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Use of iron oxide nanomaterials in wastewater treatment: a review.

As a newly emerging kind of porous material, covalent organic frameworks (COFs) have drawn much attention because of their fascinating structural features (e.g., divinable structure, adjustable porosity and total organic backbone). Since the seminal work of Yaghi and co-workers reported in 2005, the COF materials have shown superior potential in diverse applications, such as gas storage, adsorption, optoelectronics, catalysis, etc. Recently, COF materials have shown a new trend in sensing fields. This critical review briefly describes the synthesis routes for COF powders and thin films. What's more, the most fascinating and significant applications of COFs in sensing fields including explosive sensing, humidity sensing, pH detection, biosensing, gas sensing, metal ion sensing, and other substance sensing are summarized and highlighted. Finally, the major challenges and future trends of COFs with respect to their preparation and sensing applications are discussed.

Recent advances in covalent organic frameworks (COFs) as a smart sensing material.

Many organic and inorganic compounds have been developed as visible light driven photocatalysts for environment and energy application. In this work, a metal-free carbon doping–carbon nitride (BCM-C 3 N 4 ) nanocomposite was synthesized by introducing barbituric acid and cyanuric acid during the polymerization of melamine. The BCM-C 3 N 4 was characterized by structure, porosity, optical performance, and photoelectrochemical properties. Results demonstrated that BCM-C 3 N 4 sample exhibited higher surface area, lower fluorescence intensity, better photocurrent signals and more efficient charge transfer in comparison to pure C 3 N 4 . The BCM-C 3 N 4 exhibits excellent photocatalytic degradation ability of sulfamethazine (SMZ) under visible light irradiation. Much superior photocatalytic activity and high pollutant mineralization rate was achieved by BCM-C 3 N 4 , where it was 5 times than that of pristine C 3 N 4 . The effect of initial SMZ concentrations on photocatalyst was also investigated. Additionally, the trapping experiments and electron spin resonance tests demonstrated that the main active species, such as O 2 − and h + , could be produced under light irradiation. This work might provide an effective approach to the design of low-cost and highly efficient photocatalysis degradation systems for water treatment.

Highly porous carbon nitride by supramolecular preassembly of monomers for photocatalytic removal of sulfamethazine under visible light driven

The development of efficient photocatalysts for the production of hydrogen peroxide (H2O2) is a promising strategy to realize solar-to-chemical energy conversion. Graphitic carbon nitride (g-C3N4) presents giant potential for photocatalytic H2O2 production, but the sluggish charge separation depresses its photocatalytic performance. Herein, an interfacial Schottky junction composed of Ti3C2 nanosheets and porous g-C3N4 nanosheets (TC/pCN) is constructed by a facile electrostatic self-assembly route to significantly boost the spatial charge separation to promote the activation of molecular oxygen for H2O2 production. As the optimal sample, TC/pCN-2 possesses the highest H2O2 production rate (2.20 μmol L−1 min−1) under visible light irradiation (λ > 420 nm), which is about 2.1 times than that of the porous g-C3N4. The results of superoxide radical detection and rotating disk electrode measurement suggest that the two-step single-electron reduction of oxygen is the predominant reaction step during this photocatalytic H2O2 production process. The enhanced photocatalytic performance is ascribed to the formation of Schottky junction and subsequent built-in electric field at their interface, which accelerate the spatial charge separation and restrain the charge recombination. This work provides an in-depth understanding of the mechanism of photocatalytic H2O2 production, and gives ideas for the design of highly active materials for photocatalytic H2O2 production.

Ti3C2 Mxene/porous g-C3N4 interfacial Schottky junction for boosting spatial charge separation in photocatalytic H2O2 production

Fabrication of CuS/BiVO4 (0 4 0) binary heterojunction photocatalysts with enhanced photocatalytic activity for Ciprofloxacin degradation and mechanism insight

The authors here described a visual detection strategy employing 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole (AHMT) functionalized gold nanoparticles (AuNPs) to detect kanamycin (KA) in various samples. The AHMT with mercapto group was self-assembled onto the surface of AuNPs and the AHMT functionalized AuNPs (AHMT-AuNPs) aggregated when KA existed owing to the hydrogen-bonding interaction between KA and AHMT. As a result, the color of the AHMT-AuNPs solution changed from wine red-to-deep purple with the increasing concentration of KA. Taking advantage of the hydrogen-bonding interaction, KA could be quantitatively detected by the proposed sensor in the range of 0.005–0.1 μM and 0.1–20 μM, with the detection limit as low as 0.004 μM which is much lower than the maximum contamination level for KA in milk defined by the European Union. Furthermore, the proposed sensor was not affected by the interference chemicals including common amine acid, antibiotics, and metal ions. The sensor was also used to detect KA from various real samples, and the results were excellent in accord with the values measured by the high performance liquid chromatography (HPLC). This sensor exhibited a promising potential for simple and real-time detection of KA in various real samples.

A visual application of gold nanoparticles: Simple, reliable and sensitive detection of kanamycin based on hydrogen-bonding recognition

The biodegradation process of lignin by Penicillium simplicissimum was studied to reveal the lignin biodegradation mechanisms. The biodegradation products of lignin were detected using Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, different scanning calorimeter (DSC), and stereoscopic microscope. The analysis of FTIR spectrum showed the cleavage of various ether linkages (1,365 and 1,110 cm(-1)), oxidation, and demethylation (2,847 cm(-1)) by comparing the different peak values in the corresponding curve of each sample. Moreover, the differences (Tm and ΔHm values) between the DSC curves indirectly verified the FTIR analysis of biodegradation process. In addition, the effects of adding hydrogen peroxide (H2O2) to lignin biodegradation process were analyzed, which indicated that H2O2 could accelerate the secretion of the MnP and LiP and improve the enzymes activity. What is more, lignin peroxidase and manganese peroxidase catalyzed the lignin degradation effectively only when H2O2 was presented.

Tianjue Hu

Papers

A visual application of gold nanoparticles: Simple, reliable and sensitive detection of kanamycin based on hydrogen-bonding recognition

Study on biodegradation process of lignin by FTIR and DSC.

Composting of lead-contaminated solid waste with inocula of white-rot fungus

Difunctional chitosan-stabilized Fe/Cu bimetallic nanoparticles for removal of hexavalent chromium wastewater.

Use of potassium dihydrogen phosphate and sawdust as adsorbents of ammoniacal nitrogen in aerobic composting process.