Latest ArticlesAs a novel wastewater treatment strategy, the intimate coupling of photocatalysis and biodegradation (ICPB) has been attracted attention, which is ascribed to its combination of the advantages of photocatalytic reactions and biological treatment. The selection of carriers is important since it affects the stability of the system and the removal efficiency of pollutants. In this study, a novel ICPB system was successfully constructed by loading photocatalytic materials (i.e., TiO2, N-TiO2, and Ag-TiO2) and microbes onto non-woven cotton fabric. The photocatalysts were characterized by scanning electron microscope-energy dispersive spectrometer (SEM-EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). This system exhibited good performance in degrading tetracycline (TC) in water. The results showed that Ag-TiO2-ICPB had the maximum removal efficiency of tetracycline (94.7%) in 5 h, which was 16.5% higher than the photocatalysis alone. After five cycles, 82.9% of tetracycline could be still degraded through Ag-TiO2-ICPB. SEM spectrum showed microbes on the material changed little before and after the reactions. This result implied the materials were stable, and then beneficial for degrading of pollutants continuously. The intermediates were detected through ultraperformance liquid chromatography-mass spectrometer (UPLC-MS) and the plausible degradation pathways were proposed. Electron paramagnetic resonance (EPR) analysis showed OH and O2− were the main reactive oxygen species for TC degradation. In conclusion, the ICPB system with non-woven cotton fabric as a carrier has certain application prospects for antibiotic-containing wastewater.
Since the sulfur(VI) fluoride exchange reaction (SuFEx) was introduced by Sharpless and co-workers in 2014, this new-generation click chemistry has emerged as an efficient and reliable tool for creating modular intermolecular connections. Sulfonyl fluorides, one of the most important sulfur(VI) fluoride species, have attracted enormous attention in diverse fields, ranging from organic synthesis and material science, to chemical biology and drug discovery. This review aims to introduce seminal and recent progresses on the synthetic methods of sulfonyl fluorides, which include aromatic, aliphatic, alkenyl, and alkynyl sulfonyl fluorides. While not meant to be exhaustive, the purpose is to give a timely overview and insight in this field, and stimulate the development of more efficient synthetic methods of sulfonyl fluorides.
The composite catalytic materials based on the mineral kaolinite are considered to be a potential approach for solving global energy scarcity and environmental pollution, which have excellent catalytic performance, low cost and excellent chemical stability. However, pure kaolinite does not have visible light absorption ability and cannot be used as a potential photocatalytic material. Fortunately, the unique physical and chemical properties of kaolinite can be acted as a good semiconductor carrier. Herein, this paper firstly presents the mineralogical characteristics of kaolinite. Next, kaolinite-based photocatalysts (such as TiO2/kaolinite, g-C3N4/kaolinite, g-C3N4/TiO2/kaolinite, ZnO) are discussed in detail from the formation of heterostructures, synthesis-modification methods, photocatalytic mechanisms, and electron transfer pathways. Furthermore, the specific role of kaolinite in photocatalytic materials is summarized and discussed. In addition, the photocatalytic applications of kaolinite-based photocatalysts in the fields of water decomposition, pollutant degradation, bacterial disinfection are reviewed. However, the modification of kaolinite is hard, the manufacture of a large number of kaolinite-based photocatalysts is difficult, the cost of doping noble metals is expensive, and the utilization rate of visible light is low, which limits its application in industrial practice. Finally, this paper presents some perspectives on the future development of kaolinite-based photocatalysts.
As organic pollutants of emerging concern, organophosphate esters (OPEs) have shown toxicity to organisms after entering the water environment. However, research on OPEs in freshwater in Southwest China is very limited. The levels, distribution and partitioning behavior of OPEs in the Minjiang River and their influencing factors is still unknown. In this study, six OPEs, tri-n-butyl phosphate (TnBP), tri(2-chloroethyl)-phosphate (TCEP), trichloropropyl phosphate (TCPP), triphenyl phosphate (TPhP), tributoxyethyl phosphate (TBEP), and tris(2-ethylhexyl)-phosphate (TEHP), were determined in surface water, suspended particle matter (SPM) and sediments of the Minjiang River. The results showed that the average concentrations of Σ6OPEs in surface water, SPM and sediments of the Minjiang River were 199.32±124.95 ng/L, 38463.79±45641.89 ng/g dry weight (dw) and 76.45±28.00 ng/g dw, respectively. High concentrations of OPEs were detected in SPM samples, indicating that more attention should be paid to pollution in SPM. It is worth noting that the variation trend of OPEs in SPM was almost opposite to that in water but basically similar to that in sediment. The proportions of alkyl OPEs in Σ6OPEs increased from surface water to SPM and sediments. Alkyl OPEs were the main pollutants in SPM (10.44%–80.88% of Σ6OPEs, mean of 54.52%) and sediments (59.08%–81.30% of Σ6OPEs, mean of 68.91%), whereas chlorinated OPEs were the most abundant components in surface water (43.16%–75.99% of Σ6OPEs, mean of 55.50%). The water-sediment partition coefficient (logKOC) of OPEs was 4.97–7.58, while the water-SPM partition coefficient was 6.71–10.00. No significant correlations were found between logKOW and logKOC. KOW was not the main factor affecting the distribution of OPEs in the Minjiang River, China.
A self-synthesized bi-pyridine chelating resin (PAPY) could separate Cu(Ⅱ)/Ni(Ⅱ)/Fe(Ⅱ) sequentially from strong-acidic pickling wastewater by a two-stage pH-adjusted process, in which Cu(Ⅱ), Ni(Ⅱ), and Fe(Ⅱ) were successively preferred by PAPY. In the first stage (pH 1.0), the separation factor of Cu(Ⅱ) over Ni(Ⅱ) reached 61.43 in Cu(Ⅱ)-Ni(Ⅱ)-Fe(Ⅱ) systems. In the second stage (pH 2.0), the separation factor of Ni(Ⅱ) over Fe(Ⅱ) reached 92.82 in Ni(Ⅱ)-Fe(Ⅱ) systems. Emphasis was placed on the selective separation of Cu(Ⅱ) and Ni(Ⅱ) in the first-stage. The adsorption amounts of Cu(Ⅱ) onto PAPY were 1.2 mmol/g in the first stage, while those of Ni(Ⅱ) and Fe(Ⅱ) were lower than 0.3 mmol/g. Cu(Ⅱ) adsorption was hardly affected by Ni(Ⅱ) with the presence of dense Fe(Ⅱ), but Cu(Ⅱ) inhibited Ni(Ⅱ) adsorption strongly. Part of preloaded Ni(Ⅱ) could be replaced by Cu(Ⅱ) based on the replacement effect. Compared with the absence of Fe(Ⅱ), dense Fe(Ⅱ) could obviously enhance the separation of Cu(Ⅱ)-Ni(Ⅱ). More than 95.0% of Cu(Ⅱ) could be removed in the former 240 BV (BV for bed volume of the adsorbent) in the fixed-bed adsorption column process with the flow rate of 2.5 BV/h. As proved by X-ray photoelectron spectrometry (XPS) and density functional theory (DFT) analyses, Cu(Ⅱ) exerted a much stronger deprotonation and chelation ability toward PAPY than Ni(Ⅱ) and Fe(Ⅱ). Thus, the work shows a great potential in the separation and purification of heavy metal resources from strong-acidic pickling wastewaters.
Carbon dots (CDs) are metal-free fluorescent materials that can be used in optical and electronic devices, but few studies have focused on one-step synthesis routes for CDs with tunable color and high photoluminescence quantum yield (PLQY). Herein, CDs with tunable light emission were synthesized using a novel amide-assisted solvothermal approach. The as-prepared CDs were well dispersed and homogeneous, with average diameters of approximately 2.0–4.0 nm, depending on the dopants. Owing to the surface states with different ratios of nitrogen- and oxygen-related species, different CDs can exhibit blue, green, red, or white emission with relatively high PLQYs of 61.6%, 41.3%, 29.1% and 19.7%, respectively. XPS measurements, in conjunction with DFT calculations, indicate that nitrogen substitution (pyridinic/pyrrolic nitrogen) dominates the blue emission, while introducing oxygen functional groups lowered the LUMO energy level, which resulted in redder emission. In addition, the CDs are demonstrated as a bioimaging probe in bothin vitro and in vivo assays, and the white light CDs have been demonstrated to be potential fluorescent materials for white-light-emitting diode (WLED).
In this work, a novel blue-green fluorescence phosphorous oxide quantum dots (PO QDs) was synthesized by solvothermal method in N-methyl-2-pyrrolidone (NMP) solution without any protection treatment during synthesis. Upon excitation at 400 nm, PO QDs emitted blue-green fluorescence with quantum yield of 0.28. PO QDs exhibited the high inertness to air or moisture, the excellent water solubility, and stable emission intensity in a wide pH range and in high ionic strength solution. Interestingly, PO QDs could give the positive optical response to iron ions (Fe3+) and iodine ion (I−). The photoluminescence (PL) of PO QDs could be directly quenched by Fe3+. While I− quenched the PO QDs PL by means of Ag+-mediated PO QDs system via the internal filtration effects (IFE) induced by the formation of AgI. Moreover, the biocompatibility and low toxicity of PO QDs verified in bean sprout and Hela cells indicated the promising application of PO QDs in medicine related fields. Furthermore, PO QDs could also be utilized in luminescent composite film for various application scenarios
In the field of volatile organic compounds (VOCs) pollution control, adsorption is one of the major control methods, and effective adsorbents are desired in this technology. In this work, the density functional theory (DFT) calculations are employed to investigate the adsorption of typical VOCs molecules on the two-dimensional material borophenes. The results demonstrate that both structure of χ3 and β12 borophene can chemically adsorb ethylene and formaldehyde with forming chemical bonds and releasing large energy. However, other VOCs, including ethane, methanol, formic acid, methyl chloride, benzene and toluene, are physically adsorbed with weak interaction. The analysis of density of states (DOS) reveals that the chemical adsorption changes the conductivity of borophenes, while the physical adsorption has no distinct effect on the conductivity. Therefore, both χ3 and β12 borophene are appropriate adsorbents for selective adsorption of ethylene and formaldehyde, and they also have potential in gas sensor applications due to the obvious conductivity change during the adsorption.
Recent advances in the desilylative acylation of 1-alkenylsilanes with acid anhydrides under transition metal catalysis are summarized. This catalytic desilylative acylation of 1-alkenylsilanes provides an efficient route to α, β-unsaturated ketones by using rhodium or iridium as the catalyst. Moreover, various one pot sequence reactions have been developed, which can synthesize α, β-unsaturated ketones from simple starting materials in an economic way. Additionally, this approach is applied to the asymmetric synthesis of atropisomers possessing silanol groups with excellent enantioselectivity.
A novel carbon-rich g-C3N4 nanosheets with large surface area was prepared by facile thermal polymerization method using urea and 1, 3, 5-cyclohexanetriol. Plenty of carbon-rich functional groups were introduced into the surface layers of g-C3N4, which constructed the built-in electric field (BIEF) and resulted in improved charge separation; therefore, the carbon-rich g-C3N4 displayed superior photocatalytic activity for amoxicillin degradation under solar light. The contaminant degradation mechanism was proposed based on radical quenching experiments, intermediates analysis and density functional theory (DFT) calculation. Moreover, the reusing experiments showed the high stability of the material, and the amoxicillin degradation under various water matrix parameters indicated its high applicability on pollutants treatment, all of which demonstrated its high engineering application potentials.
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