Abstract: Water, soil and sediment contaminated with
metolachlor poses a threat to the environment and human health.
We determined the effectiveness of nano-zerovalent iron (NZVI) to
dechlorinate metolachlor [2-chloro-n-(2-ethyl-6-methyl-phenyl)-n-
(1-methoxypropan-2-yl)acetamide] in pH solution and the presence
of aluminium salt. The optimum dosage of degradation of 100 mlL-1
metolachlor was 1% (w/v) NZVI. The degradation kinetic rate (kobs)
was 0.218×10-3 min-1 and specific first-order rates (kSA) was
8.72×10-7 L m-2min-1. By treating aqueous solutions of metolachlor
with NZVI, metolachlor destruction rate were increased as the pH
decrease from 10 to 4. Lowering solution pH removes Fe (III)
passivating layers from the NZVI and makes it free for reductive
transformations. Destruction kinetic rates were 20.8×10-3 min-1 for
pH4, 18.9×10-3 min-1 for pH7, 13.8×10-3 min-1 for pH10. In addition,
destruction kinetic of metolachlor by NZVI was enhanced when
aluminium sulfate was added. The destruction kinetic rate were
20.4×10-3 min-1 for 0.05% Al(SO4)3 and 60×10-3 min-1 for 0.1%
Al(SO4)3.
Abstract: Theobjective of this study was to evaluate the optimal
treatment condition of Fenton oxidation process to removal
contaminant in soil slurry contaminated by petroleum hydrocarbons.
This research studied somefactors that affect the removal efficiency
of petroleum hydrocarbons in soil slurry including molar ratio of
hydrogen peroxide (H2O2) to ferrous ion(Fe2+), pH condition and
reaction time.The resultsdemonstrated that the optimum condition
was that the molar ratio of H2O2:Fe3+ was 200:1,the pHwas 4.0and
the rate of reaction was increasing rapidly from starting point to 7th
hour and destruction kinetic rate (k) was 0.24 h-1. Approximately
96% of petroleum hydrocarbon was observed(initialtotal petroleum
hydrocarbon (TPH) concentration = 70±7gkg-1)
Abstract: Residual dye contents in textile dyeing wastewater have complex aromatic structures that are resistant to degrade in biological wastewater treatment. The objectives of this study were to determine the effectiveness of nanoscale zerovalent iron (NZVI) to decolorize Reactive Black 5 (RB5) and Reactive Red 198 (RR198) in synthesized wastewater and to investigate the effects of the iron particle size, iron dosage and solution pHs on the destruction of RB5 and RR198. Synthesized NZVI was confirmed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The removal kinetic rates (kobs) of RB5 (0.0109 min-1) and RR198 (0.0111 min-1) by 0.5% NZVI were many times higher than those of microscale zerovalent iron (ZVI) (0.0007 min-1 and 0.0008 min-1, respectively). The iron dosage increment exponentially increased the removal efficiencies of both RB5 and RR198. Additionally, lowering pH from 9 to 5 increased the decolorization kinetic rates of both RB5 and RR198 by NZVI. The destruction of azo bond (N=N) in the chromophore of both reactive dyes led to decolorization of dye solutions.
Abstract: The objective of this study was to evaluate the
distribution patterns of Cd, Zn and Hg in groundwater by geospatial
interpolation. The study was performed at Rayong province in the
eastern part of Thailand, with high agricultural and industrial
activities. Groundwater samples were collected twice a year from 31
tubewells around this area. Inductively Coupled Plasma-Atomic
Emission Spectrometer (ICP-AES) was used to measure the
concentrations of Cd, Zn, and Hg in groundwater samples. The
results demonstrated that concentrations of Cd, Zn and Hg range
from 0.000-0.297 mg/L (x = 0.021±0.033 mg/L), 0.022-33.236 mg/L
(x = 4.214±4.766 mg/L) and 0.000-0.289 mg/L (x = 0.023±0.034
mg/L), respectively. Most of the heavy metals concentrations were
exceeded groundwater quality standards as specified in the Ministry
of Natural Resources and Environment, Thailand. The trend
distribution of heavy metals were high concentrations at the
southeastern part of the area that especially vulnerable to heavy
metals and other contaminants.