Adsorbable Organic Halogens Generation and Reduction During Degradation of Phenol by UV Radiation/Sodium Hypochlorite

2009 ◽  
Vol 81 (2) ◽  
pp. 178-183 ◽  
Author(s):  
Qing-fu Zeng ◽  
Jie Fu ◽  
Yin-tao Shi ◽  
Dong-sheng Xia ◽  
Hai-liang Zhu
Keyword(s):  
Uv Radiation ◽  
Sodium Hypochlorite ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

Comparative study of degradation of 4-chlorophenol by ultraviolet irradiation/sodium hypochlorite and ultraviolet irradiation/ozonation

2009 ◽  
Vol 9 (5) ◽  
pp. 601-609 ◽  
Author(s):  
J. Fu ◽  
J. Huang ◽  
Z. Liu ◽  
Q. F. Zeng ◽  
S. Q. An ◽  
...  
Keyword(s):  
Sodium Hypochlorite ◽  
Ultraviolet Irradiation ◽  
Pilot Scale ◽  
Economic Advantage ◽  
Photochemical Oxidation ◽  
Small Scale ◽  
Final Solution ◽  
Ph Values ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

The photochemical oxidation of 4-chlorophenol solutions by ultraviolet irradiation/sodium hypochlorite (UV/NaClO) and ultraviolet irradiation/ozonation (UV/O3) respectively was studied in a pilot scale photochemical reactor. The degradation efficiency of UV/NaClO was lower than that of UV/O3. The final UV absorption removals of the two processes were approximately 80% and approximately 90% respectively. During the two processes, dihydroxylated chlorophenols were the main intermediates. And pH values decreased with the oxidation being carried on. However, the UV/NaClO process was incomplete and some adsorbable organic halogens, such as ethyl 2-chloroacetate, 3,4-dichlorobut-3-en-2-one, ethyl 2,2-dichloroacetate, 2-chloro-1,1-diethoxyethane, ethyl 2,2,2-trichloroacetate and 2,4,6-trichlorophenol, still existed in the final solution. The costs of the two processes were also estimated. On a small scale, UV/NaClO process had significant economic advantage.

CHEMICAL PULPING. Oxidative degradation of AOX in softwood-based kraft mill effluents from E C F bleachin g

2012 ◽  
Vol 27 (4) ◽  
pp. 707-713 ◽  
Author(s):  
Jukka Pekka lsoaho ◽  
Suvi Tarkkanen ◽  
Raimo Alen ◽  
Juha Fiskari
Keyword(s):  
Reaction Time ◽  
Oxidative Degradation ◽  
Cost Effective ◽  
Process Conditions ◽  
Main Process ◽  
Chemical Pulping ◽  
Kraft Mill ◽  
Organic Halogens ◽  
Aox Removal ◽  
Adsorbable Organic Halogens

Abstract Softwood-based kraft mill bleaching effluents from the initial bleaching stages D0 and E1 (the bleaching sequence being D0E 1D 1 E2D2) were treated by the oxidative Fenton method (H20rFeS04) to decompose organic pollutants contammg adsorbable organic halogens (AOX). Experiments designed using the Taguchi method were applied to predict the process conditions that would result in a cost-effective and adequate removal of AOX. In addition to the composition and concentration of the reagents (H202 and Fe2+), the main process parameters selected were temperature and reaction time, while pH was adj usted to an approximate value of 4 (the volumetric ratio of the mixed effluents D0:E 1 was 3 :2). The results indicated that an AOX removal of about 70% for this mixture ( corresponding to about 50% for the mill) was achieved when the eftluent samples were treated for 60 min at 70°C with H202 and Fe2+ at a concentration of 1 600 mg/1 and 28 mg/1, respectively.

scholarly journals Adsorptive removal of adsorbable organic halogens by activated carbon

2018 ◽  
Vol 5 (12) ◽  
pp. 181507 ◽  
Author(s):  
Chengrong Qin ◽  
Baojie Liu ◽  
Lingzhi Huang ◽  
Chen Liang ◽  
Cong Gao ◽  
...  
Keyword(s):  
Activated Carbon ◽  
Theoretical Basis ◽  
Chemical Process ◽  
Chemical Compositions ◽  
Optimum Conditions ◽  
Adsorptive Removal ◽  
Organic Halogen ◽  
Organic Halogens ◽  
Aox Removal ◽  
Adsorbable Organic Halogens

Current research mainly focuses on the reduction of adsorbable organic halogen (AOX) sources, while studies on AOX monitoring and management in the environment are scarce. Organic pollutants in water are mainly fixed by sediments. Thus, in this paper, activated carbon was used to simulate the adsorption of AOX by sediments. AOX volatilization and degradation were also studied to exclude their effect on adsorption. Micromolecule chlorides were more easily volatilized and degraded than chlorobenzene and chlorophenol. The adsorption of activated carbon to AOX in bleaching wastewater was also studied and the optimum conditions for AOX removal were elucidated (particle size, 62 µm; time, 120 min; pH, 2.5; temperature, 40°C; and activated carbon dosage, 1.75 g l −1 ). AOX adsorption by activated carbon is a chemical process. Hence, the chemical compositions of the bleaching effluent with and without adsorption were analysed by GC-MS. The results revealed that activated carbon exhibits a good AOX removal effect, thereby providing a theoretical basis for monitoring the AOX distribution in the environment.

scholarly journals Effect of lignin structure on adsorbable organic halogens formation in chlorine dioxide bleaching

2019 ◽  
Vol 6 (2) ◽  
pp. 182024 ◽  
Author(s):  
Lisheng Shi ◽  
Jiayan Ge ◽  
Shuangxi Nie ◽  
Chengrong Qin ◽  
Shuangquan Yao
Keyword(s):  
Chlorine Dioxide ◽  
Model Compound ◽  
Pulp Bleaching ◽  
Model Compounds ◽  
Lignin Model Compounds ◽  
Lignin Model Compound ◽  
Lignin Model ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens ◽  
Lignin Structure

Adsorbable organic halogens (AOX) are formed in pulp bleaching as a result of the reaction of residual lignin with chlorine dioxide. The natural structure of lignin is very complex and it tends to be damaged by various extraction methods. All the factors can affect the study about the mechanism of AOX formation in the reaction of lignin with chlorine dioxide. Lignin model compounds, with certain structures, can be used to study the role of different lignin structures on AOX formation. The effect of lignin structure on AOX formation was determined by reacting phenolic and non-phenolic lignin model compound with a chlorine dioxide solution. Vanillyl alcohol (VA) and veratryl alcohol (VE) were selected for the phenolic and non-phenolic lignin model compound, respectively. The pattern consumption of lignin model compounds suggests that both VA and VE began reacting with chlorine dioxide within 10 min and then gradually steadied. The volume of AOX produced by VE was significantly higher than that produced by VA for a given initial lignin model compound concentration. In a solution containing a combination of VA and VE in chlorine dioxide, VE was the dominant producer of AOX. This result indicates that the non-phenolic lignin structure was more easily chlorinated, while the phenolic lignin structure was mainly oxidized. In addition, AOX content produced in the combined experiments exceeded the total content of the two separate experiments. It suggested that the combination of phenolic and non-phenolic lignin structure can promote AOX formation.

Controlling Adsorbable Organic Halogens (AOX) and Trihalomethanes (THM) Formation by Ozonation and Two-Step Granule Activated Carbon (GAC) Filtration

1999 ◽  
Vol 40 (9) ◽  
pp. 249-256 ◽  
Author(s):  
R. Vahala ◽  
V.-A. Långvik ◽  
R. Laukkanen
Keyword(s):  
Activated Carbon ◽  
Distribution System ◽  
Minor Importance ◽  
Chlorine Disinfection ◽  
Simulated Distribution ◽  
Organic Halogens ◽  
A Minor ◽  
Parallel Filter ◽  
Filter Bed ◽  
Adsorbable Organic Halogens

A pilot plant study in four parallel filter runs was performed in order to determine the effect of ozonation and two-step granular activated carbon (GAC) filtration on the removal of disinfection by-product (DBP) precursors. The results showed that ozonation significantly decreased the adsorbable organic halogens (AOX) (35%), simulated distribution system (SDS) AOX (37%) and SDS trihalomethanes (THM) (76%) from chemically treated and sand-filtered lake water, but did not decrease either short-term or the long-term chlorine demand. Biofiltration with exhausted GAC had a minor importance in the precursor removal (0-20%). The performance of adsorptive GAC filtration was strongly dependent on the age of the GAC filter bed, which was also seen as a strong correlation between the natural organic matter (NOM) measurements and DBP formation potential. Disinfection with chloramine produced lower THM, AOX, mutagenicity and MX (Z-3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) levels compared to chlorine disinfection.

Removal of Chlorophenols and Chlorolignins from Bleaching Effluent by Combined Chemical and Biological Treatment

1988 ◽  
Vol 20 (1) ◽  
pp. 161-170 ◽  
Author(s):  
O. Milstein ◽  
A. Haars ◽  
A. Majcherczyk ◽  
J. Trojanowski ◽  
D. Tautz ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Chemical Oxygen Demand ◽  
Biological Treatment ◽  
Oxygen Demand ◽  
Pilot Unit ◽  
Insoluble Complex ◽  
Treated Effluent ◽  
Organic Halogens ◽  
Adsorbable Organic Halogens

Organic matter from spent bleaching effluents (from chlorination (C) or extraction (E) stages, or a mixture of both) was effectively precipitated as a water insoluble complex with polyethyleneimine (polyimine). Precipitation was performed in a pilot unit operating automatically. The colour, chemical oxygen demand (COD), and adsorbable organic halogens (AOX) were reduced in the C-effluent by up to 92%, 65%, and 84%, respectively. Regarding the E-stage effluent, reduction was up to 76% for colour, 70% for COD, and 73% for AOX. No significant reduction of BOD5 was observed in the supernatant of the treated effluent. Fish toxicity was greatly reduced. Laccase increased the molecular weight of the effluent constituents, thus facilitating subsequent precipitation. After treatment with laccase, the bulk of mono- and dichlorophenol is coprecipitated with the liquors from the C and E bleaching stages. Fungi (representatives of the genera Aspergillus and Penicillium) achieved an appreciable level of degradation of chlorophenols and other chloroorganic compounds from the bleaching effluent.

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