Abstract
Non-point organic pollutants in stormwater are a growing problem in the urban environment which lack effective and efficient treatment technologies. Incorporation of conventional wastewater techniques within stormwater management practices could fundamentally change how stormwater quality is managed because contaminants can be degraded during stormwater transport or storage. This study investigated the photocatalytic reactivity of titanium dioxide functionalized with maleic anhydride (Ti-MAH) within cement pastes when compared to ordinary Portland cement. Preparation of Ti-MAH was performed by permanently bonding maleic anhydride to titanium in methanol, drying and powdering the residual material, and then inter-grinding the preparation with cement during mixing. When compared with OPC, the Ti-MAH cured cement paste is more reactive under a wider range of light wavelengths, possesses a higher band gap, sustains this heightened reactivity over multiple testing iterations, and treats organics effectively (>95% methylene blue removal). Amorphous silica within calcium-silica-hydrate, C-S-H, is theorized to bond to the powdered Ti-MAH during curing. Verification of silicon bonding to the titanium by way of MAH was demonstrated by FTIR spectra, SEM imagery, and XRD. Creating a sustainable and passive photocatalytic cement that precisely bonds silica to Ti-MAH is useful for organic contaminants in urban stormwater, but use can translate to other applications because Ti-MAH bonds readily with any amorphous silica such as glass materials, paints and coatings, optics, and LEDS, among many others.
Highlights
Permeable pavement installations have increased in usage as the practice becomes mainstream; adaptations are limited to relatively low-traffic areas, and little design consideration is given to stormwater contaminant reduction [9]
After FT-IR analysis was performed on titanium dioxide functionalized with maleic anhydride (Ti-maleic anhydride (MAH)), it was determined that a 2:1 ratio of TiO2 to MAH could be more reactive
Cycle testing was again conducted for three cycles at 30 min instead of 45 min to determine if 2Ti-MAH was more reactive than
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. The transport of organic contaminants, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides (OCPs), and per- and polyfluoroalkyl substances (PFAS), in stormwater and surface runoff has increased in occurrence and amount [1,2,3,4]. Best management practices (BMPs) within the framework of green infrastructure (GI) act to curtail and control the volume of urban runoff, but most are ineffective in organic contaminant reduction. One of the primary mechanisms for reducing urban runoff volumes as well as contaminant treatment within low-impact development (LID) is permeable pavements or permeable concrete structures [5]. Permeable pavement installations have increased in usage as the practice becomes mainstream; adaptations are limited to relatively low-traffic areas, and little design consideration is given to stormwater contaminant reduction [9]
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