Mecanismo de adsorção de paracetamol em carvões nacionais

• Autor(a) principal: Ferreira, Regiane Cristina
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/3780
• topic: Carvão ativado; Paracetamol; Adsorção em fase liquida; Fármacos; Tratamento de água (Processos); Tratamento de águas residuárias; Brasil.; Engenharias; Engenharia Química

The inadequate disposing of waste and the lack of quality in the treatment of sewage, causes contamination in water resources, which consequently affect the treatment of drinking water. Among the contaminants we can highlight the drugs. As a complementary technique to water treatment and sewage, have adsorption on activated carbon. Within this context, the objective of this work was to investigate the paracetamol adsorption mechanism in babassu coconut coal and palm coconut charcoal. The activated carbons of dende and babassu passed by chemical functionalization (HNO3 and NaOH) and physical (inert atmosphere), known as DAC, BAC, DBA, BBA, DI and BI, respectively. The chemical and physical characterization was carried out on the material fresh and functionalized, and kinetic and thermodynamic studies. The paracetamol molecule has neutral form in the range of pH 2.0-10.0 and anionic form to pH higher than 10.0. It is possible to verify characteristic of microporous materials to all samples. To the carbon functionalized in HNO3 there was a block of the micropores by oxide functional groups introduced by chemical treatment. It was observed in the Boehm method that CAD and BAC increased the amount of acidic groups, and DBA BBA results show that the functionalization have different behavior in babassu and dende; and a substantial increase of basic groups to DI and BI. Values of pHPCZ were 6.5; 3.6; 3.7; 4.4; 3.9; 3.6; 3.8 and 4.2 to DD, CAD, DBA, DI, BB, BAC, BBA and BI, respectively. Infrared spectra indicate the presence of band at 1580 cm-1, which appears in the original sample and is particularly oxidized in the treatment acid, can be associated with the stretching of C = O bonds. This band promotes the appearance of a peak at 1385 cm-1, corresponding to the vibration of the bands of -NO2. In the range of 1200-1000 cm-1, bands indicate the presence of C=O that are characteristics of ethers groups, phenols, and hydroxyl. Kinetic model of pseudo-first-order and the Langmuir model best fit to the experimental data for all samples, indicating chemisorption monolayer. At pH 2.0 and pHPCZ was verified higher adsorbed amount for all carbons which no longer occurs to pH 11.0, due to the electrostatic repulsion, indicating that in acidic pH the chemisorption may be involved. For both carbons, the functionalization with HNO3 decreases the amount adsorbed, indicating that the acid groups decrease the removal efficiency of paracetamol. To the functionalization in inert atmosphere and also with NaOH, an increase of the amount adsorbed due to the greater amount of basic groups, indicating that the chemisorption is involved in the process. The proposed mechanism of paracetamol adsorption with the activated carbon was between the carbons bonded to the ether and the pyrone group by the interaction with the carbonyl group of paracetamol; and the bond among the aromatic rings. Thermodynamic study showed an increase of the amount of paracetamol adsorption until 45 °C, due to the chemisorption, and inegligible increase of chemisorption of 45 to 55 oC, being attracted by physisorption. Values to ΔGo were negative, indicating that process is spontaneous and favorable. Positive values of ΔSº and ΔHº suggest an increase of the disorder at the solid/fluid interface and the endothermic nature. The most efficient adsorbent to the paracetamol retention is the activated carbon palm functionalized in an inert atmosphere, due to higher values of basic groups