Large-scale Water Treatment Research Articles

Metal-Organic Framework-Based Composites for the Adsorption Removal of Per- and Polyfluoroalkyl Substances from Water.

The increasing health risks posed by per- and polyfluoroalkyl substances (PFASs) in the environment highlight the importance of implementing effective removal techniques. Conventional wastewater treatment processes are inadequate for removing persistent organic pollutants. Recent studies have increasingly demonstrated that metal-organic frameworks (MOFs) are capable of removing PFASs from water through adsorption techniques. However, there is still constructive discussion on the potential of MOFs in adsorbing and removing PFASs for large-scale engineering applications. This review systematically investigates the use of MOFs as adsorbents for the removal of PFAS in water treatment. This primarily involved a comprehensive analysis of existing literature to understand the adsorption mechanisms of MOFs and to identify factors that enhance their efficiency in removing PFASs. We also explore the critical aspects of regeneration and stability of MOFs, assessing their reusability and long-term performance, which are essential for large-scale water treatment applications. Finally, our study highlights the challenges of removing PFASs using MOFs. Especially, the efficient removal of short-chain PFASs with hydrophilicity is a major challenge, while medium- to long-chain PFASs are frequently susceptible to being captured from water by MOFs through multiple synergistic effects. The ion-exchange force may be the key to solving this difficulty, but its susceptibility to ion interference in water needs to be addressed in practical applications. We hope that this review can provide valuable insights into the effective removal and adsorption mechanisms of PFASs as well as advance the sustainable utilization of MOFs in the field of water treatment, thereby presenting a novel perspective.

Sulfonated mesoporous polystyrene-1D multiwall carbon nanotube nanocomposite as potential adsorbent for efficient removal of xylene isomers from aqueous solution

Xylene isomers are notorious chemical hazards, and their efficient removal from water solutions is still challenging. The current study reports a polymer nanocomposite as a potential adsorbent for successfully removing dissolved xylene isomers from contaminated water. Polystyrene-1D multiwall carbon nanotube nanocomposite (PS-MWCNT) adsorbent was prepared using the one-step bulk polymerization method. Mesoporous PS-MWCNT was prepared using the nano-crystallization phase separation method. The sulfonation of the mesoporous PS-MWCNT nanocomposites was carried out by treating the samples with concentrated sulfuric acid at elevated temperatures. The sulfonated PS-MWCNT (HO3S-PS-MWCNT) was found to be a potential adsorbent for dissolved xylene isomers from water solution. In addition, the HO3S-PS-MWCNT can be efficiently recycled for up to 10 consecutive cycles with negligible decline in adsorption values. The exhibited equilibrium adsorption, rate of adsorption, and rapid regeneration of the HO3S-PS-MWCNT are clear indications for the possibility of practical utilization of these adsorbents in large-scale water treatment plants.

Synthesis of X@DRHC (X=Co, Ni, Mn) catalyst from comprehensive utilization of waste rice husk and spent lithium-ion batteries for efficient peroxymonosulfate (PMS) activation

Highly efficient resource recycling and comprehensive utilization play a crucial role in achieving the goal of reducing resource wasting, environmental protection, and achieving goal of sustainable development. In this work, the two kinds waste resources of agricultural rice husk and metal ions (Co, Ni, and Mn) from spent lithium-ion batteries have been skillfully utilized to synthesize novel Fenton-like catalysts. Desiliconized rice husk carbon (DRHC) with rich pore structure and large specific surface area from rice husk has been prepared and used as scalable carrier, and dandelion-like nanoparticles cluster could be grown in situ on the surface of the carrier by using metal ions contained waste water. The designed catalysts (X@DRHC) as well as their preparation process were characterized in detail by SEM, TEM, BET, XRD and XPS, respectively. Meanwhile, their catalytic abilities were also studied by activating potassium peroxomonosulfate (PMS) to remove methylene blue (MB). The results indicate X@DRHC displays excellent degradation efficiency on MB with wide pH range and stable reusability, which is suitable for the degradation of various dyes. This work has realized the recycling and high-value utilization of waste resources from biomass and spent lithium-ion batteries, which not only creates an efficient way to dispose waste resources, but also shows high economic benefits in large-scale water treatment.

Structure Evolution of Iron (Hydr)oxides under Nanoconfinement and Its Implication for Water Treatment.

In the development of nanoenabled technologies for large-scale water treatment, immobilizing nanosized functional materials into the confined space of suitable substrates is one of the most effective strategies. However, the intrinsic effects of nanoconfinement on the decontamination performance of nanomaterials, particularly in terms of structural modulation, are rarely unveiled. Herein, we investigate the structure evolution and decontamination performance of iron (hydr)oxide nanoparticles, a widely used material for water treatment, when confined in track-etched (TE) membranes with channel sizes varying from 200 to 20 nm. Nanoconfinement drives phase transformation from ferrihydrite to goethite, rather than to hematite occurring in bulk systems, and the increase in the nanoconfinement degree from 200 to 20 nm leads to a significant drop in the fraction of the goethite phase within the aged products (from 41% to 0%). The nanoconfinement configuration is believed to greatly slow down the phase transformation kinetics, thereby preserving the specific adsorption of ferrihydrite toward As(V) even after 20-day aging at 343 K. This study unravels the structure evolution of confined iron hydroxide nanoparticles and provides new insights into the temporospatial effects of nanoconfinement on improving the water decontamination performance.

Changes of putative pathogenic species within the water bacterial community in large-scale drinking water treatment and distribution systems

Although the management of microbes in drinking water is of paramount importance for public health, there remain challenges in comprehensively examining pathogenic bacteria in the water supply system at the species level. In this study, high-throughput sequencing of nearly full-length 16S rRNA genes was performed to investigate the changes of the water bacterial community in three large-scale drinking water treatment plants (DWTPs) and their corresponding distribution systems during winter and summer. Our findings revealed significant differences in the bacterial community structure between winter and summer water samples for each DWTP and its distribution management area (DMA). In the groundwater-fed DWTP, selective enrichment of mycobacterial species was observed in both seasons, and the subsequent DMA also exhibited strong selection for specific mycobacterial species. In one of the surface water-fed DWTPs, certain Legionella species present in the source water in winter were selectively enriched in the bacterial community after pre-oxidation, although they were susceptible to the subsequent purification steps. A variety of putative pathogenic species (n = 83) were identified based on our pathogen identification pipeline, with the dominant species representing opportunistic pathogens commonly found in water supply systems. While pathogen removal primarily occurred during the purification processes of DWTPs, especially for surface water-fed plants, the relative abundance of pathogenic bacteria in the DMA water flora was lower than that in the DWTP effluent flora, indicating a diminished competitiveness of pathogens within the DMA ecosystem.

Machine learning framework for modeling flocculation kinetics using non-intrusive dynamic image analysis

The implementation of a machine learning (ML) model to improve both the effectiveness and sustainability of the water treatment system is a significant challenge in the water sector, with the optimization of flocculation processes being a major setback. The objective of this study was to develop a ML model for predicting flocs evolution of the flocculation process in water treatment. Furthermore, we have devised a framework for its potential adoption in large-scale water treatment. Therefore, the paper can be split into two parts. In the first one, flocculation evolution has been studied from an experimental setup, using a non-intrusive image acquisition method. Subsequently, the ML framework has been implemented. Batch assay data of two velocity gradients (Gf 20 and 60 s−1) and flocculation time of three hours were partitioned into five groups for flocs length range 0.27–3.5 mm and upscaled using linear method. Multilayer Perceptron (MLP) and Long-Short Term Memory (LSTM) models, and traditional time series model, Auto Regressive Integrated Moving Average (ARIMA) were explored to predict floc length evolution data. The experiments illustrate the kinetics of flocculation, where the initial stage is characterized by a rapid floc growth followed by a plateau during which floc length fluctuates within a narrow range. Results demonstrate that ML is sensitive to flocculation; however, the model should be selected with care. ARIMA model is not suitable for predicting number of flocs with negative test accuracy (R2). In contrast, MLP recorded R2 of 0.86–1.0 for training and 0.92–1.0 for testing, across Gf 20 s−1 and Gf 60 s−1. LSTM model has the best prediction R2 of 0.92–1.00 for Gf 20 s−1 and accurately predicts the number of flocs across all groups and Gfs. Our study has proven that the developed framework could be replicated for water treatment modeling and promotes the application of smart technology in water treatment.

Enzyme-immobilized hierarchically porous covalent organic framework biocomposite for catalytic degradation of broad-range emerging pollutants in water

Efficient enzyme immobilization is crucial for the successful commercialization of large-scale enzymatic water treatment. However, issues such as lack of high enzyme loading coupled with enzyme leaching present challenges for the widespread adoption of immobilized enzyme systems. The present study describes the development and bioremediation application of an enzyme biocomposite employing a cationic macrocycle-based covalent organic framework (COF) with hierarchical porosity for the immobilization of horseradish peroxidase (HRP). The intrinsic hierarchical porous features of the azacalix[4]arene-based COF (ACA-COF) allowed for a maximum HRP loading capacity of 0.76 mg/mg COF with low enzyme leaching (<5.0 %). The biocomposite, HRP@ACA-COF, exhibited exceptional thermal stability (∼200 % higher relative activity than the free enzyme), and maintained ∼60 % enzyme activity after five cycles. LCMSMS analyses confirmed that the HRP@ACA-COF system was able to achieve > 99 % degradation of seven diverse types of emerging pollutants (2-mercaptobenzothiazole, paracetamol, caffeic acid, methylparaben, furosemide, sulfamethoxazole, and salicylic acid)in under an hour. The described enzyme-COF system offers promise for efficient wastewater bioremediation applications.

Fabrication and characterization of recyclable, magnetic (CoFe2O4)x/Ag2S-ZnO composites for visible-light-induced photocatalytic degradation of methylene blue dye

Magnetic (CoFe2O4)x/Ag2S-ZnO composites (where x = 0.25, 0.5, 0.75 and 1 wt% CoFe2O4) were successfully synthesised and investigated in the removal of methylene blue (MB) from aqueous medium under visible-light irradiation. X-ray diffraction (XRD) analysis confirmed the crystallinity of the as-synthesised materials and established the average crystal size of these materials to be <8.5 nm. Vibrating sample magnetometer (VSM) analysis confirmed that all cobalt ferrite doped nanocomposites exhibited ferrimagnetic behavior with saturation magnetization values varying from 6.55 to 40.52 emu/g being recorded. Near complete degradation (99 %) was attained when 1 gL−1 of (CoFe2O4)0.5/Ag2S-ZnO composite was added to a 10 ppm solution of methylene blue (MB) at neutral pH for 4 h of visible light irradiation. The catalyst showed good stability, removing 93.1 % of MB dye after five reuse cycles. The composite catalyst reported in this study is therefore a promising material for large-scale water and wastewater treatment processes.

A system dynamics approach for large-scale water treatment plant sludge management: A case study in Brazil

A simulation model for water treatment plant sludge management was proposed, based on the system dynamics approach. This model can be extended to the sludge management of a sanitation system (WTP + WWTP). The model is useful for the selection of the best destination for the sludge generated in treatment plants based on the various changes that a decision can have throughout the operation of the sanitation system. The applicability of the proposed model was tested in a case study of WTPs 3 and 4 and the Anhumas Wastewater Treatment Plant located in Campinas, the main city of the Piracicaba, Capivari and Jundiaí river basin, an important area of water resource management in Brazil. The developed model can be used by treatment plants to: select the best final destination option according to treatment technologies; select the best location for final disposal, considering transport, disposal and storage costs; verify the influence on treatment costs to adapt to a pre-defined final destination for joint management; or compare beneficial disposal costs with landfill disposal costs. The model was developed to allow for gradual increase in acceptance of the residue over time. By establishing this variable, slightly lower final costs were observed in the scenario of sending the sludge with aluminum coagulant to ceramic industries, compared to sending it to landfill, in the case study used for model development. Despite the interesting results, these values should be considered only indicative. Therefore, it can be stated that the major challenge to using the SD model is the accurate and appropriate data collection for correct simulation, as well as its historical series, for accurate evaluation of the viability of the model. The proposed simulation methods showed greater sensitivity to treatment costs, highlighting the importance of beneficial use of the proposed sludge to the technologies employed for water and sludge treatment.

Breaking water carbon nexus by the natural biological system: ultimate solution for ESG challenges

Clean water supply has become an enormous challenge in pursuance of the global warming process. Water technologies have traditionally created carbon emissions and chemical reactions that pollute the landscape, aquifers, and the air. The need for carbon footprint reduction and corporate ESG consideration has led to adopt a more environmentally friendly water treatment and management system. The Natural Biological System (NBS) is a nature-based technology for sewage and waste stream treatment and management, rehabilitating affected water bodies, reducing greenhouse gas (GHG) emissions, and rebalancing eco-systems. The NBS is a patent-tailored solution with the ability of large-scale water treatment and a negative carbon footprint promoting the user ESG rating. From Chile to India, the NBS is changing the global water-energy equation, reducing dependence on energy and maintenance, freeing up valuable water resources for on-site usage, and restoring nature's ability to preserve and protect itself and to stop the escalating climate change effects.

Remediation of Pb (II), Cd (II), and Zn (II) from aqueous solutions using porous (styrene-divinylbenzene)/Cu-Ni bimetallic nanocomposite microspheres: continuous fixed-bed column study.

Bimetallic nanoparticles (BNPs) have been used as a new line of defence against heavy metal contamination among several types of nanoparticles (NPs) due to their enhanced, synergistic activity. In this study, we investigated the adsorption behaviour of porous (styrene-divinylbenzene)/CuNi bimetallic nanocomposite (P(St-DVB)/CuNi BNC) in a continuous flow fixed-bed column and its ability to remove Pb (II), Cd (II), and Zn (II) ions from aqueous solutions. We examined how the initial metal concentration, flow rate, and bed height affected the adsorption characteristics. Experimental results confirmed that the adsorption capacity increased with increase in influent metal concentration and bed height and decreased with increase in flow rate. The breakthrough and the column kinetic parameters were successfully predicted with three mathematical models: Thomas, Yoon-Nelson, and Adams-Bohart models. Both Thomas and Yoon-Nelson models showed good agreement with the experimental results for all the operating conditions. Successful desorption of heavy metals from the P(St-DVB)/CuNi BNC was performed using 0.5 M NaOH solution, and it showed good reusability of the adsorbent during four adsorption-desorption cycles. The results show that P(St-DVB)/CuNi BNC are effective and low-cost adsorbents, and they can be used in real-time large-scale industrial water treatment processes for the removal of heavy metals.

Remediation processes of hexavalent chromium from groundwater: a short review

Abstract Understanding the sources and controlling processes of various groundwater contaminants and their removal methods is extremely important, as groundwater contamination is intricately linked to human health. Chromium (Cr) is a common groundwater contaminant with both natural and anthropogenic origins. Dissolved Cr exists in hexavalent and trivalent forms – while the former is carcinogenic and more soluble – the latter is a micronutrient at low levels and is less soluble. Therefore, most chromium removal methods rely on reducing the hexavalent chromium to its trivalent state to decrease the Cr-toxicity. In recent years, several experimental methods have been attempted for hexavalent chromium removal from aqueous media/groundwater. This paper reviews the recent findings on Cr removal by important, effective, and widely used methods such as adsorption by nanoscale zero-valent Fe-based and conventional materials, electrocoagulation (EC), and bioremediation. The reaction pathways, mechanisms, and effectiveness of each method are also highlighted. The role of parameters such as solution pH and temperature, initial Cr(VI) concentration, contact time with the reducing agent, adsorbent dose, and the presence of competing ions on Cr removal was evaluated. Many of the methods exhibit high (&amp;gt;90%) Cr removal efficiency; the main challenge would be to apply these methods for large-scale water treatment.

Robust TiO2/CuS@TiO2 composites loaded on Ti mesh with outstanding stability and photothermal effects for the enhanced photo-degradation of organic pollutions in a flowing device

A scalable strategy with commercial feasibility was developed to in situ generate TiO2 nanowires/amorphous CuS@TiO2 nanolayer (TiO2/CuS@TiO2) composites on the surface of titanium mesh through a sequent hydrothermal method, successive ionic layer adsorption and reaction (SILAR), and atomic layer deposition (ALD) techniques. The TiO2/CuS@TiO2 composites could respectively harness the incident light with different spectra at the photothermal center (CuS, visible and near-infrared light) and photocatalytic center (TiO2, UV and visible light), which leads to the effective utilization of the solar energy. Benefiting from the CuS photothermal-induced local heating effect of CuS, the adjacent micro-zone temperature could be elevated and the activation energy barrier could be reduced by 10.5 kJ mol−1, which promotes the activation of surface lattice oxygen and dissolved oxygen in the photocatalytic process. Meanwhile, the ALD generated TiO2 nanolayer could both serve as reactive centers but also protecting armor for the CuS, which prohibited the peeling and oxidation of the thermal centers, leading to a high stability of the photocatalyst, which exhibits no obvious fading after 20-cycle reuse. A flow reactor was conceived and made by 3D print and the Ti-mesh based photocatalyst was integrated, which demonstrates high photocatlytic performances, manifesting its great potential for large-scale water treatment.

Hydrothermal effect of gunningite use Pluronic F127-Gelatin as template and the ibuprofen adsorption performance

The gunningite has been successfully synthesized using Pluronic F127 and gelatin as template via hydrothermal at 100–200 °C for 12–48 h. By scanning electron microscopy, nitrogen adsorption-desorption, and X-ray diffraction, changes in structure, pore size, and morphology due to ibuprofen adsorption were investigated in gunningite. Various hydrothermal (temperature and time) parameters had an influence on the percentage elimination (%) of ibuprofens. Gunningite's specific surface area intensifies from 14.60 to 24.03 m2/g as the longer hydrothermal time. In batch adsorption studies, the resulting sample was conducted to isotherm and kinetic analysis to evaluate the distribution of ibuprofen between the liquid and solid phases. Pseudo-first-order kinetics with an adsorption capacity range of 27–34.5 mg g−1 were the best fit for the observed data. Consequently, gunningite may be considered a viable adsorbent for the large-scale treatment of water contaminated with ibuprofen and related anti-inflammatory medicines.

A loofah-based photothermal biomass material with high salt-resistance for efficient solar water evaporation

Clean water is the most basic resource for human use. Desalination, powered by solar energy to evaporate water, has arisen the wide attention compared with unsustainable and costly technologies. In this paper, a waste biomass derived evaporator composed of MXene nanosheets and loofah for high efficiency solar steam seawater desalination is proposed. After hydrophobic treatment, the upper loofah combined with MXene significantly improves the light absorption capacity. The bottom loofah, due to its natural superhydrophilicity and large holes and microchannels, not only ensures that sufficient water is pumped to the top layer for heating, but also prevents salt from accumulating on the evaporation interface. The evaporation rate of the multi-functional photothermal evaporator is up to 1.57 kg m−2 h−1, and the solar-thermal conversion efficiency is 95.5%. At the same time, the evaporator exhibits excellent self-desalination performance. In particular, the waste biomass derived evaporator based on loofah shows excellent stability and ensures its long-term performance in seawater desalination. This sustainable, cost-effective and environment-friendly photothermal composite is promising to achieve low-cost, large-scale waste water treatment and the production of clean water in water scarce areas.

A cohesive effort to assess the suitability and disparity of carbon nanotubes for water treatment.

Population growth, industrialization, and the extensive use of chemicals in daily life have all contributed to an increase in waste generation and an intensified release of organic pollutants into the aquatic environment. To ensure the quality of water (including natural resources), the removal of these pollutants from wastewater has become a challenging task for scientific community. Conventional physical, chemical, and biological treatment methods are commonly used in combinations and are not very effective. Recently, carbon nanotubes (CNTs) emerged as the most reliable and adaptable choice for efficient water treatment due to their extraordinary material properties appearing as a single-step solution for water treatment. High surface area, exceptional porosities, hollow and layered structures, and ease of chemical activation and functionalization are some properties which makes it excellent adsorption material. Hence, this review paper discusses the recent advances in the synthesis, purification, and functionalization of CNTs for water and wastewater treatment. In addition, this study also also provides a quick overview of CNTs-based advance technologies employed in water treatment and carefully assesses the benefits versus risks during large-scale water treatment. Furthermore, it concludes that identified risks to the environment and human health cannot be easily ignored and strict regulatory requirements are a must for producing low-cost innoxious CNTs.

Studies in instant water disinfection using natural oils

The present research reveals an instant and simple process for drinking water treatment by employing specific natural oils having antimicrobial properties to ensure complete elimination of harmful bacteria. The disinfection was studied for two different model bacteria, Gram-negative E. coli and Gram-positive, S. aureus. Seven natural oils, ajwain, thyme, oregano, peppermint, harsingar, cinnamon leaf and black pepper oil were evaluated and were found to yield 100% water disinfection within 1 min except for harsingar and black pepper oil. The process was also effective for the instant and 100% disinfection of real well water. The methodology for altering zeta potential, to an extent of 130%, for instant disinfection in drinking water treatment helps in selecting natural oils. Molecular docking studies indicated natural oils action as potential inhibitors of bacterial DNA gyrase. The studies indicate one of the lowest operating costs comparable to conventional chlorination. The simple methodology not requiring complex equipment has the potential to provide many options for implementations- from portability, household application to large scale water treatment plants.

Magnetic nanomaterials: Greener and sustainable alternatives for the adsorption of hazardous environmental contaminants

The global water resources have been considerably damaged by organic and inorganic pollutants generated as a result of fast urbanization and industrialization. Toxic contaminants in water pose a serious health threat to both humans and aquatic life. In terms of cost and performance, current remediation technologies are inadequate for eliminating low-concentration contaminants. Nanomaterials have unique advantages in this regard, including precisely adjustable surface areas, durability, and biocompatibility. Also, the surface functionalization of the nanoparticles can facilely be carried out to increase their selectivity and specificity towards a variety of pollutants. Among various nanomaterials the magnetic nanoparticles (MNPs) are promising class of nanomaterials due to their biocompatible, target-specific, easily regenerable, and reusable characters. They also feature simple separation techniques, high surface-to-volume ratios, and high adsorption rates. Based on these features their implication in wastewater treatment has dragged an enhanced amount of attention for the researchers. Therefore, MNPs provide a simple, low-maintenance alternative to traditional adsorbents for extracting contaminants from wastewater. Magnetic separation can reduce the environmental impact of MNPs in final effluents by managing the concentration of nanoadsorbents. MNPs are now in the development stage, however they are a promising treatment alternative for large-scale water treatment plants. The main objective of the present review is to focus on the efforts being carried out in the application of MNPs for the remediation of hazardous pollutants including organics, heavy metal ions, pharmaceutics, dyes, radioactive elements, and pathogens. Furthermore, the review present critical assessment and overview of a variety of magnetic nanomaterials and their applications to water and wastewater treatment. Finally, the feasibility of structure-property relationships, adsorption mechanisms, modeling for the removal of water pollutants, legality and toxicity, economic assessments, and future research directions for the complete utilization of MNPs are also discussed in detail.

Facilely tuning the intrinsic catalytic sites of the spinel oxide for peroxymonosulfate activation: From fundamental investigation to pilot-scale demonstration

Heterogeneous peroxymonosulfate (PMS)-based advanced oxidation processes (AOPs) have shown a great potential for pollutant degradation, but their feasibility for large-scale water treatment application has not been demonstrated. Herein, we develop a facile coprecipitation method for the scalable production (∼10 kg) of the Cu-Fe-Mn spinel oxide (CuFeMnO). Such a catalyst has rich oxygen vacancies and symmetry-breaking sites, which endorse it with a superior PMS-catalytic capacity. We find that the working reactive species and their contributions are highly dependent on the properties of target organic pollutants. For the organics with electron-donating group (e.g., -OH), high-valent metal species are mainly responsible for the pollutant degradation, whereas for the organics with electron-withdrawing group (e.g., -COOH and -NO2), hydroxyl radical (•OH) as the secondary oxidant also plays an important role. We demonstrate that the CuFeMnO-PMS system is able to achieve efficient and stable removal of the pollutants in the secondary effluent from a municipal wastewater plant at both bench and pilot scales. Moreover, we explore the application prospect of this PMS-based AOP process for large-scale wastewater treatment. This work describes an opportunity to scalably prepare robust spinel oxide catalysts for water purification and is beneficial to the practical applications of the heterogeneous PMS-AOPs.

Pharmaceutical Micropollutant Treatment with UV–LED/TiO2 Photocatalysis under Various Lighting and Matrix Conditions

The persistence of pharmaceuticals and personal care products (PPCPs) in water has been a cause for concern for several years. Many studies have successfully used TiO2/UV photocatalysis to remove these compounds from water. In order to optimize these systems for large-scale water treatment, the effects of the reaction matrix, methods to improve energy efficiency, and methods for easy catalyst separation must be considered. The following study examines the photocatalytic degradation of a cocktail of 18 PPCPs using a porous titanium–titanium dioxide membrane and the effect of solution pH on kinetic rate constants. The addition of methanol to the reaction—commonly used as a carrier solvent—had a significant effect on kinetic rate constants even at low concentrations. Solution pH was also found to influence kinetic rate constants. Compounds had higher kinetic rate constants when they were oppositely charged to the membrane at experimental pH as opposed to similarly charged, suggesting that electrostatic forces have a significant effect. The controlled periodic illumination of UV–LEDs was also investigated to increase photonic efficiency. The dual-frequency light cycle used did not cause a decrease in degradation for many compounds, successfully increasing the photonic efficiency without sacrificing performance.