Author : Mariana Umpierrez Failache
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (131 download)
Book Synopsis Development of Improved Strategies for the Remediation of Arsenic in Groundwater Using Zerovalent Iron Nanoparticles, Fungi and Plants by : Mariana Umpierrez Failache
Download or read book Development of Improved Strategies for the Remediation of Arsenic in Groundwater Using Zerovalent Iron Nanoparticles, Fungi and Plants written by Mariana Umpierrez Failache and published by . This book was released on 2022 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Arsenic (As) is a toxic metalloid widely distributed nature because of its release from geologic media, which can be exacerbated by anthropogenic activities. As occurs in inorganic and organic forms and is present as arsenate (As(V)) and arsenite (As(III)). The dominance of one or other species is highly dependent on the pH and redox potential (Eh). Speciation affects the mobility and sorption capacity of As; As(III) being more toxic, more mobile and less sorptive than As(V). Additionally, organic arsenic species can be present in both oxidation states and its occurrence and biodistribution depend principally on the biomethylation activity of microorganisms. Current methodologies for its remediation are mostly based on chemical and physical methods and have deficiencies, which motivates the exploration of new alternatives. Studies show that nanoscale zerovalent iron (nZVI) can sorb both As(III) and As(V) under laboratory and field conditions, however, the As removal efficiency of nZVI is highly dependent on the size, charge, surface functionalization, and degree of surface oxidation. Therefore, optimizing the sorption and stability of the As-nZVI complexes is critical for the development of effective soil and groundwater remediation techniques. Moreover, the development of robust methodologies for the evaluation of potential remediation technologies is highly needed. The first objective of this thesis is the study of As(V) and As(III) removal and retention capacity of pure nZVI and two different types of sulfidated nZVI. Results show that nZVI, two-step synthetized sodium sulfide sulfidated nZVI (Na2S-SnZVI), and one-step synthesized sodium dithionite sulfidated nZVI (Dt-SnZVI) have high removal efficiencies and increased stability than nanoparticles of FeS and Fe3O4. In particular, Dt-SnZVI had higher sorption capacity for both As species. Our results suggest that As removal by Dt-SnZVI involves highly stable inner sphere complexation with FeS like phases, thus sorption is less affected by potential interferences like phosphate and HA in aqueous phase. Moreover, leachability of As from Dt-SnZVI was significantly lower than from Na2S-nZVI and nZVI, which highlights the unique properties of this nanomaterial. The use of rice plants as a means to evaluate As bioavailability in the soil after treatment with Dt-SnZVI was assessed. Results show that Dt-SnZVI had a statistically significant positive impact on plant growth and chlorophyll content upon exposure to As. The application of Dt-SnZVI reduced the amount of both As(V) and As(III) in the aerial parts. Studies demonstrated that Fe remains in the roots and that P uptake was not significantly affected suggesting that Dt-SnZVI treatment is safe for plants. These results overall confirm that the use of rice plants is a robust and reliable method for assessing the reduction of the bioavailability of As in soil by Dt-SnZVI. Finally, isolation and characterization of an acidophilic fungus, Acidomyces acidophilus, from a highly heavy metal contaminated Acid Main Drainage (AMD) was performed and its As metabolism and biomethylation potential was studied. The ifungus showed that its As tolerance and removal capacity is highly dependent on pH. The mechanism involves As(V) reduction and biomethylation. Expression of arsenite methyltransferase (As3MT) gene is upregulated in the presence of As(III) at pH 3. Additionally, this fungus is capable of removing As by biosorption to biomass and is non-toxic for rice plants, suggesting that it can be potentially used for the remediation of highly acidic effluents. Overall, these studies presented will lead to the potential development of viable strategies for arsenic immobilization and encapsulation in soil and its removal from groundwater and the assessment of the effectiveness of the treatment in terms of biota bioavailability"--
