Article

Nanotechnology and Water Treatment: Applications and Emerging Opportunities

Department of Microbiology and Plant Pathology, University of Pretoria, South Africa.
Critical Reviews in Microbiology (Impact Factor: 6.09). 02/2008; 34(1):43-69. DOI: 10.1080/10408410701710442
Source: PubMed

ABSTRACT Nanotechnology, the engineering and art of manipulating matter at the nanoscale (1-100 nm), offers the potential of novel nanomaterials for treatment of surface water, groundwater, and wastewater contaminated by toxic metal ions, organic and inorganic solutes, and microorganisms. Due to their unique activity toward recalcitrant contaminants and application flexibility, many nanomaterials are under active research and development. Accordingly, literature about current research on different nanomaterials (nanostructured catalytic membranes, nanosorbents, nanocatalysts, and bioactive nanoparticles) and their application in water treatment, purification and disinfection is reviewed in this article. Moreover, knowledge regarding toxicological effects of engineered nanomaterials on humans and the environment is presented.

Download full-text

Full-text

Available from: Jacques Theron, Apr 11, 2014
29 Followers
 · 
922 Views
  • Source
    • "They have also been suggested as a good sorbent for the remediation treatment of contaminated sediments or wastewaters [3] [4]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: With increasing production and application, carbon nanotubes (CNTs) will enter into the environment in significant masses in upcoming years. CNTs have great potential to disturb the bioavailability and toxicity of other contaminants because of their high and strong adsorption capacity. This study investigated the influence of CNTs on the Cd(II) adsorption behavior by sediment–CNTs mixture at different CNTs/sediments ratios. The results showed that the adsorption kinetic data were well described by the pseudo-second-order model, and the pseudo-second-order rate constant (k2) decreased from 0.122 to 0.070 g/(mg min) with increasing CNTs/sediments ratios from 0% to 10%. Because of the different functional groups in CNTs (carboxyl groups, pKa = 2.81) and sediments (humic acid, pKa = 5.83), the removal efficiencies of Cd(II) by CNTs increased at pH 3.0, while the removal efficiencies of Cd(II) by sediments increased significantly at pH 5.7. The adsorption capacity of Cd(II) increased by the CNTs polluted sediments with ascending CNTs/sediments ratios. Cd(II) adsorption by sediments–CNTs mixture is a spontaneous (ΔG○ < 0), endothermic, and physical reaction (ΔH○ < 41 kJ/mol). Moreover, the spontaneity of the Cd(II) adsorption by sediment–CNTs mixture decreased, as indicated by less negative ΔG○ values, with increasing CNTs/sediments ratios. This is among the first study to investigate the effect of CNTs on metal adsorption by sediments. The results indicate CNTs released into sediments would change the adsorption behavior of Cd(II) by sediments and then alter the potential risk of Cd(II) and CNTs in sediments.
    Chemical Engineering Journal 03/2015; 264. DOI:10.1016/j.cej.2014.11.137 · 4.32 Impact Factor
  • Source
    • "There is a general interest in the study of plasma-liquid interactions within the scientific community for an array of applications, including but not limited to biomedicine and biological disinfection [1] [2] [3] [4] [5] [6], chemical disinfection [7] [8] [9], and agricultural applications. [10] [11] In order to successfully realize these applications and develop mature technologies, the basic science underlying these coupled plasma gas-liquid systems must be well understood. "
    [Show abstract] [Hide abstract]
    ABSTRACT: There is a growing interest in the study of plasma-liquid interactions with application to biomedicine, chemical disinfection, agriculture, and other fields. This work models the momentum, heat, and neutral species mass transfer between gas and aqueous phases in the context of a streamer discharge; the qualitative conclusions are generally applicable to plasma-liquid systems. The problem domain is discretized using the finite element method. The most interesting and relevant model result for application purposes is the steep gradients in reactive species at the interface. At the center of where the reactive gas stream impinges on the water surface, the aqueous concentrations of OH and ONOOH decrease by roughly 9 and 4 orders of magnitude respectively within 50 $\mu$m of the interface. Recognizing the limited penetration of reactive plasma species into the aqueous phase is critical to discussions about the therapeutic mechanisms for direct plasma treatment of biological solutions. Other interesting results from this study include the presence of a 10 K temperature drop in the gas boundary layer adjacent to the interface that arises from convective cooling and water evaporation. Accounting for the resulting difference between gas and liquid bulk temperatures has a significant impact on reaction kinetics; factor of two changes in terminal aqueous species concentrations like H$_2$O$_2$, NO$_2^-$, and NO$_3^-$ are observed if the effect of evaporative cooling is not included.
  • Source
    • "Various foods, sunscreens, cosmetics, paints, and adhesives contain titanium dioxide (TiO 2 ) NPs as white color pigment (US EPA, 2009; Smolander and Chaudhry, 2010). Water treatment plants now exploit the photocatalytic and antibacterial properties of ZnO, Ag, and TiO 2 NPs to produce clean potable water (Theron et al., 2008). In view of these ENPs' widespread utilizations, it is fair to assume that a significant amount of metal and metal oxide NPs is released into the water cycle through industrial and household wastewater effluent or groundwater permeating through landfills (Boxall et al., 2007; Bystrzejewska-Piotrowska et al., 2009). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Engineered nanoparticles (ENPs) are increasingly detected in water supply due to environ- mental release of ENPs as the by-products contained within the effluent of domestic and industrial run- off. The partial recycling of water laden with ENPs, albeit at ultra-low concentrations, may pose an uncharacterized threat to human health. In this study, we investigated the toxicity of three prevalent ENPs: zinc oxide, silver, and titanium dioxide over a wide range of concentrations that encompasses drinking water-relevant concentrations, to cellular systems representing oral and gastrointestinal tissues. Based on published in silico-predicted water-relevant ENPs concentration range from 100 pg/L to 100 mg/L, we detected no cytotoxicity to all the cellular systems. Significant cytotoxicity due to the NPs set in around 100 mg/L with decreasing extent of toxicity from zinc oxide to silver to titanium dioxide NPs. We also found that noncytotoxic ZnO NPs level of 10 mg/L could elevate the intracellular oxidative stress. The threshold concentrations of NPs that induced cytotoxic effect are at least two to five orders of magni- tude higher than the permissible concentrations of the respective metals and metal oxides in drinking water. Based on these findings, the current estimated levels of NPs in potable water pose little cytotoxic threat to the human oral and gastrointestinal systems within our experimental boundaries.
    Environmental Toxicology 06/2014; DOI:10.1002/tox.22015 · 3.23 Impact Factor
Show more