6-dinitrophenol (DNBP), from aqueous solution. The effect of pH, microcapsule concentration and reaction time was studied thoroughly. The optimal pH for DNBP degradation was 6.5, and at this pH and a microcapsule concentration of 1.2g/L, approximately 93% of the DNBP was degraded after 80 min. The encapsulated ferrate(VI) samples were found to be very effective in the decolorization and COD reduction of real wastewater from DNBP manufacturing. Thus, this study showed the feasible and potential use of encapsulated Fe(VI) samples in degradation of various toxic organic contaminants and industrial effluents.