Activation of peroxymonosulfate by Fe,N co-doped walnut shell biochar for the degradation of sulfamethoxazole: performance and mechanisms.

Fe and N co-doped walnut shell biochar (Fe,N-BC) was prepared through a one-pot pyrolysis procedure by using walnut shells as feedstocks, melamine as the N source, and iron(III) chloride as the Fe source. Moreover, pristine biochar (BC), nitrogen-doped biochar (N-BC), and α-Fe2O3-BC were synthesized as controls. All the prepared materials were characterized by different techniques and were used for the activation of peroxymonosulfate (PMS) for the degradation of sulfamethoxazole (SMX). A very high degradation rate for SMX (10 mg/L) was achieved with Fe,N-BC/PMS (0.5 min-1), which was higher than those for BC/PMS (0.026 min-1), N-BC/PMS (0.038 min-1), and α-Fe2O3-BC/PMS (0.33 min-1) under the same conditions. This is mainly due to the formation of Fe3C and iron oxides, which are very reactive for the activation of PMS. In the next step, Fe,N-BC was employed for the formation of a composite membrane structure by a liquid-induced phase inversion process. The synthesized ultrafiltration membrane not only exhibited high separation performance for humic acid sodium salt (HA, 98%) but also exhibited improved self-cleaning properties when applied for rhodamine B (RhB) filtration combined with a PMS solution cleaning procedure. Scavenging experiments revealed that 1O2 was the predominant species responsible for the degradation of SMX. The transformation products of SMX and possible degradation pathways were also identified. Furthermore, the toxicity assessment revealed that the overall toxicity of the intermediate was lower than that of SMX.

A walnut shell biochar-nano zero-valent iron composite membrane for the degradation of carbamazepine via persulfate activation.

In this study, novel walnut shell biochar-nano zero-valent iron nanocomposites (WSBC-nZVI) were synthesized using a combined pyrolysis/reduction process. WSBC-nZVI displayed a high removal efficiency (86 %) for carbamazepine (CBZ) compared with walnut shell biochar (70 %) and nano zero-valent iron (76 %) in the presence of persulfate (PS) (0.5 g/L catalyst, 10 mg/L CBZ, 1 mM persulfate). Subsequently, WSBC-nZVI was applied for the fabrication of the membrane using a phase inversion method. The membrane demonstrated an excellent removal efficiency of 91 % for CBZ in a dead-end system (2 mg/L CBZ, 1 mM persulfate). In addition, the effect of various operating conditions on the degradation efficiency in the membrane/persulfate system was investigated. The optimum pH was close to neutral, and an increase in CBZ concentration from 1 mg/L to 10 mg/L led to a drop in removal efficiency from 100 % to 24 %. The degradation mechanisms indicated that oxidative species, including 1O2, OH, SO4-, and O2-, all contribute to the degradation of CBZ, while the role of 1O2 is highlighted. The CBZ degradation products were also investigated, and the possible pathways and the predicted toxicity of intermediates were proposed. Furthermore, the practical use of the membrane was validated by the treatment of real wastewater.

Immobilization of photocatalytic materials for (waste)water treatment using 3D printing technology - advances and challenges.

Photocatalysis has been considered a promising technology for the elimination of a wide range of pollutants in water. Various types of photocatalysts (i.e., homojunction, heterojunction, dual Z-scheme photocatalyst) have been developed in recent years to address the drawbacks of conventional photocatalysts, such as the large energy band gap and rapid recombination rate of photogenerated electrons and holes. However, there are still challenges in the design of photocatalytic reactors that limit their wider application for real (waste)water treatment, such as difficulties in their recovery and reuse from treated (waste)waters. 3D printing technologies have been introduced very recently for the immobilization of materials in novel photocatalytic reactor designs. The present review aims to summarize and discuss the advances and challenges in the application of various 3D printing technologies (i.e., stereolithography, inkjet printing, and direct ink writing) for the fabrication of stable photocatalytic materials for (waste)water treatment purposes. Furthermore, the limitations in the implementation of these technologies to design future generations of photocatalytic reactors have been critically discussed, and recommendations for future studies have been presented.

ZnO/γ-Fe2O3/Bentonite: An Efficient Solar-Light Active Magnetic Photocatalyst for the Degradation of Pharmaceutical Active Compounds.

For applications related to the photocatalytic degradation of environmental contaminants, engineered nanomaterials (ENMs) must demonstrate not only a high photocatalytic potential, but also a low tendency to agglomeration, along with the ability to be easily collected after use. In this manuscript, a two-step process was implemented for the synthesis of ZnO, ZnO/Bentonite and the magnetic ZnO/γ-Fe2O3/Bentonite nanocomposite. The synthesized materials were characterized using various techniques, and their performance in the degradation of pharmaceutical active compounds (PhACs), including ciprofloxacin (CIP), sulfamethoxazole (SMX), and carbamazepine (CBZ) was evaluated under various operating conditions, namely the type and dosage of the applied materials, pH, concentration of pollutants, and their appearance form in the medium (i.e., as a single pollutant or as a mixture of PhACs). Among the materials studied, ZnO/Bentonite presented the best performance and resulted in the removal of ~95% of CIP (5 mg/L) in 30 min, at room temperature, near-neutral pH (6.5), ZnO/Bentonite dosage of 0.5 g/L, and under solar light irradiation. The composite also showed a high degree of efficiency for the simultaneous removal of CIP (~98%, 5 mg/L) and SMX (~97%, 5 mg/L) within 30 min, while a low degradation of ~5% was observed for CBZ (5 mg/L) in a mixture of the three PhACs. Furthermore, mechanistic studies using different types of scavengers revealed the formation of active oxidative species responsible for the degradation of CIP in the photocatalytic system studied with the contribution of h+ (67%), OH (18%), and ·O2- (10%), and in which holes (h+) were found to be the dominant oxidative species.

Synthesis of Ni-doped anatase TiO2 single crystals loaded on wood-based activated carbon for enhanced photodegradation of triphenylmethane dyes.

In this work, the Ni-doped anatase TiO2 single crystals loaded on activated carbon (Ni-T/AC) were synthesized by a sol-gel method. The chemical compositions and physical properties of as-prepared materials were analyzed by XRD, TEM, BET, FTIR, XPS, and PL characterizations. The obtained results implied that all of samples presented anatase phase with a clear mesoporous structure. The photocatalytic properties of nanocomposites were evaluated through photodegradation of crystal violet (CV), basic fuchsine (BF), and malachite green (MG). The results revealed that the catalyst Ni-T/AC-loaded AC exhibited an excellent photocatalytic activity compared with the original TiO2, and the photodegradation efficiency for CV, BF, and MG is 99.00%, 94.85%, and 98.89% after 120 min of irradiation, respectively. This enhancement may be ascribed to the small crystallite size, large specific surface area, and pore volume of the photocatalysts. In addition, the possible degradation mechanism and pathway for triphenylmethane dyes (TPMs) were also well investigated. This work provides a new, low-cost, and effective route to improve the performance of TiO2 for effective removing TPMs.

Synthesis and characterization of Ni-doped anatase TiO2 loaded on magnetic activated carbon for rapidly removing triphenylmethane dyes.

In this work, we employed the in situ synthesis method to implant Fe3O4 into activated carbon (AC), in which the synthesis of the magnetic AC (MAC) was realized. Thence, Ni-doped anatase TiO2 (NATiO2) were anchored on different addition amount of MAC to synthesize the series of Ni-TiO2/MAC photocatalysts. The chemical compositions and physical properties of these nanocomposites were analyzed by various characterization technologies. The photocatalytic capabilities of as-produced materials were then investigated via adsorption and photodegradation of triphenylmethane dyes (TPMs) as crystal violet (CV), basic fuchsine (BF), and malachite green (MG) solution. The results revealed that the removal of Ni-TiO2/AC, Ni-TiO2/2MAC, Ni-TiO2/4MAC, and Ni-TiO2/8MAC on TPMs is a very fast process and the removal efficiency can almost reach to about 90% in 10 min, and the catalyst has good cycle stability and is easy to be reused. This work provides a novel, low-cost, and effective way to rationally design and synthesize TiO2-based photocatalysts for effective removal of TPMs.

Surfactants-assisted preparation of BiVO4 with novel morphologies via microwave method and CdS decoration for enhanced photocatalytic properties.

The development of a highly efficient and rapid method for the accurate preparation of photocatalysts with novel morphologies is a hot research topic. The different morphologies of BiVO4 was prepared using surfactants-assisted microwave method, and demonstrated irregular (no surfactant), octahedral (sodium dodecyl benzene sulfonate), olive-like (polyvinylpyrrolidone) and hollow structures (ethylenediaminetetraacetic acid), respectively. The BiVO4-CdS were synthesized using the chemical-bath-deposition method with different morphologies of BiVO4 as the substrates. The hollow structure of BiVO4 displayed the highest photocatalytic performance. Moreover, the photodegradation rates of the hollow structure BiVO4-CdS on tetracycline hydrochloride and ciprofloxacin were about 1.8 and 1.5 times higher than the corresponding BiVO4, indicating that the Z-scheme heterojunction can improve the photogenerated electron pairs separation efficiency. Furthermore, the regulation mechanism of morphology and energy-band position, as produced using the surfactants, has also been thoroughly investigated in this work, which provides a novel insight into the efficient and rapid preparation of photocatalysts with special morphology and high performance.

Hierarchical fabrication Z-scheme photocatalyst of BiVO4 (0 4 0)-Ag@CdS for enhanced photocatalytic properties under simulated sunlight irradiation.

Interfacial charge separation and heterojunction system are conductive to improving its photocatalytic performance. Herein, we designed a novel photocatalyst of Z-scheme BiVO4 (0 4 0)-Ag@CdS, in which Ag was photo-deposition on the (0 4 0) facets of BiVO4 as the "linker" between BiVO4 and CdS. Characterizations of XRD and SEM clearly revealed that the BiVO4 (0 4 0)-Ag@CdS was prepared through hierarchical fabrication. The photoelectrochemical performances demonstrated BiVO4 with high proportion (0 4 0) facet and CdS with nanorods structure could drastically improve the photocatalytic performance. Then, the 100%BiVO4 (0 4 0)-Ag@CdS presented an excellent photodegradation rate towards tetracycline hydrochloride, which is 8.67 times than that of single BiVO4. In addition, the results of light assisted Fenton-like oxidation revealed that the 100%BiVO4 (0 4 0)-Ag@CdS performed the highest photodegradation rate towards 2, 4-dichlorophenoxyacetic acid with the assist of 12 mM H2O2 under the irradiation of simulated sunlight, and the photodegradation pathway was analyzed through GC-MS. This contribution provides a novel insight for improving the separation efficiency of photoelectron-hole pair and photodegradate towards refractory organic pollutants.

Constructing a Z-scheme Heterojunction of Egg-Like Core@shell CdS@TiO2 Photocatalyst via a Facile Reflux Method for Enhanced Photocatalytic Performance.

A well designed and accurate method of control of different shell thickness and electronic transmission in a Z-scheme core@shell system is conducive to obtaining an optimum photocatalytic performance. Herein, the Z-scheme heterojunction of egg-like core@shell CdS@TiO2photocatalysts with controlled shell thickness (13 nm, 15 nm, 17 nm, 22 nm) were synthesized by a facile reflux method, and the CdS@TiO2 structure was proved by a series of characterizations. The photodegradation ratio on methylene blue and tetracycline hydrochloride over the 0.10CdS@TiO2 composites with TiO2 shell thickness of 17 nm reached 90% in 250 min and 91% in 5 min, respectively, which was almost 9.8 times and 2.6 times than that of TiO2 and CdS on rhodamine B respectively under visible light. Besides, the higher total organic carbon removal ratio indicated that most of the pollutants were degraded to CO2 and H2O. The Z-scheme electronic transfer pathway was studied through radical species trapping experiments and electron spin resonance spectroscopy. Moreover, the relationship between shell thickness and photocatalytic activity demonstrated that different shell thickness affects the separation of the electron and holes, and therefore affected the photocatalytic performance. In addition, the effects of pollutants concentration, pH, and inorganic anions on photocatalytic performance were also investigated. This work can provide a novel idea for a well designed Z-scheme heterojunction of core@shell photocatalysts, and the study of photocatalytic performance under different factors has guiding significance for the treatment of actual wastewater.

Fabrication of interlayer ß-CD/g-C3N4@MoS2 for highly enhanced photodegradation of glyphosate under simulated sunlight irradiation.

Graphitic carbon nitride (g-C3N4) has been considered to be a promising metal-free photocatalyst, although the high recombination rate of charge carriers and poor absorption of visible light have limited its applications. In order to overcome these problems, an interlayer composite photocatalyst that comprised ß-cyclodextrin (ß-CD), oxygen-doped C3N4 (O-C3N4) and molybdenum disulfide (MoS2) was successfully constructed for the highly enhanced photodegradation of glyphosate in this study. The structure and morphology, optical properties, and photoelectrochemical properties of the prepared photocatalyst were characterized via a series of characterization techniques. The average fluorescence lifetime of the composite photocatalyst was extended from 6.67 ns to 7.30 ns in comparison with that of g-C3N4, which indicated that the composite photocatalyst enhanced the absorption of visible light and also inhibited the recombination of electron-hole pairs. The mass ratio of MoS2 that corresponded to O-C3N4/MoS2-5 enabled the highest removal rate under simulated sunlight irradiation, which was almost twice that achieved using pure g-C3N4. Relative species scavenging experiments revealed that ·O2 - was the main species during the process of photodegradation. Besides, a toxicity test indicated that glyphosate became less toxic or non-toxic after photodegradation. This study provided an effective, feasible and stable photocatalyst driven by simulated sunlight irradiation for the highly enhanced photodegradation of glyphosate.

Removal Effect of Atrazine in Co-Solution with Bisphenol A or Humic Acid by Different Activated Carbons.

Activated carbons (ACs) based on apricot shells (AS), wood (W), and walnut shells (WS) were applied to adsorb atrazine in co-solutions. To study the effect of Bisphenol A (BPA) on the adsorption behavior of atrazine, the adsorption performance of ACs for BPA in single solution was studied. The results demonstrated that the adsorption kinetics of BPA fitted the pseudo-second-order model, the adsorption isotherms of BPA followed the Langmuir model. Meanwhile, the adsorption kinetics of atrazine fitted the pseudo-second-order kinetics model and the isotherm was consistent with the Freundlich model both in single solution and co-solution. In addition, competitive adsorption was observed when atrazine coexisted with BPA or humic acid. For the adsorption capacity, the adsorption amount of ASAC, WAC, and WSAC for atrazine obviously decreased by 18.0%, 30.0%, and 30.3% in the presence of BPA, respectively, which was due to the π-π interactions, hydrophobic interactions, and H-bonds, resulting in the competitive adsorption between atrazine and BPA. This study contributes to the further understanding of the adsorption behavior for atrazine in co-solution.

A DNA microarray for fission yeast: minimal changes in global gene expression after temperature shift.

Completion of the fission yeast genome sequence has opened up possibilities for post-genomic approaches. We have constructed a DNA microarray for genome-wide gene expression analysis in fission yeast. The microarray contains DNA fragments, PCR-amplified from a genomic DNA template, that represent > 99% of the 5000 or so annotated fission yeast genes, as well as a number of control sequences. The GenomePRIDE software used attempts to design similarly sized DNA fragments corresponding to gene regions within single exons, near the 3'-end of genes that lack homology to other fission yeast genes. To validate the design and utility of the array, we studied expression changes after a 2 h temperature shift from 25 degrees C to 36 degrees C, conditions widely used when studying temperature-sensitive mutants. Obligingly, the vast majority of genes do not change more than two-fold, supporting the widely held view that temperature-shift experiments specifically reveal phenotypes associated with temperature-sensitive mutants. However, we did identify a small group of genes that showed a reproducible change in expression. Importantly, most of these corresponded to previously characterized heat-shock genes, whose expression has been reported to change after more extreme temperature shifts than those used here. We conclude that the DNA microarray represents a useful resource for fission yeast researchers as well as the broader yeast community, since it will facilitate comparison with the distantly related budding yeast, Saccharomyces cerevisiae. To maximize the utility of this resource, the array and its component parts are fully described in On-line Supplementary Information and are also available commercially.