In this work the complete treatment of soil spiked with lindane is studied using surfactant-aided soil-washing (SASW) to exhaust lindane from soil and electrolysis with diamond anodes to mineralize lindane from the soil washing fluid (SWF) waste. Results demonstrated that this technological approach is efficient and allow to remove this hazardous pollutant from soil. They also pointed out the significance of the ratio surfactant/soil in the efficiency of the SASW process and in the performance of the later electrolysis used to mineralize the pollutant. Larger values of this parameter lead to effluents that undergo a very efficient treatment which allows the depletion of lindane for applied charges lower than 15AhL and the recovery of more than 70% of the surfactant for the regeneration of the SWF.

In this paper, a new strategy for the electrochemical treatment of organics is introduced.It is based on the concentration of the organics by adsorption onto granular active carbon (GAC) with the consequent production of a more highly-concentrated solution of organics in methanol, which is then electrolyzed. Electrolysis in methanol supporting media allows the complete removal of the pollutant and reaction intermediates. A suitable conductivity of the electrolyte was obtained simply by adding sodium hydroxide. Results obtained in the tests carried out in this work show a great improvement in the efficiency of the removal of clopyralid when using this technology, which can lead to very important energy savings. This experiment opens the possibility of using the electrochemical technology more efficiently for the degradation of diluted wastes, which currently is known to be a very inefficient process.

In this work, it is evaluated the more critical point of a new electrochemical technology for the removal of organic pollutants based on the regeneration of granular active carbon (GAC) (that can be used efficiently to concentrate aqueous wastes) with methanol and in the electrochemical treatment of methanol with conductive diamond electrochemical oxidation (CDEO). The system proposed was studied with lindane and clopyralid. Results show that it is possible the complete removal of the raw pesticides and intermediates formed by electrolyzing these species in methanol media and that both sodium chloride and sodium hydroxide can be used as supporting electrolyte to increase the conductivity of methanol. The cell voltages obtained are quite similar to those obtained during the electrolysis of aqueous wastes. The electrolysis of these dilute solutions does not generate significant concentrations of intermediates and the depletion of the raw pollutant fits well to a pseudo-first order kinetic model. Oxidants capable to oxidize iodide to iodine are produced during the electrolysis in methanol media and they have an important influence on the degradation of the pollutants. The new technology, based on the concentration of the pollutant before electrolysis, allows to remove completely pollutants from soil and soil washing fluids in a more efficient way, although the concentration of pollutant attained and, hence, the efficiency of the overall removal process depends on the adsorption equilibria of the pollutant in aqueous and methanol media.

This work focuses on the coupling of three different approaches into the same reactor at 11 the same time: microfluidic cells, anodic oxidation with diamond anodes and an electro-12 Fenton process. In order to supply oxygen a jet aerator was used and a CB/PTFE 13 Duocel ® Al foam cathode was installed to promote the formation of hydrogen peroxide. 14 This novel concept is applied for the direct treatment (without the addition of salts or 15 other reagents) of soil washing wastes obtained in the remediation of soil spiked with 16 clopyralid. Results obtained pointed out that this approach can increase the efficiency of 17 the process by folds as compared to traditional treatment technologies. The chemical 18 analysis of the intermediates showed different reaction mechanisms: anodic oxidation, 19 electro-Fenton and a negligible contribution of coagulation. The coupled system studied 20 in this work present several advantages such as high treatment efficiency and short 21 treatment time which indicates that the development of electrochemical reactors for 22 diluted liquid wastes is progressing in an adequate direction.

BACKGROUND This work focuses on the removal of perchloroethylene (PCE) from soils spiked with this hazardous chlorinated hydrocarbon and oil by a combination of two technologies: soil washing and anodic oxidation with diamond electrodes. The first attains the transfer of the pollutant from the soil to a soil washing fluid (SWF), from which the organics are then efficiently removed. RESULTS Results show that high concentrations of sodium dodecyl sulphate (SDS) are required in the SWF for an efficient extraction of the chlorinated hydrocarbon and electrolysis has to be applied not only to the clarified liquid, but also to the interphase. The surfactant used interacts strongly with soil not only during the washing, but also during the electrolysis step. This interaction seems to play a protective role against the oxidation of SDS. The initial phase of the electrolysis is rather complex and there are several processes which modify the results importantly. CONCLUSIONS Removal of PCE by electrolysis from soil is less efficient than its removal from synthetic solutions of this chlorinated pollutant. There are two first‐order kinetic zones, which indicate an important competition for the oxidation of the different organics contained in the SWF during the electrolysis. © 2018 Society of Chemical Industry