Chlor-alkali Industry Research Articles

Self-acceleration effect of Mn/Ce-modified carbide slag in CO2 absorption for CaO/CaCO3 energy storage

Carbide slag, a solid waste from the chlor-alkali industry, can be used for CO2 capture and energy storage. Herein, the cyclic reaction activity of Mn/Ce-modified carbide slag under energy storage conditions was studied. The Mn/Ce-modified carbide slag shows energy storage density over 2100 kJ/kg and CO2 absorption capacity of 0.52 g CO2/g sorbent after 30 cycles. Notably, both carbonation and calcination rates are accelerated with the number of cycles. This self-acceleration effect is related to the evolution of oxygen vacancy concentration and texture structure of Mn/Ce-modified carbide slag during the cycles. In the cycles, CaMnO3 in the Mn/Ce-modified carbide slag reacts with the formed CaCO3 in the carbonation stage to produce more Ca2MnO4. The formation of Ca2MnO4 increases oxygen vacancies in the Mn/Ce-modified carbide slag, significantly enhancing its CO2 adsorption capacity. Thus, the release of the increased CO2 in the calcination stage generates more pores in the 10–100 nm diameter range in the modified carbide slag, facilitating rapid carbonation. Thus, the Mn/Ce-modified carbide slag exhibits good prospect for CaO/CaCO3 thermochemical energy storage.

In-Situ Electrolyte for Electrosynthesis: Scalable Anodically-Enabled One-Pot Sequence from Aldehyde to Isoxazol(in)es.

Electrochemical transformations are considered a green alternative to classical redox chemistry as it eliminates the necessity for toxic and waste producing redox reagents. Typical electrochemical reactions require the addition of a so-called supporting electrolyte - a salt bridge - and other additives, such as hexafluorisopropanol, to enhance conductivity and reaction outcomes, respectively. However, this is often accompanied by an increase in the amount of produced waste. Here, we report an "in-situ electrolyte" concept for facile, transition-metal-free, additive-free one-pot electrochemical preparation of isoxazol(in)es, important scaffolds for biologically active natural and synthetic molecules, from the respective aldehydes. The protocol utilizes no halogenated solvents and no external oxidants, while salt side-products provide the ionic conductivity necessary for the electrosynthesis. The electrolysis is performed in an undivided cell, using the state-of-the-art electrodes for the chlor-alkali industry dimensionally stable and scalable mixed metal oxide anode and platinized titanium anode of high durability. The cascade transformation comprises the condensation of aldehyde to oxime followed by its anodic oxidation and subsequent intra- and/or intermolecular [3+2] cycloadditions with an appropriate dipolarophile. Chemical yields up to 97%, and good Faradaic efficiency, scalability, and stability are observed for most substrates in a broad scope.

Stable and efficient chlorine evolution reaction with atomically dispersed Ru on surface tensile strained TiO2

Developing highly efficient and selective electrocatalysts for the chlorine evolution reaction (CER) in the chloralkali industry is of great importance. Here, we report the discovery of a new electrocatalyst for CER consisting of atomically dispersed Ru sites on surface tensile strained TiO2 (Ru-S-TiO2). The single-atom Ru species were stabilized on the strained TiO2 surface by strong metal-support interactions. The Ru-S-TiO2 is highly efficient, initiating CER at only 5 mV above the ECER, and has shown excellent stability for over 100 hours. It exhibited >95 % CER selectivity even in acidic media with low Cl− concentrations (0.2 M). Our results demonstrate that the strong metal-support interactions between the atomically dispersed Ru species and the strained TiO2 surface are crucial for the high catalytic activity, selectivity, and stability of Ru-S-TiO2 for CER. Ru-S-TiO2 holds great promise as a viable alternative to existing mixed metal oxides-based electrocatalysts for CER in the chloralkali industry.

Assessment of the migration characteristics and source-oriented health risks of heavy metals in the soil and groundwater of a legacy contaminated by the chlor-alkali industry in central China.

The chlor-alkali industry (CAI) is crucial for global chemical production; however, its operation has led to widespread heavy metal (HM) contamination at numerous sites, which has not been thoroughly investigated. This study analysed 122 soil and groundwater samples from a typical CAI site in Kaifeng, China. Our aim was to assess the ecological and health risks, identify the sources, and examine the migration characteristics of HMs at this site using Monte Carlo simulation, absolute principal component score-multiple linear regression (APCS-MLR), and the potential environmental risk index (Ei). Our findings revealed that the exceedance rates for Cd, Pb, Hg, and Ni were 71.96%, 45.79%, 49.59%, and 65.42%, respectively. Mercury (Hg) displayed the greatest coefficient of variation across all the soil layers, indicating a significant anthropogenic influence. Cd and Hg were identified as having high and extremely high potential environmental risk levels, respectively. The spatial distributions of the improved Nemerow index (INI), total ecological risk (Ri), and HM content varied considerably, with the most contaminated areas typically associated with the storage of raw and auxiliary materials. Surface aggregation and significant vertical transport were noted for HMs; As and Ni showed substantial accumulation in subsoil layers, severely contaminating the groundwater. Self-organizing maps categorized the samples into two different groups, showing strong positive correlations between Cd, Pb, and Hg. The APCS-MLR model suggested that industrial emissions were the main contributors, accounting for 60.3% of the total HM input. Elevated hazard quotient values for Hg posed significant noncarcinogenic risks, whereas acceptable levels of carcinogenic risk were observed for both adults (96.60%) and children (97.83%). This study significantly enhances historical CAI pollution data and offers valuable insights into ongoing environmental and health challenges.

A Simple Organo-Electrocatalysis System for the Chlor-Related Industry.

Consuming a substantial quantum of energy (~165 TW h), the chlor-alkali industry garners considerable scholarly and industrial interest, with the anode reaction involving the oxidation of chloride ions being a paramount determinant of reaction rates. While the dimensionally stable anode (DSA) displays commendable catalytic activity and longevity, they rely on precious metals and exhibit a non-negligible side reaction in sodium hypochlorite (NaClO) production, underscoring the appeal of metal-free alternatives. However, the molecules and systems currently available are characterized by intricate complexity and are not amenable to large-scale production. Herein, we have successfully developed an economical and highly efficient molecular catalyst, demonstrating superior performance compared with the former organic molecules in the chloride ion oxidation process (COP) for the production of both chlorine gas (Cl2) and NaClO. The molecule of 2N only needs 92 mV to reach a current density of 1000 mA cm-2, with a small cost of only 0.002 $ g-1. Furthermore, we propose a novel mechanism underpinned by non-covalent interactions, serving as the foundation for an innovative approach to the design of efficient anodes for the COP.

Long term substantial impacts of historic Chlor-Alkali production as a newly recognized source of polyhalogenated carbazoles in aquatic environments

Bottom sediments of the North American Great Lakes are characterized by a high loading (over 3,000 tonnes) of polyhalogenated carbazoles (PHCZs). The origin of this environmental contaminant loading is unclear. Here, we first examined PHCZs levels and profiles in sediment, lotus, and fish from the Ya-Er Lake (China) that has been under the influence of an obsolete chlor-alkali facility for forty years and discovered substantial PHCZs contamination. Among the PHCZs determined, 3,6-dichlorocarbazole (36-CCZ) and 3-chlorocarbazole (3-CCZ) were the most frequently detected. Sediments from backfilled land exhibited Σ11PHCZs at median concentration of 973 ng/g (dry weight), suggesting the chlor-alkali industry as an important source. Even after 20 years of dredging treatment, the concentration of Σ11PHCZs in the sediment of the oxidation ponds (median = 41.1 ng/g) remained substantially higher than in other areas globally. Furthermore, the concentration of Σ11PHCZs was found to be higher in surface sediments (median) at 66.7 ng/g if compared to middle (14.1 ng/g) and lower layers (18.2 ng/g), indicating the potential availability of PHCZs from surface sediments to aquatic plants and animals. Notably, this study detected PHCZs in both fish (26.3 ng/g lipid weight) and lotus (14.5 ng/g dry weight), with significant enrichment of 3-monobromocarbazole (3-BCZ) observed in both lotus root systems (bio-soil accumulation factor, BSAFroot = 5.04) and fish muscle (BSAFfish = 3.04).

Optimizing operational parameters for highly-concentrated sodium hydroxide production via electrodialysis with bipolar membranes from concentrated brines

Sodium hydroxide necessitates the implementation of cleaner production methods that deviate from the conventional practices in the chlor-alkali industry. New sustainable sources such as concentrated brines, which are typically regarded as waste, are currently being investigated for the production of sodium hydroxide using Electrodialysis with Bipolar Membranes (EDBM). This process has the advantages of not producing gas by-products, reducing operational risks, and providing value to waste brines after converting them into acids or alkali solutions. However, the production of sodium hydroxide via EDBM using brines is limited by the low concentration of the final base (e.g. typically below 2 M), which increases the cost of transport. This study aims to overcome this limitation by optimizing parameters such as salt-to-base volume ratio, initial salt concentration, and current density values. Notably, this research is one of the few to employ Response Surface Methodology with a Central Composite Design to maximize the final sodium hydroxide concentration; two models using second-order polynomial equations were proposed. Results showed the possibility to achieve 5.3 M NaOH under a volume ratio range of 9.8:1–10:1, a current density range of 490 A/m−2 to 500 A/m−2, and an initial salt concentration in the range of 6 M NaCl. Moreover, the energetic analysis showed values of specific energy consumption in a range of 2.5 kWh kgNaOH-1-3.5 kWh kgNaOH-1 and specific productivity of the process up to 3.08 tonNaOH year−1 m−2, which are moderate in comparison with values previously presented in literature. Finally, an economic analysis showed that energy was the most significant cost component, making up 89 % of the total process cost, which was estimated to be 0.69 € kgNaOH-1 (concentration 21.2 % w/w). Overall, these high concentration values open a real chance to shift towards sustainable production of NaOH by means of EDBM from brines, highlighting the novelty of this study.

Mercury stable isotopes in seabirds in the Ebro Delta (NE Iberian Peninsula): Inter-specific and temporal differences

Mercury (Hg) is a global pollutant, which particularly affects aquatic ecosystems, both marine and freshwater. Top-predators depending on these environments, such as seabirds, are regarded as suitable bioindicators of Hg pollution. In the Ebro Delta (NE Iberian Peninsula), legacy Hg pollution from a chlor-alkali industry operating in Flix and located ca. 100 km upstream of the Ebro River mouth has been impacting the delta environment and the neighboring coastal area. Furthermore, levels of Hg in the biota of the Mediterranean Sea are known to be high compared to other marine areas. In this work we used a Hg stable isotopes approach in feathers to understand the processes leading to different Hg concentrations in three Laridae species breeding in sympatry in the area (Audouin's gull Ichthyaetus audouinii, black-headed gull Chroicocephalus ridibundus, common tern Sterna hirundo). These species have distinct trophic ecologies, exhibiting a differential use of marine resources and freshwater resources (i.e., rice paddies prey). Moreover, for Audouin's gull, in which in the Ebro Delta colony temporal differences in Hg levels were documented previously, we used Hg stable isotopes to understand the impact of anthropogenic activities on Hg levels in the colony over time. Hg stable isotopes differentiated the three Laridae species according to their trophic ecologies. Furthermore, for Audouin's gull we observed temporal variations in Hg isotopic signatures possibly owing to anthropogenic-derived pollution in the Ebro Delta. To the best of our knowledge this is the first time Hg stable isotopes have been reported in seabirds from the NW Mediterranean.

Organocatalyst Supported by a Single-Atom Support Accelerates both Electrodes used in the Chlor-Alkali Industry via Modification of Non-Covalent Interactions.

Consuming one of the largest amount of electricity, the chlor-alkali industry supplies basic chemicals for society, which mainly consists of two reactions, hydrogen evolution (HER) and chlorine evolution reaction (CER). Till now, the state-of-the-art catalyst applied in this field is still the dimensional stable anode (DSA), which consumes a large amount of noble metal of Ru and Ir. It is thus necessary to develop new types of catalysts. In this study, an organocatalyst anchored on the single-atom support (SAS) is put forward. It exhibits high catalytic efficiency towards both HER and CER with an overpotential of 21 mV and 20 mV at 10 mA cm-2 . With this catalyst on both electrodes, the energy consumption is cut down by 1.2 % compared with the commercial system under industrial conditions. Based on this novel catalyst and the high activity, the mechanism of modifying non-covalent interaction is demonstrated to be reliable for the catalyst's design. This work not only provides efficient catalysts for the chlor-alkali industry but also points out that the SACs can also act as support, providing new twists for the development of SACs and organic molecules in the next step.

Effect of acid sites modification on the catalytic combustion of 1,2-dichloroethane: Revealing the synergy between NbOx and CeO2

1,2-Dichloroethane are primarily sourced from the emissions of the chlor-alkali industry, resulting in severe pollution of soil, air, and water. In this work, Nb/CeO2 catalysts were prepared by impregnation method, and their performance for EDC oxidation was evaluated. The addition of Nb improved the activity, selectivity, and stability of CeO2. Nb was highly dispersed on CeO2 surface in the form of NbOx, and partially entered the lattice of CeO2. This caused lattice distortion and more surface defects, thereby increasing the number of oxygen vacancies. NbOCe bonds formed in between Nb and CeO2 weakened the CeO bonds and enhanced lattice oxygen mobility. The presence of NbOx increased the number of Lewis acid (NbO) and Brønsted acid (Nb-OH) sites, which facilitated the cleavage of CCl and CC bonds. Increased acidity promoted the removal of Cl species in the form of HCl and effectively mitigated the chlorine poisoning of CeO2. In-situ DRIFTS results indicated that EDC oxidation on Nb/CeO2 catalysts followed a Mars-van Krevelen mechanism and progressed via the pathway of alcoholate → formate/methoxy → COx.

High-performance chlorinated polyvinyl chloride/polyurea nanocomposite foam with excellent solvent resistance, flame-triggered shape memory effect and its upcycling

Facing the global environmental pollution crisis related to waste plastics, the recyclable design of polymer materials and composites, especially large commodities, is the most effective and fundamental solution. Herein, an upcycling chlorinated polyvinyl chloride/polyurea (CPVC/PUA) nanocomposite foam was designed by means of the “plasticizing-foaming-reinforcing” (PFR) strategy combined with catalytic carbonization of CPVC/PUA foams. On one hand, the foam with ultra-high expansion ratio (62 times) can be facilely prepared in supercritical CO2 at lower temperature, benefited of the reactive plasticizing function of PUA monomer-polymeric methylene diphenyldiisocyanate (PMDI). On the other hand, the obtained foam is reinforced by PMDI crosslinking reaction to in situ form nano-PUA phase in the CPVC matrix and realizing robust and superior solvent resistance and flame-triggered shape memory effect. Moreover, the foam possesses remarkable ablation resistance, which is attributed to super carbonization capacity of CPVC catalyzed by PUA. This carbonization behavior endows the foam directly upcycle into functional carbon foam accompanied by the formation of HCl gas and functional aromatics. The obtained carbon foam shows attractive electromagnetic interference shielding performance, which also may be used as potential carbon source or catalyst of producing vinyl chloride monomer in the chlor-alkali industry, especially in China.

Self-adaptive amorphous CoOxCly electrocatalyst for sustainable chlorine evolution in acidic brine

Electrochemical chlorine evolution reaction is of central importance in the chlor-alkali industry, but the chlorine evolution anode is largely limited by water oxidation side reaction and corrosion-induced performance decay in strong acids. Here we present an amorphous CoOxCly catalyst that has been deposited in situ in an acidic saline electrolyte containing Co2+ and Cl- ions to adapt to the given electrochemical condition and exhibits ~100% chlorine evolution selectivity with an overpotential of ~0.1 V at 10 mA cm−2 and high stability over 500 h. In situ spectroscopic studies and theoretical calculations reveal that the electrochemical introduction of Cl- prevents the Co sites from charging to a higher oxidation state thus suppressing the O-O bond formation for oxygen evolution. Consequently, the chlorine evolution selectivity has been enhanced on the Cl-constrained Co-O* sites via the Volmer-Heyrovsky pathway. This study provides fundamental insights into how the reactant Cl- itself can work as a promoter toward enhancing chlorine evolution in acidic brine.

Photometric Determination of Trace Amounts of Aluminum in Nearly Saturated Rock Salt Solutions Used by Chlor-alkali Industry

The previously widespread mercury cell technology in chlorine production has now been replaced by more environmentally friendly membrane cell electrolysis which is a Best Available Techniques (BAT) technology. However, this requires a much cleaner brine containing contaminants (Al, Ca, Mg, etc.) in the order of ng/g at most. For this reason, it’s very important to detect trace amounts of aluminum in concentrated saline media in the simplest and fastest way. To the best of our knowledge, no one has previously developed a spectrophotometric method capable of detecting aluminum in ionic forms selectively in the order of ng/g in concentrated saline media, without any preconcentration or separation step. Our advanced analytical method provides an opportunity for this. During the analytical procedure, a colored complex ion is formed from the dissolved aluminum content of the sample with eriochrome cyanine R (ECR) ligand in buffered pH medium. The sensitivity of the measurement is increased by adding quaternary ammonium salt. The colored complex ion is formed in 15 minutes, then the absorbance measurement can be performed for 90 minutes. The effect of rock salt interference was eliminated by proper calibration. In our work the dependence of the signal on temperature, pH, time elapsed after the addition of reactants, the dosing sequence, the salinity of the medium was examined, furthermore, we studied which wavelength-absorbance values give the best fit (highest R2 value) and the highest sensitivity in case of linear calibration. Surprisingly, increasing the salinity significantly improves the sensitivity of the measurement.

(Invited) Single Cell Voltages for Safety, Predictive Maintenance, and Process Optimization of Industrial Scale Bipolar Electrolyzers (Learned Lessons From Over 30 Years Experience in Chlor-Alkali-Electrolysis)

Just like the membrane electrolysis process in the Chlor-Alkali industry 30 years ago, water electrolysis is facing a major transformation from a niche technology to become a global commodity business. 30 years ago, the unique risks of big bipolar electrolyzers were not recognized by the industry. Lessons learned from incidents and near misses led R2 to the development of the EMOS® Safety System: the state-of-the-art single cell voltage-based safety instrumented system for bipolar electrolyzers. Today, the EMOS® Safety System has become a standard in the Chlor-Alkali industry. With plans announced for much larger electrolyzers and several times higher current densities and their increasing risks, water electrolysis should be spared this painful learning process. Fortunately, EMOS® Safety System supports also bipolar water electrolyzers. Short circuits, separator failures etc. can be only detected with single cell current-voltage-curves to turn the power supply off before explosive gas reaches areas with dangerous high gas holdup.Same time the single cell voltages are used to detect any abnormal cell aging as early as possible and to correlate it with the operating conditions. For this purpose, automatically during the electrolyzer startup a neural network is trained to predict the cell voltages afterwards in real-time and to alarm already a deviation of a few mV from the measured cell voltage. Together with KPI’s like U0 and k, automatically calculated by analyzing load changes from normal electrolyzer operation for each cell, predictive maintenance, cell performance specific replacement and process optimization is possible, customized for the individual industrial plant.Examples from industrial scale electrolyzers concerning safety, maintenance and performance optimization will be presented.

Application of Bayesian Logic in the Layer of Protection Analysis of Chlor-Alkali Industry

Application of Bayesian Logic in the Layer of Protection Analysis of Chlor-Alkali Industry

Optimization of Rock Salt Washing Process to Remove Selected Chemical Impurities in Lake Katwe Rock Salt

Rich deposits of mineral salts, present in substantial economic quantities, characterize the geological bounty of Uganda. The primary location of this wealth is lake Katwe, a saline crater lake southwest of the country. However, all grades of rock salt extracted from Lake Katwe remain contaminated with chemical impurities such as calcium, magnesium, heavy metals and sulphate ions, even after solar evaporation process from the salt pans. There is a need to conduct research into possible contaminant removal methods which could increase the market value of the extracted salt, and add to the body of knowledge for future salt processing and chlor-alkali industries in Uganda. This study examined the effect of varying water volumes and temperature on the levels of Calcium, Magnesium and Sulphate ions in rock salt samples from Lake Katwe. The samples were methodically crushed and washed. The salt was then dissolved, crystallized, dried and meticulous analysis to determine the concentration of these impurities was carried out. The data was analysed and represented in Microsoft Excel and MATLAB. Results obtained revealed that a temperature of 40°C and salt-water ratio of 1:2 are the optimal parameters for maximum reduction of calcium, magnesium and sulphate impurities in rock salt. This analysis enhances the purity of salt harvested from Lake Katwe’s solar evaporation process and offers optimal washing parameters to reduce impurities in brine, thereby improving plant yield and reducing production costs across various salt grades. It also provides new information to the mining communities at Lake Katwe on how to affordably improve the percentage purity of their rock salt. The study will also contribute novel industry-tailored data for future prospective salt processing and chlor-alkali industrial plants near the Lake while also filling a knowledge gap for further research on rock salt purification.

Valorization of Seawater Reverse Osmosis Brine by Monovalent Ion-Selective Membranes through Electrodialysis.

This paper proposes the use of monovalent selective electrodialysis technology to concentrate the valuable sodium chloride (NaCl) component present in seawater reverse osmosis (SWRO) brine for direct utilization in the chlor-alkali industry. To enhance monovalent selectivity, a polyamide selective layer was fabricated on commercial ion exchange membranes (IEMs) through interfacial polymerization (IP) of piperazine (PIP) and 1,3,5-Benzenetricarbonyl chloride (TMC). The IP-modified IEMs were characterized using various techniques to investigate changes in chemical structure, morphology, and surface charge. Ion chromatography (IC) analysis showed that the divalent rejection rate was more than 90% for IP-modified IEMs, compared to less than 65% for commercial IEMs. Electrodialysis results demonstrated that the SWRO brine was successfully concentrated to 14.9 g/L NaCl at a power consumption rate of 3.041 kWh/kg, indicating the advantageous performance of the IP-modified IEMs. Overall, the proposed monovalent selective electrodialysis technology using IP-modified IEMs has the potential to provide a sustainable solution for the direct utilization of NaCl in the chlor-alkali industry.

Chlor-alkali producer Olin commits to phasing out asbestos

Olin, the world’s largest chlor-alkali producer, has agreed to immediately stop importing asbestos into the US and to stop installing and replacing asbestos-based diaphragms in 2 years. The firm has also committed to completely phasing out its use of such diaphragms in 7 years. The firm has yet to officially announce the agreement, but in an April 4 letter to the US Environmental Protection Agency, Olin CEO Scott Sutton provides details of the plan. The letter was leaked by the Asbestos Disease Awareness Organization (ADAO), an advocacy group that is pressuring all chlor-alkali producers to phase out asbestos. Olin is one of three chlor-alkali producers in the US that still use asbestos diaphragms. The other two producers are OxyChem and Westlake. More than half the US chlor-alkali industry has transitioned away from asbestos diaphragms to fluoropolymer ion-exchange membranes. The American Chemistry Council is not on board with the 7-year timeline

High-Performing Atomic Electrocatalyst for Chlorine Evolution Reaction.

Electrocatalysts facilitating chlorine evolution reaction (ClER) play a vital role in chlor-alkali industries. Owing to a huge amount of chlorine consumed worldwide, inexpensive high-performing catalysts for Cl2 production are highly demanded. Here, a superb ClER catalyst fabricated through uniform dispersion of Pt single atoms (SAs) in C2 N2 moieties of N-doped graphene (denoted as Pt-1) is presented, which demonstrates near 100% exclusive ClER selectivity, long-term durability, extraordinary Cl2 production rate (3500mmol h-1 gPt -1 ), and >140 000-fold increased mass activity over industrial electrodes in acidic medium. Excitingly, at the typical chlor-alkali industries' operating temperature (80°C), Pt-1 supported on carbon paper electrode requires a near thermoneutral ultralow overpotential of 5mV at 1mA cm-2 current density to initiate the ClER, consistent with the predicted density functional theory (DFT) calculations. Altogether these results show the promising electrocatalyst of Pt-1 toward ClER.

Photoelectrocatalytic treatment and resource utilization of industrial waste salt for chlor-alkali electrolysis

Pesticides, fine chemicals, and many other chemical industries usually produce a large amount of waste solid salt which is detrimental to the environment when treated by burning and rigid landfill. In contrast to traditional disposal strategies, resource utilization of waste salt is beneficial for both the environment and economy. However, the current technique for the resource utilization of waste salt, such as nanofiltration, is high cost and hard to popularize. In this study, the photoelectrocatalytic treatment of waste salt obtained from the glyphosate industry and its utilization as a raw material for chlor-alkali electrolysis are proved to be feasible. The waste salt consists mainly of NaCl, with ~ 1.31 wt% of organic impurities. A TiO2 nanotube electrode was employed for the photoelectrocatalytic treatment of brine with NaCl concentration of 270 g L−1 prepared from waste salt. After preliminary treatment, the total organic carbon content (TOC) of the waste salt brine was reduced to 50 mg L−1, with a removal ratio of 85%. It is able to meet the standard of refined brine in the chlor-alkali industry (TOC < 20 mg L−1) with further treatment. A study on the photoelectrocatalytic mechanism reveals that the main oxidative species contributing to the degradation are holes (h+) and chlorine active substances other than Cl∙ under the condition of high Cl− concentration. The organic impurities in the waste salt are poisonous to both the electrode and membrane in the process of chlor-alkali electrolysis, leading to an increase in the voltage. With photoelectrocatalytic treatment, most of the organic impurities can be removed so that the waste salt can be utilized as a raw material for chlor-alkali electrolysis.