The effect of temperature on the Fenton process has been studied within the range of 25−130 °C using phenol (100 mg/L) as target compound, 10 mg/L Fe2+, and a dose of H2O2 corresponding to the theoretical stoichiometric amount (500 mg/L) for mineralization. The TOC reduction was considerably improved as temperature increased. Whereas at 25 °C the TOC decreased less than 28%, a reduction of almost 80% was achieved at 90 °C. Beyond this temperature no significant improvement of mineralization was observed, although the rate of the process was considerably enhanced. Increasing the temperature leads to a more efficient consumption of H2O2 which indicates an enhanced iron-catalyzed H2O2 decomposition into radicals as temperature increases rather than the generally accepted thermal breakdown of H2O2 into O2 and H2O. Therefore, working at a temperature well above the ambient provides a way of intensifying the Fenton process since it allows a significant improvement of the oxidation rate and the mineralization percentage with reduced H2O2 and Fe2+ doses. Furthermore it would not represent a serious drawback in the case of many industrial wastewaters which may be already at that temperature. Besides, partial recovery of heat from the treated off-stream would always allow saving energy. The TOC time-evolution was well described by a kinetic model based on TOC lumps with apparent activation energy values in the range of 30−50 kJ/mol.

A coupled coagulation−adsorption and high-temperature Fenton oxidation treatment has been applied for the treatment of three different industrial wastewaters bearing high concentrations of hazardous pollutants. High percentages of chemical oxygen demand (COD) removal (>85% for the pesticide and security inks effluents and 65% for the cosmetics ones) were achieved in a first step using FeCl 3 as coagulant and bentonite as adsorbent. This reduced dramatically the amount of H 2 O 2 required in the further high-temperature (120 °C) Fenton oxidation (HTF). Using the stoichiometric amount relative to COD around 70% of the remaining organic load was mineralized. The combined treatment allowed achieving the regional discharge limits of COD and ecotoxicity at a cost substantially lower than the solution used so far where the three wastewaters are managed as hazardous wastes. Working at high temperature would not represent an important drawback since around 90% of heat can be recovered from the treated off-stream.

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A systematic comparison of UV and electrochemical detection (ED) in conjunction with NACE has been performed for capillaries with different ids ranging from 75 down to 2 microm. Ferrocene, (ferrocenylmethyl)trimethylammonium acetate, atropine and scopolamine served as model analytes. All studies were done using an ACN-based nonaqueous electrophoresis buffer. For the comparison of detection performance, particular attention was paid to the absolute and relative LODs for decreasing capillary dimensions. In case of UV detection, a significant increase in relative LODs was typically observed for capillaries smaller than 25 microm in diameter, while the absolute LODs remained nearly constant over a wide range of capillary dimensions. In contrast, ED showed some increase in relative LODs for capillaries smaller than 10 microm in diameter, but the absolute LODs decreased over the complete range of capillary diameters studied. It could be demonstrated that the straightforward end-column ED with microdisk electrodes can be applied in conjunction with small id (2 microm) capillaries. Studies with (ferrocenylmethyl)trimethylammonium acetate using such small capillaries resulted in relative and absolute LODs of 7.5 x 10(-7) and 8 x 10(-18) mol/L, respectively.

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