ABSTRACT
This study proposes the use of an ultrasound-assisted adsorption system coupled to porous ceramic fragments to improve the removal of iron from FeSO4 aqueous solution. Ultrasound was applied using an ultrasound bath at a low frequency (37 kHz, 330 W). The optimized conditions for Fe removal were achieved by 7â g of adsorbent, 40â min of sonication, 20â mg L-1 of initial Fe concentration, and 30 °C of reaction temperature. After optimizing the conditions, the method was applied for the removal of iron in groundwater. A central composite design and response surface methodology were used to evaluate the degree to which different variables had a significant effect on iron removal. The efficiency of iron removal using the selected conditions for FeSO4 solution was near to 100%. However, for groundwater samples, the maximum iron removal efficiencies of the system with and without ultrasound were 80.7% and 51.1%, respectively, indicating that the adsorption with ultrasound was significantly higher than that without ultrasound. It was shown that the proposed ultrasound-assisted adsorption system can be used to enhance the removal of inorganic iron from groundwater.
Subject(s)
Water Pollutants, Chemical , Water Purification , Adsorption , Ceramics , Hydrogen-Ion Concentration , Iron , Kinetics , Porosity , Water , Water Pollutants, Chemical/analysis , Water Purification/methodsABSTRACT
This paper proposes a greener approach to the intensification of base oil recovery for truck engines (32,500 km of use) using ethanol, propan-2-ol, 2-methylpropan-1-ol, and butan-1-ol as solvents for the extraction of base oil, combining mechanical stirring (220 rpm) and ultrasound (25 °C, 24 kHz, and 400 W). The results indicated that the recovery yields of the base oil, using the mechanical stirring and ultrasound (MS-US) system, for ethanol, propan-2-ol, 2-methylpropan-1-ol, and butan-1-ol were approximately 3.1, 25.6, 71.6, and 85.5%, respectively. By contrast, the recovery yields using only mechanical stirring were 8.8, 28.9, 58.9, and 76.1%, respectively. The system with pre-extraction could effectively remove Ca (85.3-93.0%), Mg (67.2-82.9%), Na (31.7-62.5%), and Zn (0.0-71.7%). Finally, the results showed a reduction of almost 100% for the concentrations of Al, Cr, Fe, and Mo in the pre-extraction system. The mechanical stirring (5 min) and ultrasound (5 min) system were able to intensify the extraction process using environmentally friendly solvents.
Subject(s)
Ethanol , Lubricants , SolventsABSTRACT
Microwave-induced combustion was applied to petroleum coke digestion in closed vessels for further chloride determination by ion chromatography. Samples were pressed as pellets and placed on a quartz holder. Combustion was performed using oxygen pressure of 2 MPa and 50 microl of 6 moll(-1) NH(4)NO(3) as aid for ignition. Recoveries from 97 to 102% were obtained for all studied absorbing solutions (water, H(2)O(2), Na(2)CO(3) or (NH(4))(2)CO(3)). Accuracy was evaluated using certified reference materials with agreement better than 98% using water as absorbing solution with reflux step. The limit of quantification was 3.8 microg g(-1).
Subject(s)
Chlorides/analysis , Coke/analysis , Microwaves , Petroleum/analysisABSTRACT
O uso do sistema abrasivo do bicarbonato mostrou-se efetivo nas áreas coronárias na remoçäo de placa bacteriana e manchas extrínsecas, quando comparou-se com a técnica convencional com taça de borracha e pedra-pomes. Entretanto o jato de bicarbonato removeu as manchas completamente mais rapidamente com menos fadiga para o operador. O sistema abrasivo sob microscopia mostrou-se näo injuriar o epitélio da gengiva marginal. Seu uso também verifica-se no tratamento da hipersensibilidade na área cervical com um menor desconforto para o paciente