Georg Härtel

Photochemical oxidation of p-chlorophenol by UV/H2O2 and photo-Fenton process. A comparative study.

In this study, photochemical advanced oxidation processes (AOPs) utilizing the combinations of UV/H2O2 and the photo-Fenton reaction (UV + classical Fenton reaction) were investigated in lab-scale experiments for the degradation of p-chlorophenol. The study showed that the photo-Fenton process, (a mixture of hydrogen peroxide and ferrous or ferric ion), was the most effective treatment process under acidic conditions and produced a higher rate of degradation of p-chlorophenol at a very short radiation time. It accelerated the oxidation rate by 5-9 times the rate for the UV/H2O2 process. The reaction was found to follow the first order, the reaction was influenced by the pH, the input concentration of H2O2 and the amount of the iron catalyst and the type of iron salt. The experimental results showed that the optimum conditions were obtained at a pH value of 3, with 0.03 mol/l H2O2, and 1 mmol/l Fe(II) for the UV/H2O2/Fe(II) system and 0.01 mol/l H2O2 and, 0.4 mmol/l Fe(III) for the UV/H2O2/Fe(III) system. The reactions were accompanied by the generation of Cl- which reached its maximum value at a short reaction time when using the photo-Fenton process. Finally a rough comparison of the specific energy consumption shows that photo-Fenton process reduced the energy consumption by at least 73 to 83% compared with the UV/H2O2 process.

Optimization Study for Treatment of Acid Mine Drainage Using Membrane Technology

The use of membrane technology in the treatment of Acid Mine Drainage (AMD) can result in reduction of chemical usage and sludge production making the treatment process more environmentally friendly. This study deals with the optimization of membrane filtration performance in the treatment of AMD using two nanofiltration (NF) membranes (NF99 and DK) and one reverse osmosis (RO). All membranes were used in various tests treating a model solution at two different concentration levels in order to cover the concentration of actual AMD found in the mining industry. The main parameters which were studied to determine the optimal condition for AMD filtration are pressure, pH, temperature, and flow rate. Pressure and temperature were found to have a considerable influence on flux, while rejection was only slightly influenced by pressure. The feed flow rate had no effect on rejection. The highest flux with moderate rejection was determined for NF99 while RO had the lowest flux but highest rejection. Therefore, NF is preferable for AMD treatment due to lowest energy consumption. The treatment has also been tried on a large scale to check its applicability at a commercial scale. Finally, PHREEQC has been used to determine the scaling risk in the prepared AMD.

Electrochemical Process for Reducing Chlorine Dissolved in Hydrochloric Acid

A problem often associated with the manufacture of hydrochloric acid by combustion process is that the hydrochloric acid is contaminated by dissolved chlorine. Conventional practice is to remove the free chlorine from the hydrochloric acid by adding reducing agents. As an alternative, an electrochemical chlorine reduction process has been developed and investigated both on a laboratory and pilot-plant scale. The advantages of this method are that it obviates the need to add chemicals and effectively prevents chlorine corrosion.