Degradation of brominated flame retardants present in printed circuit boards (PCBs) was tested using subcritical water in a high pressure reactor. Debromination experiments were carried out in a batch stirred reactor at three different temperatures (225 ºC, 250 ºC and 275 ºC) keeping a solid to liquid (S/L) ratio of PCB:water=1:5 during 180 min. Results indicated that debromination efficiency was increased with temperature (18.5 to 63.6% of bromine present in the original PCB was removed).Thermal decomposition of the debrominated materials was studied and compared with that of the original PCB. Thermogravimetric analyses were performed at three different heating rates (5, 10 and 20 K min -1 ), studying both the pyrolysis (inert atmosphere) and combustion (in air). Pyrolysis runs of the debrominated materials were also performed in a quartz horizontal laboratory furnace at 850 ºC, in order to study the emission of pollutants. More than 99% of the bromine was emitted in the form of HBr and Br 2 . Emissions of polycyclic aromatic hydrocarbons (PAHs) and bromophenols (BrPhs) decreased with the increase in the treatment temperature; naphthalene (10800 -18300 mg kg -1 original sample) and monobrominated phenols (12.8 -16.9 mg kg -1 original sample) were the most abundant compounds.

The disposal of waste from electrical and electronic equipment (WEEE) is an actual problem of industrialized countries.In the present work, thermal decomposition of different materials has been studied in a thermobalance at different heating rates. Kinetic models are proposed for the pyrolysis, gasification and combustion of crushed wood pellets (CWP), halogen-free electrical wires (EWs) and printed circuit boards (PCBs). Three different heating rates were used at each atmosphere condition. One set of parameters can explain all the experiments at the different atmospheres and at the three different heating rates used. In the case of CWP, a model considering three independent first-order reactions gave very good correlations all the heating rates tested both in inert and oxidant atmosphere. The decomposition of synthetic materials (EW and PCB) is modelled by using n-th order kinetics. On the other hand, mixtures of these three materials have been prepared and tested for decomposition behaviour. A weighted sum of the curves simulated using kinetics of the materials separately gives a good concordance with the experimental curve in the case of PCBs, indicating that there is not chemical interaction between CWP and PCBs when heated and decomposed. This would indicate that the production of pollutants in the decomposition will not be affected by the presence of the other material.Nevertheless, a strong interaction is found with the mixtures between biomass and EW.

Combustion and pyrolysis runs at 850 ºC were carried out in a laboratory scale horizontal 10 reactor with different materials combining biomass and waste electrical and electronic 11 equipment (WEEE). Analyses are presented of the carbon oxides, light hydrocarbons, 12 polycyclic aromatic hydrocarbons (PAHs), polychlorinated benzenes (ClBzs), polychlorinated 13 phenols (ClPhs), polybrominated phenols (BrPhs), polychlorinated dibenzo-p-dioxins and 14 dibenzofurans (PCDD/Fs). Results showed that gas emissions were mainly composed of CO 15 and CO 2 ; the high level of CO found in the pyrolytic runs was easily transformed into CO 2 by 16 reaction with oxygen. The total amount of light hydrocarbons emitted was somewhat higher in 17 the samples containing WEEE, methane being the most abundant light hydrocarbon in all the 18 runs. However, the presence of WEEE reduced the emission of PAHs which clearly decreased 19 with the increase of the oxygen. The total amount of BrPhs increased in the decomposition of 20 the samples containing WEEE, reaching its maximum in pyrolysis runs. Emission of PCDD/Fs 21 was enhanced in pyrolytic conditions and they were easily destroyed in the presence of oxygen. 22 23

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Polyvinyl chloride (PVC) waste generation has significantly increased in recent years and their disposal is considered a major environmental concern. Removal techniques of chlorine from PVC waste are being studied to minimize a negative environmental impact. In this work, the use of K2CO3 as an alkaline additive to improve the dechlorination efficiency (DE) in the hydrothermal degradation of PVC wires was studied. Different experiments were carried out varying both temperature (175 ºC, 200 ºC, 225 ºC, 235 ºC and 250 ºC) and K2CO3 concentration (0.025 M, 0.050 M and 0.125 M), using a solid/liquid ratio of 1:5 in order to determine the evolution of the dechlorination efficiency with time. About 4.66, 21.1, 24.4, 45.7 and 92.6 wt. % of chlorine in PVC wire was removed during hydrothermal dechlorination (HTD) with an additive/chlorine ratio of 1:25 (K2CO3 solution of 0.050 M) at 175, 200, 225, 235 and 250 ºC, respectively. Optimal additive/chlorine ratio decreased to 1:50 (K2CO3 solution of 0.025 M) at 250 ºC, obtaining a dechlorination degree of 99.1% after 4 hours without the need of metallic catalysts. Concerning the solid phase behavior during dechlorination, a linear correlation between the DE reached and the weight loss of PVC was found including every experiment performed in this work.