Rita R.N. Marques

Performance of Sludge Based Activated Carbons in Catalytic Wet Air Oxidation of Phenol

The catalytic potential of sludge based materials produced by steam or CO2 activation from non-treated dewatered raw sludge or dewatered mesophilic anaerobically digested sludge were tested in the oxidation of phenol. Batch and continuous experiments were conducted to assess activity and stability of these novel carbons in terms of phenol conversion, carbon burn-off and metal leaching. Overall, their catalytic activity can be considered satisfactory when compared to commercial carbons. However, further research on the preparation, activation and hardening of these sludge based materials is required to improve their thermal and mechanical stability and resistance to metal leaching during the catalytic wet air oxidation of phenol.

Catalytic Wet Oxidation of Acrylic Acid: Studies with Manganese-based Oxides

Development of active, stable and economical catalysts for oxidation of acrylic acid contained in industrial effluents is nowadays of great importance. Several manganese-based solids catalysts supported in Ce, Zr, Ti and Al oxides were prepared in our laboratory by incipient wetness impregnation for oxidation of acrylic acid in a batch high-pressure reactor at slurry conditions under 200°C and 15 bar of oxygen partial pressure. The Mn-Ce-O catalyst was the most active leading to high conversions (92.3%) in terms of total organic carbon (TOC) and total degradation of acrylic acid in the first 30 min of reaction. The TOC reductions were lower with Mn-Zr-O (45.6%), Mn-Ti-O (43.6%) and Mn-Al-O (28.2%) as well as acrylic acid was not completely degraded even after 180 min of reaction. The impregnation method used for catalyst preparation was compared with the co-precipitation procedure, being the last one less effective for TOC reduction (87.0%) although the same activity to oxidation of acrylic acid was observed. Acetic and formic acids were found as reaction intermediates being refractory compounds for the catalysts supported in Zr, Ti and Al. Catalyst stability was also evaluated and Mn-Ce-O prepared by impregnation showed low leaching of Mn to the liquid phase as well as carbon adsorption was not found strengthening the catalyst potentialities in the treatment of wastewaters containing acrylic acid. Since under non-catalytic conditions acrylic acid is refractory up to high temperatures (260°C), this work offers a step forward in the design of an economical catalyst able to promote acrylic acid oxidation in the liquid-phase at lower operating conditions than those used in non-catalytic systems.

The role of emotion regulation difficulties in the relationship between attachment representations and depressive and anxiety symptoms in the postpartum period

BACKGROUND Insecure attachment representations have been established as a vulnerability factor for postpartum depressive symptoms. However, there is a lack of studies on the effects of attachment (in)security on postpartum anxiety symptoms, and on the mechanisms through which attachment representations may affect womens postpartum adjustment, namely, emotion regulation difficulties. METHODS The sample included 450 women in the postpartum period (up to 12 months postpartum), who were recruited both online (advertisements on social media) and in person (study was presented by the researchers during the womens postpartum hospitalization). RESULTS Approximately one third of the women with clinically significant symptoms (33.3%) presented comorbid symptoms of anxiety and depression, and these women presented more insecure attachment representations and more emotion regulation difficulties (p < .001) than did women without comorbid symptoms (p < .001). The relationship between more insecure attachment representations and depressive and anxiety symptoms occurred both directly and indirectly through emotional regulation difficulties. LIMITATIONS The cross-sectional nature of the study, the use of self-report questionnaires that do not allow the establishment of clinical diagnosis and the self-selected bias in recruitment were study limitations. CONCLUSIONS The results underline the need for attention to anxiety symptomatology, which is a condition that co-occurs frequently in this period. Interventions that focus on promoting adaptive strategies of emotional regulation are relevant rather than more intensive interventions to change attachment representations.