[Health risk assessment of heavy metals and metalloid in drinking water in a region of Huaihe River Basin from 2015 to 2019].

OBJECTIVE: To evaluate the chronic health risk of heavy metals and metalloid in drinking water through oral ingestion in a typical area. METHODS: Monitoring data of seven heavy metals and metalloid elements(Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd) in drinking water in a typical area of Huaihe River Basin were collected from 2015 to 2019. The health risks of heavy metals and metalloid in drinking water in the area were assessed using the classic four-step health risk assessment model. RESULTS: The average concentrations of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd in drinking water in the typical area of Huaihe River Basin were(0.13±0.45), (0.49±0.49), (0.34±0.99), (1.10±2.49), (32.29±126.64), (2.13±0.50) and(0.03±0.04) µg/L, respectively. In which, Hg, Mn and Ni exceeded the limit of the Standard for Drinking Water(GB 5749-2006), the exceedance rates were 2.14%, 6.79% and 0.3%, respectively, and the maximum exceedance times were 2.61, 8.90 and 0.34, respectively. The chronic non-carcinogenic risks of Hg, As, Pb, Ni, Mn, Cr~(6+) and Cd were 1.32×10~(-2), 4.99×10~(-2), 2.97×10~(-3), 1.68×10~(-3), 7.04×10~(-3), 2.17×10~(-2) and 1.83×10~(-3), respectively. The carcinogenic risks of As, Pb, Cr~(6+) and Cd were 2.24×10~(-5), 8.82×10~(-8), 3.25×10~(-5) and 5.86×10~(-7), respectively. CONCLUSION: Hg, Mn and Ni in drinking water exceeded the standard in a typical area of Huaihe River Basin from 2015 to 2019. The chronic non-carcinogenic risks of Hg, As and other 7 heavy metals and metalloid are at an acceptable level(HQ≤1), while As and Cr~(6+) have certain carcinogenic risks(10~(-6)≤CR≤10~(-4)).

An experimental study on the use of a sequencing-batch membrane bioreactor (SBMBR) for the treatment of mixed municipal wastewater.

Several water treatment techniques have been combined using the sequencing batch reactor with the membrane bioreactor for addressing water pollution. However, cleaning of the membrane is dependent on the approach involved as well as the operating conditions. In the present study, the sequencing-batch membrane bioreactor was used to treat real mixed municipal wastewater. The pollutant removal and membrane filtration performances were examined. The results show that the average removal rates of chemical oxygen demand (COD), total nitrogen, NH3-N, total phosphorus, and turbidity were 90.75, 63.52, 92.85, 87.58, and 99.48%, respectively, when the system was in continuous operation for 95 days. The membrane had a significant effect on COD and turbidity removal and provided stable performances for nitrogen and phosphorus removal. By observing the appearance of the membrane modules before and after the cleaning operation, it was concluded that the deposited sludge and granular sediment on the membrane surface can be effectively removed by hydraulic cleaning. In addition, recovery of membrane filtration performance to 60% of that of a new membrane can be achieved. Furthermore, we found that different sequences and duration of cleaning have different effects on the recovery of membrane filtration performance.

Facile and efficient hypervalent iodine(III)-mediated meso-functionalization of porphyrins.

Highly facile and efficient synthesis of a variety of meso-functionalized porphyrins was accomplished by PhI(OAc)(2)-NaAuCl(4) mediated direct nucleophilic substitution reactions of [5,10,15-triphenylporphyrinato]zinc(II) (Zn1) with different amines and thiophenols. When [5,15-dibromo-10,20-diphenylporphyrinato]zinc(II) (Zn12) was used as the starting porphyrin under similar conditions, the double nucleophilic substitution products were obtained in good yields.

Practical and efficient synthesis of various meso-functionalized porphyrins via simple ligand-free nickel-catalyzed C-O, C-N, and C-C cross-coupling reactions.

Various meso-functionalized porphyrins were conveniently synthesized by direct reactions of meso-bromoporphyrins with oxygen-, nitrogen-, and carbon-based nucleophiles in moderate to high yields via practical, efficient, and ligand-free nickel-catalyzed C-O, C-N, and C-C bond-forming reactions. The central metal ions of the substrate porphyrin have much effect on the reactions. Introduction of Ni(II) as a central metal ion into the substrate porphyrin markedly accelerated the cross-coupling.

C-F bond activation by modified sulfinatodehalogenation: facile synthesis and properties of novel tetrafluorobenzoporphyrins by direct intramolecular cyclization and reductive defluorinative aromatization of readily available beta-perfluoroalkylated porphyrins.

A facile and efficient synthesis of various novel fluorinated extended porphyrins has been developed. The method is based on the direct intramolecular cyclization and reductive defluorinative aromatization of readily available beta-perfluoroalkylated porphyrins by highly selective C-F bond activation under modified sulfinatodehalogenation reaction conditions. Various beta-(omega-chloroperfluoroalkyl)-meso-tetraphenylporphyrins prepared readily by sulfinatodehalogenation reaction or palladium-catalyzed cross-coupling reaction were treated with Na2S2O4/K2CO3 (10:10 equiv per RF tail) in DMSO at 100 degrees C for 10-30 min, resulting in good yields of novel beta-tetrafluorobenzo-meso-tetraphenylporphyrins. That further reduction of C-F bonds of the products was not observed under the optimal conditions indicates the high selectivity of the reaction. It was found that the amount of sodium dithionite, base, and central metal ion of substrate porphyrins play important roles in the reaction. Detailed mechanism investigations and systematic studies on X-ray crystallographic structure and photophysical and electrochemical properties of a series of new tetrafluorobenzoporphyrins are also reported.

A general and efficient palladium-catalyzed intramolecular cyclization reaction of beta-brominated porphyrins.

A general and efficient synthesis of fused five-membered porphyrins from the readily available beta-brominated porphyrins via palladium-catalyzed intramolecular cyclization has been developed, which can be applied for various metal complexes of beta-brominated porphyrins or free base ones and generally results in good yields of the fused five-membered porphyrins.

Unexpected bromination ring-opening of tetraarylporphyrins.

An unexpected, mild, efficient bromination ring-opening method has been developed for convenient synthesis of various novel biladienes or brominated porphyrins by controlling the amounts of NBS used.

A novel and facile Zn-mediated intramolecular five-membered cyclization of beta-tetraarylporphyrin radicals from beta-bromotetraarylporphyrins.

A novel and facile method for the Zn-mediated intramolecular cyclization of beta-porphyrin radicals has been developed for the convenient and effective construction of newly fused five-membered porphyrin systems from readily available beta-bromotetraarylporphyrins.