Removal Of Chlorine Research Articles

Reactions between SiCl4 and H2O on rutile TiO2 surfaces in atomic layer deposition of SiO2 by first-principles calculations

Atomic layer deposition of SiO2 using SiCl4 and H2O is a classical process, which was initially developed for applications in the field of microelectronics. Recently, it has been demonstrated as an effective surface engineering of nanomaterials in many other applications, including catalysis, pharmaceuticals, and energetic materials. However, fundamental mechanisms of SiO2 film growth at the atomic scale have not been fully understood. In this work, DFT calculations were performed to understand the atomic mechanisms of SiO2 film growth from SiCl4 and H2O precursors on the bare and hydroxylated TiO2 surfaces. Climbing image−nudged elastic band (CI-NEB) method was used to find saddle points and the activation energies for the chemical reactions of several possible mechanisms. The recombination of the by-product HCl with the surfaces and the removal of surface chlorine were also calculated. The results show that SiCl4 can be continuously dissociated on the surface or react with H2O after the first dissociation/ligand exchange reaction. The activation energies from CI-NEB results point out the benefit of the surface hydroxylation in facilitating the initial reaction of SiCl4 on the surface and reducing the production of the adsorbed atomic chlorine as gaseous HCl is released as a by-product. The recombination of the HCl by-product with the surface by either molecular dissociation or ligand exchange reaction with –OH groups can further create atomic chlorine. The removal of the adsorbed chlorine is unlikely, accounting for a certain amount of Cl impurity found by experiments. The calculation results provide an atomic level prediction for designing experimental conditions to achieve desired film quality.

Analysis of Drinking Water treatment costs – with an Application to Groundwater Purification Valuation

Understanding the factors affecting drinking water production costs is crucial for choosing a cost-effective solution for public drinking water supply systems. An important determinant of water treatment costs is the purification of raw water. Despite water purification being a well-acknowledged ecosystem service, its monetary value has not been assessed much yet. We present the first study analysing the determinants of drinking water production costs and valuating groundwater purification in the Czech Republic. We tested the impact of the type of raw water, the amount of drinking water produced, electric power consumption and treatment technologies and chemicals. The results suggested that drinking water production from groundwater was cheaper than from surface water. Even though drinking water production from groundwater was cheaper than from surface water, the application of some technologies, for example, chlorine or manganese removal, increased the production cost. Hence groundwater production costs can exceed surface water production costs. The outcome of the regression was applied for the valuation of groundwater purification. The valuation was further used for the development of monetary drinking water accounts within the System of Environmental- Economic Accounting – Ecosystem Accounting.

Continued assessment of chlorine reactivity with environmental materials for hazard assessment of large scale releases

Many toxic industrial chemicals (TICs) such as chlorine and ammonia are reactive with commonly encountered environmental materials. The amount of TIC material reacted in the environment can be an important factor in the consequences of a release. Typically characterized with a dry deposition rate in atmospheric dispersion models, dry deposition has predominately been studied in field-scale experiments at concentration levels typical for air pollution (ppb or ppt levels), but much higher concentrations are relevant in hazard consequence assessment.For consequence assessment purposes, reduction of gas phase chlorine concentration (whether by chemical reaction or adsorption/desorption processes) will reduce the impact of a release. In previous experiments with chlorine, a kinetic model accounting for the maximum mass that can react at a surface (maximum deposition) was proposed and found to agree with available data (Spicer et al., 2021). The importance of maximum deposition will be most important for high chlorine concentrations and may not be possible to detect (or even be important) in air pollution studies. Furthermore, limitation by maximum deposition indicates that the reaction between chlorine and environmental surfaces is actually a second order chemical reaction, while in contrast, the standard (air pollution) approach for modeling dry deposition in atmospheric dispersion models is a first order reaction. The relationship between the two approaches is explored. Current atmospheric dispersion models do not limit the mass of chlorine (or any other contaminant) that can be removed by environmental surfaces. Consequently, there is a possibility of atmospheric dispersion models overestimating the removal of chlorine by dry deposition which would result in under-prediction of the potential hazard.As reported here, new experimental measurements with plant materials and materials characterizing built environments show that the rate of chlorine removal can be described as a first order, heterogeneous reaction provided the effect of maximum deposition is taken into account. The experimental apparatus used in the study was designed to expose selected materials to chlorine with initial concentration of (nominally) 1000 ppm in air with controlled gas velocity having turbulence levels that are comparable to the atmosphere. The materials tested in the two studies were intended to characterize typical environmental materials for various land use categories including built environments appropriate for consequence assessments.

Controlling Role of CaClOH in the Process of Dechlorination for Municipal Solid Incineration Fly Ash Utilization

The existence of high chlorine components in municipal solid waste incineration fly ash (IFA) has become a key bottleneck in the utilization of IFA as building materials. In this work, the chlorides in IFA were classified as alkali chlorine, calcium chloride, and calcium aluminum chloride, whereas CaClOH was the dominant phase of calcium chloride. For the first time, the effects of CaClOH on chlorine elimination for IFA-derived products by water-washing treatment or high-temperature treatment were carefully examined. The results indicated that IFA chlorine removal was closely linked to CaClOH phase dissolution, decomposition, volatilization, and transformation. CaClOH was easily removed by water washing and had excellent thermostability, even at 1300 °C. As shown in the results of XRD and XRF, the siliceous component would combine with CaClOH to volatilize as SiCl4, whereas the aluminous component would react with CaClOH to form chlorine-fixed and stable calcium aluminum chloride phases. The calcium aluminum chloride instead of CaClOH was in favor of the transformation of residual chlorine from soluble chlorine to chemically fixed chlorine. Therefore, the detoxification mechanism of chlorine for IFA could be summarized as washing dechlorination, volatilization dechlorination, and chemical fixation. As an application, the synergistic treatment of IFA with siliceous/aluminous materials could greatly reduce risks from soluble chlorine, while IFA-derived products were used as building materials.

Investigation of the occurrence characteristics of organic components in high-sulfur waste residues (HSWR)

High-sulfur waste residues (HSWR) is a typical byproduct produced in the printing and dyeing industry that has hazardous properties, such as flammability and reactivity, etc. It is of great significance for the directional and harmless treatment of waste residues in the later stage on the research in-depth of the occurrence characteristics of each component in HSWR. In this paper, the combinatorial analysis method is employed to perform in-depth research on the phase composition, surface chemical situation of element, and the occurrence state of functional groups of the waste residue from multiple perspectives. The results show that the organic and inorganic components in HSWR are intricately interwoven, and exhibit significant thermal instability at high temperatures, with a maximum weight less of 86.66%. Carbon mainly exists in the states of C-H/C-OH/C-C, C-O/C-NH2, and C=O/C-N/C-S/CHx and constitutes the main chain of the carboxylic ring. Sulfur mainly occurs in three forms, namely, amorphous aggregated sulfur, sulfur-containing inorganic salts such as sulfate, and nitrogen-heterocyclic organic compounds containing sulfhydryl groups and methyl sulfur groups. These organic compounds constitute branch chains of the organic phase, and combine with metal cations through hydroxyl or carboxyl groups, and deposit on the surface of inorganic agglomerated sulfur. This wrapping structure increases the stability of volatile compounds in the slag and increases the difficulty of sulfur and chlorine removal. These findings provide a material basis for the later development of safe and effective HSWR disposal techniques.

Application of Carbon Salicylate@Alumina Nanocomposite for Removal of Organic and Inorganic Pollutants from Wastewater

In this paper, a novel nanocomposite (carbonic salicylate @ aluminum oxide nanocomposite, AC-COO-Sal@Al2O3) and modifier carbon biosorbents were synthesized from low-cost raw materials (commercial activated carbon). Infrared spectra demonstrated the presence of several active groups in the material matrixes of nanocomposite and biosorbents. X-ray diffraction analysis showed that the surfaces were in the form of crystals embedded into the amorphous structure. There is good thermal stability up to 800 °C and also in acidic and alkaline mediums. The modifier of the activated carbon (AC), carbonic acid (AC-COOH), carbonic salicylate (MAC-COO-Sal), and the nanocomposite were applied to remove the hazard species from wastewater. The different parameters (pH, time, concentration, and temperature) were applied to explain the removal process. The removal percentages and capacities were 97–100% and 166–266 mg/g with a relative standard deviation of 0.2–0.8% (n = 5). The lower detection limit of the tested dye was 0.6–1.9 μg/L which indicates the higher sensitivity detection of methylene blue in wastewater. Also, the method was successfully applied for the removal of free chlorine and metal ions from the contaminated water samples.

Thermal Degradation and Organic Chlorine Removal from Mixed Plastic Wastes

Plastic waste accumulation has been growing due to the increase in plastic generation and the lack of infrastructure for recycling. One of the approaches is to treat the mixed plastic waste (MPW) through thermal processes to produce feedstocks for other applications. However, the presence of polyvinyl chloride (PVC) in MPW would produce HCl during processing and has negative impacts (emission, catalyst poisoning, etc.). In addition, due to the high heterogeneity of MPW, it is difficult to generate consistent experimental data. In this study, MPW was homogenized through double compounding–extrusion and then formed into a sheet to be treated at 400 °C. The solid products at various mass losses were characterized by heat and chlorine content, Fourier-transform infrared (FTIR) spectroscopy, and elemental composition analysis. It was found that the thermal degradation of MPW started at ~260 °C. The chlorine removal efficiency increased with mass loss and reached an asymptotic value of ~84% at ~28% mass loss, and the remaining chlorine can be attributed to inorganic sources. A PVC de-chlorination model was developed for MPW using TGA data for PVC and MPW to determine organic chlorine removal efficiency. These results show that PVC de-chlorination was not affected by other plastics at this temperature. As the mass loss increases, the heat content first increases and then decreases. It was found that mass loss is a universal parameter for organic chlorine removal efficiency and heat content. The elemental composition analysis and FTIR spectroscopy also shed more light into the chemical changes during MPW thermal degradation.

A laser-assisted chlorination process for reversible writing of doping patterns in graphene

Chemical doping can be used to control the charge-carrier polarity and concentration in two-dimensional van der Waals materials. However, conventional methods based on substitutional doping or surface functionalization result in the degradation of electrical mobility due to structural disorder, and the maximum doping density is set by the solubility limit of dopants. Here we show that a reversible laser-assisted chlorination process can be used to create high doping concentrations (above 3 × 1013 cm−2) in graphene monolayers with minimal drops in mobility. The approach uses two lasers—with distinct photon energies and geometric configurations—that are designed for chlorination and subsequent chlorine removal, allowing highly doped patterns to be written and erased without damaging the graphene. To illustrate the capabilities of our approach, we use it to create rewritable photoactive junctions for graphene-based photodetectors.

The biogeochemical cycling of chlorine.

Chlorine has important roles in the Earth's systems. In different forms, it helps balance the charge and osmotic potential of cells, provides energy for microorganisms, mobilizes metals in geologic fluids, alters the salinity of waters, and degrades atmospheric ozone. Despite this importance, there has not been a comprehensive summary of chlorine's geobiology. Here, we unite different areas of recent research to describe a biogeochemical cycle for chlorine. Chlorine enters the biosphere through volcanism and weathering of rocks and is sequestered by subduction and the formation of evaporite sediments from inland seas. In the biosphere, chlorine is converted between solid, dissolved, and gaseous states and in oxidation states ranging from -1 to +7, with the soluble, reduced chloride ion as its most common form. Living organisms and chemical reactions change chlorine's form through oxidation and reduction and the addition and removal of chlorine from organic molecules. Chlorine can be transported through the atmosphere, and the highest oxidation states of chlorine are produced by reactions between sunlight and trace chlorine gases. Partial oxidation of chlorine occurs across the biosphere and creates reactive chlorine species that contribute to the oxidative stress experienced by living cells. A unified view of this chlorine cycle demonstrates connections between chlorine biology, chemistry, and geology that affect life on the Earth.

Removal of chlorine from zinc sulfate solution: a review.

During zinc hydrometallurgy process, the chloride ions in the materials go into the leaching solution, which have abominable effects on equipment, electrowinning, and environment. So, it is necessary to remove chloride ions from zinc sulfate solution. The present review outlines the current research of removal methods of chlorine by holistically highlighting the advantages and mechanisms. The main techniques used to remove chloride ions from zinc sulfate solution are also discussed in detail. Among the methods, the precipitation method using copper slag to remove chlorine is widely used and the chlorine removal rate is up to 98%. In addition, the combination of electrochemistry and nanofiltration technology can form a closed-loop production process with less waste output and near-zero emissions. In addition, the challenges and possible future directions of chlorine removal from zinc sulfate solutions are also delineated.

Dechlorination and vitrification of electrochemical processing salt waste

Electrochemical reprocessing of spent nuclear fuel in molten chloride salt is a promising strategy for the advanced nuclear fuel cycle. However, the generated chloride nuclear waste cannot be vitrified into borosilicate glass due to the low solubility of Cl in the glass. To dechlorinate salt waste before immobilizing it in the borosilicate glass, H2C2O4 could be used at a temperature below 300 °C. The chlorine removal efficiency could reach up to 99% if the dechlorination parameters, such as thermal treatment temperature and the molar ratio of H2C2O4 to Cl, were optimized. The Cl was removed as HCl during dechlorination, while the remaining cations which formed oxalates were decomposed into carbonates at a temperature above 500 °C. The residual carbonates were finally vitrified into a borosilicate waste glass form, and the waste loading could reach up to 35 wt%, at which the PCT-7 normalized elemental (Li, Na, K, Cs, and B) releases were lower than 1.5 g/m2. This work can be treated as a practical approach to treat chloride nuclear waste.

Comparison of Commercial Dechlorination Chemicals used in Reverse Osmosis Processes

Objectives : The objective of this study was to find a promising dechlorination chemical which can replace sodium bisulfite (SBS), which is mainly used as a dechlorination agent in reverse osmosis processes but can cause odor issues.Methods : Candidate chemicals were selected in consideration of economic feasibility, ease of use, and toxicity. These included sodium metabisulfite (SM), sodium thiosulfate (ST), and sodium sulfite (SS). We investigated the effect of organic matters in water on residual chlorine decomposition and compared the appropriate injection amounts for each dechlorination chemicals. Also, the effect of the pH of treated water upon dechlorination was assessed.Results and Discussion : Upon injection of dechlorination chemicals at the theoretical chlorine removal point, the chlorine was not completely removed but 10% to 40% remained. In ultrapure water, it was possible to completely dechlorinate by injecting 1.6 to 2.6 times more than the theoretical injection amount: 1.8, 2.2, and 3.1 times more for ST, SM, and SS, respectively. Considering only the injection amount, ST is an efficient dechlorination chemical for water with pH 9 or higher, and SM is for pH 9 or lessConclusion : Considering the product price and user convenience, it is feasible to use ST, which can resolve the odor problem.

Effect of microplastics on microbial dechlorination of a polychlorinated biphenyl mixture (Aroclor 1260)

Microplastics (MPs) and polychlorinated biphenyls (PCBs) generally coexist in the environment, posing risks to public health and the environment. This study investigated the effect of different MPs on the microbial anaerobic reductive dechlorination of Aroclor 1260, a commercial PCB mixture. MP exposure inhibited microbial reductive dechlorination of PCBs, with inhibition rates of 39.43%, 23.97%, and 17.53% by polyethylene (PE), polypropylene (PP), and polystyrene (PS), respectively. The dechlorination rate decreased from 1.63 μM Cl− d−1 to 0.99–1.34 μM Cl− d−1 after MP amendment. Chlorine removal in the meta-position of PCBs was primarily inhibited by MPs, with no changes in the final PCB dechlorination metabolites. The microbial community compositions in MP biofilms were not significantly different (P > 0.05) from those in suspension culture, although possessing greater Dehalococcoides abundance (0.52–0.81% in MP biofilms; 0.03–0.12% in suspension culture). The co-occurrence network analysis revealed that the presence of MPs attenuated microbial synergistic interactions in the dechlorinating culture systems, which may contribute to the inhibitory effect on microbial PCB dechlorination. These findings are important for comprehensively understanding microbial dechlorination behavior and the environmental fate of PCBs in environments with co-existing PCBs and MPs and for guiding the application of in situ PCB bioremediation.

Removal of disinfection byproducts and toxicity of chlorinated water by post-treatments of ultraviolet/hydrogen peroxide and ultraviolet /peroxymonosulfate

Post-treatment of ultraviolet (UV) irradiation is not efficient in eliminating toxicity of chlorinated water. Removal of disinfection byproducts (DBPs) and toxicity of chlorinated water by UV/hydrogen peroxide (UV/H2O2) and UV/peroxymonosulfate (UV/PMS) was investigated. In the absence of bromide, adding H2O2 or PMS enhanced the removal of nitrogenous DBPs and total organic chlorine (TOCl) than UV alone (1200 mJ/cm2). UV/PMS decreased the cytotoxicity from 10.6 to 4.4 mg-Phenol/L and genotoxicity from 7.1 to 2.0 μg-4-NQO/L, more efficient than UV/H2O2. However, results were quite different in the presence of bromide. PMS led to the increased formation of total organic bromine (TOBr) in chlorinated water. UV/PMS was therefore less efficient in toxicity removal than UV/H2O2. In the presence of bromide, UV/H2O2 decreased the cytotoxicity and genotoxicity by 85% and 68%, while UV/PMS only removed the cytotoxicity and genotoxicity by 59% and 46%. In the UV/PMS process, SO4˙- was more efficient on toxicity removal than ˙OH. Contributions of UV irradiation, ˙OH and SO4˙- were 55%, 14% and 31% to cytotoxicity removal, and 49%, 15% and 36% to genotoxicity removal. This study demonstrated the feasibility of using UV/H2O2 and UV/PMS as post-treatments to enhance the removal of DBPs and toxicity of chlorinated water.

Co-carbonization of a mixture of waste insulation electric cables (WIEC) and lignocellulosic waste, for the removal of chlorine: Biochar properties and their behaviors

The valorization of noble metals from the recycling of electric cables, generates a negative effect with regard to the production of polymeric residues, mainly composed of polyvinyl chloride (PVC), polyethylene (PE) and polypropylene (PP). Waste insulation electrical cables (WIEC) can be recovered thermochemical, in combustion or gasification processes, however, these residues have a high chlorine content in their composition, which can cause damage to thermochemical recovery equipment, if used in gross. This work has the objective to study the effects of the temperatures and the mixtures proportions in the carbonizations and co-carbonizations of waste insulation electrical cables with lignocellulosic waste. The mixtures with different waste insulation electrical cables ratios (100, 75, 50, 25 and 0%), were carbonized at 300 °C and retention time of 30 min and showed chlorine removals above 66%. With the 50% waste insulation electrical cables mixture having a removal below the 25% and 0% mixtures (with 100% chlorine removals), the dechlorination being 84.9%. Tests were also carried out with 50:50 mixtures of waste insulation electrical cables and lignocellulosic waste for temperatures of 275, 300 and 325 °C with retention times of 30, 45 and 60 min. After being subjected to an acetone wash, it was obtaining removals of around 80%. For the mixture at 300 °C and 30 min (M300-30), mixture at 300 °C and 60 min (M300-60) and the mixture at 325 °C and 30 min (M325-30) thus having the best chlorine removals, being 81%, 81.9% and 86.7% respectively. For the determination of these mixtures, immediate analysis, approximate analysis, fluorescence x-ray and calorific value tests were performed. With the analyzes carried out, it was possible to perform calculations of the kinetics of the behavior of biochars. It was possible to observe that with the increase in temperature the activation energy of the biochar reduced, that is, the biochar decreased adsorption.

Dechlorination during pyrolysis of plastics: The potential of stepwise pyrolysis in combination with metal sorbents

Pyrolysis liquid is a valuable product that could be re-introduced into the refinery or petrochemical industry following circular economy principles. However, halogens in the liquid product hinder this approach by causing corrosion of subsequent technologies. Dehalogenation is, therefore, a necessary step that aims to reduce halogen content below the set limit of 10 ppm. Research on this topic often includes contradictory results, and dehalogenation is still not widely used in large-scale operations. The present study explores the possibility of chlorine removal from a model plastic mixture, including 10% PVC utilizing various pyrolysis conditions, stepwise pyrolysis, and sorbents based on Ca(OH)2, Fe3O4, and Fe. Results suggest that it is not suitable to use sorbents in-situ as the captured Cl in the form of chlorides was released at higher temperatures increasing the chlorine content in the liquid products. The limit of 10 ppm for refinery introduction was reached by combining stepwise pyrolysis and sorbents ex-situ. Fe3O4 displayed the best efficiency, while its reduced form was the most efficient considering its low surface area. The obtained results are a necessary preliminary step for the development of a reliable dehalogenation procedure for municipal plastic waste being underway.

Evaluation of a green-sustainable industrialized cleaner utilization for refractory cyanide tailings containing sulfur

In order to achieve the clean treatment of refractory cyanide tailings containing sulfur, a novel microwave-assisted chlorination thermal treatment recovery technology was proposed in this paper. On the basis of studying the mineralogy of cyanide tailings, the treatment capacity of common chlorinated agents for refractory cyanide tailings containing sulfur was compared. CaCl2 as the best chlorination agent, gold recovery and chlorine removal rates were 85.2% and 95%, under the optimal conditions. The specific action mechanism of CaCl2 in the process of microwave roasting was studied. Under the action of microwave, CaCl2 accelerated decomposition into chlorine-containing gas and rapidly diffused in cracks caused by thermal stress to ensure gold volatilization and chlorination. Finally, the approach and mechanism of removing residual harmful substances in roasting slag were proposed based on the environmental assessment of roasting slag. Environmental pollution and corrosion of building materials can be effectively avoided in the later transportation and secondary utilization of roasting slag.

Formation of organic chloride in the treatment of textile dyeing sludge by Fenton system

In the oxidation treatment of textile dyeing sludge, the quantitative and transformation laws of organic chlorine are not clear enough. Thus, this study mainly evaluated the treatment of textile dyeing sludge by Fenton and Fenton-like system from the aspects of the influence of Cl−, the removal of polycyclic aromatic hydrocarbons (PAHs) and organic carbon, and the removal and formation mechanism of organic chlorine. The results showed that the organic halogen in sludge was mainly hydrophobic organic chlorine, and the content of adsorbable organic chlorine (AOCl) was 0.30 mg/g (dry sludge). In the Fenton system with pH=3, 500 mg/L Cl−, 30 mmol/L Fe2+ and 30 mmol/L H2O2, the removal of phenanthrene was promoted by chlorine radicals (•Cl), and the AOCl in sludge solid phase increased to 0.55 mg/g (dry sludge) at 30 min. According to spectral analysis, it was found that •Cl could chlorinate aromatic and aliphatic compounds (excluding PAHs) in solid phase at the same time, and eventually led to the accumulation of aromatic chlorides in solid phase. Strengthening the oxidation ability of Fenton system increased the formation of organic chlorines in liquid and solid phases. In weak acidity, the oxidation and desorption of superoxide anion promoted the removal and migration of PAHs and organic carbon in solid phase, and reduced the formation of total organic chlorine. The Fenton-like system dominated by non-hydroxyl radical could realize the mineralization of PAHs, organic carbon and organic chlorines instead of migration. This paper builds a basis for the selection of sludge conditioning methods.

Novel process for deep removal of chlorine and recycling of chlorinated tailings from titanium-bearing blast-furnace slag

Given the high chloride ion content in chlorinated tailings that harm the surrounding environment cannot be directly utilized, a new process for the deep removal of chloride ions from chlorinated tailings with additives was proposed. The products obtained included tailing slag, which can be used as a building material, and salt, which can be used in industry. Theoretical calculations and experiments were performed to determine the feasibility of the new process. The results showed that the chloride ions from the chlorinated tailings and sodium ions from the additives formed NaCl, which could be removed during water leaching. NaOH served as a better additive than sodium sulfate. An increase in the molar ratio and the prolongation of ball-milling was beneficial for the dechlorination of the water leaching residue. An increase in the roasting temperature leads to an increase in particle size, which worsens the kinetics of subsequent leaching and reduces the leaching rate. The developed process can obtain tailings with chloride ion content of less than 0.1%, which meets the standard for building materials applications. Meanwhile, NaCl with a purity greater than 99% could be obtained, preventing chloride ion pollution of water resources and the comprehensive utilization of chlorinated tailing.

ADSORPTION OF ACTIVE CHLORINE AND TECHNOLOGY OF AN AQUEOUS SOLUTION DECHLORINATION BY MODIFIED ACTIVATED CARBON

The influence of the modified activated carbon activation type on the degree of adsorption of active chlorine from the aqueous solution was studied. The influence of water flow rate and purification process duration on the adsorption of active chlorine by modified activated carbon was researched and the optimal parameters of the dechlorination regime were determined. The proposed method of extraction of active chlorine by modified activated coal obtained from peach shells can be used in natural and sewage treatment processes for the removal of the active chlorine and chlorine compounds. The design of the mass transfer apparatus with a fixed layer of adsorbent has been developed. The technology of dechlorination aqueous solution by modified activated carbon allows to increase the efficiency of purification up to 99%.