Adsor??o de diclofenaco, estradiol e sulfametoxazol em carv?es ativados e nanotubos de carbono : estudos cin?ticos e termodin?micos.

Programa de P?s-Gradua??o em Engenharia Ambiental. PRO?GUA, Pr?-Reitoria de Pesquisa e P?s Gradua??o, Universidade Federal de Ouro Preto.Neste trabalho foram determinados os par?metros cin?ticos e termodin?micos da adsor??o de tr?s f?rmacos (sulfametoxazol (SMX), diclofenaco (DCF) e estradiol (E2)) em tr?s tipos de carv?o ativado em p? (pinus, CAPI; mineral, CAPII; e casca de coco, CAPIII) e nanotubos de carbono (NTC). Os resultados indicaram que n?o houve a forma??o de NTC de boa qualidade e por consequ?ncia a adsor??o em NTC foi desfavor?vel para os f?rmacos estudados, ao passo que o CAPI foi o melhor carv?o dentre os testados, provavelmente porque ? b?sico e apresenta di?metro m?dio dos poros (12,09 ?) compat?vel com o tamanho (10 a 12 ?) dos f?rmacos testados. A adsor??o dos tr?s f?rmacos com CAPI se mostrou favor?vel, com energia livre de Gibs na faixa de -28 a -30 kJ.mol-1. Os ensaios de adsor??o com CAPI conduzidos a 25 oC indicaram valores de capacidade m?xima (QMAX) de 135,94; 259,63 e 73,83 mg.g-1 para SMX, DCF e E2, respectivamente. Langmuir foi o melhor modelo de equil?brio para descrever a adsor??o de SMX, sendo que para, DCF e E2, o modelo de Freundlich foi o que melhor se ajustou aos dados experimentais. Os dados indicam que, provavelmente, houve intera??o eletrost?tica entre o CAPI e os f?rmacos SMX e DCF, ao passo que para o E2 a adsor??o ocorreu por fracas for?as de van der Waals. Para os estudos cin?ticos o modelo de pseudo-segunda ordem foi o que melhor se ajustou a todos os f?rmacos, com tempo de equil?brio de 120 min. O estudo de competi??o adsortiva mostrou que a adsor??o de E2 foi prejudicada pela presen?a do SMX e DCF, que, comparado aos estudos monocomponentes, foram adsorvidos em menor quantidade pelo CAPI, com valores de QMAX de apenas 16 e 14 mg.g-1, respectivamente.In this study it was determined the kinetic and thermodynamic parameters of adsorption of three drugs (sulfamethoxazole (SMX), diclofenac (DCF) and estradiol (E2)) in three types of powdered activated carbon (pinus, PACI; mineral, PACII and coconut shell, PACIII) and carbon nanotubes (CNT). The results indicated that the adsorption with CNT was unfavorable for the studied drugs due to the fact of bad quality of CNT produced while PACI was the best adsorbent among the cabons, probably because it is basic, and has an average pore diameter (12.09 ?) consistent with the size (10 to 12 ?) of the tested drugs. The adsorption of the three drugs with PACI proved favorable with Gibbs free energy in the range of -28 to -30 kJ.mol-1. The adsorption isotherm models lead to values of maximum capacity (QMAX) of 135.94; 259.63 and 73.83 mg.g-1 at temperature of 25oC for SMX, DCF and E2, respectively. Langmuir was the best model to describe the SMX adsorption, however for DCF and E2, the Freundlich model best fited the experimental data. The results indicate there was probably an electrostatic interaction between PACI and SMX and DCF drugs, while E2 adsorption seemed to have occurred by weak van der Waals forces. For kinetic studies the model of pseudosecond order was the one that best fitted to all drugs adsorption data. The ideal contact time found for the adsorption process was 120 min. About the competition study, it was observed that the adsorption of E2 was hampered by the presence of SMX and DCF, so that the adsorption capacity (QMAX) was much lower (16 and 14 mg g-1, respectively) when compared to monocomponent studies

Uso de pol?meros molecularmente impressos (MIP) para recupera??o seletiva de ?cidos graxos vol?teis (AGV) produzidos no tratamento anaer?bio.

Programa de P?s-Gradua??o em Engenharia Ambiental. N?cleo de Pesquisas e P?s-Gradua??o em Recursos H?dricos, Universidade Federal de Ouro Preto.Os ?cidos graxos vol?teis (AGVs) produzidos durante o metabolismo anaer?bio podem levar ao mal funcionamento de reatores acarretando em baixa produ??o de biog?s e menor remo??o de demanda qu?mica de oxig?nio (DQO). Por outro lado, alguns AGVs possuem elevado valor de mercado e, ao serem removidos poderiam, al?m de beneficiar o desempenho dos reatores anaer?bios, serem utilizados em diversas aplica??es industriais. Pelo exposto, esta pesquisa objetivou sintetizar e caracterizar adsorventes seletivos, os pol?meros molecularmente impressos (MIP), para serem aplicados como adsorventes de AGVs em sistemas anaer?bios operados em batelada ou sob alimenta??o cont?nua. Foram sintetizados diversos materiais e devido aos valores do par?metros de efici?ncia de impress?o (IF?1,5) foram selecionados 5 materiais (dos quais: dois foram sintetizados via bulk em diferentes condi??es de s?ntese - MIP4 e MIP5 ? e tr?s foram sintetizados em s?ntese h?brida: um foi sintetizado em superf?cie magn?tica ? MMIP - e dois foram sintetizados na presen?a de s?lica, sendo um sem part?culas magn?ticas ? HMIP ? e um com part?culas magn?ticas - HMMIP. Com tais materiais realizou-se estudos de cin?tica, de isoterma, equil?brio termodin?micos, de seletividade, aplicabilidade e regenera??o/reuso. Por fim, alguns materiais foram aplicados de diferentes formas a fim de avaliar a efici?ncia dos pol?meros para remover os AGVs gerados em reatores anaer?bios. Os resultados evidenciam que o MMIP apresentou maior superf?cie espec?fica e que todos os materiais sintetizados s?o mesoporosos, com exce??o do MIP4 e HMIP. Os dados de cin?tica mostraram que os processos seguem o modelo de pseudo n ordem e que as constantes cin?ticas (kn) dos MIPs foram sempre superiores ?s dos respectivos NIPs. O modelo de Sips foi o que melhor descreveu os dados e obteve valores de capacidade m?xima de adsor??o (Qmax) de 209,72;156,09; 68,89; 61,08 e 33,76 mg.g-1 para MIP5, MIP4, HMIP, HMMIP e MMIP, respectivamente ? 25oC. Os dados termodin?micos demonstraram que todos os processos s?o espont?neos, endot?rmicos e entropicamente dirigidos. Os dados de seletividade apresentaram valores de coeficiente de seletividade relativa (k?) superiores a unidade, logo s?o materiais seletivos ? ?cido isoval?rico (template escolhido para gerar uma cavidade seletiva n?o apenas a ele, mas aos principais AGVs) mesmo em meios com mol?culas estruturalmente parecidas. As an?lises de aplica??o dos adsorventes em batelada em efluente de reator anaer?bio apresentaram valores de Qe superiores para os pol?meros quando comparados aos valores dos materiais comerciados analisados (resina de troca i?nica e quitosana). Ao analisar a influ?ncia na produ??o de metano em reator anaer?bio na presen?a de HMMIP, foi poss?vel notar um acr?scimo de 66% na produ??o desse biog?s. Tal resultado comprova que a remo??o dos AGVs gerados e acumulados em reatores anaer?bios melhora a remo??o da DQO e contribui para aumento da gera??o de biog?s. Ademais foram analisados os tempos de sedimentabilidade convencional e imantada para o MMIP e HMMIP. O MMIP demandaria menor tanque de decanta??o devido ? maior velocidade de sedimenta??o (~ 3 m.h-1 ), no entanto ambos os materiais apresentaram boa sedimenta??o. O processo imantado destaca-se por possibilitar a separa??o dos adsorventes magn?ticos tanto da parte l?quida quanto do lodo gerado no fundo dos reatores. Os testes de coluna de adsor??o foram realizados em diversas concentra??es e vaz?es para os pol?meros h?bridos e resina de troca i?nica. O processo mais eficiente, de acordo com efici?ncia total do processo de adsor??o em coluna (EPads), foi o HMMIP com valor de 74%. Por fim, concluiu-se que foram sintetizados materiais com potencial para ampliar os estudos em larga escala, uma vez que os resultados foram extremamente satisfat?rios.The volatile fatty acids (VFAs) produced during anaerobic metabolism can lead to a malfunction of reactors thereby causing a low removal of chemical oxygen demand (COD). Moreover, the VFAs have high market value and if recovered can, besides improving the performance of anaerobic reactors, be used in several industrial sectors. Therefore, the aim of this work was to synthesize and characterize selective adsorbents, the so called molecularly imprinted polymers (MIPs). These materials were applied as adsorbents of VFAs in anaerobic systems operated in batch or under continuous feed. Several materials were synthesized and due to imprinting factor parameter (IF?1.5) five of these were selected (of which: two were synthesized via bulk in different conditions-MIP4 and MIP5-, three were synthesized in hybrid synthesis: one on a magnetic surface -MMIP- and two were synthesized in the presence of silica, one without the presence of magnetic particles -HMIP- and one with magnetic particles -HMMIP. These materials were evaluated by kinetic, isothermal, thermodynamic, selectivity, applicability and by adsorbent reuse experiments. Finally, some of these materials were applied in different process to evaluate the MIPs efficiency to remove the VFAs generated in anaerobic reactors. The specific area results showed that the MMIP presented the higher specific surface value. Moreover, due to the pore size results, all materials were classified as mesoporous, except the MIP4 and HMIP. The kinetic data follow the pseudo n order model and the kinetic constants (kn) of MIPs were higher than the ones of the respective NIPs. The isotherm results were well adjusted to the Sips model and generated Qmax values of 209.72; 156.09; 68.89; 61.08 and 33.76 mg.g-1 for MIP5, MIP4, HMIP, HMMIP and MMIP, respectively at 25?C. Thermodynamic data indicated that all processes are spontaneous, endothermic and entropically directed. The selectivity data presented values of relative selectivity coefficient (k') greater than one unit, so they are selective materials for isovaleric acid (template chosen to create a specific cavity not only to it, but to the main VFAs) even in media with molecules structurally similar. The applicability analysis of the adsorbents in batch process with an anaerobic reactor effluent showed higher Qe values for the polymers when compared to the values of commercial materials analyzed (ion exchange resin and chitosan). Through the analysis of methane production influence on anaerobic reactor in the presence of HMMIP, it was possible to notice an increase of 66% in the production of this biogas. This result proves that VFAs removal generated and accumulated in anaerobic reactors improves the COD removal and contributes to increased biogas generation. In addition, the conventional and magnetized sedimentation times for MMIP and HMMIP were analyzed. The MMIP require a smaller sedimentation tank due to the higher settling velocity (~ 3 m.h-1 ), however, both materials showed good sedimentation. The magnetized process stands out by allowing the separation of the magnetic adsorbents both from the liquid part and from the sludge generated at the bottom of the reactors. The adsorption column tests were performed under several concentrations and flow rates for the hybrid polymers and ion exchange resin. The most efficient process, according to the efficiency of the adsorption process (EPads), was the HMMIP with a value of 73.74%. Finally, it was concluded that the synthesized materials have potential to continue the studies on a large scale, since the results were extremely satisfactory

Activated carbons from agricultural by products (pine tree and coconut shell), coal, and carbon nanotubes as adsorbents for removal of sulfamethoxazole from spiked aqueous solutions : kinetic and thermodynamic studies.

In this study, four different adsorbent materials: commercial powdered activated carbon (PAC) from pine tree (PAC-I) and coconut shell (PAC-III) agricultural crop wastes, coal (PAC-II), and carbon nanotubes (CNT) were tested and compared for the removal of sulfamethoxazole (SMX) from spiked aqueous solutions. The kinetic, extrathermodynamic, and thermodynamic parameters for the adsorption of SMX on PACs and CNT were also determined. The results indicate that PAC-I was the best adsorbent for SMX adsorption. SMX adsorption was only favorable with PAC-I and CNT, leading to Gibbs free energies in the range of −39 to −44 kJ mol−1 and showing that the adsorption process was spontaneous in all temperature ranges (15–45 ◦C) tested. Langmuir model best described SMX adsorption on PAC-I and led to maximum adsorption capacity of∼131mgg−1 (at 25 ◦C), which was∼4.6 times higher than that observed for CNT. The mechanism of SMX adsorption on PAC-I and CNT was suggested with basis on thermodynamic and extrathermodynamic parameters. The kinetic studies showed the pseudo-second-order model best described SMX adsorption, yielding k2 values of 0.0035 and 0.0016 gmg−1 min−1 for PAC-I and CNT, respectively

Pharmaceuticals and endocrine disrupting compounds in Brazilian waters: occurrence and removal techniques

<p></p><p>ABSTRACT The human activities have increased the presence of several microcontaminants in water bodies. Of these, more recently, drugs and endocrine disrupters have called the attention of the scientific community due to their increasing exposure. The sources of contamination include cleaning and personal hygiene products, various classes of drugs, natural hormones and their by-products, as well as several substances applied to the production of plastics and resins, present in sewage, landfill leachate and industrial effluents. In this perspective, this paper aims to compile the data of microcontaminants occurrence in Brazilian natural and treated waters, as well as to discuss the efficiency of different water treatment techniques to remove such compounds.</p><p></p

Influence of synthesis conditions on the production of molecularly imprinted polymers for the selective recovery of isovaleric acid from anaerobic effluents.

Two molecularly imprinted polymers (MIPs) ? poly(methacrylic acid?co?TRIM) (TRIM, trimethylolpropanetrimethacrylate) and poly(acylamide?co?TRIM) ? were synthesized in different solvents for the selective recovery of isovaleric acid (template) generated during the anaerobic digestion process. The chemical and structural characterizations of the synthetic adsorbent were carried out by Fourier transform infrared spectroscopy, TGA and porosimetry through N2 adsorption?desorption isotherms. The selective and adsorptive performances of the imprinted polymers were evaluated by kinetic, isothermal, thermodynamic and selectivity studies and by adsorbent reuse experiments. The poly(methacrylic acid?co?TRIM) synthesized with dimethyl sulfoxide:chloroform presented higher selectivity and adsorption capacity for isovaleric acid in the presence of six volatile fatty acids. The kinetic results were well adjusted to the pseudo?nth order and intraparticle diffusion models, leading to k values of 10?4 and 6 ? 10?5 for the best synthesis of MIPs and not?imprinted polymers, respectively. Moreover, the Sips model best described the adsorption isotherm and generated a maximum adsorption capacity of ca 209 mg g?1 (at 25 ?C). Cycles of MIP use?desorption?reuse indicated that the selective adsorbent performed better than commercial adsorbents, losing less than 3% of adsorption capacity after three cycles