Dechlorination iron-catalyzed

However, arylmagnesium organometaUics can only be used in a few cases " like an iron-catalyzed homocoupling (equation 92) . Iron catalysis is further used for the dechlorination of electron-rich aryl chlorides by Grignard reagents . ... 

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... 

Cobalt and nickel porphyrins have also been used for catalyzing the chemical dechlorination with a reductant, namely titanium(III) citrate or nanoscale Zero Valent Iron (nZVI), of e.g. atrazine, (2-chloro-4-(ethylamine)-6-(isopropylamine)-s-triazine), a widely used herbicide which is a persistent groundwater contaminant [38]. Nickel 5,10,15,20-tetrakis(l -methyl-4-pyridinium)porphyrintetra(p-toluene-sulfonate) (TMPyP) was activated by nZVI, while cobalt porphyrins (TMPyP,5,10,15,20-tetrakis(4-hydroxyphenyl)-21 H,23H-porphine-(TP(OH)P) and 4,4, 4",4 -(porphine-5,10,15,20-tetrayl)tetrakis (benzenesulfonic acid)-(TBSP)) were activated by titanium(lll) citrate as the electron donor. All these processes probably could be more efficient using electrochemical methods. 

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