RESUMO
The decomposition of volatile organic compounds by photocatalytic oxidation (PCO) has been widely studied. However, the technological development of this oxidative technique has to address how to handle the formation of transformation products. The work presented here investigates the original combination of a dense membrane separation process and PCO to intensify the trapping and reduction of PCO transformation products. Specific monitoring of toluene PCO transformation products, such as benzene and formaldehyde, in the outflow of both permeate and retentate compartments was proposed. The influence of operating parameters on the process, i.e., light intensity, pressure, membrane type, and catalyst mass, was also studied. The results reveal that membrane separation-PCO hybridization is particularly effective for reducing the presence of benzene and formaldehyde in the effluent treated. The benzene concentration in the outflow of the hybrid module can be reduced by a factor of 120 compared to that observed during the PCO of toluene alone.
RESUMO
BACKGROUND: Despite the increasing use of Alcohol-Based Hand Rub solutions, few studies have quantified the concentrations of inhaled ethanol. OBJECTIVE: The aim of this study was to assess ethanol exposure during hygienic and surgical hand disinfection practices. METHOD: Ethanol concentrations were measured at the nose level of a wooden dummy and human volunteers. Two systems were used in parallel to determine short-term ethanol vapor exposures: activated charcoal tubes followed by gas chromatography analysis and direct reading on a photoionization detector (PID). Exposure was assessed for 4 different sequences (N=10) reproducing hand rubs for simple surgery, nursing care, intensive care and surgical scrub. RESULTS: The ethanol concentrations measured were of a similar order between the dummy and volunteers. The concentrations obtained by PID were higher than the gas chromatography values for the simple care (45%) and nursing care (27%) sequences and reflected specific exposure peaks of ethanol, whereas ethanol concentrations were continuously high for intensive care (440 mg m(-3)) or surgical scrub (650 mg m(-3)). CONCLUSION: Ethanol concentrations were similar for these two exposure assessment methods and demonstrated a relationship between handled doses and inhaled doses. However, the ethanol vapors released during hand disinfection were safe for the healthcare workers.
