Membranas compósitas de óxido de grafeno depositadas em fibras ocas cerâmicas para purificação de efluentes contaminados com fármacos

• Autor(a) principal: Cardoso, Aline Maria de Jesus Machado
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFU
• Texto Completo: https://repositorio.ufu.br/handle/123456789/37676; http://doi.org/10.14393/ufu.di.2023.68
• topic: Óxido de grafeno; Membranas compósitas; Fibra oca cerâmica; Fármacos; Graphene oxide; Composite membranes; Ceramic hollow fiber; Pharmaceuticals; Engenharia Química; CNPQ::ENGENHARIAS::ENGENHARIA QUIMICA

Micropollutants such as pharmaceuticals, generally, cannot be completely removed or degraded by conventional water and sewage treatment processes, and are therefore discarded directly or self-purified in water bodies. In view of this, this work proposed an additional process alternative to conventional treatments for the purification of effluents containing drugs through the use of composite membranes of graphene oxide and ethylenediamine deposited on hollow alumina fibers pretreated with dopamine. The alumina hollow fibers were produced by the phase inversion method followed by sintering at 1400°C. Then, these substrates were pre-treated with a 0.01 M dopamine solution in order to promote better adhesion of the graphene oxide composite membranes. The substrates showed asymmetrical pore distribution, with an outer layer roughness of 122.5 ± 5.6 nm and hydraulic permeability of 2.47 ± 0.08 L h-1 m-2 kPa-1. After pretreatment with dopamine, the roughness of the outer layer of the substrate decreased to 118.6 ± 10.7 nm. Suspensions of graphene oxide at concentrations of 0.025, 0.050 and 0.075 mg mL-1 with 5% m/m of ethylenediamine were prepared to cover the hollow alumina fibers, resulting in the composite membranes called OG25, OG50 and OG75, respectively. The composite membranes OG25, OG50 and OG75 presented, respectively, thickness of the graphene oxide layer of 0.18 ± 0.02, 0.23 ± 0.01 and 0.27 ± 0.01 μm, roughness in the outer layer of 96.43 ± 3.13, 79.90 ± 4.49 and 42.32 ± 3.50 nm and hydraulic permeability of 0.4390 ± 0.0161, 0.4243 ± 0.0097 and 0.0746 ± 0, 0019 L h-1 m-2 kPa-1. Then, the graphene oxide composite membranes were applied in tests of permeation of NaCl and Na2SO4 salts and in the retention process of drugs rifampicin, methylene blue and propranolol contained in aqueous solutions. Permeation tests were carried out at 5 bar and room temperature. The cross-flow velocity was set at 0.461 ± 0.003 m/s. For the saline NaCl solution with an initial concentration of 2000 mg/L, the membranes OG25, OG50 and OG75 presented, respectively, stabilized permeate flux of 449.18 ± 0.40, 33.05 ± 0.66 and 12.60 ± 0.20 L h-1 m-2 and NaCl retention of 1.63 ± 0.01, 7.48 ± 0.06, 3.81 ± 0.02%. For the Na2SO4 saline solution with an initial concentration of 1000 mg/L, the membranes OG25, OG50 and OG75 presented, respectively, permeate fluxes of 41.37 ± 0.44, 10.44 ± 0.17 and 11.88 ± 0.32 L h-1 m-2 and Na2SO4 retention of 22.08 ± 0.08, 31.69 ± 0.15 and 40.97 ± 0.11%. The stabilized permeate fluxes through the OG25, OG50 and OG75 membranes for filtration of the rifampicin solution were 67.63 ± 1.94, 11.25 ± 0.32 and 18.03 ± 0.20 L h-1 m-2, with retentions of 14.11 ± 0.02, 52.75 ± 9.89 and 52.44 ± 7.01%. For filtration of the propranolol solution, the fluxes stabilized by the OG50 and OG75 membranes were 6.24 ± 0.05 and 12.28 ± 0.20 L h-1 m-2, with retentions of 6.76 ± 1.45 % and 34.49 ± 4.07%, respectively. For filtration of the methylene blue solution, the fluxes stabilized by the OG50 and OG75 membranes were 20.58 ± 0.76 and 13.98 ± 0.56 L h-1 m-2, with retentions of 14.02 ± 1.46 and 38.45 ± 0.86%, respectively. Therefore, it can be concluded that increasing the concentration of the graphene oxide suspension decreases the permeate flux, but increases the selectivity of the membrane. Finally, the system proposed here is promising for use as an additional/tertiary process to the conventional treatment of effluents containing drugs.