Poly(ethylene glycol) (PEG), both as an oligomer and as a high molecular weight polymer, has been used as a surfactant active component in many applications, in its pure and unmodified structure, or as a block segment within more complex structures. Apart from assuming helical or coil conformations it may also undergo aggregation, depending on the solvent. In this work, we characterized the aggregation of PEG in water using surface tensiometry and turbidimetry. Aggregation was characterized by a non‐persistent surface tension plateau at higher PEG contents and confirmed by turbidimetry, which was correlated to the derivative of osmotic pressure in relation to concentration. One can divide a surface tension‐concentration curve into two regions, delimited by a characteristic concentration: one following a Langmuir adsorption isotherm (starting from a plateau equal to pure water surface tension) ending in a second plateau, and a second one (beginning at this plateau) following a Freundlich isotherm. The calculated surface excess for PEG segment adsorption was consistent with segment aggregation, indicating more two characteristic concentrations correlated to this occurrence. A total of three characteristic mer concentrations were found (6.2 × 10−7, 6 × 10−6, and 2 × 10−4mol L−1) and related to PEG segment aggregation states.

This work aims to investigate the electrochemical treatment of petrochemical industry effluents (from the northwest region of Brazil) mediated by active chlorine species electro-generated at Ti/Ru0.3Ti0.7O2 and BDD anodes by applying 15 and 45 mA cm−2. Chemical oxygen demand (COD) determinations and toxicity analyses were carried out in order to evaluate the process extension as well as the possible reuse of the wastewater after treatment, respectively. Toxicity was evaluated by assessing the inhibition of lettuce (Lactuca sativa) stem growth, seed germination as well as the production of nitrite and nitrate species. Results clearly evidenced that, the best COD reduction performances were reached at BDD anode, achieving almost 100% of removal in short times. Degradation of nitrogen-organic compounds generated nitrite and nitrate which participate as nutrients for lettuce plants. Toxicity results also indicated that the electrogenerated active chlorine species are persistent in the effluent after the treatment, avoiding the stem growth, and consequently affecting the germination.

This work aims to investigate the treatment of a real petrochemical effluent (commonly named produced water (PW)) by electro-generated active chlorine species using Ti/Ru0.3Ti0.7O2, Ti/Pt and BDD anodes in a batch cell by applying 45 mA cm-2. Chemical oxygen demand (COD) and spectrophotometric measurements were carried out to follow the elimination of organic matter as well as the concentration of active chlorine species was determined at the end of the treatment. Results clearly indicated that, removal efficiencies about 42% and 52%, in terms of COD, were achieved with BDD and Ti/Pt anodes, respectively. Conversely, Ti/Ru0.3Ti0.7O2 anode reached up to 85% of organic matter elimination, as consequence of the efficient production of active chlorine species (ClO2-, ClO2, Cl2) by the catalytic action of the anode during the electrochemical treatment.