Faqin Dong

The role of nano-sized manganese coatings on bone char in removing arsenic(V) from solution: Implications for permeable reactive barrier technologies.

Although the removal of arsenic(V) (As(V)) from solution can be improved by forming metal-bearing coatings on solid media, there has been no research to date examining the relationship between the coating and As(V) sorption performance. Manganese-coated bone char samples with varying concentrations of Mn were created to investigate the adsorption and desorption of As(V) using batch and column experiments. Breakthrough curves were obtained by fitting the Convection-Diffusion Equation (CDE), and retardation factors were used to quantify the effects of the Mn coatings on the retention of As(V). Uncoated bone char has a higher retention factor (44.7) than bone char with 0.465 mg/g of Mn (22.0), but bone char samples with between 5.02 mg/g and 14.5 mg/g Mn have significantly higher retention factors (56.8-246). The relationship between retardation factor (Y) and Mn concentration (X) is Y = 15.1 X + 19.8. Between 0.2% and 0.6% of the sorbed As is desorbed from the Mn-coated bone char at an initial pH value of 4, compared to 30% from the uncoated bone char. The ability of the Mn-coated bone char to neutralize solutions increases with increased amounts of Mn on the char. The results suggest that using Mn-coated bone char in Permeable Reactive Barriers would be an effective method for remediating As(V)-bearing solutions such as acid mine drainage.

Spectroscopic study on biological mackinawite (FeS) synthesized by ferric reducing bacteria (FRB) and sulfate reducing bacteria (SRB): Implications for in-situ remediation of acid mine drainage

Mackinawite (FeS), widespread in low temperature aquatic environments, is generally considered to be the first Fe sulfide formed in sedimentary environments which has shown effective immobilization of heavy metals and toxic oxyanions through various sorption reactions. The spectroscopic study researches on mackinawite formed by FRB and SRB and its environmental implication for in-situ remediation of acid mine drainage where contains large amounts of Fe3+ and SO42-. The XRD result of biologically synthetic particles shows that these particles are mainly composed of mackinawite (FeS0.9). The Raman peaks observed at 208, 256, 282, 298cm-1 are attributed to FeS stretching vibrations of mackinawite. The Attenuated Total Reflection-Fourier Transform Infrared Spectroscopy (ATR-FTIR) reveals that the diagnostic bands of low intensity for these FeS particles occur at 412-425cm-1 and 607-622cm-1, which are assigned to the stretching vibrations of SS and FeS bonds. The Raman and IR vibrations from organic components both confirm that these particles are biogenic origin. The IR spectra of biologically synthesized mackinawite for different aging times show that the nano-sized particles mackinwate will be completely oxidized within 10h. All these findings have good implications for in-situ remediation of acid mine drainage.

MicroRNA-191, acting via the IRS-1/Akt signaling pathway, is involved in the hepatic insulin resistance induced by cigarette smoke extract

Cigarette smoke causes insulin resistance, which is associated with type 2 diabetes mellitus (T2DM). However, the mechanism by which this occurs remains poorly understood. Because the involvement of microRNAs (miRNAs) in the development of insulin resistance is largely unknown, we investigated, in hepatocytes, the roles of miR-191 in cigarette smoke extract (CSE)-induced insulin resistance. In L-02 cells, CSE not only decreased glucose uptake and glycogen levels but also reduced levels of insulin receptor substrate-1 (IRS-1) and Akt activation, effects that were blocked by SC79, an activator of Akt. CSE also increased miR-191 levels in L-02 cells. Furthermore, the inhibition of miR-191 blocked the decreases of IRS-1 and p-Akt levels, which antagonized the decreases of glucose uptake and glycogen levels in L-02 cells induced by CSE. These results reveal a mechanism by which miR-191 is involved in CSE-induced hepatic insulin resistance via the IRS-1/Akt signaling pathway, which helps to elucidate the mechanism for cigarette smoke-induced T2DM.

A high-efficiency photocatalyst, flaky anatase@natural rutile composite using one-step microwave hydrothermal synthesis

A flaky photocatalytic composite of anatase@natural rutile(A@NR) was obtained using one-step microwave hydrothermal synthesis, which was designed to overcome the low photocatalytic efficiency stemming from high electron-hole recombination and a narrow photoresponse range. The characterizations were completely elucidated using X-ray diffraction, field emission scanning electron microscopy, Brunauer Emmett Teller surface area, ultraviolet–visible diffuse reflectance spectroscopy, and photoluminescence spectra. The efficiency of A@NR in photocatalytic degradation of methyl orange was determined to be close to that of P25 under UV light and superior to that of P25 under visible light. The excellent photocatalytic activity results from the synergistic effects of substituting Fe ions, which alter the band structure, and the isomerism of anatase and natural rutile, which separates the photogenerated electron holes. The calculated apparent quantum efficiencies of 32.8 and 12.9% for A@NR, under UV and visible light irradiation, respectively, show a higher catalytic activity and a more effective photoinduced electron-hole separation in A@NR than in P25.

Contribution of surface functional groups and interface interaction to biosorption of strontium ions by Saccharomyces cerevisiae under culture conditions

Contribution of surface functional groups and detailed interface interaction for biosorption of strontium ions by Saccharomyces cerevisiae under culture conditions was investigated through chemical modification, in addition to spectroscopic and mesoscopic methods. The results showed that the biosorption ratio decreased approximately 10%, 60%, and 70% for ester group, carboxyl group, and amino group modified yeast cells, respectively. Fourier transform infrared spectroscopy and surface functional group potentiometric titration results revealed that –NH2, –COOH, and –OH were the major binding groups. The amino group displayed the greatest contribution to biosorption of strontium ions, followed by the carboxyl group and, finally, the ester group. Electrostatic interaction was the initial role and establishment of a coordination complex was the most common mechanism of interface interaction between strontium ions and the yeast cell surface. Mesoscopic analysis suggested that strontium ions may be first adsorbed on the cell surface and then transported into the cytoplasm. Transmembrane transport and the bioaccumulation model revealed that yeast cells may regulate the distribution of strontium ions through a transportation mechanism. A detailed interface interaction was discussed for S. cerevisiae biosorption of low concentration strontium ions under culture conditions. The results suggested that optimal biosorption for a microorganism relies upon enrichment of proteins and polysaccharides on the cell surface.

Effects of riboflavin and AQS as electron shuttles on U(VI) reduction and precipitation by Shewanella putrefaciens

Understanding the mechanisms for electron shuttles (ESs) in microbial extracellular electron transfer (EET) is important in biogeochemical cycles, bioremediation applications, as well as bioenergy strategies. In this work, we adapted electrochemical techniques to probe electrochemically active and redox-active Shewanella putrefaciens. This approach detected flavins and humic-like substances of Shewanella putrefaciens, which were involved in electron transfer to the electrode. A combination of three-dimensional excitation-emission (EEM) florescence spectroscopy methods identified a mixture of riboflavin and humic-like substances in supernatants during sustained incubations. The reductive behaviour of U(VI) by Shewanella putrefaciens in the presence of riboflavin (RF) and anthraquinone-2-sulfonate (AQS) was also investigated in this study. The results indicated that RF and AQS significantly accelerated electron transfer from cells to U(VI), thus enhancing reductive U(VI). The precipitate was further evidenced by SEM, FTIR, XPS and XRD, which demonstrated that chernikovite [H2(UO2)2(PO4)2·8H2O] became the main product on the cell surface of S. putrefaciens. In a contrast, U(IV) mainly existed amorphously on the cell surface of S. putrefaciens with added RF and AQS. This work has significant implications in elucidating RF and AQS as electron shuttles that are efficient in reduction of uranium in geological environments.

Interface effect of ultrafine mineral particles and microorganisms

Ultrafine mineral particles and individual microorganisms are important components of atmospheric particulate matter and have high correlations in morphology, coexistence, and aerodynamic behavior. However, the interaction between atmospheric particles and microorganisms in air is ignored while much attention has paid to the harm caused by atmospheric particles to humans. In addition to serving as a carrier for microorganisms, a living nutrient source for organisms, and indirectly reducing the atmospheric CO2 content, atmospheric particulate matter may also have impact on microorganisms due to their own size effect, surface activity, and component toxicity, so as to increase the degree of joint harm to humans and expand the transmission route. Interface effect of ultrafine mineral particles and microorganisms has great significance in atmospheric ultrafine mineral microbial biomigration and adsorption, surface biological change behavior, inhalable mineral granules (IMG) hazards, and toxicological risk reasonable assessment. It is essential for developing a scientific air quality standard, origination of air transport fine particles and collection of ancient biological environment information, biological metallurgy and soil synergies activation of IMG microbial/gas/solid, even biological protection in aircraft. To verify IMG/single, multi-strain particle interaction mechanism, the change of mineral particle size, surface morphology of IMG in interfacial interaction process, surface charge, surface groups, mineral surface adsorption, and migration and change of elements, phase change, surface restructuring, dissolution, and the type and quantity of free radicals over the time must be considered. Through analyzing adsorption process and mineral crystallization induced by bacteria, exploring the amount and species change of acid, enzymes, sugar, the microbial oxidation damage, and other biological effects in vitro by Ames test et al., studying the variation of cell membrane structure and metabolism of common microorganism, and then proving the microorganisms activity characteristic expression of fine IMG and its attachment, the interface characteristics and the production of biofilm interaction, the toxicity model of IMG interface/microbial membrane system could be established. After a rigorous peer-review process, 15 papers about mineral particles and microorganisms or cells were accepted for publication in the Environmental Science and Pollution Research Special Issue: IMPM. The brief introduction of articles accepted for SI: IMPM is given as follows: In the paper of BThe interface interactions behavior between E. coli and two kinds of fibrous minerals,^ batch experiments were performed to deal with the interaction of Escherichia coli and two fibrous minerals (brucite and palygorskite), and the interface and liquid phase characteristics in the short-term interaction processes were discussed. Studies of short-term interaction between E. coli and brucite and palygorskite can help to understand the effect of fibrous minerals on microeubiosis of human normal flora and the contribution of microbial behaviors on the fibrous minerals weathering in the natural environment. Li et al. found that the existence of the bacteria cells and EPS significantly affected the surface properties of calcite and provides a theoretical basis for the mechanism of PM fine particulate matter on human health impact for further study. Responsible editor: Philippe Garrigues

Variation of preserving organic matter bound in interlayer of montmorillonite induced by microbial metabolic process

This paper aimed to investigate the variation of preserving organic matter bound in the interlayer space of montmorillonite (Mt) induced by a microbe metabolic process. We selected Bacillus pumilus as the common soil native bacteria. The alteration of d001 value, functional group, and C,N organic matter contents caused by bacteria were analyzed by XRD, FTIR, and elementary analyzer, respectively. XRD results showed that the d001 value of montmorillonite increased with the concentration decreasing and decreased with the culture time increasing after interacting with bacteria indicating the interlayer space of montmorillonite was connected with the organic matter. The findings of long-term interaction by resetting culture conditions implied that the montmorillonite buffered the organic matter when the nutrition was enough and released again when the nutrition was lacking. The results of the elementary analyzer declared the content of organic matter was according to the d001 value of montmorillonite and N organic matter which played a major impact. FTIR results confirmed that the Si-O stretching vibrations of Mt were affected by the functional group of organic matter. Our results showed that the montmorillonite under the influence of soil bacteria has a strong buffering capacity for preserving organic matter into the interlayer space in a short-term. It might provide critical implications for understanding the evolution process and the preservation of fertilization which was in the over-fertilization or less-fertilization conditions on farmland.

Infrared and Raman spectroscopic characterizations on new Fe sulphoarsenate hilarionite (Fe2((III))(SO4)(AsO4)(OH)·6H2O): Implications for arsenic mineralogy in supergene environment of mine area.

Hilarionite (Fe2 (SO4)(AsO4)(OH)·6H2O) is a new Fe sulphoarsenates mineral, which recently is found in the famous Lavrion ore district, Atliki Prefecture, Greece. The spectroscopic study of hilarionite enriches the data of arsenic mineralogy in supergene environment of a mine area. The infrared and Raman means are used to characterize the molecular structure of this mineral. The IR bands at 875 and 905cm(-1) are assigned to the antisymmetric stretching vibrations of AsO4(3-). The IR bands at 1021, 1086 and 1136cm(-1) correspond to the possible antisymmetric and symmetric stretching vibrations of SO4(2-). The Raman bands at 807, 843 and 875cm(-1) clearly show that arsenate components in the mineral structure, which are assigned to the symmetric stretching vibrations (ν1) of AsO4(3-) (807 and 843cm(-1)) and the antisymmetric vibration (ν3) (875cm(-1)). IR bands provide more sulfate information than Raman, which can be used as the basis to distinguish hilarionite from kaňkite. The powder XRD data shows that hilarionite has obvious differences with the mineral structure of kaňkite. The thermoanalysis and SEM-EDX results show that hilarionite has more sulfate than arsenate.

Reciprocity Effect Between Silicate Bacterium and Wollastonite

This chapter studies the reciprocity effect between wollastonite and a strain of silicate bacterium isolated from purple soil. The changes of pH value, glucose (GLU) residual concentration, electrolyte, and Mn, Si, Fe, etc., in the culture liquid with wollastonite after 48 h were analyzed. The results show that the GLU consumption of silicate bacterium with wollastonite was 2.5 times of the bacterial control. It indicates that wollastonite can obviously promote silicate bacterium growth, but the silicate bacteria cells were badly broken and even distorted observed by SEM. The solubilization of Si element by silicate bacterium from wollastonite reached above ten times that of the wollastonite control. At the same time, three typical peak intensities in FTIR of wollastonite (898 cm−1, 925 cm−1, 962 cm−1) lowered obviously after the interaction with silicate bacterium, which shows that a great deal of Si has dissolved. Therefore, it is clear that wollastonite has a remarkable effect on the growth of silicate bacterium and there has been an obvious solubilization of Si.