Effect of flavin adenine dinucleotide (FAD) on Desulfovibrio desulfuricans corrosion of pipeline welded joint.

The impact of Flavin adenine dinucleotide (FAD) on sulfate-reducing bacteria (SRB) corrosion of a pipeline welded joint (WJ) was investigated under anaerobic condition in this paper. The results showed that the thickness of the corrosion product on heat affected zone (HAZ) was lower than that on base metal (BM) and welded zone (WZ), and the FAD addition enhanced the development of the protruding microbial tubercles on the WJ. The local corrosion degrees of the BM and WZ coupons were significantly higher than that of the HAZ coupon. Besides, the FAD addition simultaneously promoted local corrosion of all three zones of the WJ in the SRB inoculated environment, and the promotion role was much more pronounced on the WZ coupons. The selective promotion effect of FAD on SRB corrosion in the WJ was attributed to the special structure of the WZ, the selected SRB attachment and the FAD/FADH2 redox feedback cycle.

Low efficiency of cathodic protection in marine tidal corrosion of X80 steel in the presence of Pseudomonas sp.

Owing to the effects of seawater erosion, dry/wet cycles, dissolved oxygen and microorganisms, the corrosion of steel in marine tidal environments is a serious threat to the safe and stable operation of marine equipment and facilities. Among them, microbiologically influenced corrosion (MIC) of steel has received increasing attention. Cathodic protection (CP) is frequently used to control the corrosion of offshore steel structures. However, in the presence of microorganisms, implementation of CP and its specific effects remain controversial. In this study, the influence of Pseudomonas sp. on the CP efficiency of Zn sacrificial anodes (ZnSAs) during the tidal corrosion of X80 steel was studied. The results showed that CP efficiency exceeded 92% in an abiotic tidal environment. However, in the biotic tidal environment, Pseudomonas sp. significantly reduced the CP efficiency. Pseudomonas sp. and its biofilm promoted the corrosion of steel under CP, inhibited the formation of a complete calcareous deposit layer, which weakened the CP efficiency of ZnSA in the marine tidal environment.

Accelerated role of exogenous riboflavin in selective Desulfovibrio desulfuricans corrosion of pipeline welded joints.

Effect of exogenous riboflavin on sulfate-reducing bacteria (SRB) corrosion of a spirally welded joint (WJ) of X80 steel was investigated by SEM/EDS, XPS, 3D ultra-depth microscopy and electrochemical measurements. The main style of SRB corrosion of the WJ is local corrosion. The local corrosion sensitivity of the heating affected zone (HAZ) of the WJ was always lower than that of the weld zone (WZ) and base metal (BM) in all the SRB-inoculated mediums. SRB corrosion of the WJ is selective. With the dosage increase of riboflavin, the selective pitting corrosion of the WJ becomes more pronounced.

Corrosion behavior of X80 pipeline steel local defect pits under static liquid film.

In this work, the corrosion electrochemical information under different thicknesses of liquid film was tested. The local corrosion development process of X80 steel under different thicknesses of liquid film was studied by combining the detection and analysis of scale and the matrix corrosion morphology. The corrosion was studied by EIS. The composition and microstructures of corrosion scale at different locations were detected by EDS and SEM, and the metal matrix was detected by 3D topography technology to analyze the local corrosion. The results show that a liquid film with a thickness greater than or equal to 1 mm has no effect on the mechanism of the corrosion process, but has a control effect on the corrosion rate and the time of each stage in corrosion. The corrosion process can be divided into two stages: in the early stage, the concentration of ions inside and outside ADP is the same, so the corrosion is uniform; in the later stage, due to the influence of CO2 dissolution and mass transfer distance, the cathodic reaction is mainly outside ADP and the anodic reaction is mainly inside ADP. In addition, corrosion acidification occurs in ADP, which enhances the corrosion process in ADP.

Hazardous Petroleum Sludge-Derived Nitrogen and Oxygen Co-Doped Carbon Material with Hierarchical Porous Structure for High-Performance All-Solid-State Supercapacitors.

Rational design and sustainable preparation of high-performance carbonaceous electrode materials are important to the practical application of supercapacitors. In this work, a cost-effective synthesis strategy for nitrogen and oxygen co-doped porous carbon (NOC) from petroleum sludge waste was developed. The hierarchical porous structure and ultra-high surface area (2514.7 m2 g-1) of NOC electrode materials could provide an efficient transport path and capacitance active site for electrolyte ions. The uniform co-doping of N and O heteroatoms brought enhanced wettability, electrical conductivity and probably additional pseudo-capacitance. The as-obtained NOC electrodes exhibited a high specific capacitance (441.2 F g-1 at 0.5 A g-1), outstanding rate capability, and cycling performance with inconspicuous capacitance loss after 10,000 cycles. Further, the assembled all-solid-state MnO2/NOC asymmetrical supercapacitor device (ASC) could deliver an excellent capacitance of 119.3 F g-1 at 0.2 A g-1 under a wide potential operation window of 0-1.8 V with flexible mechanical stability. This ASC device yielded a superior energy density of 53.7 W h kg-1 at a power density of 180 W kg-1 and a reasonable cycling life. Overall, this sustainable, low-cost and waste-derived porous carbon electrode material might be widely used in the field of energy storage, now and into the foreseeable future.

Predicted no-effect concentrations for mercury species and ecological risk assessment for mercury pollution in aquatic environment.

Mercury (Hg) exists in different chemical forms presenting varied toxic potentials. It is necessary to explore an ecological risk assessment method for different mercury species in aquatic environment. The predicted no-effect concentrations (PNECs) for Hg(II) and methyl mercury (MeHg) in the aqueous phase, calculated using the species sensitivity distribution method and the assessment factor method, were 0.39 and 6.5×10(-3)µg/L, respectively. The partition theory of Hg between sediment and aqueous phases was considered, along with PNECs for the aqueous phase to conduct an ecological risk assessment for Hg in the sediment phase. Two case studies, one in China and one in the Western Black Sea, were conducted using these PNECs. The toxicity of mercury is heavily dependent on their forms, and their potential ecological risk should be respectively evaluated on the basis of mercury species.

The potential risk assessment for different arsenic species in the aquatic environment.

The different toxicity characteristics of arsenic species result in discrepant ecological risk. The predicted no-effect concentrations (PNECs) 43.65, 250.18, and 2.00×10(3)µg/L were calculated for As(III), As(V), and dimethylarsinic acid in aqueous phase, respectively. With these PNECs, the ecological risk from arsenic species in Pearl River Delta in China and Kwabrafo stream in Ghana was evaluated. It was found that the risk from As(III) and As(V) in the samples from Pearl River Delta was low, while much high in Kwabrafo stream. This study implies that ecological risk of arsenic should be evaluated basing on its species.

Solvent controlled sugar-rhodamine fluorescence sensor for Cu(2+) detection.

A "turn-on" fluorescence probe for Cu(2+) detection has been reported according to a Cu(2+) triggered spirolactam ring-opening reaction. The probe is a double-responsive fluorescent and colorimetric Cu(2+)-specific sensor in aqueous solution containing 20% of acetonitrile with high selectivity and excellent sensitivity (limit of detection is 12 µg L(-1)). Furthermore, the significant color changes visible to the naked eye at the concentration of 3 µM (ca. 0.20 mg L(-1)) are about ten times lower than the WHO (World Health Organization) recommended level (2.0 mg L(-1)) for Cu(2+) ions in drinking water.

A "turn-on" fluorescent Hg2+ chemosensor based on Ferrier carbocyclization.

A "turn-on" fluorescent chemosensor with excellent selectivity and satisfactory sensitivity on Hg(2+) detection in 100% water media has been established employing a carbohydrate based Ferrier carbocyclization reaction. The probe has also presented satisfactory results for the imaging of Hg(2+) ions in cells and organisms.

Toxicity-based assessment of the treatment performance of wastewater treatment and reclamation processes.

The reclamation and reuse of wastewater is one of the possible ways to relieve the serious fresh water resource crisis in China. Efficient reclamation treatment technologies ensure the safe reuse of reclaimed water. In order to screen out and evaluate technologies appropriate for reclamation treatment, a great deal of efforts have been brought to bear. In the present study, a toxicity-based method including a Photobacterium phosphoreum test for acute toxicity and SOS/umu test for genotoxicity, accompanied by the traditional physicochemical parameters DOC (dissolved organic carbon) and UV254 (absorbance at 254 nm), was used to measure the treatment performance of different reclamation processes, including the anaerobic-anoxic-oxic biological process (A2O) and subsequent physical/chemical reclamation processes (ultrafiltration, ozonation, chlorination). It was found that for the secondary effluent after the A2O process, both the toxicity and physicochemical indices had greatly decreased compared with those of the influent. However, chemical reclamation processes such as ozonation and chlorination could possibly raise toxicity levels again. Fortunately, the toxicity elevation could be avoided by optimizing the ozone dosage and using activated carbon after ozonation. It was noted that by increasing the ozone dosage to 10 mg/L and employing activated carbon with more than 10 min hydraulic retention time, toxicity elevation was controlled. Furthermore, it was shown that pre-ozonation before activated carbon and chlorination played an important role in removing organic compounds and reducing the toxicity formation potential. The toxicity test could serve as a valuable tool to evaluate the performance of reclamation processes.

A biological safety evaluation on reclaimed water reused as scenic water using a bioassay battery.

An assessment method based on three toxicity tests (algae growth inhibition, daphnia immobilization and larval fish toxicity) was used to screen the biological safety of reclaimed water which was reused as sole replenishment for scenic water system in a park (SOF Park) in northern China. A total of 24 water samples were collected from six sites of water system in the SOF Park in four different seasons. The results indicated that: (1) the reclaimed water directly discharged from a reclamation treatment plant near the SOF Park as influent of park had relatively low biological safety (all samples were ranked as C or D); (2) the biological safety of reclaimed water was improved greatly with the ecological reclamation treatment processes composing of artificial wetland system and followed oxidation pond system; (3) the biological safety of reclaimed water in the main lake of SOF Park kept at a health status during different seasons (all samples were ranked as A); (4) there was some certain correlation (R2 = 0.5737) between the sum of toxicity scores and dissolved organic carbon for the studied water samples. It was concluded that the assessment method was reliable to screen the safety of reclaimed water reused as scenic water, and the reclaimed water with further ecological purification processes such as artificial wetland and oxidation pond system can be safely reused as scenic water in park.