Specific interfacial chemical reactions applied to water quality control exemplified by heterogeneous photocatalysis and electro-sorption
Date
2023
Authors
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Publisher
University of Delaware
Abstract
Water is an essential natural resource for maintain healthy ecosystem. However, the rapid growth of population has led to an imbalance between the demand and availability of water, resulting in the degradation of groundwater and surface water quality, the expansion of irrigated agriculture, and the pressure on limited water resources. These factors contribute to the global water demand and put excessive stress on the environment. Freshwater, which is less than 3% of the world's water resources, is becoming increasingly scarce. The loss of water quality is a major cause of water scarcity. In this study, the microbial inactivation and water desalination technologies are two key areas of focus in addressing the water quality issue. Moreover, this study further applied biochar with rhizobia for soil health improvement. ☐ One promising water disinfection technology for the future is heterogeneous disinfection through semiconductor technology, which does not produce disinfection by-products. Although photocatalytic microbial inactivation mechanisms have been proposed, there is still limited understanding of how it causes bacterial death at the start of a mass microbial death. Understanding the inactivation mechanism is crucial for the development of effective disinfection technology, the creation of efficient materials for large-scale use, and the design of reactors. ☐ Water demand is rising due to rapid population growth, urbanization and increasing water needs from agriculture, industry, and energy generation. Compared to the seawater, brackish water, contained less than 10 g/L of salinity, is a potential portable water recourses for the next decades, especially for inland and remoted areas. Among the water desalination technologies, electrochemical electrode deionization, capacitive deionization (CDI), is a low cost, energy-saving and few/no additional chemical or secondary pollution desalination technologies. However, understanding the critical processes during the electrosorption is still in needed. In this study, we focus on identifying electric double layers, adsorption characterization, and the interfacial chemical reaction of electrode and electrolyte. ☐ A synchrotron-based cutting-edge bio-image technique (transmission X-ray microscopy, TXM) and a biophysical approach (Atomic force microscopy, AFM) have been developed and applied to identify the interfacial reaction of nanomaterial and 3D cellular structure of microbial cells under visible-light-responsive photocatalysis inactivation. AFM and TXM provide direct observations on interactions between a single-cell and nano-materials at the nanoscale, which are useful for the early diagnosis of cell damage. Meanwhile, a novel kinetic model for predicting antimicrobial processes was also developed. ☐ The reversible potential, which is controlled by H+ and OH- ions, plays a role in ion electrosorption during the design of CDI systems for water desalination, but is generally neglected. The reversible potential, influenced by the electrolyte pH, and the externally applied (polarization) potential, both contribute to the ion storage capacity. The interaction between the reversible and polarization potential at the electrode-electrolyte interface is an area of focus. Additionally, ionic mobility has been found to be significant in electrosorption processes. Results show that negatively charged bamboo biochar and positively charged activated carbon (F400) have electrosorption removal capabilities for cations and anions, respectively. ☐ Three types of soils, i.e., silt loam, loam, and alkaline silt loam, mixed with bamboo biochar at 0.5, 5, 10 (w/w) % were studied. Three different biochar particle sizes were tested. The addition of certain amount (5%) of biochar in the presence of R. leguminosarum improved pea growth in terms of leaf size in all three types of soils studied. ☐ This dissertation has addressed the importance of understanding the specific interfacial chemical and biological reactions that occur at the interface during heterogeneous photocatalysis microbial infection and electrosorption. New prospective and technologies of identifying photo-inactivation and biochar-based soil improvement processes and clarifies the critical factors that affected the electrosorption processes have been provided.
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Keywords
Groundwater degradation, Biochar, Electrochemistry, Photocatalysis inactivation, Electrosorption