Water treatment processes.  III.  Removing dissolved inorganic contaminants from water

Clifford, Dennis; Subramonian, Suresh; Sorg, Thomas J.

doi:10.1021/es00153a001

Cited by 146 publications

(54 citation statements)

References 15 publications

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“…9 Similar selective adsorption performance has also been reported by Zhang et al using superhydrophobic nanoporous polydivinylbenzene. 10 Due to their excellent selective adsorption performance, fast adsorption kinetics, good working capacity and recyclable use performance, these materials have great advantages over those traditional absorbent materials such as active carbons, 11,12 which suffer from a number of drawbacks, including slow adsorption kinetics, poor selectivity and limited working capacity. Owing to the global scale of severe water pollution arising from oil spills and industrial organic pollutants, the creation of efficient absorbent materials for separation and removal of oils or organic pollutants from water should be of great importance to address environmental issues.…”

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confidence: 99%

Superhydrophobic conjugated microporous polymers for separation and adsorption

Sun

Tan

et al. 2011

Energy Environ. Sci.

572

285

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Superhydrophobic conjugated microporous polymers show good selectivity, fast adsorption kinetics, excellent recyclability and absorbencies for a wide range of organic solvents and oils, which make them the promising candidates for potential applications, including liquid-liquid separation, water treatment and so on.Superhydrophobic surfaces (water contact angle (CA) larger than 150 ) have generated extensive commercial and academic interest. [1][2][3][4][5][6][7] In recent years, there has been an increased interest in generation and utilization of the surface superhydrophobicity of a solid for direct separation or selective adsorption of oil or hydrophobic organic solvents from water. The first example for oil-water separation by using superhydrophobic and superoleophilic coating mesh has been reported by Jiang et al. 8 Along this line, more recently, the creation of nanometre-or micrometre-sized porous materials with excellent surface superhydrophobicity has been reported and successfully used for separation and adsorption of oils or organic solvents from water. For example, Yuan et al. reported the selective adsorption of oil from water by a superwetting nanowire membrane. 9 Similar selective adsorption performance has also been reported by Zhang et al. using superhydrophobic nanoporous polydivinylbenzene. 10 Due to their excellent selective adsorption performance, fast adsorption kinetics, good working capacity and recyclable use performance, these materials have great advantages over those traditional absorbent materials such as active carbons, 11,12 which suffer from a number of drawbacks, including slow adsorption kinetics, poor selectivity and limited working capacity. Owing to the global scale of severe water pollution arising from oil spills and industrial organic pollutants, the creation of efficient absorbent materials for separation and removal of oils or organic pollutants from water should be of great importance to address environmental issues. Broader contextOwing to the global scale of severe water pollution arising from oil spills and industrial organic pollutants, the creation of efficient absorbent materials for separation and removal of oils or organic pollutants from water should be of great importance to address environmental issues. Here we report for the first time the surface superhydrophobicity of the conjugated microporous polymers (CMP) as well as their excellent adsorption performance for oils and organic solvents. Due to their open pore structures and excellent surface superhydrophobicity, oils or non-polar organic solvents can be easily absorbed and separated from water by the CMP without adsorption of water. The CMP also show excellent adsorption performance for those polar organic solvents and toxic organic solvents with the absorbencies ranging approximately from 700 wt% to 1500 wt% for the HCMP-1 and 600 wt% to 2300 wt% for the HCMP-2, respectively. By loading the CMP, the hydrophilic sponge can be changed to be oleophilic to oil. With a loading of 7.0 mg cm À3 of the HCMP-1 ...

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confidence: 99%

Superhydrophobic conjugated microporous polymers for separation and adsorption

Sun

Tan

et al. 2011

Energy Environ. Sci.

572

285

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“…There are a variety of methods currently available for removal of arsenic from contaminated water. Conventional technologies, such as coagulation, do not discriminate between arsenic and other elements and involve alteration of the water chemistry and addition of other chemicals (7). Current technologies, such as activated alumina sorption, polymeric anion exchange, and polymeric ligand exchange (6), are more effective for As(V) than As(III), and most commonly used methods require prior oxidation of all of the As(III) to As(V) (10,30).…”

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confidence: 99%

Enhanced Arsenic Accumulation in Engineered Bacterial Cells Expressing ArsR

Košťál

Yang²,

et al. 2004

Appl Environ Microbiol

192

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The metalloregulatory protein ArsR, which offers high affinity and selectivity toward arsenite, was overexpressed in Escherichia coli in an attempt to increase the bioaccumulation of arsenic. Overproduction of ArsR resulted in elevated levels of arsenite bioaccumulation but also a severe reduction in cell growth. Incorporation of an elastin-like polypeptide as the fusion partner to ArsR (ELP153AR) improved cell growth by twofold without compromising the ability to accumulate arsenite. Resting cells overexpressing ELP153AR accumulated 5-and 60-fold-higher levels of arsenate and arsenite than control cells without ArsR overexpression. Conversely, no significant improvement in Cd 2؉ or Zn 2؉ accumulation was observed, validating the specificity of ArsR. The high affinity of ArsR allowed 100% removal of 50 ppb of arsenite from contaminated water with these engineered cells, providing a technology useful to comply with the newly approved U.S. Environmental Protection Agency limit of 10 ppb. These results open up the possibility of using cells overexpressing ArsR as an inexpensive, high-affinity ligand for arsenic removal from contaminated drinking and ground water.Arsenic (As) is an extremely toxic metalloid that adversely affects human health. Both highly toxic trivalent arsenite [As(III)] and less-toxic pentavalent arsenate [As(V)] have been associated with increased risk of skin, kidney, lung, and bladder cancer (12). The toxicity of arsenic is attributed to the substitution of As(V) for phosphate, affinity of As(III) for protein thiol groups, and protein-DNA and DNA-DNA crosslinking (20). Arsenic enters the water supply primarily from geochemical sources, such as the mining of arsenopyrite gold ores (16), which constitute about one-third of world gold reserves. Additional contaminations arise from anthropomorphic sources such as arsenical-containing herbicides, pesticides, and the widely used wood preservative chromated copper arsenic (17, 21). Untreated, highly toxic arsenic effluent has been disposed of in rivers and ended up in groundwater. An estimated 20 million Americans consume water containing arsenic at levels presenting a potentially fatal cancer risk (9). Worldwide, 57 million people have been exposed to arsenic through contaminated wells in Bangladesh (18). These incidents again serve as a reminder of the toxic consequences of arsenic mobilization and the needs for efficient removal of arsenic in aquatic systems (19).Because of the toxicity, the regulatory limit on arsenic in the United States is currently set at 10 ppb. There are a variety of methods currently available for removal of arsenic from contaminated water. Conventional technologies, such as coagulation, do not discriminate between arsenic and other elements and involve alteration of the water chemistry and addition of other chemicals (7). Current technologies, such as activated alumina sorption, polymeric anion exchange, and polymeric ligand exchange (6), are more effective for As(V) than As(III), and most commonly used methods require pri...

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“…However, for detection of multiple toxic metals with near-equal sorption affinity present in a sample, further research is needed to achieve preseparation of the metals prior to feeding in the mini-column. [30][31][32] The presence of common cations (Na þ and Ca 2þ ) in the sample at much higher concentration compared with trace toxic metals does not interfere with the detection technique. Calcium, though a divalent cation, has a poor affinity for the HFO binding sites and also forms a weak metal-hydroxy complex.…”

Section: Shortcomings and Challengesmentioning

confidence: 99%

Sensing of toxic metals through pH changes using a hybrid sorbent material: Concept and experimental validation

Chatterjee

SenGupta

2009

AIChE Journal

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This article reports a new hybrid sorbent material that is capable of detecting trace concentration of toxic metals, such as zinc, lead, copper, nickel, etc., through pH changes only. The material is essentially a composite granular material synthesized through rapid fusion of a mixture of amorphous hydrated ferric oxide (HFO) and akermanite or calcium magnesium silicate (Ca 2 MgSi 2 O 7 ). When a water sample is rapidly passed through a mini-column containing this hybrid material, effluent pH at the exit always remains alkaline (%9.0) because of slow hydrolysis of akermanite and steady release of hydroxyl (OH À ) ions. This exit solution turns pink through the addition of a phenolphthalein indicator. Commonly encountered electrolytes containing sodium, calcium, chloride, and sulfate have no impact on the exit pH from the mini-column. However, when trace concentration of a heavy metal (say lead) is present in the sample water, a considerable drop in pH ([2 units) is observed for the exiting solution. At this point, the solution turns colorless through the addition of a phenolphthalein indicator. Moreover, the change in the slope of pH, i.e., ÀdpH/dBV, provides a sharp, noticeable peak for each toxic metal where BV is the bed volumes of solution fed. The technique allowed detection of zinc and lead through pH swings in synthesized samples, spiked Bethlehem City water, and also in Lehigh River water in the presence of phosphate and natural organic matter (NOM). Using a simple preconcentration technique, lower than 10 lg/l of lead was detected with a significant peak. From a mechanistic viewpoint, high sorption affinity of HFO surface sites toward toxic metal cations, ability of akermanite to maintain near-constant alkaline pH for a prolonged period through slow hydrolysis and labile metal-hydroxy complex formation causing dissipation of OH À ions from the aqueous phase provide a synergy that allows detection of toxic metals at concentrations well below 100 lg/l through pH changes. Nearly all previous investigations pertaining to toxic metals sensing use metalselective enzymes or organic chromophores. This simple-to-operate technique using an inexpensive hybrid material may find widespread applications in the developing world for rapid detection of toxic metals through pH changes. V

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Water treatment processes. III. Removing dissolved inorganic contaminants from water

Cited by 146 publications

References 15 publications

Superhydrophobic conjugated microporous polymers for separation and adsorption

Superhydrophobic conjugated microporous polymers for separation and adsorption

Enhanced Arsenic Accumulation in Engineered Bacterial Cells Expressing ArsR

Sensing of toxic metals through pH changes using a hybrid sorbent material: Concept and experimental validation

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