Browsing by Author "Li, Qilin"
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Item A Distributed Hydrologic Model of The Woodlands, TX: Modeling Hydrologic Effects of Low Impact Development(2012-09-05) Doubleday, George; Bedient, Philip B.; Li, Qilin; Raun, Loren H.This thesis utilizes a distributed hydrologic model to predict hydrologic effects of Low Impact Development (LID), and also analyzes runoff from small sub-areas within the watershed. City planners and developers rely on accurate hydrologic models, which enable them to design flood-proof developments and effectively mitigate flooding downstream. Common hydrologic models use a lumped approach, which averages the physical characteristics of basins for model calculations, limiting their ability to estimate runoff within the basin. In contrast, distributed hydrologic models, which divide the watershed into a grid system, can be used to predict runoff at any location within the watershed. The fully distributed hydrologic model, VfloTM, is used to model stormwater runoff in The Woodlands, TX watershed, and to demonstrate the effectiveness of the master planned community. This thesis also suggests that a calibrated VfloTM model can accurately predict stormwater runoff from small sub-areas within a watershed.Item A New Assay Method for Scale Inhibitor Detection at Low Concentrations(2014-04-23) Liu, Ya; Tomson, Mason B.; Bedient, Philip B.; Li, QilinAccurate detection of scale inhibitors has always been crucial to scale control in industry. However, analyzing scale inhibitors at low concentrations, especially with polymeric scale inhibitors, remains an ongoing challenge. This paper presents an assay method designed to detect all types of scale inhibitors, especially at low concentrations, and an expert program developed to guide the method. The program guides the preparation of a field brine barite solution at a fixed barite super-saturation. Scale inhibitor concentration is then measured via the method of standard additions, assuming a linear relationship between the scale inhibitor concentration and the logarithm of barite induction time. Seven different scale inhibitors, including phosphonates, carboxylates and sulfonates, were detected in two typical synthetic brines at low concentrations. In addition, this assay method has also been applied to scale inhibitor detection in actual field brines. In general, this easily-implemented method can directly detect the residual level of any scale inhibitors in field brine about 0.1 mg/L active. Emphasis in this paper is on low concentrations. Measurement of low concentration scale inhibitors not only helps to monitor scaling tendency but also effectively prevents overuse of scale inhibitors and thereby protects the environment and saves money. This is one of the few methods that can detect most scale inhibitors at such low concentrations. Field applications, strengths, and interferences are discussed using laboratory and field examples.Item A New Frontier in Texas: Managing and Regulating Brackish Groundwater(James A. Baker III Institute for Public Policy, 2015) Buono, Regina M.; Zodrow, Katherine R.; Alvarez, Pedro J.J.; Li, Qilin; James A. Baker III Institute for Public PolicyProviding access to clean water is a grand challenge in engineering, and supplying sufficient, clean water is a problem around the globe. This challenge is visible in Texas, where drought coincides with population growth and increases in water demand. The 2012 Texas State Water Plan reports a 2,700 million cubic meters (MCM) gap between fresh water supply and demand in 2010, a number predicted to grow to 3,100 MCM by 2060 if new sources of water are not developed or substantial decreases in demand are not obtained. Due to the inherent political difficulty of decreasing water demand, policy makers and water providers are evaluating new water sources, including wastewater for direct or indirect reuse and brackish groundwater for desalination or direct use. It has been estimated that Texas aquifers contain more than 3,300,000 MCM of brackish groundwater, which, if converted to freshwater, could meet current consumption needs for 150 years, albeit at a greater water treatment cost. Using Texas as a case study, this article addresses which policies are desirable to best manage the supply of brackish groundwater. We review the geological, technical, and legal contexts of groundwater in Texas and situate brackish groundwater within those constructs. We consider efforts by other U.S. states to regulate brackish groundwater and identify desirable goals for its management, including facilitating access to and incentivizing use of brackish groundwater and protecting fresh water aquifers from potential saline intrusion related to brackish groundwater production. Various brackish groundwater policies are examined, and policy recommendations regarding use of the resource are offered.Item A Polysulfone/Cobalt Metal–Organic Framework Nanocomposite Membrane with Enhanced Water Permeability and Fouling Resistance(American Chemical Society, 2022) Gil, Eva; Huang, Xiaochuan; Zuo, Kuichang; Kim, Jun; Rincón, Susana; Rivera, José María; Ranjbari, Kiarash; Perreault, François; Alvarez, Pedro; Zepeda, Alejandro; Li, Qilin; Nanosystems Engineering Research Center for Nanotechnology Enabled Water TreatmentUltrafiltration membranes are widely used in water and wastewater applications. The two most important membrane characteristics that determine the cost-effectiveness of an ultrafiltration membrane process are membrane permeability and fouling resistance. Metal–organic frameworks (MOFs) have been intensively investigated as highly selective sorbents and superior (photo) catalysts. Their potential as membrane modifiers has also received attention recently. In this study, a non-functionalized, water-stable, nanocrystalline mixed ligand octahedral MOF containing carboxylate and amine groups with a cobalt metal center (MOF-Co) was incorporated into polysulfone (PSF) ultrafiltration (UF) membranes at a very low nominal concentration (2 and 4 wt %) using the conventional phase inversion method. The resultant PSF/MOF-Co_4% membrane exhibited water permeability up to 360% higher than of the control PSF membrane without sacrificing the selectivity of the membrane, which had not been previously achieved by an unmodified MOF. In addition, the PSF/MOF-Co_4% membrane showed strong resistance to fouling by natural organic matter (NOM), with 87 and 83% reduction in reversible and irreversible NOM fouling, respectively, compared to the control PSF membrane. This improvement was attributed to the increases in membrane porosity and surface hydrophilicity resulting from the high hydrophilicity of the MOF-Co. The capability of increasing membrane water permeability and fouling resistance without compromising membrane selectivity makes the MOF-Co and potentially other hydrophilic MOFs excellent candidates as membrane additives.Item Alumoxane/ferroxane nanoparticles for the removal of viral pathogens: the importance of surface functionality to nanoparticle activity(The Royal Society of Chemistry, 2012) Maguire-Boyle, Samuel J.; Liga, Michael V.; Li, Qilin; Barron, Andrew R.; Richard E. Smalley Institute for Nanoscale Science and TechnologyA bi-functional nano-composite coating has been created on a porous Nomex fabric support as a trap for aspirated virus contaminated water. Nomex fabric was successively dip-coated in solutions containing cysteic acid functionalized alumina (alumoxane) nanoparticles and cysteic acid functionalized iron oxide (ferroxane) nanoparticles to form a nanoparticle coated Nomex (NPN) fabric. From SEM and EDX the nanoparticle coating of the Nomex fibers is uniform, continuous, and conformal. The NPN was used as a filter for aspirated bacteriophage MS2 viruses using end-on filtration. All measurements were repeated to give statistical reliability. The NPN fabrics show a large decrease as compared to Nomex alone or alumoxane coated Nomex . An increase in the ferroxane content results in an equivalent increase in virus retention. This suggests that it is the ferroxane that has an active role in deactivating and/or binding the virus. Heating the NPN to 160 C results in the loss of cysteic acid functional groups (without loss of the iron nanoparticleﾒs core structure) and the resulting fabric behaves similar to that of untreated Nomex , showing that the surface functionalization of the nanoparticles is vital for the surface collapse of aspirated water droplets and the absorption and immobilization of the MS2 viruses. Thus, for virus immobilization, it is not sufficient to have iron oxide nanoparticles per se, but the surface functionality of a nanoparticle is vitally important in ensuring efficacy.Item Aqueous-Processed, High-Capacity Electrodes for Membrane Capacitive Deionization(American Chemical Society, 2018) Jain, Amit; Kim, Jun; Owoseni, Oluwaseye M.; Weathers, Cierra; Caña, Daniel; Zuo, Kuichang; Walker, W. Shane; Li, Qilin; Verduzco, Rafael; NSF Nanosystems Engineering Research Center, Nanotechnology-Enabled Water TreatmentMembrane capacitive deionization (MCDI) is a low-cost technology for desalination. Typically, MCDI electrodes are fabricated using a slurry of nanoparticles in an organic solvent along with polyvinylidene fluoride (PVDF) polymeric binder. Recent studies of the environmental impact of CDI have pointed to the organic solvents used in the fabrication of CDI electrodes as key contributors to the overall environmental impact of the technology. Here, we report a scalable, aqueous processing approach to prepare MCDI electrodes using water-soluble polymer poly(vinyl alcohol) (PVA) as a binder and ion-exchange polymer. Electrodes are prepared by depositing aqueous slurry of activated carbon and PVA binder followed by coating with a thin layer of PVA-based cation- or anion-exchange polymer. When coated with ion-exchange layers, the PVA-bound electrodes exhibit salt adsorption capacities up to 14.4 mg/g and charge efficiencies up to 86.3%, higher than typically achieved for activated carbon electrodes with a hydrophobic polymer binder and ion-exchange membranes (5–13 mg/g). Furthermore, when paired with low-resistance commercial ion-exchange membranes, salt adsorption capacities exceed 18 mg/g. Our overall approach demonstrates a simple, environmentally friendly, cost-effective, and scalable method for the fabrication of high-capacity MCDI electrodes.Item Assessing Photocatalytic Oxidation Using Modified TiO2 Nanomaterials for Virus Inactivation in Drinking Water: Mechanisms and Application(2013-06-05) Liga, Michael; Li, Qilin; Alvarez, Pedro J.; Barron, Andrew R.; Tao, Yizhi JanePhotocatalytic oxidation is an alternative water treatment method under consideration for disinfecting water. Chlorine disinfection can form harmful byproducts, and some viruses (e.g. adenoviruses) are resistant to other alternative disinfection methods. Photocatalytic oxidation using nano-sized photocatalytic particles (e.g. TiO2, fullerene) holds promise; however, it is limited by its low efficiency and long required treatment times. This research focuses on improving virus inactivation by photocatalytic oxidation by modifying catalysts for improved activity, by analyzing virus inactivation kinetics, and by elucidating the inactivation mechanisms of adenovirus serotype 2 (AdV2) and bacteriophage MS2. Modifying TiO2 with silver (nAg/TiO2) or silica (SiO2-TiO2) improves the inactivation kinetics of bacteriophage MS2 by a factor of 3-10. nAg/ TiO2 increases hydroxyl radical (HO•) production while SiO2 increases the adsorption of MS2 to TiO2. These results suggest that modifying the photocatalyst surface to increase contaminant adsorption is an important improvement strategy along with increasing HO• production. The inactivation kinetics of AdV2 by P25 TiO2 is much slower than the MS2 inactivation kinetics and displays a strong shoulder, which is not present in the MS2 kinetics. nAg/TiO2 initially improves the inactivation rate of AdV2. SiO2-TiO2 reduces the AdV2 inactivation kinetics since adsorption is not significantly enhanced, as it is with MS2. Amino-C60 is highly effective for AdV2 inactivation under visible light irradiation, making it a good material for use in solar disinfection systems. The efficacy of amino-fullerene also demonstrates that singlet oxygen is effective for AdV2 inactivation. When exposed to irradiated TiO2, AdV2 hexon proteins are heavily damaged resulting in the release of DNA. DNA damage is also present but may occur after capsids break. With MS2, the host interaction protein is rapidly damaged, but not the coat protein. The kinetics of MS2 inactivation are rapid since it may quickly lose its ability to attach to host cells, while AdV2 kinetics are slower since the entire capsid must undergo heavy oxidation before inactivation occurs. Adenovirus inactivation likely occurs through breaching the capsid followed by radical attack of DNA and core proteins.Item Bi-Polymer Electrospun Nanofibers Embedding Ag3PO4/P25 Composite for Efficient Photocatalytic Degradation and Anti-Microbial Activity(MDPI, 2020) Habib, Zunaira; Lee, Chang-Gu; Li, Qilin; Khan, Sher Jamal; Ahmad, Nasir Mahmood; Jamal, Yousuf; Huang, Xiaochuan; Javed, Hassan; NSF Nanosystem Engineering Research Center for Nanotechnology Enabled Water TreatmentUsing a bi-polymer system comprising of transparent poly(methyl methacrylate) (PMMA) and poly(vinyl pyrrolidone) (PVP), a visible light active Ag3PO4/P25 composite was immobilized into the mats of polymeric electrospun nanofibers. After nanofibers synthesis, sacrificial PVP was removed, leaving behind rough surface nanofibers with easy access to Ag3PO4/P25 composite. The remarkable photocatalytic efficiency was attained using a PMMA and Ag3PO4/P25 weight ratio of 1:0.6. Methyl orange (MO) was used to visualize pollutant removal and exhibited stable removal kinetics up to five consecutive cycles under simulated daylight. Also, these polymeric nanofibers (NFs) revealed an important role in the destruction of microorganisms (E. coli), signifying their potential in water purification. A thin film fibrous mat was also used in a small bench scale plug flow reactor (PFR) for polishing of synthetic secondary effluent and the effects of inorganic salts were studied upon photocatalytic degradation in terms of total organic carbon (TOC) and turbidity removal. Lower flow rate (5 mL/h) resulted in maximum TOC and turbidity removal rates of 86% and 50%, respectively. Accordingly, effective Ag3PO4/P25 immobilization into an ideal support material and selectivity towards target pollutants could both enhance the efficiency of photocatalytic process under solar radiations without massive energy input.Item Brackish Groundwater: Current Status and Potential Benefits for Water Management(James A. Baker III Institute for Public Policy, 2016) Buono, Regina M.; Zodrow, Katherine R.; Alvarez, Pedro J.J.; Li, Qilin; James A. Baker III Institute for Public PolicyItem Co-transport of Carboxyl-functionalized Multi-walled Carbon Nanotubes and Kaolinite in Saturated Porous Media(2015-04-22) Wang, Tianxiao; Li, Qilin; Alvarez, Pedro J; Tomson, Mason BCo-transport behavior of carboxylated multiwalled carbon nanotubes (COOH-MWCNTs) and kaolinite in various solution ionic strength (IS) and pH were investigated. Results on electrophoretic mobility of CNT, kaolinite and quartz sand as well as particle size of CNT-kaolinite mixture, CNT alone and kaolinite alone were consistent with the DLVO theory. Large particle sizes of kaolinite-CNT mixture revealed potential heteroaggregations especially at 1 mM NaCl, pH=3 and 10 mM NaCl and pH=9. Deposition of CNT was enhanced during the co-transport at 1mM NaCl and pH=3 due to the low mobility of CNT-kaolinite heteroaggregate while decreased at pH=5 in 1 mM NaCl, pH=9 in 10 mM NaCl and pH=9 in 100 mM NaCl because of site blocking by kaolinite. Kaolinite mobility increased in the presence of CNT at pH=3 in 1 mM NaCl caused by site blocking and at pH=9 in 10 mM NaCl resulted from low single collector efficiency of large particles.Item Development and Evaluation of Electrospun Nanocomposite Coatings for Solar Membrane Distillation(2019-02-19) Kellogg, Bernie; Li, QilinThe objective of this research was to develop and evaluate a cost effective electrospun photothermal coating for solar membrane distillation (MD). Polyvinyl alcohol (PVA) with embedded carbon black (CB) nanoparticles were electrospun directly onto surface hydrophilized polyvinylidene fluoride (PVDF) membranes to impart a resistance free photothermal layer. PVA was chosen as a cost-effective alternative to previously reported photothermal coatings of Polyvinyl alcohol, N-methyl-4(4’-formylstyryl)pyridinium methosulfate acetal (SbQ-PVA) CB composites. To evaluate efficacy of photothermal coatings, both conventional MD and solar MD tests were carried out. Coatings were also tested for stability in feed solutions of varying NaCl concentrations and pH. PVA/CB coatings were found to have improved water stability compared to existing photothermal coatings and did not sacrifice MD performance.Item Development of a Predictive and Mechanistic Model for Capacitive Deionization(2015-10-22) Heldenbrand, Amy M; Li, Qilin; Alvarez, Pedro J.J.; Tomson, Mason BThe objective of this research was to develop a mechanistic and predictive model for capacitive deionization (CDI). The commonly-known Gouy Chapman Stern (GCS) model was modified to account for finite ion size and pore geometry by including the Carnahan-Starling (CS) equation of state and considering boundary conditions resulting from difference in pore shape and size and the subsequent impact on potential and concentration profiles. This GCS-CS model with pore geometry was applied to six model activated carbons (MACs) of uniform pore size to analyze the effect of influent salt concentration, pore size and geometry, and applied voltage on ion removal. The general trends found in modeling results were consistent with data presented in the literature. These findings were then compared with the commonly used CDI models, which could not replicate them. This indicates the complexity present in this new model is necessary for accurate representation of ion adsorption in CDI.Item Editorial: Advanced technologies for industrial wastewater reclamation(Frontiers Media S.A., 2023) Deng, Shihai; Hu, Jiangyong; Ong, Say-Leong; Li, Qilin; Han, JieItem Effect of D-Tyrosine on Bacterial Biofilms: Mechanisms and Potential Applications in Membrane Biofouling Control(2016-04-22) Yu, Cong; Li, QilinBiofouling leads to diverse detrimental effects in water treatment and distribution systems. D-Tyrosine can be produced by a variety of bacteria and inhibits formation as well as triggers disassembly of biofilms thus has been proposed for biofouling control applications. The impact of D-tyrosine in different biofilm formation stages in G+ and G- bacteria was studied, and a non-monotonic correlation between D-tyrosine concentration and biofilm inhibition effect was revealed. D-Tyrosine inhibited attachment and biofilm formation in Pseudomonas aeruginosa and Bacillus subtilis with an effective concentration of 5 nM. Extracellular protein was decreased in P. aeruginosa biofilms, but increased in those of B. subtilis. Exopolysaccharides production by P. aeruginosa was increased at low concentrations and reduced at high concentrations while no impact was found in B. subtilis. These results suggest that distinct mechanisms are involved at different D-tyrosine concentrations and they may be species specific. Further investigation of the biofilm related gene expression in P. aeruginosa indicated repression of quorum sensing genes at high (200 µM) and low (5nM) effective concentrations but not at non-inhibitive concentrations (1 µM). Lipopolysaccharides production was reduced and the genes were down regulated by D-tyrosine at 5 nM but not at 200 µM. The efflux pump, flagella and racemase genes were also repressed by 5 nM D-tyrosine. Efflux pump is closely related to quorum sensing while how flagella and racemase are affected is unclear. At low concentration, D-tyrosine may serve as a signal molecule to regulate LPS production and quorum sensing, biofilm formation is inhibited through which. At micromolar level, the biofilm inhibition effect decreased with D-tyrosine concentration and could possibly be attributed to the repression of quorum sensing. D-Tyrosine was incorporated onto a nanofiltration membrane using FAU type zeolite nanoparticles covalently bound to the membrane surface as carriers to develop a long-lasting environmentally friendly anti-biofouling membrane. The initial P. aeruginosa cell attachment and subsequent biofilm formation were inhibited. D-tyrosine was gradually released from the membrane in ultrapure water for 5 days and the membrane retained its anti-biofouling capability for 6 days. The membrane alleviated flux decline and irreversible cell adhesion on membrane surface in dead-end filtration.Item Effect of Kaolinite on the Fate and Transport of Carbon Nanotubes(2018-02-15) Wang, Tianxiao; Li, QilinFate and transport of the engineered nanomaterials (ENMs) in aquatic systems has been increasingly concerned due to their potential human exposure and reported toxicity to the living organisms. The ubiquitous naturally occurring colloids (NOC) is an important impacting factor controlling the aqueous stability and subsurface transport of ENMs in porous media. This study investigated the effect of kaolinite on the aggregation, stability and subsurface mobility of carboxyl-functionalized multi-walled carbon nanotubes (COOH-MWCNT) under a range of environmentally relevant solution conditions. The increase of ionic strength and decrease of pH enhanced the heteroaggregation. CNT and kaolinite can form both primary and secondary heteroaggregates under different solution conditions. The effect of heteroaggregation strongly depends on the CNT-to-kaolinite ratio; it can either increase or decrease the stability of the suspension depending on the structure of the heteroaggregates formed. Ca2+ and dissolved NOM played opposite roles on the stability of CNT. The addition of Ca2+ induced the heteroaggregation through bridging effect and charge screening while NOM hindered the aggregation via steric effect in low Ca2+ conditions. When Ca2+ reached a high concentration range, the effect of Ca2+ dominated and induced large heteroaggregates, destabilizing the CNT-kaolinite system. In natural surface waters, CNT exhibits decreased stability, a notable portion of which is attributed to the naturally occurring colloids. The effect of other water quality parameters (e.g., ionic composition) also contributes to the decreased stability. Flow cytometry, a common technique for cell analysis in biological field, was applied in analyzing aggregations in Alexa Fluor 633 dyed carbon nanotubes (AFCNT) and kaolinite mixture under various pH and ionic strength conditions. By testing the extremely low concentrations of AFCNT and kaolinite mixture samples, the flow cytometer rapidly provided data needed in quantitatively determining the degree of homo- and heteroaggregations. It can be applied on future aggregation studies of ENM-NOC systems and provide meaningful information for the risk management of ENMs in aquatic environments. The mobility of CNT in porous media is strongly dependent on the degree of CNT-kaolinite heteroaggregation and the formation of the aggregates. Results demonstrated that significant CNT-kaolinite heteroaggregations occurred under extremely low pH (pH=3 in 1 mM NaCl) or extremely high ionic strength (pH=9, 100 mM NaCl) conditions. Under the conditions when large secondary aggregation formed at low pH, kaolinite hindered CNT mobility through straining effect. However, CNT transport was facilitated by kaolinite when primary heteroaggregates are the main formation in high ionic strength and high pH. When there were no CNT-kaolinite interactions, CNT mobility was enhanced probably because kaolinite competed with CNT for the adsorption sites on porous media. Findings in the study highlighted the important role of naturally occurring colloids, dissolved natural organic matter and solution chemistry on the environmental fate and transport of CNT. It provides fundamental information for the risk assessment of CNT in natural water systems.Item Electrochemical ammonia synthesis via nitrate reduction on Fe single atom catalyst(Springer Nature, 2021) Wu, Zhen-Yu; Karamad, Mohammadreza; Yong, Xue; Huang, Qizheng; Cullen, David A.; Zhu, Peng; Xia, Chuan; Xiao, Qunfeng; Shakouri, Mohsen; Chen, Feng-Yang; Kim, Jung Yoon (Timothy); Xia, Yang; Heck, Kimberly; Hu, Yongfeng; Wong, Michael S.; Li, Qilin; Gates, Ian; Siahrostami, Samira; Wang, HaotianElectrochemically converting nitrate, a widespread water pollutant, back to valuable ammonia is a green and delocalized route for ammonia synthesis, and can be an appealing and supplementary alternative to the Haber-Bosch process. However, as there are other nitrate reduction pathways present, selectively guiding the reaction pathway towards ammonia is currently challenged by the lack of efficient catalysts. Here we report a selective and active nitrate reduction to ammonia on Fe single atom catalyst, with a maximal ammonia Faradaic efficiency of ~ 75% and a yield rate of up to ~ 20,000 μg h−1 mgcat.−1 (0.46 mmol h−1 cm−2). Our Fe single atom catalyst can effectively prevent the N-N coupling step required for N2 due to the lack of neighboring metal sites, promoting ammonia product selectivity. Density functional theory calculations reveal the reaction mechanisms and the potential limiting steps for nitrate reduction on atomically dispersed Fe sites.Item Electrochemically-active carbon nanotube coatings for biofouling mitigation: Cleaning kinetics and energy consumption for cathodic and anodic regimes(Elsevier, 2021) Rice, Douglas; Rajwade, Kimya; Zuo, Kuichang; Bansal, Rishabh; Li, Qilin; Garcia-Segura, Sergi; Perreault, François; Nanosystems Engineering Research Center for Nanotechnology-Enabled Water TreatmentBiofouling is a major obstacle in engineered systems exposed to aqueous conditions. Many attempts have been made to engineer the surface properties of materials to render them resistant to biofouling. These modifications typically rely on passive antimicrobial or anti-adhesive surface coatings that prevent the deposition of bacteria or inactivate them once they reach the surface. However, no surface modification strategy completely prevents biofilm formation, and, over time, surfaces will be fouled and require cleaning. In this work, we demonstrate the capacity of electrochemical carbon nanotube coatings in dispersing biofilms formed on the surface. A systematic analysis of the biofilm removal kinetics in function of applied current density is made to identify the optimal current conditions needed for efficient surface cleaning. Operating the electrochemically active surface as a cathode produces superior results compared to when it is operated as an anode. Specifically, the 5.00 A m−2 and 2.50 A m−2 cathodic conditions produced rapid cleaning, with complete biofilm dispersal after 2 min of operation. Surface cleaning is attributed to the generation of microbubbles on the surface that scours the surface to remove the adhered biofilm. Energy consumption analyses indicate that the 2.50 A m−2 cathodic condition offers the best combination of cleaning kinetics and energy consumption achieving 99% biofilm removal at an energy cost of ~$ 0.0318 m−2. This approach can be competitive compared to the current chemical cleaning strategies, while offering an opportunity for a more sustainable and integrated approach for biofouling management in engineered systems.Item Electrodes for selective removal of multivalent ions through capacitive deionization(2023-08-29) Verduzco, Rafael; Jain, Amit; Kim, Jun; Li, Qilin; Zuo, Kuichang; Rice University; William Marsh Rice University; United States Patent and Trademark OfficeA method of forming an electrode for capacitive deionization includes depositing an slurry onto a substrate, wherein the slurry comprises a porous material, a first crosslinkable hydrophilic polymer, and a crosslinker for the first crosslinkable hydrophilic polymer; annealing the slurry deposited on the substrate to create a crosslinked porous layer on the substrate; depositing an solution comprising an ion-exchange material, a second crosslinkable hydrophilic polymer, and a crosslinker for the second crosslinkable hydrophilic polymer onto the crosslinked porous layer; and optionally annealing and/or drying the solution on the crosslinked porous layer.Item Emergence of microplastics in African environmental drinking water sources: A review on sources, analysis and treatment strategies(Elsevier, 2024) Adewuyi, Adewale; Li, Qilin; NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water TreatmentThe emergence of microplastics (MPs) as microcontaminants in environmental drinking water sources is a problem in Africa that requires immediate action. Therefore, this review focused on understanding the sources of MPs in African water systems, treatment strategies, analytical methods for identification and quantification, and Africa's pollution index. From the findings, the source of MPs in African water systems was attributed to unregulated importation of plastic products, poor waste management, lack of awareness, poor environmental value system and the inability of local polymer industries to adjust to new policies on plastic management. Most studies identified microfibers and microbeads to be the primary sources of plastics that break down to MPs in African drinking water sources, with polystyrene (PS), polypropylene (PP), and polyethylene (PE) being frequently detected. Current methods for identification, and quantification of MPs in most studies conducted in Africa were not developed in Africa but was adopted from developed countries and, in some cases, modified to meet specific analytical requirements. More studies are necessary for in-depth understanding of the fate and pollution index of MP in African environmental water systems. Furthermore, the interaction between MP and other pollutants in the water system still needs to be better understood. This review suggests membrane and rapid sand filtration methods as promising methods that may be considered for removing MPs from water systems in Africa.Item Emergency of per- and polyfluoroalkyl substances in drinking water: Status, regulation, and mitigation strategies in developing countries(Elsevier, 2024) Adewuyi, Adewale; Li, Qilin; NSF Nanosystems Engineering Research Center for Nanotechnology-Enabled Water TreatmentThe detection of per- and polyfluoroalkyl substances (PFAS) in water presents a significant challenge for developing countries, requiring urgent attention. This review focuses on understanding the emergence of PFAS in drinking water, health concerns, and removal strategies for PFAS in water systems in developing countries. This review indicates the need for more studies to be conducted in many developing nations due to limited information on the environmental status and fate of PFAS. The health consequences of PFAS in water are enormous and cannot be overemphasized. Efforts are ongoing to legislate a national standard for PFAS in drinking water. Currently, there are few known mitigation efforts from African countries, in contrast to several developing nations in Asia. Therefore, there is an urgent need to develop economically viable techniques that could be integrated into large-scale operations to remove PFAS from water systems in the region. However, despite the success achieved with removing long-chain PFAS from water, more studies are required on strategies for eliminating short-chain moieties in water.