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A method that combines disproportionation and magnesium-vapor-reduction in one step, which is different from traditional magnesium thermal reduction, was designed for synthesizing advanced silicon-based anode materials.

A novel mesoporous g-C3N4 loaded with biomass porous carbon was synthesized by molten salt assisted thermal polycondensation, and the formation of hollow tubular structure increased the specific surface area.

Polyvinyl chloride (PVC) plastic wastes can bring a series of problems during pyrolysis or incineration such as the emission of dioxins, corrosion, slagging in the reactors, etc. Hydrothermal treatment of PVC plastics has been intensively studied as it can efficiently remove chlorine from PVC plastics under relatively mild reaction conditions (220-300 °C) to provide value-added products. Meanwhile, the research progress, knowledge gaps, and challenges in this field have not been well addressed yet. This paper gives a comprehensive review of hydrothermal dechlorination of PVC plastics regarding reactors, process variables and fundamentals, possible applications, and challenges. The main pathways of hydrothermal dechlorination of PVC plastics are elimination and -OH nucleophilic substitution. Catalytic hydrothermal and co-hydrothermal optimize the chemical reactions and transportation, boosting the dechlorination of PVC plastics. Hydrochar derived from PVC plastics, on the one hand, is coalified close to sub-bituminous and bituminous coal and can be used as low-chlorine solid fuel. On the other hand, it is also a porous material with aromatic structure and oxygen-containing functional groups, with good potential as adsorbent or energy storage materials. Further studies are expected to focus on waste liquid treatment, revealing the energy and economic balance, reducing the dechlorination temperature and pressure, expanding the application of products, etc. for promoting the implementing the hydrothermal treatment of PVC plastic wastes.

Defects (oxygen vacancy and Ti3+) play crucial roles in determining band structure, light absorption, and catalytic activity of TiO2. Herein, a synchronous crystallization and constraint reduction strategy was reported to construct controllable defective TiO2 using sodium borohydride (NaBH4) as the reductant. The constraint decomposition effect of NaBH4 in pore channels of TiO2 aerogels enables the defects migrate from surface to bulk region effectively, and bulk defects are more stable. Moreover, the species and concentration of defects can be controlled by changing the calcination temperature in this case. An optimum temperature for the NaBH4 treatment was found to be 500 °C. After the reduction at 500 °C, defective TiO2 with maximum bulk oxygen vacancies shows excellent visible light absorption performance, effective separation of photogenerated charge carriers, and suitable band edge, and the removal rate was 94.9% for rhodamine B (RhB) under visible light which was about 325% higher than that of TiO2 without oxygen vacancy.

As a new nonmetallic photocatalysis material, it is of great attention to develop the carbon nitride (g-C3N4) with good structure and optical properties. Herein, a mesoporous g-C3N4 was prepared by molten salt-assisted silica (SiO2) aerogel template method, the properties of physicochemical and optical were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), specific surface area and pore analysis, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray energy spectrum (XPS), diffuse reflectance spectrum, fluorescence spectrum (PL) and zeta potential, respectively. Rhodamine B (RhB) was used for a series of adsorption and photocatalytic degradation experiments, and the reactive species and the degree of RhB degradation in the reaction process were tested by electron spin resonance (ESR) and UV–Vis absorption spectrum, respectively. The synergistic effect of adsorption and photocatalytic degradation was investigated. The results show that the mesoporous g-C3N4 was synthesized successfully, and presented a hollow tubular porous structure and good optical properties. With the highest specific surface area (164.65 m2·g−1) and narrower band gap (2.47 eV), the sample of M-CN-500 shown the highest degradation rate of RhB (90.9%) after 150 min illumination, and the adsorption capacity and zeta potential were both affected by pH variation. The kinetic model verified that the photocatalytic degradation rate of RhB by mesoporous g-C3N4 was enhanced with the synergistic effect of adsorption. It was also demonstrated that the O2− and h+ were the primary reactive species, and the RhB structure fracture was the main reason in the photocatalytic degradation. A mesoporous g-C3N4 was prepared by molten salt-assisted silica (SiO2) aerogel template method, and the synergistic effect of adsorption and photocatalytic degradation on this catalyst was investigated. Because of its special hollow tubular and porous structure, mesoporous g-C3N4 with high specific surface area can not only improve the adsorption performance, but also enhance the photocatalytic efficiency.

Toxic solvents and chemicals are usually used to prepare carbon nitride. Therefore, a low-toxic template-free method was proposed to prepare gauze-like porous graphitic carbon nitride (CCM18) with high specific surface area. The morphology, crystal and surface structure, specific surface area and optical properties of CCM18 were characterized, and the removal efficiency for tetracycline hydrochloride (TC) degradation under simulated sunlight was evaluated. The results showed that CCM18 has a specific surface area of 107.4 m2 g-1, stronger light absorption capacity and a band gap energy of 2.92 eV. The degradation rate of TC by CCM18 was more than twice that of BCN. The experiment of radical scavengers confirmed that superoxide radicals (O2-) and hydroxyl radical (OH) were the major active species. The enhanced performance of CCM18 for TC degradation (82%) and the stability of CCM18 that can be reused multiple times indicated the prospect of industrial application.

Ranitidine is widely concerned due to it is mainly related to the transformation into highly toxic carcinogenic products and non-readily biodegradable characteristics in aquatic environment. In this study, biodegradation of ranitidine during rural human feces (HF) aerobic composting was investigated. Results show that both levels of ranitidine are quickly removed in the first-3-day composting. The microorganisms play a vital role in the ranitidine degradation, especially for Firmicutes at the thermophilic period. The effect of ranitidine on the aerobic composting was further analyzed under the normal content (10 mg/kg) and high content (100 mg/kg). The 10 mg/kg ranitidine quickens temperature rise and organic matter degradation of the composting, while the 100 mg/kg ranitidine produces inhibiting effects. However, the effects only occur in the early stage of composting, and then tend to disappear with the removal of ranitidine. Fluorescence spectra confirm that humification and aromatization of dissolved organic matters (DOMs) in the substrates are fastened in 10 mg/kg group, while delayed in 100 mg/kg group. Metagenomic analysis reveals that relative abundances of Firmicutes and sequences related to carbohydrates metabolism increase in the groups mixed with the ranitidine at the early period. The findings provide the first new and systematical insights into degradation characteristics and potential effect of ranitidine during the rural HF composting.

Graphitic carbon nitride (g-C

The complex seawater matrix has significantly influenced the determination of estuarine dissolved Hg(II), hindering its monitoring and risk assessment in maricultural areas. In this work, SiO

Previous studies demonstrated that water film thickness (WFT) is a key factor that affects the fluidity of mortar. Changes in the sand-cement (S/C) ratio and polycarboxylate superplasticizer (PCE) dosage will affect the WFT. In this study, several mortar samples with different S/C ratios and different PCE dosages were prepared, and the basic properties of the mortar were measured. The results show that as the S/C ratio increases, the packing density of the mortar will decrease, the WFT will decrease, and the cohesiveness will increase, resulting in a decrease in the flow spread and strength of the mortar. When the PCE dosage is increased, the packing density of the mortar will increase, the WFT will increase, and the cohesiveness will decrease, which increases the flow spread of the mortar. When the water-cement (W/C) ratio is low, the S/C ratio has a significant effect on the strength, and the strength will increase with the increasing of the PCE dosage. When the W/C ratio is high, the strength of the mortar will be reduced once the PCE dosage exceeds the saturation value. In the case of different S/C ratios or different PCE dosages, the WFT can be used as a measure of mortar cohesiveness and flow spread.

The effects of polycarboxylate superplasticizers (PCEs) on the dispersing properties and initial hydration of cement particles with various water-to-cement (w/c) ratios was investigated, including the water film thickness (WFT), rheology, fluidity, adsorption of PCEs, zeta potential, degree of hydration, hydration products. The experimental results demonstrate that the initial rheological and fluidity parameters were more sensitive to the PCE dosage at a lower w/c because the WFT and the zeta potential on cement particles change more significantly. Moreover, the higher adsorption amounts of the PCEs at a lower w/c lead to a stronger inhibition of the initial hydration, whilst, at the same PCE dosage, the cement pastes have a more rapid fluidity loss and quicker hydration reactions at a higher w/c due to a lower adsorption amount of the PCE on cement particles.

The chloride profile in carbonated concretes with fly ash were measured after rapid chloride permeability test, so as to investigate the influence of carbonation degree on chloride ions diffusion and distribution. It is found that fly ash improved the carbonation resistance of concrete with low water-to-binder ratios while reduced that with high water-to-binder ratios. The capacities of binding chloride and chloride penetration resistance were enhanced in the early stage of carbonation. However, both abilities were significantly reduced in the late carbonation stage. Moreover, in the late but not completely carbonated stage, a peak appeared in the chloride concentration profile.

A kind of n–p (SnO2)1.3/(α ∼ Bi2O3)x/(β ∼ Bi2O3)1−x nanocomposite (SB-15) was synthesized with polyvinyl alcohol (PVA) as a template by solid state synthesis. XRD and HR-TEM confirmed the formation of n–p (SnO2)1.3/(α ∼ Bi2O3)x/(β ∼ Bi2O3)1−x. Particle size is found to be about 18 nm from HR-TEM images. FE-SEM clearly detected the boundary between SnO2 nanoparticles and Bi2O3 polyhedron particles. The special morphology and coexisting of α-Bi2O3 and β-Bi2O3 in SB-15 make it have a stronger visible light absorption range as far as 725 nm. PL and photocurrent test shows that the SB-15 has the best photocarriers separation capability. About 99% decolorization ratio of Rh.B was achieved in only 5 min. About 70% Cr6+ was degraded within 20 min and it is about 60% for tetracycline in the coexisting system (Te with Cr6+ solution), introducing it as a promising photocatalytic material. This work has addressed the method of phase-selective synthesis of n–p SnO2/α ∼ Bi2O3/β ∼ Bi2O3 by convenient solid state synthesis, which should be useful for the studies of other composites.

Street dust is a vital pertinent indicator to urban environmental quality, while only limited information is available on Hg from street dust in a subtropical city, as well as the bonding reactions...

Hydrothermal treatment (HTT) is able to remove chlorine effectively from polyvinyl chloride (PVC), however, the reaction temperature is critical in practical application. Less energy-intensive hydrothermal dechlorination condition with cupric ion (Cu2+) has been proposed in this study. In particular, Cu2+ was applied in HTT of PVC at temperature ranging from 200 °C to 240 °C. It has been found that the introduction of Cu2+ distinctly accelerated PVC decomposition and dechlorination at 220 °C. When Cu2+ concentration was increased from 0.01 mol/L to 0.20 mol/L, the dechlorination efficiency was significantly improved from 15.46 %–67.89 %. Dramatic dechlorination occurred as residence time was longer than 15 min during HTT. Besides, both elimination and substitution dominated the HTT dechlorinaton. The facilitated dechlorination after the addition of Cu2+ was mainly due to the enhanced dispersion and formation of micropores in hydrochar. On the whole, HTT could be a promising pretreatment technology for copper-containing PVC in electronic wastes to prepared chlorine free hydrochar for combustion or pyrolysis applications, the optimal HTT condition would be 220 °C, 60 min with 0.1 mol/L Cu2+. acceptedVersion

The existence of polycarboxylate ether superplasticizer (PCE) affects cement dissolution and usually retards cement hydration. It is still unclear how the adsorbed PCE retard the cement hydration process at dissolution stage or at generation of the hydration products stage. Herein, a new method to simulate the initial dissolution reaction between cement and PCE by using water instead of lime saturated solution as a solvent is proposed. In addition, this work analyzes the early hydration characteristics of cement paste with the PCE, using the techniques of calorimetric, adsorption measurement, zeta potential, XRD, thermogravimetry, ICP−OES and dynamic light scatting. It was found that the PCE can improve the initial dissolution rate of cement and then retard cement hydration by its dispersing effect. The complexation between the PCE and Ca2+ ions, the increase in Al3+ ions, and the reduction of hydration products are responsible for the retardation effect of cement hydration.

Mature compost and rice bran were used as bulking agents to perform Food Waste Rapid Composting (FWRC) in a patented composting bin. The characteristics of CO

In the traditional Fenton process, the efficient generation of hydroxyl radical (HO) strongly relies on an acidic circumstance and the iron ions would precipitate and form large amounts of hazardous iron-containing sludge at alkaline pH. To realize stable heterogeneous Fenton-like catalytic degradation at alkaline condition, Fe

Generally, TiO2 aerogel prepared by the sol-gel technique is amorphous and it exhibits special catalytic property only in the crystalline state after calcination at high temperature, but the calcination will significantly decrease aerogel’s specific surface area. Thus the aim of this study is to prepare co-existing crystalline phase Sn-TiO2 aerogel without annealing. It was synthesized by ultrasonic-assisted sol-gel method using stannous chloride as dopant. Results indicated that the uncalcined Sn-TiO2 aerogel composed by amorphous and anatase phase (denoted as co-existing phases) has a specific surface area of 172.4 m2/g. Optimal degradation efficiency of 96% for tetracycline hydrochloride was achieved within 30 min of UV irradiation using the co-existing phases Sn-TiO2 aerogel, due to the synergistic effect of adsorption and photocatalytic activity.

A novel n–p SnO2/Bi2O3 composite was synthesized by template free one step solid-state reaction synthesis. The as-prepared composite was characterized by XRD, HR-TEM, FE-SEM, UV–Vis, PL, and XPS. The photocatalytic capacity of n–p SnO2/Bi2O3 was evaluated by monitoring the decolorization of Rh.B solution. The results indicate that: (1) The photocatalyst exhibited a unique flake-like powder structure. SnO2 particles closely scattered on the surface of nano-flake structure of Bi2O3; (2) Compared with pure SnO2 and Bi2O3, all the composite samples extended the edge of absorbance to visible light region as long as 520 nm(sample S500) ; (3) The composite calcined at 500 ℃(sample S500) showed the highest separation capability of photo electrons and holes; (4) About 99% Rh.B can be completely decolorized within 30 min, and the reaction rate constant of S500 is about 10 times higher than that of pure SnO2 and Bi2O3; (5) The decolorization ratio was as high as 95% even in the 5th cycle which means the SnO2/Bi2O3 composite is chemically stable; (6)Active species test showed that (·O2−), holes (h+) were the main active species during the decoloration of the Rh.B solution.

Graphitic carbon nitride microspheres photocatalyst (CN-MCA) was prepared through supramolecular self-assembly with post-heating treatment, which starts from the combination of the raw materials melamine and cyanuric acid. The as-prepared samples were characterized in detail by X-ray diffraction, Fourier transform infrared spectroscopy, new high-resolution field-emission scanning electron microscopy, specific surface areas analysis, UV–Vis diffused reflectance spectrum, photoluminescence spectrum, and thermal analysis. The structural characterization results reveal that the as-prepared CN-MCA has the same chemical structure as CN-M, but appears as microspheres with nanoporous surfaces. Compared to the CN-M, CN-MCA microspheres exhibit higher specific surface areas, stronger optical absorption and lower PL intensity, which allow more active sites, more effective visible-light harvesting and more efficient migration rate of photogenerated charge. Consequently, we observed that CN-MCA microspheres exhibit higher photocatalytic activity in the photodegradation of tetracycline hydrochloride under visible light irradiation. Moreover, the degradation efficiency of tetracycline hydrochloric acid under 2 h of visible light irradiation was 80.54% when the dosage of CN-MCA was 1.0 g/L; the initial concentration of the tetracycline hydrochloride solution was 10 mg/L; and the initial pH was 7.

The biomass-derived N-doped porous carbons have been proved promising adsorbent material, due to their good CO2/N2 selectivity and excellent CO2 adsorption performance. However, many researchers simply studied the effect of nitrogen groups or narrow micropores (less than 0.7 nm) on CO2 uptake at 1 bar and ignored the role of different pressures. In this study, a promising porous carbon derived from eucalyptus bark with high CO2 adsorption capacity was prepared by urea-assisted hydrothermal and KOH activation. The obtained porous carbons were found to be mainly microporous and showed rich nitrogen content. Among the materials, at 1 bar, NPC700 exhibits high CO2 adsorption of 4.20 mmol/g and 6.98 mmol/g at 25 °C and 0 °C, respectively. Based on Grand canonical Monte Carlo (GCMC) simulation, the adsorption density and adsorption energy on graphite slit pore with different pore sizes (0.6–2.0 nm) and N-doped functional groups (pyridinic-N, pyrrole-N and graphitic-N) were calculated. And the results showed that the nitrogen functional groups played a crucial contribution on CO2 adsorption capacity at relative low pressure (0–0.16 bar). In the case of relative high pressure (0.16–1 bar), the narrow micropores volume determined the CO2 uptake capacity.

Much attention has been focused on the synthesis of TiO2 based materials as photocatalysts for water pollutant treatment, it still needs overcome difficulties of separation of TiO2 photocatalyst from the treated water and the recombination of photo-induced carriers to improve catalytic activities. In this paper, a magnetical core-shell Fe3O4@SiO2@Sn-TiO2 (FST-S) composite photocatalyst was designed and prepared via prepared via Stober and sol-gel methods. The effect of Sn2+ coating TiO2 on the surface of Fe3O4@SiO2 nanoparticles was principally investigated. The photocatalytic performance and recyclability of FST-S were evaluated by photodegradation of tetracycline hydrochloride (TC). Experimental results show that Sn2+ doping increased the content of TiO2 in composite photocatalyst. Because some Sn2+ ions lead to the decrease in the stability of Sn2+-TiO2 nanoparticles and then low-stable Sn2+-TiO2 nanoparticles enter into the composite photocatalyst by condensation with the Sn2+-TiO2 outer shells of FST-S. The photodegradation results show that FST-S sample exhibits an outstanding photocatalytic capacity with a superior degradation rate of 98.2% within 40 min and a good reusability without significant decrease of activity after reused for six cycles. The reaction rate constant (k) of the FST-S was 3.86 times compared with that of without Sn doping Fe3O4@SiO2@Sn (FST). Reactive species scavenging experiments revealed that O2-• it plays a dominant role in photodegradation process. The distinct enhancement of photocatalytic activity of Fe3O4@SiO2@Sn-TiO2 is mainly ascribed to the high amount of TiO2 and low recombination rate of photogenerated electron-holes. This work initiates a novel strategy to prepare magnetical core-shell photocatalysts with excellent activity.

Hydrophobic silica aerogels are attractive and highly efficient adsorbent for oil wastewater. However, the hydrophobicity seriously affects their dispersibility in water and limits the application for cationic and anionic dyes adsorption. Herein, a green sol-gel method was developed to prepare silica aerogels by using rice husk ash as silica source. The results demonstrate that heat treatment significantly impacts surface functional groups and pores of silica aerogels, which can be easily adjusted by changing heat treatment temperature. Cationic (Methyl blue, MB) and anionic (Congo red, CR) dyes were used to evaluate the adsorption ability of modified silica aerogels. The maximum MB and CR adsorption capacities of silica aerogel treat at 500℃ (SA-500) reached to 428.9 and 437.2 mg/g, respectively, which was achieved by simple control of pH. Besides, the adsorption of MB and CR by the SA-500 obeys the pseudo-second-order adsorption model. Electrostatic attraction and hydrogen bonds are critical for the adsorption of MB and CR. Furthermore, the adsorption efficiency of SA-500 for MB and CR was still as high as 95.5 % and 89.5 %, respectively, after 10 cycles of adsorption/desorption. Thus, SA-500 shows a promising application in removing both cationic and anionic dyes from wastewaters.

In the traditional Fenton process, the efficient generation of hydroxyl radical (HO ) strongly relies on an acidic circumstance and the iron ions would precipitate and form large amounts of hazardous iron-containing sludge at alkaline pH. To realize stable heterogeneous Fenton-like catalytic degradation at alkaline condition, Fe3O4 submicrospheres with SiO2 coating were successfully synthesized by using water glass as the silica sources via a facile ultrasound assisted method. The as-obtained Fe3O4@SiO2 spheres were further used as catalysts for the Fenton-like degradation of tetracycline hydrochloride (TC). The Fe3O4@SiO2 submicrospheres exhibited superior catalytic activity in higher pH environment (pH value = 11), and the degradation efficiency toward TC was ca. 80% after ten successive runs. The kinetics for the catalytic degradation of TC were agreed well with the second-order kinetic model. The reaction rate constant (k) over the Fe3O4@SiO2 submicrospheres at a pH value of 11 was 7.69 times greater than that at a pH value of 3. Reactive species scavenging experiments revealed that HO and superoxide radical (O2− / HO2− ) played a dominant role during the Fenton-like degradation of TC at pH 3 and pH 11, respectively. Possible Fenton-like degradation pathways of TC were proposed through the identification of intermediates using the high performance liquid chromatography coupled with mass spectrometry (HPLC-MS), which involved cleavage of methyl groups, N-dimethyl group, and hydroxy groups, ring-opening reaction, etc. The degradation efficiency of TC was close to 91.5% and total organic carbon (TOC) in solution was eliminated by about 41.4% at the optimized conditions. In a word, with the unique acidic surface properties and abundant Si-OH bonds, the Fe3O4@SiO2 submicrospheres exhibited well dispersion, good catalytic activity, strong alkali resistance and excellent recyclability in an ultrasonic-Fenton-like system.

In order to construct tighter heterostructures, a novel Z-scheme β-Bi2O3/g-C3N4 composite (xBC) was synthesized by in-situ growth method. The crystal phase, morphology, chemical composition, optical and photoelectrochemical properties of the composites were investigated by XRD, FT-IR, SEM, TEM, XPS, UV–vis DRS, EIS, etc. The characterizations verified that β-Bi2O3 nanosheets grew uniformly on the surface of g-C3N4. Meanwhile, the photocatalytic performance of xBC composites were also evaluated by degrading Rhodamine B (RhB) and p-Nitrophenol (PNP) under visible-light irradiation. As a result, 0.5BC exhibited the most superior performance, the removal efficiencies reached 71.6% for PNP in 300min and 94.8% for RhB in 120 min, with a rate constant (0.0233min−1) of 7.1 and 5.8 times than that of g-C3N4 and β-Bi2O3, respectively. Evidences that Z-scheme carries transfer path were strongly confirmed by XPS, PL and reactive species analysis.

A novel α/β-Bi2O3 hetero-phase junction (xBB) was successfully prepared by a simple in-situ growth method without further calcination, in which α-Bi2O3 served as the substrate for the growth of β-Bi2O3 nanosheets. The nanocomposites were well characterized by XRD, SEM, TEM, UV–vis DRS, XPS, EIS, etc. The characterizations testified that the bismuth oxides of two crystal phases were in close contact, and the hetero-phase junction was formed. The photocatalytic performance was evaluated by degradation of rhodamine B (RhB) and tetracycline hydrochloride (TC-HCl) under visible light illumination. With the optimum mass ratio, 0.5BB sample exhibited the highest photocatalytic activity, the removal rates were 82.7 % for TC-HCl in 120 min and 94.9 % for RhB in 90 min, and a rate constant of 0.0297min−1 was evaluated for RhB degradation, which were higher than that of pure α-Bi2O3 (0.0019 min−1) and β-Bi2O3 (0.0028 min−1) by a factor of 15.6 and 11.9, respectively. The synthetic method provides a promising route for the in-situ construction of hetero-phase junction nanocomposites.