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Development of an iron oxide nanoparticle-activated carbon adsorbent for water treatment of common human pharmaceutical chemicals
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Abstract(s)
Nas últimas décadas assistiu-se a um enorme crescimento da Industria Farmacêutica (World Health Organization, 2011), o que levou a um aumento exponencial da quantidade e do número de compostos de origem farmacêutica que se podem encontrar no ambiente (Weber et al, 2014). Este novo tipo de poluentes designados por “human pharmaceutical compounds” (HPCs), como o ibuprofen (IBU), o paracetamol (PAR), o ácido acetilsalicílico (ASA), ou a amoxicilina (AMOX).
Quando consumidos, tanto as drogas não metabolizadas como os seus metabolitos são libertados no ambiente por via das excreções. Sendo as drogas, e, ou os seus metabolitos biologicamente ativos, mesmo uma pequena quantidade dos mesmos pode ter impacto sobre os seres presentes nos meios aquáticos (Bacsi et al, 2016). Sendo alguns destes compostos particularmente resistentes aos tratamentos comummente usados no processamento das águas residuais, tal tem levado à procura de novos processos de tratamento de águas residuais (Ghafoori et al, 2014).
Neste trabalho mostramos os resultados obtidos com um novo material compósito criado de modo a maximizar a adsorção e a facilitar o processo de separação e regeneração do adsorvente. Assim damos conta da síntese do um adsorvente de carvão ativado com propriedades magnéticas (PACMAG), este material combina a capacidade de adsorção do carvão ativado pulverizado (PAC) e as propriedades magnéticas de nanopartículas de óxido de ferro (FeNPs).
As nanopartículas de óxido de ferro (FeNPs) foram sintetizadas por coprecipitação em meio básico, por este método foi possível obter nanopartículas com um rendimento quantitativo, mostrando estas um potencial zeta positivo, e uma ponto de carga zero a pH entre 8 e 9. Estas partículas forma posteriormente embutidas em carvão ativado pulverizado, resultando o novo material PACMAG.
Foi testada a capacidade de adsorção de diversos HPC, nomeadamente o IBU, o PAR e o ASA, pelo PACMAG. Foram realizadas isotérmicas ao longo de 24 horas. O IBU foi escolhido como composto modelo para os analgésicos aromáticos, tendo sido as condições otimizadas para este composto. O comportamento do IBU foi comparado com o da AMOX, um antibiótico não aromático. De acordo com os resultados obtidos para estes dois fármacos foi determinado que, para concentrações de 15 mg/L de droga, o tempo de contacto necessário é de 120 minutos, e que o conteúdo em PAC ótimo, do adsorvente, é de 300 mg/L. Nestas condições observou-se uma remoção de 92,22 ± 0,08 % e de 79,90 ± 0,05 % para o IBU e a AMOX respetivamente. Em condições idênticas, foram repetidos, os testes de adsorção do IBU e da AMOX, usando água residual (WW) de uma Estação de Tratamento de Águas Residuais (ETAR) como solvente. Nestas condições observou-se uma diminuição da quantidade de droga adsorvida para 49,52 ± 0,15 % e 26,54 ± 0,01% para o IBU e para a AMOX, respetivamente. Tal deve-se à presença de outras moléculas orgânicas que competem com os fármacos em estudo pelos sítios de adsorção. Aumentando a quantidade de PAC no adsorvente para 1000 mg/L, o que foi feito para o caso da AMOX, a remoção aumenta para 76,720 ± 0,001%.
Finalmente mostra-se que o PACMAG pode ser regenerado usando a reação de Fenton. O PACMAG regenerado removeu 53,840 ± 0,004% de AMOX de uma solução AMOX-WW. De acordo com os testes de sedimentação o PACMAG necessita de apenas 5 minutos para na presença de um campo magnético sedimentar, de modo a permitir a sua separação da água tratada.
Os resultados deste trabalho são uma contribuição para a melhoria dos processos de tratamento de águas residuais, em particular na remoção de HPC compostos cada vez mais prevalentes nas águas a tratar.
In recent years, there was a big market growth in the pharmaceutical industry (World Health Organization, 2011). As a result, there has also been an increase in pharmaceutical pollutants present in the environment (Weber et al, 2014). These emerging pharmaceutical pollutants are common human pharmaceutical compounds (HPCs) such as ibuprofen (IBU), paracetamol (PAR), acetylsalicylic acid (ASA), and amoxicillin (AMOX). When consumed, the unmetabolized drugs and their metabolites reach the environment through human excretion. Because they are biologically active, a small amount can be a source of possible problems for aquatic creatures (Bacsi et al, 2016). Because some pharmaceutical components are very recalcitrant to common wastewater treatment techniques, new wastewater treatment processes are being explored (Ghafoori et al, 2014). A new composite adsorbent material is created in order to address the separation difficulty and the limited adsorption of other adsorbents. The aim of this research is to synthesize a magnetic activated carbon adsorbent (PACMAG) that combines the adsorbing capabilities of powdered activated carbon (PAC) and the magnetic properties of iron oxide nanoparticles (FeNPs). The FeNPs, were synthesized by co-precipitation in a basic medium which resulted in a quantitative yield, the afforded particles have a positive zeta potential and a point of zero charge between pH 8 and 9. These were then embedded in powdered activated carbon in order to produce PACMAG with 103 ± 5 % yield. PACMAG was first tested for its adsorption capacity in various HPCs, namely IBU, PAR, and ASA. The adsorption ability of PACMAG was assessed from isotherms of 24 hours. The adsorption of IBU by PACMAG, which was the chosen model compound for aromatic analgesics was further optimized. Several adsorption isotherms were determined by varying the amount of adsorbent and drug present in the system. The behavior of IBU was compared with AMOX, a non-aromatic antibiotic. Based on the behavior of both HPCs (IBU and AMOX) in the presence of PACMAG, the optimum parameters for the adsorption are 120 min adsorption time for 15 mg/L drug concentration, and 300 mg/L PAC content in the adsorbent. This resulted in a 92.22 ± 0.08 % and in a 79.90 ± 0.05 % removal for IBU and AMOX respectively. In the same conditions, IBU and AMOX adsorption was tested using the wastewater (WW) from Estação de Tratamento de Águas Residuais (ETAR) as solvent. In wastewater, a decreases in drug adsorption to 49.52 ± 0.15 % and 26.54 ± 0.01% IBU and AMOX, respectively, was observed. This is due to the presence of other organic molecules in the system that compete for the adsorption sites. By increasing the PAC content of the adsorbent to 1000 mg/L, which was done for AMOX, the percent removal can be increased up to 76.720 ± 0.001 %. Finally, PACMAG can be regenerated using the Fenton reaction. The regenerated PACMAG removed 53.840 ± 0.004% of AMOX in an AMOX-WW mixture. Based on the sedimentation test, PAGMAG is more time efficient because it requires 5 minutes at the presence of a magnet to settle, and separate the particles from the water supply. The results of this work can contribute for the improvement of water treatment processes particularly in the removing of HPCs. Being nowadays, this kind of compounds is a growing problem in water treatment.
In recent years, there was a big market growth in the pharmaceutical industry (World Health Organization, 2011). As a result, there has also been an increase in pharmaceutical pollutants present in the environment (Weber et al, 2014). These emerging pharmaceutical pollutants are common human pharmaceutical compounds (HPCs) such as ibuprofen (IBU), paracetamol (PAR), acetylsalicylic acid (ASA), and amoxicillin (AMOX). When consumed, the unmetabolized drugs and their metabolites reach the environment through human excretion. Because they are biologically active, a small amount can be a source of possible problems for aquatic creatures (Bacsi et al, 2016). Because some pharmaceutical components are very recalcitrant to common wastewater treatment techniques, new wastewater treatment processes are being explored (Ghafoori et al, 2014). A new composite adsorbent material is created in order to address the separation difficulty and the limited adsorption of other adsorbents. The aim of this research is to synthesize a magnetic activated carbon adsorbent (PACMAG) that combines the adsorbing capabilities of powdered activated carbon (PAC) and the magnetic properties of iron oxide nanoparticles (FeNPs). The FeNPs, were synthesized by co-precipitation in a basic medium which resulted in a quantitative yield, the afforded particles have a positive zeta potential and a point of zero charge between pH 8 and 9. These were then embedded in powdered activated carbon in order to produce PACMAG with 103 ± 5 % yield. PACMAG was first tested for its adsorption capacity in various HPCs, namely IBU, PAR, and ASA. The adsorption ability of PACMAG was assessed from isotherms of 24 hours. The adsorption of IBU by PACMAG, which was the chosen model compound for aromatic analgesics was further optimized. Several adsorption isotherms were determined by varying the amount of adsorbent and drug present in the system. The behavior of IBU was compared with AMOX, a non-aromatic antibiotic. Based on the behavior of both HPCs (IBU and AMOX) in the presence of PACMAG, the optimum parameters for the adsorption are 120 min adsorption time for 15 mg/L drug concentration, and 300 mg/L PAC content in the adsorbent. This resulted in a 92.22 ± 0.08 % and in a 79.90 ± 0.05 % removal for IBU and AMOX respectively. In the same conditions, IBU and AMOX adsorption was tested using the wastewater (WW) from Estação de Tratamento de Águas Residuais (ETAR) as solvent. In wastewater, a decreases in drug adsorption to 49.52 ± 0.15 % and 26.54 ± 0.01% IBU and AMOX, respectively, was observed. This is due to the presence of other organic molecules in the system that compete for the adsorption sites. By increasing the PAC content of the adsorbent to 1000 mg/L, which was done for AMOX, the percent removal can be increased up to 76.720 ± 0.001 %. Finally, PACMAG can be regenerated using the Fenton reaction. The regenerated PACMAG removed 53.840 ± 0.004% of AMOX in an AMOX-WW mixture. Based on the sedimentation test, PAGMAG is more time efficient because it requires 5 minutes at the presence of a magnet to settle, and separate the particles from the water supply. The results of this work can contribute for the improvement of water treatment processes particularly in the removing of HPCs. Being nowadays, this kind of compounds is a growing problem in water treatment.
Description
Dissertação de mestrado, Inovação Química e Regulamentação, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016
Keywords
Carvão ativado com propriedade magnéticas Nanopartículas de magnetite Carvão ativado Tratamento de águas Human Pharmaceutical Compounds Adsorção