A novel BiOCl (110)/rGO/Ag3PO4 (111) heterostructure for efficient detoxification of 2,4-dichlorophenol.

An effective method using nontoxic and efficient photocatalysts are crucial for wastewater treatment. Bismuth oxychloride (BiOCl) is considered as one of the valuable photocatalysts due to its unique layered plate like structure, however higher recombination and unsatisfied visible light absorption efficiency seriously affecting its applications. Addition of tetrahedral silver phosphate (Ag3PO4) which is known for its superior photocatalytic efficiency under visible light is believed to be the solution for the issue. Upon further adding of reduced graphene oxide (rGO) could form a bridging structure and enhance the activity. Considering the merits of these materials the BiOCl (110)/rGO/Ag3PO4 (111) heterojunction has been successfully constructed for 2,4-dichlorophenol (DCP) enhanced detoxification. The efficiency in degradation was found to be 94.8% by BiOCl/rGO/Ag3PO4 (k = 0.01879 min-1) that was greater to that of pure Ag3PO4 (∼1.9 times; k = 0.00818 min-1) and pure BiOCl (∼2.8 times; k = 0.00642 min-1) after 60 min of visible light irradiation. The mechanism of degradation was explained through the principle of heterojunction energy-band theory. Furthermore, 2,4-dichlorophenol (2,4-DCP) degradation products identification was carried out by ESI/LC-MS to propose the degradation pathway. Furthermore, the phytotoxicity of the intermediate products was investigated by estimating the germination index (GI) values on Phaseolus vulgaris (P. vulgaris) at different time intervals and the GI values were found to be 10.79% and 80.17% before and after degradation respectively. Thus, our results revealed that efficient and significant toxicity reduction was observed in this photodegradation.

Synthesis of N-doped carbon dots for highly selective and sensitive detection of metronidazole in real samples and its cytotoxicity studies.

The current investigation reports the synthesis of N-CDs using glucosamine, ascorbic acid, and ethylenediamine precursors by a simple hydrothermal technique. The formation of N-CDs was proved by various characterisation techniques such as X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Fourier-Transform Infrared Spectrophotometer (FT-IR). The optical properties were investigated by fluorescence and UV-vis spectrophotometer. Also, N-CDs showed high selectivity in detecting the MTZ compared to several other analytes. However, the metronidazole serves as an antibiotic against several microbial diseases but also a genotoxic, carcinogenic to the human when used in excessive dosage. The synthesised N-CDs showed high selectivity in detecting the MTZ compared to several other analytes. Besides, the cytotoxicity of the N-CDs was studied to evaluate its toxicity against the HeLa cancer cells. It showed 65.6% cell viability and 34.3% toxicity against the cancerous cells, and similarly 71% of cells viability against H9C2 cells. Thus, the current investigation explores the promising selective sensing of N-CDs against MTZ, along with that, it proved its cytotoxicity against HeLa cancerous cells and non-toxicity against H9C2 cells. The synthesised CDs can be better MTZ sensors and anti-cancer agents on further development at the industrial scale.

Facile synthesis of ZnO nanoparticles by Actinidia deliciosa fruit peel extract: Bactericidal, anticancer and detoxification properties.

Synthesis of nanoparticles by eco-friendly method pulled an extensive concern worldwide due its biocompatibility and wide range of applications as catalysts, microbicidal agents, cancer treatment, sensors etc. Though different chemical methods available for preparation of ZnO nanoparticles, synthesis by utilizing plant material is an excellent substitute and green method as well. The present study describes preparation of ZnO nanoparticles by low-cost green synthetic way using Actinidia deliciosa (kiwi) fruit peel extract and its excellent biological and catalytic properties. The synthesized nanoparticles were well characterized by UV visible spectroscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and Energy-dispersive X-ray spectroscopy (EDAX). The bactericidal activity of the ZnO nanoparticles was determined by using Staphylococcus aureus (S. aureus), while mechanism of cell death was studied by SEM images. Superior anticancer activity was also observed in inhibiting the colon cancer cells (HCT116) by the ZnO nanoparticles. In addition, ZnO nanoparticles showed efficient photocatalytic activity towards degradation of p-bromophenol, about 96.3% within 120 min. Furthermore, phytotoxicity of the intermediate products was analyzed using Vigna radiata (V. radiata) as a model plant. About 8.0% of germination index (GI) was observed in pure p-BP while it increased to 82.3%, and exhibited that the detoxification of p-BP was attained after 120 min of degradation. Thus, the present study demonstrates ZnO nanoparticles prepared from simple, rapid, inexpensive, eco-friendly and efficient green method gives alternative root for biomedicine and wastewater treatment technologies.

Operational and biological analyses of branched water-adjustment and combined treatment of wastewater from a chemical industrial park.

The combined biological processes of branched water-adjustment, chemical precipitation, hydrolysis acidification, secondary sedimentation, Anoxic/Oxic and activated carbon treatment were used for chemical industrial wastewater treatment in the Taihu Lake Basin. Full-scale treatment resulted in effluent chemical oxygen demand, total nitrogen, NH3-N and total phosphorus of 35.1, 5.20, 3.10 and 0.15 mg/L, respectively, with a total removal efficiency of 91.1%, 67.1%, 70.5% and 89.3%, respectively. In this process, short-circuited organic carbon from brewery wastewater was beneficial for denitrification and second-sulfate reduction. The concentration of effluent fluoride was 6.22 mg/L, which also met the primary standard. Gas Chromatography-Mass Spectrometry analysis revealed that many types of refractory compounds were present in the inflow. Microbial community analysis performed in the summer by PCR-denaturing gradient gel electrophoresis and MiSeq demonstrated that certain special functional bacteria, such as denitrificans, phosphorus-accumulating bacteria, sulfate- and perhafnate-reducing bacteria, aromatic compound-degrading bacteria and organic fluoride-degrading bacteria, present in the bio-tanks were responsible for the acceptable specific biological pollutant reduction achieved.

Multi-pathway assessment of human health risk posed by polycyclic aromatic hydrocarbons.

To assess aggregate exposure to polycyclic aromatic hydrocarbons (PAHs) via several environmental media and pathways, a probabilistic framework for multi-pathway health risk assessment that integrates PAHs potency equivalence factors, risk estimation modeling, and Monte Carlo simulation was applied to a case study in Nanjing, which is an important industrial city in China. Incremental lifetime risk of additional cancers posed by exposure to 16 USEPA priority PAHs in air, water, soil, and fish was assessed. Risks to three age groups, infants, children, and adults, through various exposure pathways, including oral ingestion, dermal absorption, and inhalation, were estimated. Results of the analysis of risk indicated that B[a]P, B[b]F, and BA were the predominant PAHs pollutants in Nanjing. Risk of additional cancer for local adults was on average 2.62 × 10(-5). The risks were primarily due to ingestion of fish and inhalation, which contributed 99 % of the total risks. By contrast, risk to infants was essentially negligible. Results of a sensitivity analysis indicated that the input variables of concentration of PAHs in fish (C f), the body weight (BW), and the ingestion rate of fish (IRf) were the major influences on estimates of risks.

Can Coronene and/or Benzo(a)pyrene/Coronene ratio act as unique markers for vehicle emission?

Coronene is a high molecular weight polycyclic aromatic hydrocarbon with seven aromatic rings. It, more specifically a lower ratio of Benzo[a]pyrene to Coronone (BaP/COR), is suggested as a marker for vehicle emission. In the present study, emissions of Coronene were measured from residential combustions of wood, crop straw, and pellets. The detection of COR in non-vehicle emission sources, and comparable BaP/COR ratios between the solid fuel combustion and vehicle emissions indicated that the generality of COR or the BaP/COR ratio as markers for the vehicle emission would be questionable, especially for the area where solid fuel combustion dominated the PAHs emission.

Influence of fuel mass load, oxygen supply and burning rate on emission factor and size distribution of carbonaceous particulate matter from indoor corn straw burning.

The uncertainty in emission estimation is strongly associated with the variation in emission factor (EF), which could be influenced by a variety of factors such as fuel properties, stove type, fire management and even methods used in measurements. The impacts of these factors are complicated and often interact with each other. Controlled burning experiments were conducted to investigate the influences of fuel mass load, air supply and burning rate on the emissions and size distributions of carbonaceous particulate matter (PM) from indoor corn straw burning in a cooking stove. The results showed that the EFs of PM (EF(PM)), organic carbon (EFoc) and elemental carbon (EF(EC)) were independent of the fuel mass load. The differences among them under different burning rates or air supply amounts were also found to be insignificant (p > 0.05) in the tested circumstances. PM from the indoor corn straw burning was dominated by fine PM with diameter less than 2.1 microm, contributing 86.4% +/- 3.9% of the total. The size distribution of PM was influenced by the burning rate and air supply conditions. On average, EF(PM), EF(OC) and EF(EC) for corn straw burned in a residential cooking stove were (3.84 +/- 1.02), (0.846 +/- 0.895) and (0.391 +/- 0.350) g/kg, respectively. EF(PM), EF(OC) and EF(EC) were found to be positively correlated with each other (p < 0.05), but they were not significantly correlated with the EF of co-emitted CO, suggesting that special attention should be paid to the use of CO as a surrogate for other incomplete combustion pollutants.

Emissions of parent, nitrated, and oxygenated polycyclic aromatic hydrocarbons from indoor corn straw burning in normal and controlled combustion conditions.

Emission factors (EFs) of parent polycyclic aromatic hydrocarbons (pPAHs), nitrated PAHs (nPAHs), and oxygenated PAHs (oPAHs) were measured for indoor corn straw burned in a brick cooking stove under different burning conditions. The EFs of total 28 pPAHs, 6 nPAHs and 4 oPAHs were (7.9 +/- 3.4), (6.5 +/- 1.6) x 10(-3), and (6.1 +/- 1.4) x 10(-1) mg/kg, respectively. Fuel charge size had insignificant influence on the pollutant emissions. Measured EFs increased significantly in a fast burning due to the oxygen deficient atmosphere formed in the stove chamber. In both restricted and enhanced air supply conditions, the EFs of pPAHs, nPAHs and oPAHs were significantly higher than those measured in normal burning conditions. Though EFs varied among different burning conditions, the composition profiles and calculated isomer ratios were similar, without significant differences. The results from the stepwise regression model showed that fuel burning rate, air supply amount, and modified combustion efficiency were the three most significant influencing factors, explaining 72%-85% of the total variations.

Influence of fuel moisture, charge size, feeding rate and air ventilation conditions on the emissions of PM, OC, EC, parent PAHs, and their derivatives from residential wood combustion.

Controlled combustion experiments were conducted to investigate the influence of fuel charge size, moisture, air ventilation and feeding rate on the emission factors (EFs) of carbonaceous particulate matter, parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives from residential wood combustion in a typical brick cooking stove. Measured EFs were found to be independent of fuel charge size, but increased with increasing fuel moisture. Pollution emissions from the normal burning under an adequate air supply condition were the lowest for most pollutants, while more pollutants were emitted when an oxygen deficient atmosphere was formed in the stove chamber during fast burning. The impacts of these factors on the size distribution of emitted particles was also studied. Modified combustion efficiency and the four investigated factors explained 68%, 72%, and 64% of total variations in EFs of PM, organic carbon, and oxygenated PAHs, respectively, but only 36%, 38% and 42% of the total variations in EFs of elemental carbon, pPAHs and nitro-PAHs, respectively.

Polanyi-based models for the adsorption of naphthalene from aqueous solutions onto nonpolar polymeric adsorbents.

In this research, naphthalene was adopted as the representative model compound of PAHs, and static adsorption of naphthalene from aqueous solution onto three commercial polymeric adsorbents with different pore structure was investigated. Nonlinear isotherms models, i.e., Freundlich, Langmuir, and Polanyi-Dubinin-Manes (PDM) models were tested to fit experimental data, and the experimental data were found to fit well by the PDM model. Through both isotherm modeling and constructing "characteristic curve," Polanyi theory was useful to describe the adsorption process of naphthalene by polymeric adsorbents, providing evidence that a micropore filling phenomenon was involved during the adsorption process. In addition, a good linear correlation was obtained between the naphthalene adsorption capacities and the micropore volume of adsorbents (Vmicro), whereas no linear relationship was found between the naphthalene adsorption capacities and the specific surface area of adsorbents. Based on the PDM model, the micropore volumes of adsorbents was introduced to normalize the equilibrium adsorbed volume (qv), plots of qv/V(micro) vs adsorption potential density for naphthalene on three different polymeric adsorbents were collapsed to a single correlation curve, which would be of great benefit to predict the adsorption capacity of adsorbent for the purpose of adsorption engineering design.

Adsorption equilibria and kinetics for phenol and cresol onto polymeric adsorbents: effects of adsorbents/adsorbates structure and interface.

Phenol and cresol (o-, m-, and p-) were selected as the adsorbates with different dipole moment (cresol>phenol, methyl being electron-drawing group) and solubility (phenol>cresol, methyl being hydrophobic group). Macropore polymers (NDA-1800 and XAD-4), hypercrosslinked polymers (NDA-100), and chemically modified adsorbents (NDA-150 and NDA-99), were comparatively used to investigate the adsorption properties including equilibria, thermodynamics and kinetics. First, all of the results about equilibria show that the adsorption data fit well to the Freundlich model. The adsorption capacity of NDA-99 and NDA-150 especially for phenol is larger in a certain extent than other three types of polymers. The hydrophobic interaction from large specific surface was mainly occurred, while the polar groups containing oxygen and amine markedly enhance the adsorption process via hydrogen interaction. Furthermore, the adsorption amount for NDA-99 and XAD-4 decrease linearly with the solubility of solutes tested. Then, the negative values of enthalpy demonstrate the predominantly exothermic and physical solid-extraction processes. Finally, the relatively more rapid adsorption process could be found onto NDA-150 than NDA-99, with the reason of the double larger pore size of the former. In conclusion, solubility of solute, together with surface area, pore size and modified groups, extremely exerts influences to the adsorption performances.

Immobilization study of biosorption of heavy metal ions onto activated sludge.

Activated sludge was immobilized into Ca-alginate beads via entrapment, and biosorption of three heavy metal ions, copper(II), zinc(II), and chromimum(II), from aqueous solution in the concentration range of 10-100 mg/L was studied by using both entrapped activated sludge and inactivated free biomass at pH < or = 5. A biphasic metal adsorption pattern was observed in all immobilized biomass experiments. The biosorption of metal ions by the biosorbents increased with the initial concentration increased in the medium. The adsorption rate of immobilized pretreated activated sludge(PAS) was much lower than that of free PAS due to the increase in mass transfer resistance resulting from the polymeric matrix. Biosorption equilibrium of beads was established in about 20 h and the adsorbed heavy metal ions did not change further with time. No significant effect of temperature was observed in the test for free biomass while immobilized PAS appeared to be strong temperature dependent in the test range of 10 and 40 degrees C. Besides, the content of activated sludge in the calcium alginate bead has an influence on the uptake of heavy metals. The sorption equilibrium was well modeled by Langmuir isotherm, implying monomolecular adsorption mechanism. Carboxyl group in cell wall played an important role in surface adsorption of heavy metal ions on PAS.