Guoji Ding

Insight on fractal assessment strategies for tin dioxide thin films.

Tin oxide is a unique material of widespread technological applications, particularly in the field of environmental functional materials. New strategies of fractal assessment for tin dioxide thin films formed at different substrate temperatures are of fundamental importance in the development of microdevices, such as gas sensors for the detection of environmental pollutants. Here, tin dioxide thin films with interesting fractal features were successfully prepared by pulsed laser deposition techniques under different substrate temperatures. Fractal method has been first applied to the evaluation of this material. The measurements of carbon monoxide gas sensitivity confirmed that the gas sensing behavior is sensitively dependent on fractal dimensions, fractal densities, and average sizes of the fractal clusters. The random tunneling junction network mechanism was proposed to provide a rational explanation for this gas sensing behavior. The formation process of tin dioxide nanocrystals and fractal clusters could be reasonably described by a novel model.

Microstructure evolution and advanced performance of Mn3O4 nanomorphologies

Mn(3)O(4) morphologies with tetragonal single-crystal nanostructures including nanoparticles, nanorods and nanofractals were successfully prepared by a widely applicable chemical reaction route. The morphologies were synthesized using the reactants MnCl(2)·4H(2)O, H(2)O(2), and NaOH in a suitable surfactant and alkaline solution. The dripping speed of the NaOH solution plays an important role in the microstructure evolution of Mn(3)O(4) morphologies. The difference in the dripping speed of NaOH solutions leads to different Mn(3)O(4) nanomorphologies, which are called nanoparticles, nanorods and nanofractals. The average grain size of the Mn(3)O(4) nanoparticles ranged from a few to several tens of nanometers. The Mn(3)O(4) nanorods were smooth, straight, and the geometrical shape was structurally perfect. Their lengths ranged from several hundred nanometers to a few micrometers, and their diameters ranged from 10 nm to 30 nm. The fractal branches of the Mn(3)O(4) nanofractals were a few micrometers in length and several hundred nanometers in width. The catalytic properties of these Mn(3)O(4) nanomorphologies for the degradation of phenol were evaluated in detail. The results indicated that the Mn(3)O(4) nanofractals possess remarkable catalytic activity for the degradation of phenol in water treatment.

Efficient one-pot synthesis of peapod-like hollow carbon nanomaterials for utrahigh drug loading capacity

In this paper, peapod-like hollow carbon nanomaterial was fabricated via an efficient one-pot hydrothermal route. The carbon-silica composite was employed as the precursor and cetyltrimethylammonium bromide (CTAB) as the morphology-controlled agent. SEM and TEM results indicated that the carbon shell and the silica core in the precursor were not closely linked but rattle-type structure. After removing the silica template, the obtained carbon product had uniform peapod-like morphology, interconnected pores and high specific surface areas (above 800.0 m(2)/g). We found that CTAB played an important role in the formation of the products with peapod-like morphology. The particle sizes of the hollow carbon nanospheres were readily adjusted by varying the dosage of tetraethoxysilane (TEOS) and the volume ratio of ethanol and water. Based on the experimental results, the formation mechanism of the hollow carbon nanomaterial was also discussed. By virtue of their unique nanostructure and porous properties, the peapod-like hollow carbon nanomaterial exhibited ultrahigh drug loading capacity above 98.4% for doxorubicin hydrochloride (DOX).

Mixed-solvothermal slow release synthesis of ZnxCd1−xSynanorods with high visible light photocatalytic activities

A mixed-solvothermal method starting from dithizone as a slow release source was developed for synthesizing ZnxCd1−xSy photocatalysts with high visible light photocatalytic activities. XRD, TEM, SEM, XRF, BET, UV-Vis DR, Raman and PL spectra were employed to characterize the crystal phases, morphologies, chemical compositions and optical properties of the obtained products. Interestingly, the released zinc ions could form nanoparticles on the surface of nanorods and the excessive growth of sulfur could bring some new optical properties. The visible light photocatalytic properties of the products were also evaluated by photocurrent measurements in steady state conditions. The results indicated that ZnxCd1−xSy, especially Cd0.78Zn0.22S0.94, exhibited excellent photocatalytic activities, about 10 times higher than the commercial CdS and about 5 times higher than the typical CdS QDs. As a result, a possible mechanism was proposed to explain the formation of the ZnxCd1−xSycatalysts.

Degradation of halogenated benzenes in solution by electron beam irradiation method.

In this work, the dehalogenation and degradation of halogenated benzenes (chlorobenzenes, bromobenzene) under electron beam radiation were investigated. Several factors affected the degradation of halogenated benzenes by the electron beam radiation method, such as the dose of the electron beam, the initial pH value of the solutions and the kind of halogen. The rule of dehalogenation and degradation followed the order: bromobenzene > 1,2,4‐trichlorobenzene > p‐dichlorobenzene > chlorobenzene. The final products were found to be benzene and diphenyl. Dehalogenation of halogenated benzenes occurred in the presence of NaOH. Based on the results, a general reaction pathway for the degradation of halogenated benzenes is proposed.

Two physical strategies to reinforce a nonmetallic photocatalyst, g-C3N4: vacuum heating and electron beam irradiation

Herein, we demonstrated two physical strategies, namely, vacuum heating and electron beam irradiation, to reinforce a nonmetallic photocatalyst, g-C3N4. These two post-treatments also improved the visible light absorption properties of g-C3N4; however, electron beam irradiation was more destructive, and it caused a determined change in the chemical bonds and band structure of the compound. According to the post-processing parameters mentioned in this article, vacuum heating (38 ± 2 mTorr for 4 days at 200 °C) enhanced the photocatalytic efficiency of the original g-C3N4 by 2.5 times, whereas electron beam irradiation (760 kGy at 1.8 MeV and 8 mA s−1) improved it by 4.5 times. Finally, the post-treated photocatalysts were stable during photocatalytic oxidation, which is important for practical applications.

Microplastics in sewage sludge from the wastewater treatment plants in China

Sludge disposal such as land application is suspected as a significant source of microplastic (MP) pollution in the environment. To examine such a hypothesis, the present study was conducted to investigate the occurrence of MPs in sludge by analyzing 79 sewage sludge samples collected from 28 wastewater treatment plants (WWTPs) in 11 Chinese provinces. MP concentrations in the sludge samples ranged from 1.60-56.4 × 103 particles per kilogram of dry sludge, with an average of 22.7 ± 12.1 × 103 particles per kilogram of dry sludge. Thereinto, the sludge-based MP contents were greater in eastern China than in western China and varied during different months. Their colors and types were mainly white (59.6%) and fibers (63%), respectively. Microscope Fourier Transform infrared spectroscopy revealed that most of MPs belonged to polyolefin, acrylic fibers, polyethylene and polyamide. Some WWTP parameters, such as servicing area, proportion of industrial wastewater, secondary treatment and sludge dewatering may have affected MP concentrations in sludge. Based on the total sludge production in China, the average amount of sludge-based MPs entering into natural environmental was estimated to be 1.56 × 1014 particles per year. The findings confirmed that sewage sludge discharge is an important source of MP pollution in the environment. Further evaluation of the associated environmental hazards with MPs is deemed necessary.

Molecular characteristics of the refractory organic matter in the anaerobic and aerobic digestates of sewage sludge

The chemical characteristics of the refractory organic matter in anaerobic and aerobic digestates are hardly known although they are significant for further improving the degradation of organic matter during sludge digestion. Thus, in this study, various techniques are used to analyze the molecular properties of the total organic matter in raw sludge and mesophilic anaerobic and aerobic digestates (AnD and AoD, respectively). The results show that AnD has lower organic matter content, but the maturity and aromatization of its organic matter are lower than those of AoD. The FTIR and XPS spectra show that AoD has higher proportions of protein-like and aromatic groups and lower percentages of polysaccharide-like materials and ammonia nitrogen compared with AnD. The solid-phase fluorescence spectra indicate that AoD has a higher content of fluorescence organic matter, but its biodegradability and chemical accessibility are lower than those of AnD. Pyrolysis GC/MS analysis shows that the digestates are enriched with more lignin-like and aromatic groups and contain lower oxycompounds compared with raw sludge, especially AoD. These findings provide new insights into the molecular characteristics of the refractory organic matter in anaerobic and aerobic digestates and also provide a possible strategy to further enhance the degradation of organic matter in sewage sludge.

Radiolysis and photolysis studies on active transient species of berberine.

In this paper, the photochemical and photobiological characters of the active radicals of berberine (BBR) was investigated for finding an efficient and safe photosensitizer with highly active transient products using in Photodynamic therapy (PDT) study. The active species of BBR was generated and identified by using pulse radiolysis method. In neutral aqueous solution, BBR react with hydrated electron and hydroxyl radical, forming the radical anion and neutral radical of BBR, and the related reaction rates were determined as 3.5×10(10) and 6.7×10(9) M(-1) s(-1), respectively. Further, the capability of BBR to photosensitize DNA cleavage was testified by laser flash photolysis (LFP) method, the results demonstrated that BBR neutral radical could react with guanine mononucleotide (K=1.9×10(9) M(-1) s(-1)) via electron transfer to give the guanine neutral radical. Additionally BBR selective cleavage single and double strand DNA at guanine moiety was observed. Finally, combining with the thermodynamic calculation, the possible photodamage mechanism of dGMP and DNA induced by BBR was clarified.