Performance of continuous aerated iron electrocoagulation process for arsenite removal from simulated groundwater and management of arsenic-iron sludge
TL;DR: In this article, a continuous aerated iron electrocoagulation process (CAIEC) was used to remove arsenite from the simulated arsenite contaminated groundwater by using continuous iron electrodes as both anode and cathode.
About: This article is published in Sustainable Energy Technologies and Assessments.The article was published on 2021-10-01. It has received 21 citations till now. The article focuses on the topics: Arsenite & Arsenic.
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TL;DR: In this article, the authors focused on ultrasound-assisted electrochemical (US/electrochemical) processes, so-called sonoelectrochemical processes of various organic pollutants, and discussed the strategies to avoid passivation, enhanced generation of reactive oxygen species, and mixing effect.
69 citations
TL;DR: In this article , the authors assessed the possibility of electrochemically activated persulfate (PS) based advanced oxidation process (EAOP) for arsenite removal from the aqueous medium.
16 citations
TL;DR: In this article, the authors assessed the possibility of electrochemically activated persulfate (PS) based advanced oxidation process (EAOP) for arsenite removal from the aqueous medium.
16 citations
TL;DR: The ability of electrocoagulation (EC) to treat water and wastewater effectively is well-known and several improvements have been adopted in EC processes to enhance treatability, performance, or reduce environmental impacts as mentioned in this paper .
Abstract: The ability of electrocoagulation (EC) to treat water and wastewater effectively is well-known. There are several improvements that have been adopted in EC processes to enhance treatability, performance, or reduce environmental impacts. Such improvements include: addition of air and hydrogen peroxide to generate radicals; use of an air cathode to reduce energy consumption; polarity reversal for reducing electrode passivation; and use of renewable energy generation as the source of electrical energy. Each of these improvements exploits different mechanisms to improve the applicability of EC. There are several emerging applications where EC has been shown to be suitable, including microplastics, nanoparticles, emerging contaminants, oil and grease, and disinfection.
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References
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01 Jan 2001
TL;DR: A survey of well waters from throughout Bangladesh, excluding the Chitt;agong Hill Tracts, has shown that water from 27% of the'shallow' tubewells, that is, wells less than 150 m deep, exceeded the Bangladesh standard for arsenic in drinking water (50 flg L -I) as mentioned in this paper.
Abstract: A survey of well waters (n=3534) from throughout Bang- '
ladesh, excluding the Chitt;agong Hill Tracts, has shown
that water from 27% of the 'shallow' tubewells, that is
wells less than 150 m deep, exceeded the Bangladesh
standard for arsenic in drinking water (50 flg L -I). 46%
exceeded the WHO guideline value of 10 flg L-I. Figures
for 'deep' wells (greater than 150 m deep) were 1% and
5%, respectively. Since it is believed that there are a total of
some 6-11 million tubewells in Bangladesh, mostly
exploiting the depth range 10-50 m, some 1.5-2.5 million
wells are estimated to be contaminated with arsenic
according to the Bangladesh standard. 35 million people
are believed to be exposed to an arsenic concentration in
drinking water exceeding 50 flg L-I and 57 million people
exposed to a concentration exceeding 10 flg L -I.
There is a distinct regional pattern of arsenic contamination
with the greatest contamination in the south and
south-east of the country and the least contamination in
the north-west and in the uplifted areas of north-central
Bangladesh. However, there are occasional arsenic 'hot
spots' in the generally low-arsenic regions of northern
_Bangladesh. In arsenic-contaminated areas, the large
degree of well-to-well variation within a village means that
it is diffic'ult to predict whether a given well will be contaminated
from tests carried out on neighbouring wells.
The young (Holocene) alluvial and deltaic deposits are
__ m8-s_caffe_c.ted_whereas_the older alluvial_sediments in the
,I
tion' hypothesis in which pyrite oxidation in the zone of
water table fluctuation is assumed to release arsenic and
ultimately to be responsible for the groundwater arsenic
problem. There is no evidence to support the proposition
that the groundwater arsenic problem is caused by the
recent seasonal drawdown of the water table due to a
recent increase in irrigation abstraction.
Monitoring of groundwaters at two-weekly intervals at
a number of sites, and at different depths, has shown some
variation with time but there is as yet no convincing evidence
for seasonal changes. Dramatic changes in contamination
are not expected within such a short timescale. A
monitoring programme should be undertaken at a range of
sites to monitor possible long-term changes. In the three
contaminated areas studied in most detail, the arsenic concentration
increases most rapidly between 10-20 m below
ground level.
\Vhile arsenic is the single greatest problem in Bangladesh
groundwaters, other elements of concern from a
health point of view, are manganese, boron and uranium.
Some 35% of the groundwaters sampled exceeded the
WHO guideline value for manganese (0.5 mg L-I). The
spatial pattern of the arsenic and manganese problem areas
was significantly different and only 33% of shallow well
waters complied with the WHO guideline values for both
arsenic and manganese.
831 citations
TL;DR: The observation that As( III) is oxidized in parallel to the oxidation of Fe(II) by O2 and by H2O2 and that the As(III) oxidation is not inhibited by *OH-radical scavengers at neutral pH is significant for the understanding of arsenic redox reactions in the environment and in arsenic removal processes as well as for theUnderstanding of Fenton reactions in general.
Abstract: The oxidation kinetics of As(III) with natural and technical oxidants is still not well understood, despite its importance in understanding the behavior of arsenic in the environment and in arsenic removal procedures. We have studied the oxidation of 6.6 μM As(III) by dissolved oxygen and hydrogen peroxide in the presence of Fe(II,III) at pH 3.5−7.5, on a time scale of hours. As(III) was not measurably oxidized by O2, 20−100 μM H2O2, dissolved Fe(III), or iron(III) (hydr)oxides as single oxidants, respectively. In contrast, As(III) was partially or completely oxidized in parallel to the oxidation of 20−90 μM Fe(II) by oxygen and by 20 μM H2O2 in aerated solutions. Addition of 2-propanol as an •OH-radical scavenger quenched the As(III) oxidation at low pH but had little effect at neutral pH. High bicarbonate concentrations (100 mM) lead to increased oxidation of As(III). On the basis of these results, a reaction scheme is proposed in which H2O2 and Fe(II) form •OH radicals at low pH but a different oxidant...
736 citations
TL;DR: In this paper, the effect of adsorbent dose, solution pH, and contact time has been investigated to remove arsenite ions [As(III)] by activated alumina.
519 citations
TL;DR: The sediments of 12-40 m deep cores from the Red River delta contain arsenic levels of 2-33 microg/g and show a remarkable correlation with sediment-bound iron and in all three areas, the groundwater arsenic pollution seem to be of natural origin and caused by reductive dissolution of arsenic-bearing iron phases buried in aquifers.
495 citations
TL;DR: The fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials, which can be classified as the homogeneity Fenton mechanism induced by surface-leached iron, the heterogeneous catalysis mechanism, and the heterogeneity reaction-induced homogeneous mechanism are reviewed.
Abstract: The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals (OH) from reactions between recyclable solid catalysts and H2O2 at acidic or even circumneutral pH. Hence, it can effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology. Due to the complex reaction system, the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating, and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies. Iron-based materials usually possess high catalytic activity, low cost, negligible toxicity and easy recovery, and are a superior type of heterogeneous Fenton catalysts. Therefore, this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials. OH, hydroperoxyl radicals/superoxide anions (HO2/O2(-)) and high-valent iron are the three main types of reactive oxygen species (ROS), with different oxidation reactivity and selectivity. Based on the mechanisms of ROS generation, the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron, the heterogeneous catalysis mechanism, and the heterogeneous reaction-induced homogeneous mechanism. Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed. Finally, related future research directions are also suggested.
365 citations