Generation Of Reactive Chlorine Species Research Articles

Utilizing the immanent chloride ions in wastewater for reactive chlorine species photogeneration towards effective ammonia nitrogen removal

Utilizing the immanent salt (Cl–) in wastewater to generate reactive chlorine species (RCS) satisfies the future needs for sustainable, on-demand, and decentralized ammonia nitrogen (NH4+-N) removal. The microstructural evolution of bismuth oxychloride (BiOCl) photocatalyst under irradiation benefits for overcoming the competition between Cl– and H2O oxidation and achieving high N2 selectivity. Herein, internal electric field (IEF) engineering by carbon doping is applied to promote photocatalytic RCS generation rate over BiOCl. The carbon dopant not only enhances the IEF intensity of BiOCl by a factor of 2.1 times for carrier dynamics promotion, but also improves Cl– oxidation against H2O oxidation. An RCS production rate of 0.23 mg/L min−1 is realized over carbon-doped BiOCl (C-BiOCl) through the accelerated interaction between lattice and environmental Cl–, which is twice that of the undoped BiOCl (0.11 mg/L min−1). The relation between IEF intensity and RCS generation rate over C-BiOCl manifests a correlation coefficient of 0.96. Effective NH4+-N degradation with N2 selectivity of > 99 % is validated. The system is competent in dealing with saline NH4+-N wastewater with a wide range of NH4+-N (20 ∼ 200 mg N/L) and NaCl (6 ∼ 10 g/L) concentrations. In the treatment of realistic landfill leachate (884 mg N/L NH4+-N), C-BiOCl displays a photocatalytic NH4+-N removal efficiency of up to 95.6 % while maintaining the NO2−-N (∼2 mg N/L) and NO3−-N (∼40 mg N/L) levels. This system provided an interesting and innovative idea for wastewater self-purification.

Degradation of 4-chlorophenol through in situ generation of reactive chlorine species in a Zn2CoOx electrocatalytic system

Chloride ion significantly impacts the degradation efficiency of organic pollutants in chemical industrial wastewater during electrocatalytic process, therefore utilization of Cl− to in situ produce reactive chlorine species (RCS) is desired for electrocatalytic degradation of pollutants. We developed a novel catalyst by incorporating Zn into CoOx (ZnnCoOx) as anode for the electrocatalytic removal of 4-chlorophenols (4-cp) in Cl−-containing wastewater. Characterization and electrochemical performance of ZnnCoOx catalysts indicated that Zn incorporation increased Co2+/Co3+ ratio, resulting in lattice distortion and the formation of oxygen vacancy (OV). Electrocatalytic experiments showed that Zn2CoOx (i.e., ZnCo = 2:1) had the highest electrochemical reactivity, and the 4-cp degradation rates (kobs) showed a positive correlation with OV. The identified reactive species involved in 4-cp degradation included O2•− and RCS. The formation mechanism of reactive species and the degradation pathways of 4-cp during electrocatalytic process using the Zn2CoOx anode were proposed. Overall, the developed ZnnCoOx catalyst as anode can utilize Cl− to in situ produce RCS and exhibit an effective performance on the 4-cp degradation in Cl−-containing wastewater.

The diverse roles of halide ions in the degradation of bisphenol A via UV/peracetic acid process at different pH values: Radical chemistry, and transformation pathways

UV/Peracetic Acid (UV/PAA), as an innovative advanced oxidation process (AOP), is employed to treat bisphenol A (BPA) in water through the generation of hydroxyl radicals (•OH) and carbon-centered radicals (R−C•). The impact of halide ions (Cl−; Br−; I−) on the efficiency of UV/PAA was investigated for the first time under varying pH levels. The presence of halide ions exerted an influence on the reactivity of •OH and R−C•, exhibiting varying degrees of impact across different pH conditions. It was discovered that pH exerts a significant influence on its efficiency, with optimal removal performance observed at a pH 9. The degradation of BPA was inhibited by Cl− through the generation of reactive chlorine species (RCS), which triggers the interconversion between •OH and R−C•. Reactive bromine species (RBS) were produced in the presence of Br−, facilitating BPA degradation and generating HOBr as a supplementary source of •OH radicals. I− primarily generate reactive iodine species (RIS) through photolysis, which facilitates the degradation of BPA. The transformation of BPA involves hydroxylation, demethylation, halogenation, and cleavage reactions to form various products and pathways. The toxicity test demonstrates that the UV/PAA treatment of BPA exhibits lower toxicity, thereby indicating its environmentally friendly.

Rapid Inactivation of Fungal Spores in Drinking Water by Far-UVC Photolysis of Free Chlorine.

Effective and affordable disinfection technology is one key to achieving Sustainable Development Goal 6. In this work, we develop a process by integrating Far-UVC irradiation at 222 nm with free chlorine (UV222/chlorine) for rapid inactivation of the chlorine-resistant and opportunistic Aspergillus niger spores in drinking water. The UV222/chlorine process achieves a 5.0-log inactivation of the A. niger spores at a chlorine dosage of 3.0 mg L-1 and a UV fluence of 30 mJ cm-2 in deionized water, tap water, and surface water. The inactivation rate constant of the spores by the UV222/chlorine process is 0.55 min-1, which is 4.6-fold, 5.5-fold, and 1.8-fold, respectively, higher than those of the UV222 alone, chlorination alone, and the conventional UV254/chlorine process under comparable conditions. The more efficient inactivation by the UV222/chlorine process is mainly attributed to the enhanced generation of reactive chlorine species (e.g., 6.7 × 10-15 M of Cl•) instead of hydroxyl radicals from UV222 photolysis of chlorine, which is verified through both experiments and a kinetic model. We further demonstrate that UV222 photolysis damages the membrane integrity and benefits the penetration of chlorine and radicals into cells for inactivation. The merits of the UV222/chlorine process over the UV254/chlorine process also include the more effective inhibition of the photoreactivation of the spores after disinfection and the lower formation of chlorinated disinfection byproducts and toxicity.

Optimization of BiVO4 coatings for high yield photoelectrochemical production of reactive chlorine species

Photoelectrochemical (PEC) synthesis of valuable chemicals, such as hydrogen and oxidants, is widely studied as a potential alternative to replace conventional synthesis processes with high carbon footprint. In the present study two different approaches were used to improve photoelectrochemical activity of BiVO4 coatings, i.e. doping with molybdenum and heterostructuring with BiOCl. Crystalline structure, chemical composition and morphology of the coatings were characterized using X-ray diffraction, energy-dispersive spectroscopy and scanning electron microscopy techniques. Performance of the photoelectrodes was tested in the solutions of Na2SO4 and NaCl. PEC activity was found to increase in the sequence BiVO4 < Mo_BiVO4 < Mo_BiVO4/BiOCl and the enhancement was much more pronounced in chloride medium. Mo doping was found to double incident photon to current conversion efficiency (from 5% to 10%) as well as Faradaic efficiency of photoinduced generation of reactive chlorine species (RCS) (from an average of 36% to 78%). Formation of hypochlorite and chlorite (ClO− and ClO2−) was determined experimentally. Construction of heterojunction between Mo_BiVO4 and BiOCl promoted separation of photogenerated electrons and holes and led to significant enhancement of photocurrent. Moreover, presence of BiOCl layer was found to catalyze photooxidation of ClO− to ClO2−. Findings of the study demonstrate the potential of BiVO4-based coatings for photoelectrochemical production of RCS via saline water splitting.

Coupling with in-situ electrochemical reactive chlorine species generation and two-phase partitioning method for enhanced microalgal biodiesel production

Microalgal-based biofuel production is of great significance in alleviating energy crisis and achieving carbon neutrality. However, the excessive costs and high solvent consumption in lipids extraction from microalgal obstruct the widespread application of biodiesel in practice. Reported herein is the construction of facile strategy for lipids extraction via electrocatalytic pretreatment and a subsequent two-phase partitioning method. Electrocatalytic pretreatment method adopts the solar as power source and avoids the drying of microalgal biomass, in favor of carbon neutrality requirement. During this process, eco-friendly electrode with high specific surface area could contribute to the sufficient generation of reactive chlorine species (RCS), facilitating the outflows of intracellular lipid. As a result, assisted with two-phase partitioning method, a satisfied performance of lipid recovery (86.72 %) was obtained. Notably, compared with traditional solvent method, two-phase partitioning method greatly reduced the dosage of organic solvent, which is an economical or environmental technique.

Generation of reactive chlorine species via molecular oxygen activation on a copper chloride loaded hydrothermal carbonaceous carbon for advanced oxidation process

In this study, we first achieve effective generation of reactive chlorine species (RCS) by molecular oxygen (O2) activation on a copper chloride loaded hydrothermal carbonaceous carbon (CuCl-HTCC). O2 can be adsorbed and activated by the cuprous (Cu(I)) from the CuCl-HTCC, and then converted into superoxide radical-hydrogen peroxide-hydroxyl radical, and chloride on the surface of CuCl-HTCC can be converted to RCS. This system holds two advantages: (1) plenty of Cu(I) exists in CuCl-HTCC can contribute to O2 activation heterogeneously. Its efficiency is much higher than that of homogeneous reactions in which Cu(I) cannot exist stably; (2) this process is a rapid heterogeneous process. Cu(I) can contribute to RCS generation with very fast kinetic through multi-steps. As a result, 10 mg/L of pollutants like phenol or ibuprofen were almost completely degraded in 120 min. This is a new and efficient method for generating RCS through the O2 activation process.

Simultaneous removal of organics and ammonia using a novel composite magnetic anode in the electro-hybrid ozonation-coagulation (E-HOC) process toward leachate treatment

To achieve simultaneous organics and ammonia (NH4+-N) removal toward leachate treatment, this study designed a composite anode (CA+), in which iron powders were attracted to RuO2-IrO2/Ti tube surface by an inserted magnet and utilized in electro-hybrid ozonation-coagulation (E-HOC). The E-HOC (CA+) resulted in higher chemical oxygen demand (COD) and NH4+-N removal with most content of CO2/H2O and gaseous N in product compared with E-HOC (Fe+), electrolysis ozonation and single ozonation. Reactive chlorine species (RCS) and coagulants were co-produced by compositing RuO2-IrO2/Ti and Fe powders, resulting in multiple reactions including electrocoagulation, ozone oxidation, synergistic between ozone and coagulants (SOC), electrolytic chloride and synergistic oxidation between active chlorine and ozone (SCO) occurred. Hydroxyl radical (•OH) generated through SOC reaction was promoted due the RCS generation in E-HOC. The interaction between •OH and Cl-/ClO- also contributed to enhanced Cl•/ClO• production. Consequently, synergy of chlorine, coagulants and ozone enhanced reactive species generation which contributed to favorable organics and NH4+-N removal. Enhanced •OH and RCS are also attributed to conversion of bio-refractory organics like polyphenol, polycyclic aromatics and S-containing to biodegradable ones, e.g., aliphatic compounds and CHO. This study provides an easily operating strategy for leachate treatment with high content organics and NH4+-N.

Formation of persistent free radicals and reactive chlorine species during photochemical processes of Polychlorophenols: Effect of temperature, humidity and particles

Persistent free radicals (PFRs) generated by polychlorophenol pollutions (CPs) have attracted widespread attention, while the hazards of reactive chlorine species (RCS) generated during the oxidation process of PFRs to environment and human health have been largely ignored. In this study, the PFRs and RCS generation pathways in gas and on Si3O10H8 cluster from 2,4,6-trichlorophenol (2,4,6-TCPs) and pentachlorophenol (PCPs) initiated by OH radical are investigated by quantum chemistry method. In the gas phase, 2,4,6-TCPs mainly undergoes H-abstraction reaction to generate PFRs, while on Si3O10H8 cluster, the OH-addition reaction at the phenolic hydroxyl site becomes dominant and the addition product is dehydrated into PFRs under the synergisticeffectof H2O and Si3O10H8 cluster. Conversely, PCPs mainly undergoes H-abstraction reaction both in the gas phase and on Si3O10H8 clusters to form PFRs. This is because the PCPs form strong hydrogen bonds with Si3O10H8 clusters and the (highest occupied molecular orbital) HOMO of PCPs moves to higher energy levels, which reduces the electron binding ability and promotes the electrophilic reaction of OH radical. Introducing a carbonyl group ortho to the carbonyl group of phenolate-type PFRs leads to spontaneous ring-opening and subsequent decomposition into a series of RCS that can react with Cl, NO2 and O2 to form phosgene, chloroformyl peroxynitrate and peroxychloroformyl radical, respectively. These generated chlorine-containing compounds are highly irritating to human eyes and skin and have potential environmental toxicity.

Removal of metronidazole from wastewater by electrocoagulation with chloride ions electrolyte: The role of reactive chlorine species and process optimization

Electrocoagulation (EC) has been attracting increasing amounts of attention due to its ability to remove the pollutants in widespread wastewater. Chloride ions (Cl−) are the most commonly used electrolyte in the EC process. However, the role of the reactive chlorine species (RCS) generated near the electrode is often being underemphasised. In this study, the experiments focused on the generation of RCS and its contribution to the removal of metronidazole (MNZ) during EC. The present findings demonstrated the presence of Cl and ClO near the anode in solution, which dominated the degradation of MNZ. The MNZ decomposition pathways was proposed based on the generation of intermediate products. The toxicity of MNZ and its main degradation products was evaluated by Toxicity Estimation Software Tool (TEST) model and most of intermediates were less toxic than MNZ. Furthermore, the flocs could adsorb part of MNZ by characterizing the flocs using SEM-EDS, FT-IR, XRD and XPS. The contribution ratio of the flocs adsorption and the RCS oxidation for removing MNZ were 57.30% and 41.70%, respectively. Response surface methodology (RSM) was applied to optimize the operation parameters. The present work reveals a new mechanism of EC and manifest good potential for removing antibiotics from chloride-containing wastewater.

Integrating electrochemical oxidation and flow-electrode capacitive deionization for enhanced organic degradation and perchlorate removal in high salinity waters

This study aimed to assess the application of an electrochemical oxidation (ECO) and flow-electrode capacitive deionization (FCDI) sequential hybrid process for the treatment of high-concentration ions, organic pollutants (i.e., humic acid, alginate, benzoic acid, phenol, and 4-chlorophenol), and marine algae. The ECO system led to the rapid generation of reactive chlorine species (RCS) via anodic oxidation of the boron-doped diamond (BDD) electrode under optimum current in the NaCl-based feed solution, which caused the reduction of total organic carbon (TOC) and the degradation of algae cells. However, the formation of undesirable by-products (i.e., toxic perchlorate) was triggered by direct electrolysis. Concurrently, the optimal operational conditions of the FCDI system were evaluated based on the monitoring of process performance according to various parameters (i.e., applied voltage, electrode mass loading, electrolyte concentration in the flow electrode, feed solution concentration, and adsorption/desorption phase operation). Finally, the superiority of the ECO–FCDI hybrid process was confirmed and clearly demonstrated via the effective decomposition of organic compounds and the complete removal of toxic perchlorate by-product together with the effect of deionization. To the best of our knowledge, this work is the first to develop and apply the ECO–FCDI integrated process for the removal of a broad spectrum of pollutants (including both organics and ions) and to attain successful desalination.

A full mechanistic and kinetics analysis of carbon tetrachloride (CCl4) sono-conversion: Liquid temperature effect

In this study, a model of CCl4 sono-pyrolysis inside an acoustic bubble is used to provide a novel mechanistic and kinetics study of CCl4 conversion. The impact of fluid temperature (10–50 °C) on CCl4 conversion and the resulted products is illustrated for various aqueous CCl4 concentrations and acoustic intensities (0.7–1.5 W/cm2). With a concentration less than 3 × 10−3 M, 1 W/cm2 is sufficient for the complete degradation of CCl4 at 20 °C. However, at 10 °C, 1.5 W/cm2 is much than enough to degrade CCl4 completely, regardless of its concentration in solution. The generation of reactive chlorine species (RCS) increased proportionately with the temperature rise when the intensity was 0.7 W/cm2. In contrast, between 1 and 1.5 W/cm2, increasing the liquid temperature from 10° to 40 °C has a beneficial effect on the sonolytic activity of the cavity. However, this positive impact continues to be observed only for·OH radicals when the bulk liquid temperature is greater than 40 °C (the yield of RCS, H·, HCl, and HOCl is amortized). According to the simulation results, it was concluded that the rapid sono-degradation of nonvolatile pollutants in the presence of CCl4 was mainly due to the RCS and·OH radicals generated at the efficient bubble collapse.

The ClO· generation and chlorate suppression in photoelectrochemical reactive chlorine species systems on BiVO4 photoanodes

Photoelectrochemical generation of reactive chlorine species (PEC-RCS) is a promising approach for wastewater treatment. However, the inevitable byproduct of harmful oxychloride (such as ClO3− and ClO4−) severely limits the practical applications of full-spectrum solar-driven PEC-RCS systems. Herein, we investigated three typical photoelectrodes including TiO2, WO3 and BiVO4 for PEC-RCS system and the formation of RCS and toxic oxychlorides. In BiVO4 photoelectrochemical cell, the concentration of ClO3− was lower than 0.2 mg/L and the ClO4− was undetectable within 2 h of reaction. In contrast, the concentrations of ClO3− were 2.3 mg/L and 2.7 mg/L in the widely used WO3 and TiO2 PEC-RCS processes, respectively, which exceeded the health standard of 0.7 mg/L raised by the European Food Safety Authority (EFSA). We proposed that the valence band dependent photoelectrochemical properties of BiVO4 photoelectrodes could lead to the restricted HO· radical production and the non-HO·-mediated RCS generation, which synergistically inhibited the ClO3− formation in the RCS activation process.

An efficient strategy for selective oxidation of ammonia nitrogen into N2 over BiOCl photocatalyst

Selective oxidation of ammonia nitrogen (NH4+-N) into N2 is critical to remove the superfluous nitrogen in the hydrosphere and control the fixed nitrogen inventory for the global nitrogen cycle. Herein, on the basis of chlorine radical chemistry, we report the photocatalytic denitrogenation over BiOCl with high N2 selectivity (>97 %). Efficient Cl– conversion into reactive chlorine species (RCS) is achieved, serving as the predominant reactive species for NH4+-N oxidation. According to the zero-order kinetics of Cl– for RCS generation, as well as the Cl– extraction/insertion over BiOCl, a Cl–-mediated Mars-van Krevelen mechanism is revealed, by which the catalytic performance shifts from the undesired deactivation (because of photocorrosion) towards the remarkably enhanced reactivity. This system exhibits great potential for the denitrogenation of saline wastewater, also provides an interesting strategy to activate inert chemical bond via the chlorine cycle.

Evaluation of hydroxyl radical and reactive chlorine species generation from the superoxide/hypochlorous acid reaction as the basis for a novel advanced oxidation process

The reaction of hypochlorous acid (HOCl) with superoxide radical (O2•–) – a source of hydroxyl radical (HO•) and various reactive chlorine species (RCS) – was investigated as the basis for a novel non-photochemical advanced oxidation process (AOP). Moderately stable (t1/2 ~ minutes) aqueous O2•– stocks were prepared by several approaches at pH>12 and either (a) added directly to aqueous free available chlorine (FAC; i.e., HOCl/OCl–) at circumneutral pH, or (b) premixed with alkaline FAC and then acidified to pH 7, to degrade various organic probe compounds via in situ generated HO• and RCS. Radical production was optimal at [HO2•/O2•–]0/[FAC]0 ~ 2, with ~0.8 mol HO• formed/mol FAC consumed, and HO• and RCS exposures reaching ~5×10−10 and ~10−9 M×s, respectively. Similar trends were observed in natural waters and organic matter-amended phosphate buffer containing up to 5 mgC/L of dissolved organic carbon. Direct formation of oxyhalides, trihalomethanes (THMs), and haloacetic acids (HAAs), was minimal, though THM and HAA formation was moderately enhanced during post-chlorination of O2•–/FAC-treated solutions. This process could provide a beneficial addition to the range of available AOPs due to its high radical exposures, simplicity, rapid time-scales, potential for on-site O2•– generation, and widespread accessibility of FAC and other reagents.

Graphene oxide and CuO double quantum dot composites (GOQD-q-CuO) with enhanced haloperoxidase-like activity and its application in colorimetric detection of H2O2 and glucose

We report herein, double quantum dot composites of graphene oxide and CuO (GOQD-q-CuO), formed by a low-temperature solution process, possess enhanced haloperoxidase (HPO)-like catalytic activity, which catalyze the oxidation of Cl− by H2O2 to generate reactive chlorine species (RCS). A sensitive and selective colorimetric sensor was then developed via the oxidation of 3,3ʹ,5,5ʹ-tetramethylbenzidine (TMB) by the GOQD-q-CuO catalytic system through the generation of RCS for H2O2 and glucose detection, with detection limits of 0.5 and 2.5 μM and linear ranges between 2.5–200 and 5–400 μM, respectively. This sensor was further applied to glucose detection in clinical serum samples showing no significant differences with the hexokinase method. Additionally, we demonstrate that the GOQD modulates the catalytic activity of q-CuO by reversing its zeta potential, producing an overall negatively charged surface, therefore GOQD-q-CuO has much higher affinity than CuO to the positively charged chromogenic substrate TMB, yielding higher HPO-like activity. Moreover, the presence of Cl− accelerates electron transfer to facilitate Cu2+ reduction to Cu+ on the GOQD-q-CuO surface, speeding up the overall catalytic reaction for the RCS generation, therefore, higher detection sensitivity was achieved.

Biofilm eradication by in situ generation of reactive chlorine species on nano-CuO surfaces

Herein, we constructed a nano-CuO film on copper foil for the in situ generation of reactive chlorine species (RCS) for the contact killing of bacteria and biofilm suppression and dispersal. Both Staphylococcus aureus and Escherichia coli were susceptible to this treatment. Additionally, we demonstrate the solid nano-CuO interface-based heterogeneous Fenton chemistry rather than leached copper-ion-based homogeneous Fenton chemistry is responsible for RCS generation and bacterial cytotoxicity. This process is modulated by the H2O2 and Cl− concentrations in bacterial growth environment. The potential applications for in situ generation of RCS might be the incorporation of CuO nanoparticles into functional food contact surfaces as well as coating materials for marine biofouling control.

Activity of sol-gel derived nanocrystalline WO3 films in photoelectrochemical generation of reactive chlorine species

Conventional chlor-alkali method used for production of chlorine gas and chlorine-based disinfectants is among the most energy-intensive processes in chemical industry, therefore, more sustainable alternatives with lower carbon footprint are sought. Photoelectrochemical (PEC) generation of reactive chlorine species (Cl2, HClO, ClO−) is a promising technology in the area of water disinfection and purification, as it combines the advantages of (i) using the renewable solar energy; (ii) possibility to produce disinfectants on-site and on-demand and (iii) eliminates the need for sophisticated infrastructure for storage and handling of chlorine species.In the present study nanocrystalline tungsten (VI) oxide layers were formed on conducting glass substrate using simple sol-gel synthesis technique and polytethylene glycol as a structure-directing agent. It is shown that addition of PEG in moderate amounts favours formation of the structure of interconnected nanocrystalline particles, which ensures effective separation and transport of photogenerated charge carriers and, therefore, is crucial for the photoelectrochemical activity of the films. This is corroborated by the analysis of SEM and XRD data, revealing the influence of polytethylene glycol from the initial stages of WO3 phase crystallization. Faradaic efficiency of photoelectrochemical hypochlorite formation is shown to be about 30%, and antimicrobial effect of PEC chlorination with WO3 photoanodes is demonstrated on Gram-positive Bacillus sp. and Gram-negative E.coli C41(DE3) bacteria.

Enhanced chlorine evolution from dimensionally stable anode by heterojunction with Ti and Bi based mixed metal oxide layers prepared from nanoparticle slurry

This study reports enhanced current (CERCS) and energy efficiency (EERCS) of reactive chlorine species (RCS) generation on Ir7Ta3Oy anode by Ti/Bi mixed metal oxide heterojunction layers despite reductions in pseudo-capacitance and film conductivity. In potentiostatic electrolysis of 50 mM NaCl solutions, dramatic improvement (0.61 mmol cm−2 hr−1 at 2.5 V NHE) was noted by simple coating of thin (~2 μm) TiO2 layer from ball-milled TiO2 nanoparticle (80–100 nm) suspension, even with moderate elevation in voltammetric wave. Decoration of Bi2O3 particles (1 – 2 μm) showed limited or adverse effects for RCS generation and stability. However, Bi-doped TiO2 layers prepared from polyol-mediated or co-precipitation methods marked the highest CERCS (~100%) and EERCS (8.16 mmol Wh−1 at 2.5 V NHE) by increased mixing level and effective shift in surface charge. Surface ·OH exclusively mediated the RCS generation whose further transformation to higher oxide could be restrained by the heterojunction layer.

Effect of reactor configuration on the kinetics and nitrogen byproduct selectivity of urea electrolysis using a boron doped diamond electrode

Electrochemical systems have emerged as an advantageous approach for decentralized management of source-separated urine with the possibility of recovering or removing nutrients and generating energy. In this study, the kinetics and byproduct selectivity of the electrolytic removal of urea were investigated using a boron doped diamond working electrode under varied operational conditions with a primary focus on comparing undivided and divided reactors. The urea removal rate in the undivided and divided reactors was similar, but the divided reactor had an increased required cell voltage needed to maintain the equivalent current density. The current efficiency was similar for 0.1, 0.25, and 0.5 A (33.3, 83.3, 167 mA/cm2), suggesting no interference from competing reactions at higher potentials. In a divided reactor, increasing the anolyte pH reduced the urea removal rate presumably from hydroxyl radical scavenging by hydroxide. Further, for all divided reactor experiments, the final pH was less than 1, suggesting that the transport of protons across the ion exchange membrane to the cathode was slower than the oxidation reactions producing protons. The nitrogen byproduct selectivity was markedly different in the undivided and divided reactors. In both reactors, nitrate (NO3−) formed as the main byproduct at the anode, but in the undivided reactor it was reduced at the stainless steel cathode to ammonia. In the presence of 1 M chloride, the urea removal kinetics improved from the generation of reactive chlorine species, and the byproduct selectivity was shifted away from NO3− to presumably chloramines and N2. Overall, these results indicate that the electrochemical reactor configuration should be carefully considered depending on the desired outcome of treating source-separated urine (e.g., nitrogen recovery, H2 generation).