Degradation of polyvinyl alcohol (PVA) by UV/chlorine oxidation: Radical roles, influencing factors, and degradation pathway

The self-designed reactor to achieve efficient degradation of polyvinyl alcohol under high-pressure and high-temperature conditions

A huge amount of polyvinyl alcohol (PVA) fabric is abandoned from nuclear power plants every year, the traditional treatment process will occupy land resources and pollute the environment; therefore, a lot of research has been carried out on the chemical treatment of PVA fabric. Herein, the performance of degradation of polyvinyl alcohol under high-pressure and high-temperature conditions is investigated. The effects of the initial pH value, reaction temperature, molar ratio of H2O2/Fe2+, and H2O2 dosage on PVA degradation were evaluated. In the tested ranges in this work, the degradation of PVA fabric via high-pressure and high-temperature method was optimum at the initial pH value of 4, reaction temperature of 300℃, molar ratio of H2O2/Fe2+ as 10, and H2O2 dosage of 13 g/L. The PVA removal rate and TOC removal rate were 99.99% and 97.36%, respectively. Meanwhile, the high-pressure and high-temperature methods also had a great effect on the removal of Rhodamine-B and Reactive Red X-3B, the removal rates of Rhodamine-B and Reactive Red X-3B were 99.83% and 99.76%, respectively. The reaction mechanism of high-pressure and high-temperature methods was also discussed in this study.

Oxidant-mediated radical reactions of the azole fungicide TEB in aquatic media: Degradation mechanism and toxicity evolution

The degradation of tebuconazole (TEB) by UV/H2O2, UV/NaClO, and ozonation was investigated in this research. The experimental findings unveiled that under the specified conditions, the degradation percentages of TEB were raised to 99% within 40 s, 5 min, and 3 min for UV/H2O2, UV/NaClO and ozonation, respectively. The mineralization percentages within 1 h were 59%, 31% and 8% for the three AOPs. UV/H2O2 and UV/NaClO technologies mainly acted through OH·, while O3 treatment primarily relied on the free radicals such as 1O2 and O2·-. UV-based AOPs achieved almost complete dechlorination within 1 h, whereas O3 treatment had a less effective dechlorination, reaching only 27.61%. Notably, UV alone achieved a dechlorination percentage of 43.07%. By identifying the TPs, we found that the three AOPs shared three similar degradation pathways. The degradation mechanism of TEB mainly entailed the removal of the benzene ring, tert-butyl group and triazolyl group. Toxicity assessment revealed an initial increase followed by a gradual decrease in toxicity for UV/NaClO and O3 treatments, whereas UV/H2O2 treatment exhibited a sustained decrease. This was due to the presence of TP278 and TP303 by UV/NaClO and TP168 and TP153 by ozonation. After estimating the costs of the three AOPs, UV/H2O2 standed out as the best choice for achieving a 90% degradation percentage and exhibiting lower toxicity performance, while O3 treatment was favored for low TOC demands. These research findings provided valuable reference for understanding the degradation mechanism and developing a new technology of the removal of TEB.

Highly biocidal poly(vinyl alcohol)-hydantoin/starch hybrid gels: A "Trojan Horse" for Bacillus subtilis

HYPOTHESIS

Poly (vinyl alcohol) (PVA) cryogels can be functionalized with n-Halamines to confer biocidal features useful for their application as wound-dressing tools. Their efficacy can be boosted by stably embedding a polymeric bacterial food source (e.g., starch) in the gel matrix. The bioavailability of the food source lures bacteria inside the gel network via chemotactic mechanisms, promoting their contact with the biocidal functionalities and their consequent inactivation.

EXPERIMENTS

The synthesis of a novel hydantoin-functionalized PVA (H-PVA-hyd) is proposed. The newly synthesized H-PVA-hyd polymer was introduced in the formulation of H-PVA-based cryogels. To promote the cryogelation of the systems we exploited phase-separation mechanisms employing either a PVA carrying residual acetate groups (L-PVA) or starch as phase-segregating components. The permanence of the biocidal functionality after swelling was investigated via proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared (FT-IR) microscopy. The activated H-PVA-hyd cryogels have been tested against bacteria with amylolytic activity (Bacillus subtilis) and the outcomes were analyzed by direct observation via confocal laser scanning microscopy (CLSM).

FINDINGS

The cryogels containing starch resulted in being the most effective (up to 90% bacterial killing), despite carrying a lower amount of hydantoin groups than their starch-free counterparts, suggesting that their improved efficacy relies on a "Trojan Horse" type of mechanism.

Changes in Tablet Color Due to Light Irradiation: Photodegradation of the Coating Polymer, Hypromellose, by Titanium Dioxide

The color of the tablets and capsules produced by pharmaceutical companies is important from the perspectives of product branding and counterfeiting. According to some studies, light can change tablet color during storage. In this study, tablets comprising amlodipine besylate (AB), a well-known light-sensitive drug, were coated with commonly used coating materials and exposed to light. Compared to the tablets that were not exposed to light, the color of those exposed to light changed over time. In fact, a faster and more pronounced color change was observed in the tablets exposed to light; however, the amount of AB did not decrease significantly in these tablets. The coating materials and their amounts were varied to clarify the materials involved in the color change. Based on the results, titanium dioxide and hypromellose may be involved in the color change process. As titanium dioxide is a photocatalyst, it may induce or promote chemical changes in hypromellose upon light irradiation. Overall, care should be exercised during selection of the coating polymer because titanium dioxide may promote photodegradation of the coatings while protecting the tablet's active ingredient from light.

Thermal oxidation of degradation products from thermoplastic polyvinyl alcohol: Determination on oxidation temperature and residence time

The degradable protective articles made of thermoplastic polyvinyl alcohol (TPVA) are widely used in nuclear power plants, and they are thermally decomposed after use to reduce solid waste. However, in the real decomposition of TPVA, the temperature in the oxidation reactor is not self-sustaining; as a result, the degradation products contain a lot of CO, resulting in more pollution and energy waste. In this paper, jet stirred reactor (JSR) and Chemkin software were used to study the reaction kinetics characteristics of the oxidation process of degradation products from TPVA in the range of 550 °C-700 °C. Both experiments and kinetic simulation show that a higher average temperature of the oxidation reactor is needed to achieve lower CO emissions. When using 5% or 10% TPVA degradation solution, the average temperature should not befall below 625 °C or 675 °C. The corresponding residence time should be greater than 6 s and 5 s respectively. The combination of research findings and engineering practice provides great help to the optimization of the actual work process.

The s-oph enzyme for efficient degradation of polyvinyl alcohol: soluble expression and catalytic properties

BACKGROUND

Polyvinyl alcohol (PVA) is one of the most widely used water-soluble polymers with remarkable mechanical properties. However, water-soluble polymers are among the major organic pollutants of streams, river, and marine ecosystems. Once dispersed in aqueous systems, they can directly interfere with the life cycle of aquatic organisms via direct toxic effects. There is thus an urgent need for microorganisms or enzymes that can efficiently degrade them. Oxidized PVA hydrolase plays an important role in the pathway of PVA biodegradation. It is the key enzyme in the second step of the pathway for complete degradation of PVA.

METHODS AND RESULTS

The s-oph gene was cloned from the laboratory-isolated strain Sphingopyxis sp. M19. This gene was expressed in the Escherichia coli system pET32a/s-oph expression vector, with the products forming an inclusion body. By binding with a molecular chaperone, pET32a/s-oph/BL21 (DE3)/pGro7 was successfully constructed, which enabled the s-oph gene to be solubly expressed in E. coli. The protein encoded by the s-oph gene was purified at a yield of 16.8 mg L-1, and its catalytic activity reached 852.71 U mg-1. In the s-oph enzyme reaction system, the efficiency of PVA degradation was increased to 233.5% compared with that of controls.

CONCLUSIONS

The s-oph enzyme exhibited the characteristics of being able to degrade PVA with high efficiency, specificity, and stability. This enzyme has good potential for practical application in ameliorating plastic pollution and protecting the environment.

Electrocoagulation treatment of furniture industry wastewater

Electrocoagulation was investigated as a method for treating wastewater containing polyvinyl acetate (PVAc) from the furniture industry. The study evaluated the evolution of iron concentration and passivation during the treatment process. Laboratory-scale experiments were conducted to evaluate the effects of inter-electrode distance (d), current density, and mode on treatment performance. Three values of d (0.3, 0.6, and 0.9 cm) were studied and found to have no significant effect on performance. However, lower d values resulted in reduced energy consumption due to a decrease in applied voltage. Three values of current density (132, 158, and 197 A m^-2) were studied under two current modes, Direct Current (DC) and Alternating Pulsed Current (APC). The best treatment performance for DC occurred under 158 A m^-2 (the treated wastewater was characterized by pH = 4.59 ± 0.02, conductivity = 996 ± 21 μS cm^-1, COD = 1940 ± 55 mgO₂ L^-1, TSS = 105 ± 14 mg L^-1, and Fe = 50.39 ± 1.87 mgFe L^-1). For APC, the best performance was achieved under 197 A m^-2 (the treated wastewater was characterized by pH = 6.33 ± 0.06, conductivity = 988 ± 17 μS cm^-1, COD = 1942 ± 312 mgO₂ L^-1, TSS = 199 ± 55 mg L^-1, and Fe = 44.68 ± 4.60 mgFe L^-1). Despite the promising results, treatment performance was insufficient to meet the legal requirements for water discharge. APC was found to be a more economically viable approach, as it reduced anode wear, electrode passivation, and energy consumption. The quantity of iron released increased with d, and the effect of current density on iron concentration was found to be non-linear. However, applying APC reduced the iron content for all tested current densities. The tests showed that EC was effective in removing chemical oxygen demand (COD) and total suspended solids (TSS), achieving removal efficiencies above 92% and 99%, respectively. However, the studied treatment procedures were insufficient to meet the EU legal requirements for water discharge. Therefore, the obtained wastewater should undergo a post-treatment process.

Environmental-friendly regenerated lignocellulose functionalized cotton fabric to prepare multi-functional degradable membrane for efficient oil-water separation and solar seawater desalination

Freshwater pollution and shortage have become an imminent problem. Therefore, it is necessary to develop a multi-functional membrane for the production of fresh water. In this work, the regenerated lignocellulose modified cotton fabric was developed as a novel, multi-functional and degradable membrane (LCPT@CF) for efficient oil-water separation and solar steam generation for the first time. The fabrication method has the merits of simple, environmentally friendly and cost effective. The regenerated lignocellulose was adhered on the surface of cotton fabric by tannic acid and polyvinyl alcohol complexes tightly, and the multilayered structures of the LCPT@CF can be formed, which endowed the membranes with underwater superoleophobic property and durability. The underwater superoleophobic property enabled LCPT@CF to purify various kinds of oil-in-water emulsions with a separation efficiency of more than 99.90%. Moreover, benefiting from the excellent photothermal conversion capacity of regenerated lignocellulose, the LCPT@CF achieved high evaporation rate of 1.39 kg m^-2 h^-1 and favorable evaporation efficiency of 84% under 1 sun illumination, and the LCPT@CF also presented excellent salt-resistance for evaporating seawater for 20 cycles, without salt accumulation. More importantly, the LCPT@CF could be naturally degradable by microorganisms in the natural condition within 3 months, which had outstanding environmental friendliness. These above results demonstrated that the green and efficient LCPT@CF could play great potential in oil-water separation and sewage purification.

Occurrence and removal of conventional pollutants, estrogenicities, and fecal coliform in village sewage treatment plants along the Yangtze River, China

The present study investigated the occurrence and removal efficiency of some conventional pollutants, estrogenic effects, and fecal coliform in influents and/or effluents of village sewage treatment plants (STPs) in the upper, middle, and lower reaches of the Yangtze River Basin. The water quality of sewage from the village STPs showed significant seasonal and spatial variability. The removal rates of conventional pollutants by the village STPs were mostly lower than urban STPs, thereby resulting in that the water quality compliance rate of the effluents was only 33.3%. In addition, the average removal rate of estrogenic compounds was only 22.2%, which caused the estrogenicity of effluent to exceed the safety threshold. And E2 was determined to be the main estrogenic component. Moreover, ultraviolet (UV) disinfection, as the main disinfection treatment process of sewage along the Yangtze River Basin, was unable to meet the discharge standard of fecal coliform. The sequential chlorine (10 mg L^-1)-UV (20 mJ cm^-2) disinfection was found to both achieve up-to-standard discharge of fecal coliform and increase the removal rate of estrogenic effect from 3.78 to 9.86%. Overall, the present study provides valuable information on the conventional pollutants, estrogenic effects, and fecal coliform in sewage from village STPs along the Yangtze River Basin, and practical suggestions for basin-wide pollution control.

Volatile organic compounds generation pathways and mechanisms from microplastics in water: Ultraviolet, chlorine and ultraviolet/chlorine disinfection

Disinfection in water treatments induces microplastics (MPs) to produce various derivative products, among which the volatile organic compounds (VOCs) are still poorly understood. Ultraviolet (UV), chlorine and UV/chlorine disinfections were used to treat polypropylene (PP), polystyrene (PS) and polyvinylchloride (PVC) in this study. Modifications were observed on the MP surfaces, including melting, cracks, folds, and even forming oxygen-containing structures, resulting in the release of a diversity of VOCs. The polymer types of MPs influenced the VOCs characteristics. PP released alkanes, alkenes and aldehydes, while PVC released alkanes, alkenes and halogenated hydrocarbons. VOCs from PS were dominated by unique aromatic alkanes, alkenes and aldehydes. These derived VOCs are generated during different disinfections with distinct mechanisms. UV-C at 254 nm induced direct scission and radical oxidation on MPs. The derived VOCs were mainly bond-breaking fragments. Chlorination relied on HOCl/OCl^- electrophilic reactions, resulting fewer VOCs since C-C skeleton MPs have strong resistance to electrophilic reactions. UV/chlorination promotes the generation of chlorine radicals and hydroxyl radicals, thereby causing oxidative damage. Various oxidized VOCs, such as benzaldehyde and acetophenone, were formed. The disinfection reactions can produce various VOCs from MPs, posing potential risks to the ecological environment and human beings.

Removal of ofloxacin from wastewater by chloride electrolyte electro-oxidation: Analysis of the role of active chlorine and operating costs

Electro-oxidation (EO) has received increasing attention as an efficient and green method for removing pollutants from wastewater. Chloride anions (Cl^-), which commonly exist in wastewater, can act as an electrolyte for the EO process. However, the role of reactive chlorine species (RCS) generated near electrodes is often underestimated. In this study, we generated hydroxyl radicals (OH) and RCS in a boron-doped diamond (BDD) electrode system and investigated its degradation mechanism for ofloxacin (OFX) removal. The findings suggested that OFX degradation was dominated by OH existing near the anode in solution, with RCS playing a supporting role. Based on the produced intermediates, we proposed an OFX decomposition pathway. The biological toxicities of the intermediates were evaluated through the ECOSAR and T.E.S.T. procedure. Nearly half of the intermediates are less toxic than the parent compound. After optimizing the operating parameters by the response surface methodology, 20 mg/L OFX was almost completely degraded after 10 min of reaction in 1.45 g/L NaCl with a current density (j) of 18 mA/cm², and the total organic carbon was decreased by 30.55 %. The energy consumption and current efficiency were 0.648 kW·h/g_TOC and 8.65 %, respectively. Comparing the operating costs of the proposed and other EO methods, our method emerged as a viable new treatment scheme for similar polluted wastewaters. This study aims to comprehensively understand the potential application value of BDD electrodes in the treatment of Cl^- containing organic wastewater.

Analysis of Adhesion at the Interface of Steamed Bread and Eggshell

The adhesion phenomenon of polymers occurs in nature and in human activity. In the present paper, an adhesion system of steamed bread and eggshell was observed in formation when steamed bread and eggshells were placed in close contact and cooled slightly in the ambient air. The adhesion phenomena and mechanism of the adhesion interface between the steamed bread and eggshell were investigated and systematically discussed. Strong-bond interfaces were observed by scanning electron microscope (SEM). The formation process and mechanism of the strong-bond adhesion were also analyzed molecular dynamics simulation technology, and the results are discussed. The simulation analyses showed that the starch molecules at the calcite (104) crystal face were diffused in a water vapor environment, and the formation and solidification of multiple hydrogen bonds in the starch chain and oxygen atoms in the calcium carbonate were observed in detail during cooling. The diffusion rate of hydrogen atoms in hydroxyl groups on the calcite surface decreased gradually with the decrease of the cooling temperature of the steamed bread's upper surface. The strong adhesion of the steamed bread and eggshell is attributed to the synthetic effect of the absorption, diffusion, surface chemistry, and the formation of multiple hydrogen bonds between the starch from the steamed bread and the calcium carbonate crystals in eggshell. The interesting findings are helpful for the design of strong bonds, and provide an idea for new environmentally friendly adhesive materials.

Biodegradation of Biodegradable Polymers in Mesophilic Aerobic Environments

Finding alternatives to diminish plastic pollution has become one of the main challenges of modern life. A few alternatives have gained potential for a shift toward a more circular and sustainable relationship with plastics. Biodegradable polymers derived from bio- and fossil-based sources have emerged as one feasible alternative to overcome inconveniences associated with the use and disposal of non-biodegradable polymers. The biodegradation process depends on the environment's factors, microorganisms and associated enzymes, and the polymer properties, resulting in a plethora of parameters that create a complex process whereby biodegradation times and rates can vary immensely. This review aims to provide a background and a comprehensive, systematic, and critical overview of this complex process with a special focus on the mesophilic range. Activity toward depolymerization by extracellular enzymes, biofilm effect on the dynamic of the degradation process, CO2 evolution evaluating the extent of biodegradation, and metabolic pathways are discussed. Remarks and perspectives for potential future research are provided with a focus on the current knowledge gaps if the goal is to minimize the persistence of plastics across environments. Innovative approaches such as the addition of specific compounds to trigger depolymerization under particular conditions, biostimulation, bioaugmentation, and the addition of natural and/or modified enzymes are state-of-the-art methods that need faster development. Furthermore, methods must be connected to standards and techniques that fully track the biodegradation process. More transdisciplinary research within areas of polymer chemistry/processing and microbiology/biochemistry is needed.

Synergistic effect of nitrate on UV-chlorine photochemical degradation of carbamazepine

We investigated the use of UV-chlorine advanced oxidation process for the removal and transformation of carbamazepine (CBZ), and its photochemical synergy with NO₃^- for the production of ^.OH towards enhancing CBZ removal in aqueous solution. Production of ^.OH by UV-chlorine system with/without NO₃^- was studied under different conditions, by using salicylic acid (SA) as the chemical probe for ^.OH. Initial concentration of 30 mg/L SA, 5 and 10 mg/L chlorine, and 0-10 mg/L NO₃^- under irradiation at 254 nm (3.026 W/L) in a photochemical reactor was used. Aqueous solutions containing 10 mg/L chlorine and spiked with 4 mg/L NO₃^- gave the highest reproducible generation of ^.OH. Using initial concentrations of 10 mg/L CBZ and 10 mg/L chlorine, 60 % CBZ was removed after 10 min of irradiation without NO₃^-, while 72 % CBZ was removed with 4 mg/L NO₃^- added. There was no noticeable CBZ removal after 10 min of irradiation in the presence of NO₃^- without chlorine. Corresponding dark reactions were also conducted, with no noticeable degradation of CBZ. Samples were analyzed via UHPLC, LC-MS, and TOC (total organic carbon) analyzer for CBZ and TOC concentrations respectively. Although, there was significant reduction in CBZ concentration during both photochemical degradation processes, the was low TOC removal (~10%) in each case. The two photochemical degradation processes also seem to generate similar degradation products indicating that the addition NO₃^- of the UV-chlorine process might not have changed the degradation mechanism. The results indicate that NO₃^- could act synergistically in a UV-chlorine system to increase CBZ removal and reduce the quantity of free chlorine required to achieve a target removal efficiency. This could facilitate reduction in the potential production of chlorinated byproducts in the system.

Wastewater treatment plants act as essential sources of microplastic formation in aquatic environments: A critical review

According to extensive in situ investigations, the microplastics (MPs) determined in current wastewater treatment plants (WWTPs) are mostly aged, with roughened surfaces and varied types of oxygen-containing functional groups (i.e., carbonyl and hydroxyl). However, the formation mechanism of aged MPs in WWTPs is still unclear. This paper systematically reviewed MP fragmentation and generation mechanisms in WWTPs at different treatment stages. The results highlight that MPs are prone to undergo physical abrasion, biofouling, and chemical oxidation-associated weathering in WWTPs at different treatment stages and can be further decomposed into smaller secondary MPs, including in nanoplastics (less than 1000 nm or 100 nm in size), suggesting that WWTPs can act as a formation source for MPs in aquatic environments. Sand associated mechanical crashes in the primary stage, microbes in active sewage sludge-related biodegradation in the secondary stage, and oxidant-relevant chemical oxidation processes (light photons, Cl₂, and O₃) in the tertiary stage are the dominant causes of MP formation in WWTPs. For MP formation mechanisms in WWTPs, external environmental forces (shear and stress forces, UV radiation, and biodegradation) can first induce plastic chain scission, destroy the plastic molecular arrangement, and create abundant pores and cracks on the MP surface. Then, the physicochemical properties (modulus of elasticity, tensile strength and elongation at break) of MPs shift consequently and finally breakdown into smaller secondary MPs or nanoscale plastics. Overall, this review provides new insights to better understand the formation mechanism, occurrence, fate, and adverse effects of aged microplastics/nanoplastics in current WWTPs.

Kinetics and Mechanism of Degradation of Reactive Radical-Mediated Probe Compounds by the UV/Chlorine Process: Theoretical Calculation and Experimental Verification

The UV/chlorine process, by combining chlorination with UV irradiation, has been recently considered as a highly efficient advanced oxidation process (AOP) technology in water treatment. Nitrobenzene (NB), benzoic acid (BA), and p-chlorobenzoic acid (pCBA) are widely used as model probe compounds in the UV/chlorine system to calculate the second-order rate constants of the specific radical reaction with target contaminates by a competitive kinetics method. A comprehensive understanding of probe compounds' reaction mechanism with reactive radicals is critical for investigation of the UV/chlorine reaction system. Here, we evaluated the radical-mediated reaction kinetics and mechanism of NB, BA, and pCBA in the UV/chlorine process using theoretical calculations and experimental studies. The main reactive radicals ^•OH, ^•ClO, and ^•Cl in the UV/chlorine process for the initial reaction with NB, BA, and pCBA can be explained by H-abstraction and addition pathways. The ΔE ^0,≠ values for the ^•OH reaction with NB, BA, and pCBA were in the range of 5.0-8.0, 3.7-8.2, and 3.4-8.2 kcal mol^-1, respectively. The ΔE ^0,≠ values for ^•ClO and ^•Cl reactions with these three probe compounds were higher than those of ^•OH, indicating slower ^•ClO- and ^•Cl-initiated reactions than that of the ^•OH-initiated reaction. The theoretically calculated radical-mediated reaction kinetic rate constants (k _CP ^C) for NB, BA, and pCBA were 4.58 × 10^-3, 1.28 × 10^-2, and 1.6 × 10^-2 s^-1, respectively, which was consistent with the experimentally determined pseudo-first-order rate constant (k _CP ^RR) in the UV/chlorine process. Interestingly, theoretical calculations showed that ^•ClO and ^•Cl played an important role in subsequent reactions of NB-OH radicals, converting to hydroxylated and chlorinated products, which were further confirmed by experimental products' identification. The findings from this study indicated that quantum chemistry calculations provide an effective means to investigate the reaction kinetics and mechanism of chemicals in the UV/chlorine process.

Low-cost and highly efficient production of bacterial cellulose from sweet potato residues: Optimization, characterization, and application

Bacterial cellulose (BC) is an emerging biological material with unique properties and structure, which has attracted more and more attention. In this study, Gluconacetobacter xylinus was used to convert sweet potato residues (SPR) hydrolysate to BC. SPR was directly used without pretreatment, and almost no inhibitors were generated, which was beneficial to subsequent glucan conversion and SPR-BC synthesis. SPR-BC production was 11.35 g/L under the optimized condition. The comprehensive structural characterization and mechanical analysis demonstrated that the crystallinity, maximum thermal degradation temperature, and tensile strength of SPR-BC were 87.39%, 263 °C, and 6.87 MPa, respectively, which were superior to those of BC produced with the synthetic medium. SPR-BC was added to rice straw pulp to enhance the bonding force between fibers and the indices of tensile, burst, and tear of rice straw paper. The indices were increased by 83.18%, 301.27%, and 169.58%, respectively. This research not only expanded the carbon source of BC synthesis, reduced BC production cost, but also improved the quality of rice straw paper.

High-efficiency and energy-saving alternating pulse current electrocoagulation to remove polyvinyl alcohol in wastewater

Conventional direct current electrocoagulation (DC-EC) has disadvantages such as easy passivation of electrodes, high energy consumption, and large sludge production, which limit its use in polyvinyl alcohol (PVA) wastewater. Therefore, alternating pulse current electrocoagulation (APC-EC) has been developed to overcome these problems. In this study, the influencing factors and energy consumption of PVA treatment by APC-EC and DC-EC were explored, and the best operating conditions of APC-EC were obtained via the response surface method (RSM). The best process conditions for APC-EC were determined to be the electrode type of Fe/Fe, current density of 1.0 mA cm⁻², initial pH of 7, electrode distance of 2.0 cm, supporting electrolyte of 0.08 mol L⁻¹ NaCl, initial PVA concentration of 150 mg L⁻¹, duty cycle of 30%, and frequency of 500 Hz. In addition, the floc properties of APC-EC and DC-EC were compared to explore the basic mechanism for the removal of PVA. Adsorption and co-precipitation with hydroxide iron complexes are the main methods for removing PVA from wastewater in the APC-EC process. Compared with DC-EC, the application of APC-EC can reduce electrode passivation and production of sludge and operating costs, and improve electrode stability and PVA removal efficiency. This study provides a new strategy and method for the PVA removal from wastewater by APC-EC with low cost and high efficiency, showing broad prospect for the applications of the APC-EC in removing PVA.

Compared with DC-EC, the application of APC-EC can reduce electrode passivation and production of sludge and operating costs, and improve electrode stability and PVA removal efficiency.

Biodegradation of poly (vinyl alcohol) by an orychophragmus rhizosphere-associated fungus Penicillium brevicompactum OVR-5, and its proposed PVA biodegradation pathway

In recent years, the utilisation of endophytes has emerged as a promising biological treatment technology for the degradation of plastic wastes such as biodegradation of synthetic plastics. This study, therefore, aimed to explore and extensively screen endophytic fungi (from selected plants) for efficient in vitro polyvinyl alcohol (PVA) biodegradation. In total, 76 endophytic fungi were isolated and cultivated on a PVA screening agar medium. Among these fungi, 10 isolates showed potential and were subsequently identified based on phenotypical characteristics, ITS ribosomal gene sequences, and phylogenetic analyses. Four strains exhibited a maximum level of PVA-degradation in the liquid medium when cultivated for 10 days at 28 °C and 150 rpm. These strains showed varied PVA removal rates of 81% (Penicillium brevicompactum OVR-5), 67% (Talaromyces verruculosus PRL-2), 52% (P. polonicum BJL-9), and 41% (Aspergillus tubingensis BJR-6) respectively. The most promising PVA biodegradation isolate 'OVR-5', with an optimal pH at 7.0 and optimal temperature at 30 °C, produced lipase, manganese peroxidase, and laccase enzymes. Based on analyses of its metabolic intermediates, as identified with GC-MS, we proposed the potential PVA degradation pathway of OVR-5. Biodegradation results were confirmed through scanning electron microscopy and Fourier transform infrared spectroscopy. This study provides the first report on an endophytic P. brevicompactum strain (associated with Orychophragmus violaceus) that has a great ability for PVA degradation providing more insight on potential fungus-based applications in plastic waste degradation.

Sodium hypochlorite and Cu-O-Mn/ columnar activated carbon catalytic oxidation for treatment of ultra-high concentration polyvinyl alcohol wastewater

Complete degradation of high concentration polyvinyl alcohol (PVA) is challenging. In this article, a two-stage process of NaClO pre-oxidation and columnar activated carbon (loaded with metal active components) catalytic oxidation was used to treat high concentration PVA wastewater. The degree of polymerization of PVA is 2400 and the water concentration is 15 wt %. In the first stage, NaClO efficiently broken long chain to short, the viscosity of PVA solution decreased from 45,100 mPaS to 4.65 mPaS. And in the second stage, the short chain was further oxidized to small molecules under H₂O₂ with catalysts. The solution COD decreased from 206,240 mg/L to 38.38 mg/L. The composition of catalysts and the reaction conditions were optimized, the degradation mechanism was discussed. According to the experimental results, small pore size (8-10 mesh) activated carbon loaded copper and manganese catalyst (C₁M₁AC-S) was the best choice. The optimal conditions of C₁M₁AC-S were: molar ratio of copper to manganese was 2:1, the loading rate was 25 wt% and the dosage was 9.76 mg/100 ml. The whole process is mild (25 °C-40 °C) and reaction time is short (100 min). Moreover, free radical scavenging experiments shown that the catalytic oxidation stage follows the mechanism of hydroxyl radical reaction.

Photoinduced Radical Emission in a Coassembly System

Developing radical emission at ambient conditions is a challenging task since radical species are unstable in air. In the present work, we overcome this challenge by coassembling a series of tricarbonyl-substituted benzene molecules with polyvinyl alcohol (PVA). The strong hydrogen bonds between the guest dopants and the PVA host matrix protect the free radicals of carbonyl compounds after light irradiation, leading to strong solid state free radical emission. Changing temperature and peripheral functional groups of the tricarbonyl-substituted benzenes can influence the intensity of the radical emission. Quantum-chemical calculations predict that such free radical fluorescence originates from anti-Kasha D₂ →D₀ vertical emission by the anion radicals. The photoinduced radical emission by the tricarbonyl-substituted benzenes was successfully utilized for information encryption application.

The role of carbonate radicals on the kinetics, radical chemistry, and energy requirement of UV/chlorine and UV/H2O2 processes

Quantitative insight into the HCO₃^--dependent degradation kinetics is critical to improve understanding of the UV processes for the most-cost effective application. In this study, we developed a kinetic model to precisely predict the kinetics in UV/H₂O₂ and UV/chlorine processes. The second-order rate constants of HO, Cl, ClO, Cl₂^-, and CO₃^- with carbamazepine (CBZ) were fitted as 1.3 × 10⁹, 1.9 × 10⁹, 1.8 × 10⁶, 1.1 × 10⁵, and 4.5 × 10⁶ M^-1 s^-1, respectively. Based on the model, we investigated the significant impact of bicarbonate (HCO₃^-) and subsequently generated carbonate radical (CO₃^-) on CBZ degradation, radical chemistry, and energy requirement of UV/H₂O₂ and UV/chlorine processes. The presence of HCO₃^- inhibited CBZ degradation in UV/H₂O₂ and UV/chlorine processes to different degree. Contributions of HO, Cl, ClO, Cl₂^-, and CO₃^- to CBZ degradation in UV/H₂O₂ and UV/chlorine processes in the absence/presence of HCO₃^- were investigated. HO and CO₃^- make comparable contributions to CBZ degradation in UV/H₂O₂ process in the presence of HCO₃^- (2 mM), while ClO is always the main contributor at various HCO₃^- concentration of 0-2 mM. Furthermore, the presence of HCO₃^- in both processes increased the corresponding EE/O, when CBZ was degraded by an order of magnitude. Overall, HCO₃^- and CO₃^- influence the reactions and mechanism of UV/H₂O₂ and UV/chlorine processes, and have higher impact on UV/H₂O₂ process.

Photo aging of polypropylene microplastics in estuary water and coastal seawater: Important role of chlorine ion

Photo aging of microplastics (MPs) in water environment are relevant to free radical associated polymer chain reaction, and various photo chemical reactive constitutes (i.e., Cl^-, Br^-, NO₃^-, CO₃^2-, and natural organic matters) would affect the reaction, leading to a great difference in the photo aging mechanism of MPs between freshwater and seawater system. This study investigated light induced photo aging process of polypropylene (PP) MPs in ultrapure water, estuary water, and seawater. Results revealed that the aging rate of PP MPs was significantly decreased in estuary water and seawater compared with that in ultrapure water, leading to a longer resistance time after emission in marine environment. Besides, lower carbonyl index was found with the increased aqueous Cl^- concentration, highlighting the important role of Cl^- in the inhibitory effect for PP MPs aging process in seawater. This is due to the formation of Cl₂^•- in seawater which could react with HO₂• and prevent the formation of O₂^•-, thus inhibit the photo aging process of PP MPs under light irradiation. The finding in this study clearly indicates the impact of the water matrices on the photo aging rate of MPs in natural water.

Modeling degradation kinetics of gemfibrozil and naproxen in the UV/chlorine system: Roles of reactive species and effects of water matrix

The UV/chlorine system has been regarded as an efficient oxidation technology for the removal of aqueous micropollutants. However, the roles of the possible radical species for this system on the elimination under environmentally relevant conditions/real waters were still largely unknown. Herein, the specific roles of radical species in the UV/chlorine oxidation degradation of gemfibrozil and naproxen as representative micropollutants were quantified by a steady-state kinetic prediction model considering the effects of water matrices. Overall, the model predicted results are consistent with the experimental data well. •OH and reactive chlorine species (RCS, such as Cl•, ClO•, and Cl₂•^-) contributions to gemfibrozil and naproxen degradation were water matrix specific. In pure water, both primary reactive species (i.e., •OH and Cl•) and secondary species ClO• dominated gemfibrozil and naproxen degradation, and their individual and the sum of the contributions to degradation rates reduced with pH increase of from 5 to 9. In the presence of Cl^-, we found that Cl₂•^- and in particular ClO• were responsible for the enhanced degradation with increasing Cl^- concentrations due to the considerable ClO• reactivity of gemfibrozil (1.93 × 10⁹ M^-1 s^-1) and naproxen (9.24 × 10⁹ M^-1 s^-1) and the rapid transformation of Cl₂•^- to ClO•. The presence of HCO₃^- notably facilitated the degradation in the UV/chlorine process because of the generation of CO₃•^-. CO₃•^- showed high reactivity with gemfibrozil and naproxen corresponding to respective second-order reaction rate constants of 2.45 × 10⁷ and 3.50 × 10⁷ M^-1 s^-1. Dissolved organic matter induced obvious scavenging for •OH, Cl•, and ClO• and greatly retarded the degradation. The constructed model considering the effects of above water matrix has successfully predicted the oxidation degradation kinetics in real waters, and both •OH and CO₃•^- are the predominant reactive species in the degradation. This study is helpful for comprehensive understanding the roles of possible radical species in micropollutant removal by UV/chlorine oxidation under real water matrix.

Degradation of Polyvinyl Alcohol in US Wastewater Treatment Plants and Subsequent Nationwide Emission Estimate

Polyvinyl alcohol (PVA) is a water-soluble plastic commercially used in laundry and dish detergent pods (LDPs) for which a complete understanding of its fate in the environment and subsequent consequences is lacking. The objective of this study was to estimate the US nationwide emissions of PVA resulting from domestic use of LDPs, corroborated by a nationwide, online consumer survey and a literature review of its fate within conventional wastewater treatment plants (WWTPs). Peer-reviewed publications focusing on the degradation of PVA in critical processes of WWTPs were shortlisted as a part of the literature review, and subsequent degradation data was extracted and applied to a model with a set of assumptions. Survey and model results estimated that approximately 17,200 ± 5000 metric ton units per year (mtu/yr) of PVA are used from LDPs in the US, with 10,500 ± 3000 mtu/yr reaching WWTPs. Literature review data, when incorporated into our model, resulted in ~61% of PVA ending up in the environment via the sludge route and ~15.7% via the aqueous phase. PVA presence in the environment, regardless of its matrix, is a threat to the ecosystem due to the potential mobilization of heavy metals and other hydrophilic contaminants.

Novel consortia of enterobacter and pseudomonas formulated from cow dung exhibited enhanced biodegradation of polyethylene and polypropylene

This study prioritizes the biodegradation potential of novel bacterial consortia formulated from cow dung samples towards low-density polyethylene (LDPE) and polypropylene (PP) in comparison with our previous studies. Ten possible consortia were formulated using 10 selected isolates with >10% weight reduction of LDPE and PP, these were pre-treated under UV for 1 h, and their biodegradation potential was studied for 160 days. The isolates present in prioritized consortia were characterized by standard microbiology and 16SrRNA gene sequencing methods. Out of 10 bacterial consortia formulated, potential consortium-CB3 showed greater percentage degradation (weight reduction) of 64.25 ± 2% and 63.00 ± 2% towards LDPE and PP films, respectively (p < 0.05) at 37 °C compared to other consortia. Significant structural variations due to the formation of bacterial biofilm were observed in CB3 treated LDPE and PP films. The three bacteria-IS1, IS2, and IS3-that constituted CB3 were found to be novel strains and designated to be Enterobacter sp nov. bt DSCE01, Enterobacter cloacae nov. bt DSCE02, and Pseudomonas aeruginosa nov. bt DSCE-CD03, respectively. This novel consortium can be scaled up for enhanced degradation of plastic polymers and probably design cost-effective bio-digester for industrial applications using CB3 as potential inoculum.

Polyvinyl alcohol based-drug delivery systems for cancer treatment

Polyvinyl alcohol (PVA) is a biodegradable semicrystalline synthetic polymer that has been used for biomedical applications for several years. In the pharmaceutical area, PVA has been widely used to prepare solid dispersions to improve the solubility of drugs. Furthermore, it has been demonstrated that PVA is highly biocompatible and non-toxic in in-vitro and in-vivo studies. Several reports provided in this review suggest a promising strategy for cancer treatment. Thus far, the current therapy includes a combination of surgery, chemotherapy, and radiotherapy, the effectivity can be limited due to the heterogeneous manifestations of the disease, dose-related toxicity, and side effects. A promising strategy is the implementation of a targeted therapy using hydrogels, microparticles, or nanoparticles (NPs), capable of encapsulating, protecting, transporting, and targeted administration of a therapeutic agent. Considering the relevance of the PVA in conjunction with their copolymers, it has become a promising biodegradable material to build novel functional composites used in the fabrication of hydrogels, microparticles, nanoparticles, and nanocomposites for drug delivery systems in cancer treatment.

Computerized Pathway Generator for the UV/Free Chlorine Process: Prediction of Byproducts and Reactions

The ultraviolet (UV)/free chlorine process is a very promising treatment technology to remove persistent organic contaminants (POCs, e.g., pharmaceutical and personal care products) from water. The radical chain reactions involved in the UV/free chlorine process are very complicated, and the reaction pathways for organic contaminants degradation are largely unknown. Therefore, we developed a computerized pathway generator that uses graph theory and experimentally determined reaction rules that were reported for the UV/free chlorine process. Our pathway generator predicts all possible intermediates, byproducts, and elementary reactions that are involved in the oxidation of organic contaminants. For example, the degradation of tricholoroethylene (TCE) produces 497 species (i.e., intermediates and byproducts) and 6608 elementary reactions. The predicted species from our pathway generator not only predict the major and stable byproducts that were observed in our experiments (e.g., CHCl₂COOH, CHCl(OCl)COOH, etc.) but also include many other minor and toxic byproducts that were produced but not measured because they have a short lifetime. Overall, our pathway generator significantly improves our understanding of the reaction pathways that are involved in organic contaminant degradation in the UV/free chlorine process.

Efficient Degradation of Organoarsenic by UV/Chlorine Treatment: Kinetics, Mechanism, Enhanced Arsenic Removal, and Cytotoxicity

Roxarsone (ROX) has been widely used as an organoarsenic additive in animal feeding operations and poses a risk to the environment. Here, we first report the efficient degradation of ROX by UV/chlorine, where the kinetics, removal of total arsenic (As), and cytotoxicity were investigated. The kinetics study presented that reactive chlorine species (RCS) and HO^• were the dominant species to react with ROX. Furthermore, the degradation rate of ROX can reach the maximum value at pH 7.5 due to the formation of more RCS. The degradation of ROX was affected by the amount of chlorine, pH, and water matrix. Through product analysis and Gauss theoretical calculation, two possible ROX degradation pathways were proposed. The free radicals attacked the As-C bond of ROX and resulted in releasing arsenate (As(V)). It was the reason that for an enhancement of the removal of total As by ferrous appeared after UV/chlorine, and over 98% of the total As was removed. In addition, cytotoxicity studies indicated that the cytotoxicity significantly enhanced during the degradation of ROX by UV/chlorine. However, by combination of UV/chlorine and adsorption, cytotoxicity can be greatly eliminated, probably due to the removal of As(V) and chlorinated products. These results further demonstrated that UV/chlorine treatment could be an effective method for the control of the potential environmental risks posed by organoarsenic.

Kinetic and mechanistic investigation of water taste and odor compound 2-isopropyl-3-methoxy pyrazine degradation using UV-A/Chlorine process

The present study was launched as a continuation of global efforts to tackle problems associated with two important aesthetic characteristics, taste and odor (T&O), of drinking water. The UV-A/Chlorine process, a promising advanced oxidation process (AOP), was evaluated for the first time for the removal of 2-isopropyl-3-methoxy pyrazine (IPMP), a widely reported compound in the literature that causes unpleasant taste and odor when present in water at or below the ng L^-1 level. It was found that the studied process was efficient for the removal of IPMP in both ultrapure and drinking water. The initial chlorine dosage influenced significantly the degradation efficiency under initial neutral pH values. Degradation efficiency of IPMP was slightly inhibited by using drinking water as matrix. Scavenging experiments highlighted the significant role of various reactive species (e.g. HO, ClO, Cl, Cl₂^-) generated during the process that have not been studied comprehensively until now. In addition, the significant role of HO was further verified by Electron paramagnetic resonance spectroscopy (EPR) experiments. Overall, the formation of diverse radicals during the UV-A/Chlorine treatment enhanced the degradation of IPMP, promoting mainly the formation of hydroxy, hydroperoxy and dealkylated derivatives. In contrast, chlorinated by-products were only identified in traces.

Insights into electrochemical decomposition mechanism of lipopolysaccharide using TiO2 nanotubes arrays electrode

Electrochemical decomposition of lipopolysaccharide (LPS) was firstly investigated over titania nanotubes (TNTs) arrays electrode. The TNTs layer of this electrode consisted of numerous tubular structures which arranged tightly, and the average diameter of each nanotube is 100 ± 5 nm. The degradation of LPS and polysaccharides followed pseudo-first-order kinetics. The optimal LPS removal ratio was nearly 80 %. The endotoxin toxicity of LPS steadily decreased during the electrolysis process. The acute toxicity of the intermediates increased suddenly at the beginning of electrochemical degradation process (< 5 min), then maintained high inhibition ratio (> 95 %) for about 150 min, and decreased significantly (< 10 %) after electrolysis for 240 min. After 20 min of electrolysis, LPS with molecular weight of 116,854 Da was transformed into small molecular compounds with molecular weights of 59,312 - 12,209 Da. Possible degradation and detoxification mechanisms of LPS including electric-field-force-driving accumulation, adsorption and direct electron transfer on TNTs arrays electrode, and •OH oxidation were proposed. This study underscores that electrochemical technique can be applied to eliminate and decrease the toxicity of LPS from contaminated water.

Application of Fenton pre-oxidation, Ca-induced coagulation, and sludge reclamation for enhanced treatment of ultra-high concentration poly(vinyl alcohol) wastewater

Poly(vinyl alcohol) (PVA) wastewater contains up to 10,000 mg/L dissolved organic carbon. A concentration of this magnitude results in a high chemical oxygen demand (COD), which generates major problems for industrial wastewater treatment in general, and the textile and chemical industries, in particular. Thus, we propose a two-stage treatment process that uses Fenton pre-oxidation, coupled with Ca-induced coagulation, to reduce the PVA and COD wastewater concentration. The optimal concentrations of FeSO₄ and CaCl₂ per gram of PVA were 0.8 g/g-PVA and 4.0 g/g-PVA, respectively, which is significantly lower than that of other reported treatments. Due to successful oxidation, the long chains of PVA molecules were broken up and the OH groups were partially oxidized to COOH. During the coagulation stage, Ca²⁺ was able to efficiently bind with the PVA pre-oxidation products, thereby forming insoluble compounds. Given initial COD and PVA concentrations of 20,450 and 10,000 mg/L, respectively, a maximum of 81.3 % COD and 96.0 % PVA was removed following this two-stage procedure. Furthermore, the sludge residue was used to remove Sb(III) from the wastewater, achieving an Sb(III) adsorption capacity of 16.0 mg/g. Thus, this study provides new insight into affordable and effective treatment of high concentration PVA-containing wastewater.

Degradation of diiodoacetamide in water by UV/chlorination: Kinetics, efficiency, influence factors and toxicity evaluation

The formation and control of haloacetamides (HAcAms) in drinking water have raised high attention due to their high genotoxicity and cytotoxicity, especially the most cytotoxic one, diiodoacetamide (DIAcAm). In this study, the degradation of DIAcAm by UV/chlorination was investigated in terms of degradation kinetics, efficiency, influencing factors, oxidation products and toxicity evaluation. Results revealed that the degradation of DIAcAm by UV/chlorine process followed pseudo-first-order kinetics, and the rate constant between DIAcAm and OH radicals was determined as 2.8 × 10⁹ M^-1 s^-1. The contribution of Cl to DIAcAm degradation by UV/chlorine oxidation was negligible. Increasing chlorine dosage and decreasing pH significantly promoted the DIAcAm degradation during UV/chlorine oxidation, but the presence of bicarbonate (HCO₃^-) and natural organic matter (NOM) inhibited it. The mass balance analysis of iodine species was also evaluated during UV/chlorine oxidation of DIAcAm. In this process, with DIAcAm decreasing from 16.0 to 0.8 μM-I in 20 min, IO₃^-, I^- and HOI/I₂ increased from 0 to 6.3, 6.1 and 0.5 μM-I, respectively. The increase of CHO cell viability during DIAcAm degradation indicated that the toxicity of DIAcAm could be decreased by chlorination, UV irradiation and UV/chlorine oxidation treatments, in which UV/chlorine oxidation was more effective on toxicity reduction than chlorination and UV irradiation alone.

Synthesis of Modified Starch/Polyvinyl Alcohol Composite for Treating Textile Wastewater

In this work, we demonstrated a strategy to design a modified starch/polyvinyl alcohol composite (CCSP), which was employed as a highly efficient and economical fixed-bed adsorbent for treating textile wastewater. Characterization revealed that most of the CCSP was shaped with the morphology of sphericity, and had some water swelling properties. The crystallinity of the CCSP was lower than that of native starch and polyvinyl alcohol, and its average particle size gradually increased with the dosage increase of cationic starch in the preparation. Adsorption experiments showed that the adsorption capacities of CCSP were more than 605 and 539 mg/g for Reactive Black 5 and Reactive Orange 131, respectively, which were over 10 times larger than that of commercial activated carbon (AC). The mixture adsorbent composed of CCSP and AC could remove starch, polyvinyl alcohol, and dyes from textile wastewater completely and simultaneously combined with the fixed-bed technique, and its adsorption capacity was conducted as a function of the bed height and flow rate. Most importantly, the disabled mixture adsorbent could be converted into regenerated AC through a chemical activation process, thereby avoiding the production of solid waste. This study will provide a new efficient green sustainable method for treating textile wastewater.

Halogen-Mediated Partial Oxidation of Polyvinyl Alcohol for Tissue Engineering Purposes

Partial oxidation of polyvinyl alcohol (PVA) with potassium permanganate turned out to be an efficient method to fabricate smart scaffolds for tissue engineering, endowed with biodegradation and protein delivery capacity. This work considered for the first time the use of halogens (bromine, chlorine and iodine) as less aggressive agents than potassium permanganate to perform controlled PVA oxidation, in order to prevent degradation of polymer molecular size upon chemical modification. Oxidized PVA solutions were chemically characterized (i.e., dinitrophenylhydrazine assay, viscosity measurements, molecular size distribution) before preparing physically cross-linked hydrogels. Scaffolds were assessed for their mechanical properties and cell/tissue biocompatibiliy through cytotoxic extract test on IMR-90 fibroblasts and subcutaneous implantation into BALB/c mice. According to chemical investigations, bromine and iodine allowed for minor alteration of polymer molecular weight. Uniaxial tensile tests demonstrated that oxidized scaffolds had decreased mechanical resistance to deformation, suggesting tunable hydrogel stiffness. Finally, oxidized hydrogels exhibited high biocompatibility both in vitro and in vivo, resulting neither to be cytotoxic nor to elicit severe immunitary host reaction in comparison with atoxic PVA. In conclusion, PVA hydrogels oxidized by halogens were successfully fabricated in the effort of adapting polymer characteristics to specific tissue engineering applications.

Photochemical oxidation of PPCPs using a combination of solar irradiation and free available chlorine

The degradation of pharmaceuticals and personal care products (PPCPs) by using solar photolysis in the presence of free available chlorine (FAC) was investigated in simulated drinking water. The combination of free available chlorine and sunlight irradiation dramatically accelerated the degradation of all the contaminants tested through the generation of hydroxyl radicals, reactive chlorine species (RCS) and ozone. Contaminants containing electron-donating moieties degraded quickly and were preferentially degraded by RCS and/or HO oxidation. Primidone, ibuprofen and atrazine, which contain electron-withdrawing moieties, were mainly degraded by HO. Trace amounts of O₃ contributed greatly to carbamazepine's degradation. Degradation of PPCPs was accelerated in oxygenated solutions. Increasing chlorine concentrations barely enhanced removal of PPCPs bearing electron-withdrawing moieties. Higher pH generally decreased the degradation rate constants along with reduced levels of HO and Cl, but diclofenac, gemfibrozil, caffeine and carbamazepine had peak degradation rate constants at pH 7-8. The cytotoxicity using Chinese hamster ovary (CHO) cell did not show significant enhancement in solar/FAC treated water. Combining chlorination with sunlight may provide a simple and energy-efficient approach for improving the removal of organic contaminants during water treatment.