6 research outputs found
Removal of Intermediate Aromatic Halogenated DBPs by Activated Carbon Adsorption: A New Approach to Controlling Halogenated DBPs in Chlorinated Drinking Water
During
chlorine disinfection of drinking water, chlorine may react
with natural organic matter (NOM) and bromide ion in raw water to
generate halogenated disinfection byproducts (DBPs). To mitigate adverse
effects from DBP exposure, granular activated carbon (GAC) adsorption
has been considered as one of the best available technologies for
removing NOM (DBP precursor) in drinking water treatment. Recently,
we have found that many aromatic halogenated DBPs form in chlorination,
and they act as intermediate DBPs to decompose and form commonly known
DBPs including trihalomethanes and haloacetic acids. In this work,
we proposed a new approach to controlling drinking water halogenated
DBPs by GAC adsorption of intermediate aromatic halogenated DBPs during
chlorination, rather than by GAC adsorption of NOM prior to chlorination
(i.e., traditional approach). Rapid small-scale column tests were
used to simulate GAC adsorption in the new and traditional approaches.
Significant reductions of aromatic halogenated DBPs were observed
in the effluents with the new approach; the removals of total organic
halogen, trihalomethanes, and haloacetic acids by the new approach
always exceeded those by the traditional approach; and the effluents
with the new approach were considerably less developmentally toxic
than those with the traditional approach. Our findings indicate that
the new approach is substantially more effective in controlling halogenated
DBPs than the traditional approach
Formation of Brominated Disinfection Byproducts during Chloramination of Drinking Water: New Polar Species and Overall Kinetics
The
formation of brominated disinfection byproducts (Br-DBPs),
which are generally significantly more cytotoxic and genotoxic than
their chlorinated analogues, in chloramination has not been fully
examined. In this work, the formation of new polar Br-DBPs in simulated
drinking waters was examined using state-of-the-art ultraperformance
liquid chromatography/electrospray ionization-triple quadrupole mass
spectrometry. As many as 29 aliphatic, aromatic, or nitrogenous polar
Br-DBPs were detected in chloramination, and five of them (including
2,4,6-tribromoresorcinol, 2,6-dibromo-4-nitrophenol, 2,2,4-tribromo-5-hydroxy-4-cyclopentene-1,3-dione,
2,2,4-dibromochloro-5-hydroxy-4-cyclopentene-1,3-dione, and 2,2,4-bromodichloro-5-hydroxy-4-cyclopentene-1,3-dione)
were tentatively identified. Unlike chlorination, chloramination favored
the formation of aromatic and nitrogenous polar Br-DBPs and was mild
enough to allow polar intermediate Br-DBPs to accumulate. To further
explore the formation mechanism of Br-DBPs in chloramination, a quantitative
empirical model involving 33 major reactions was developed to describe
the overall kinetics. According to the modeling results, bromochloramine
and monobromamine were the major species responsible for 54.2–58.1%
and 41.7–45.7%, respectively, of the formed Br-DBPs, while
hypobromous acid accounted for only 0.2% of the formed Br-DBPs; direct
reactions between monochloramine and natural organic matter accounted
for the majority of the formed chlorinated DBPs (93.7–95.1%);
hypochlorous acid and hypobromous acid in the chloramination were
at ng/L or subng/L levels, which were not enough to cause polar intermediate
Br-DBPs to decompose
Fe-Single-Atom Nanozyme Catalysts for Sensitive and Selective Detection of Nitrite via Colorimetry and Test Strips
Here, a sensitive and selective strategy for the detection
of nitrite
via colorimetry and test strips was developed based on Fe-single-atom
catalysts (Fe SACs) through the oxidation–reduction and diazotization
reactions. Fe SACs possess excellent oxidase-like (OXD) catalytic
activity, which can catalyze the oxidation of the colorless 3,3′,5,5′-tetramethylbenzidine
(TMB) into blue TMBox with the appearance of an obvious absorbance
peak at 652 nm in the presence of oxygen. With the addition of nitrite
(NO2–), the oxidation–reduction
and diazotization reactions between TMB/TMBox and nitrite can induce
the color of the solution to change from blue to green and finally
to yellow, with the increase of the peak at 445 nm. Based on this
strategy, a dual-signal-ratio colorimetric detection method for nitrite
was proposed. Within the concentration range of 1–120 μM,
the ratio of A652/A445 has a favorable linear relationship with the logarithm
concentration of NO2–, with a detection
limit of 0.238 ÎĽM. By combining smartphones with the colorimetric
method, a more intuitive, visual, and convenient test strip detection
platform was developed, which can be utilized for the detection of
nitrite within 2–200 μM. The analysis strategy based
on the Fe-single-atom nanozyme catalysis integrated with the specific
redox/diazotization reaction not only provides a dual-signal ratio
sensing with good sensitivity but holds the advantage of good selectivity
for the utilization of the specific chemical reaction, which has broad
application prospects in food safety supervision and food screening
Antitumorigenic activity of peonidin-3-glucoside or cyaniding-3-glucoside in xenografted nude mice.
<p>(A) Body weight of animals. (B) H&E staining for kidney, liver, and spleen. (C and D) Effects on tumor volume and tumor weight. Nude mice bearing MDA-MB-453 cells as xenografts were treated with control (saline), or group 1 (peonidin-3-glucoside (6 mg/kg/day)) or group 2 (cyaniding-3-glucoside (6 mg/kg/day)). Values are means ± SE (n = 10). *P<0.05. (E) H & E staining, expression of phospho-HER2 and Ki67. Control: saline; Group 1: peonidin-3-glucoside (6 mg/kg/day); group 2: cyaniding-3-glucoside (6 mg/kg/day).</p