Humic chlorination

Hydrodechlorination is a common reaction of chlorinated pesticides such as atrazine (eq. 15), alachlor, and metolachlor (2) (eq. 16). These reactions are catalyzed primarily by transition metals or by soil surfaces (clays or humic substances). 

Pretreatment For most membrane applications, particularly for RO and NF, pretreatment of the feed is essential. If pretreatment is inadequate, success will be transient. For most applications, pretreatment is location specific. Well water is easier to treat than surface water and that is particularly true for sea wells. A reducing (anaerobic) environment is preferred. If heavy metals are present in the feed even in small amounts, they may catalyze membrane degradation. If surface sources are treated, chlorination followed by thorough dechlorination is required for high-performance membranes [Riley in Baker et al., op. cit., p. 5-29]. It is normal to adjust pH and add antisealants to prevent deposition of carbonates and siillates on the membrane. Iron can be a major problem, and equipment selection to avoid iron contamination is required. Freshly precipitated iron oxide fouls membranes and reqiiires an expensive cleaning procedure to remove. Humic acid is another foulant, and if it is present, conventional flocculation and filtration are normally used to remove it. The same treatment is appropriate for other colloidal materials. Ultrafiltration or microfiltration are excellent pretreatments, but in general they are... 

Prepai ative isolation of nonvolatile and semivolatile organic compounds fractions (hydrophobic weak acids, hydrophobic weak bases, hydrophobic neutrals, humic and fulvic acids) from natural and drinking waters in optimal conditions was systematically investigated by solid-phase extraction method with porous polymer sorbents followed by isolation from general concentrate of antropogenic and/or toxic semivolatile compounds produced in chlorination and ozonation processes. 

Under drinking water plant treatment conditions, humic materials and/ or resorcinol do not produce trihalomethanes with chlorine dioxide even when a slight excess of chlorine (1 percent to 2 percent) is present. Also, saturated aliphatic compounds are not reactive with chlorine dioxide. Alcohols are oxidized to the corresponding acids. 

The breakdown of organic contaminants present in the MU water to produce ammonia (from nitrogenous contaminants), phenols and carboxylic acids (from humic and fulvic acids), and tri-halomethanes (from the by-products of chlorination)... 

Finneran KT, HM Foirbush, CVG VanPraagh, DR Lovley (2002) Desulfitobacterium metalUreducens sp. nov., an anaerobic bacterium that couples growth to the reduction of metals and humic acids as well as chlorinated compounds. Int J Syst Evol Microbiol 52 1929-1935. 

Park J-W, Dec J, Kim JE, Bollag J-M (2000) Transformation of chlorinated phenols and anilines in the presence of humic acid. J Environ Qual 29 214-240... 

Tanaka F, Fukushima M, Kikuchi A, Yabuta H, Ichikawa H, Tatsumi K (2005) Influence of chemical characteristics of humic substances on the partition coefficient of a chlorinated dioxin. Chemosphere 58 1319-1326... 

Sabljic, A., Lara, R., Ernst, W. (1989) Modelling association of highly chlorinated biphenyls with marine humic substances. Chemosphere 19, 1665-1676. 

Japenga et al. [56] determined polychlorinated biphenyls and chlorinated insecticides in River Elbe estuary sediments by a procedure in which the sediments were pretreated with acetic acid, mixed with silica and Soxhlet-extracted with benzene/hexane. Humic material and elemental sulphur were removed by passing the extract through a chromatographic column containing basic alumina, on which sodium sulphite and sodium hydroxide were adsorbed. Silica fractionation was followed by gas chromatography to analyse chlorinated pesticides, polychlorinated biphenyls and polyaromatic hydrocarbons. Recovery experiments with standard solutions gave recoveries of 90-102%. 

Gaffney et al. 1987). Cyanogen chloride is formed in drinking water from reaction of humic substances with chloramine produced during chlorination (Jacangelo et al. 1989 Ohya and Kanno 1987). 

Van Duuren BL, Melchionne S, Seidman I, et al. 1986. Chronic bioassays of chlorinated humic acids in B6C3F1 mice. Environ Flealth Perspect 69 109-117. 

Photolytic. Photoproducts reported from the sunlight irradiation of propanil (200 mg/L) in distilled water were 3 -hydroxy-4 -chloropropionanilide, 3 -chloro-4 -hydroxypropionanilide, 3, 4 -di-hydroxypropionanilide, 3 -chloropropionanilide, 4 -chloropropionanilide, propionanilide, 3,4-di-chloroaniline, 3-chloroaniline, propionic acid, propionamide, 3,3, 4,4 -tetrachloroazobenzene, and a dark polymeric humic substance. These products formed by the reductive dechlorination, replacement of chlorine substituents by hydroxyl groups, formation of propionamide, hydrolysis... 

Kronberg L, Holmbom B, Reunanen M, Tikkanen L (1988) Identification and quantification of the Ames mutagenic compound 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone and of its geometric isomer (E)-2-chloro-3-(dichloromethyl) -oxobutenoic acid in chlorine-treated humic water and drinking water extracts. Environ Sci Technol 22 1097-1103... 

Zhang X, Minear RA (2006) Formation, adsorption and separation of high molecular weight disinfection byproducts resulting from chlorination of aquatic humic substances. Water Res 40(2) 221-230... 

Zhang X, Minear RA, Barrett SE (2005) Characterization ofhigh molecular weight disinfection byproducts from chlorination of humic substances with/without coagulation pretreatment using UF-SEC-ESI-MS/MS. Environ Sci Technol 39(4) 963-972... 

Uses. As a reagent for albumin detection in making herbicides. It is found as a by-product after chlorination of water containing humic materials. 

---