Adsorbable organic halides

Disinfection by-products (e.g., adsorbable organic halides such as trihalomethanes) are more than 50% decreased compared to equivalent chlorine treatments in standardized AOX test with STABREX3. In practice, disinfection by-products are decreased even further in STABREX applications because less oxidant is required to control the microbial fouling process compared to bromine or chlorine applications. 

The pulp and paper industry is the largest industrial process water user in the U.S.5 In 2000, a typical pulp and paper mill used between 15,140 and 45,420 L (4000 to 12,000 gal) of water per ton of pulp produced. 1 2 3 4 General water pollution concerns for pulp and paper mills are effluent solids, biochemical oxygen demand (BOD), and color. Toxicity concerns historically occurred from the potential presence of chlorinated organic compounds such as dioxins, furans, and others (collectively referred to as adsorbable organic halides, or AOX) in wastewaters after the chlorination/ extraction sequence. With the substitution of chlorine dioxide for chlorine, discharges of the chlorinated compounds have decreased dramatically. 

Analytical methods for 12 chlorinated phenolics and adsorbable organic halides (AOXs). Samples of air emissions and water discharges from each mill must be tested using the laboratory methods included in the rule. The new methods will enable more timely and accurate measurements of releases of these pollutants to the environment and will be used to ensure compliance with air emission and water discharge permit limits... 

Final Effluent (for BAT) or Bleach Plant Effluent (for PSES) AOX (adsorbable organic halides) 1-Day maximum 0.951 kg/Te... 

Contribution to adsorbable organic halide (AOX) load in the receiving ecosystems. 

Following the prophetic speculations of Kharasch and Reinmuth [A] and the crucial CIDNP experiments of the Amsterdam group [22], the main features of the mechanism are now clear. Electron transfer from the magnesium surface to adsorbed organic halide gives rise to alkyl radicals and halide ions. Further recombination steps lead to the alkylmagnesium halide. Two matters especially remain controversial whether the electron transfer step involves a discrete radical anion intermediate, and to what extent radicals leave the metal surface to diffuse into the solution. Recent arguments have been summarized [23, 24], commented on [25], and pursued [26]. The implications for practical work may be summarized briefly as follows ... 

Ong, S.K. et al.. Toxicity and bioconcentration potential of adsorbable organic halides from bleached laundering in municipal wastewater. Environ. Toxicol. Chem., 15,138,1996. 

Y. Noma, S. Yamane, and A. Kida. Adsorbable organic halides (AOX), AOX formation potential, and PCDDs/DFs in landfill leachate and their removal in water treatment processes. ]. Mater. Cycles Waste Manag., 3 126-134, 2001. 

Electrocatalysis employing Co complexes as catalysts may have the complex in solution, adsorbed onto the electrode surface, or covalently bound to the electrode surface. This is exemplified with some selected examples. Cobalt(I) coordinatively unsaturated complexes of 2,2 -dipyridine promote the electrochemical oxidation of organic halides, the apparent rate constant showing a first order dependence on substrate concentration.1398,1399 Catalytic reduction of dioxygen has been observed on a glassy carbon electrode to which a cobalt(III) macrocycle tetraamine complex has been adsorbed.1400,1401... 

Mussini, P.R., Ardizzone, S., Cappelletti, G., Longhi, M., Rondinini, S. and Doubova, L.M. (2003) Surface screening effects by specifically adsorbed halide anions in the electrocatalytic reduction of a model organic halide at mono- and polycrystalline silver in acetonitrile. J. Electroanal. Chem. 552, 213-221. 

As well as the adsorption of halogen atoms or molecules, the adsorption of halide anions to gold surfaces has been extensively studied and a comprehensive review of the area has been published by Magnussen [168]. The degree of specific adsorption to gold surfaces increases in the order F < Cl < Br < 1 with only weakly specifically adsorbed. The presence of halide anions can also affect the electrodeposition of organic molecules such as pyridine on Au surfaces with chloride and bromide solutions suppressing the formation of ordered N-bonded pyridine layers [169]. 

Specifically adsorbed inorganic ions as halide anions [23] and organic substances can inhibit corrosion (see e.g. [24]). 

---