On the fundamental aspects of apatite and quartz flotation using a Gram positive strain as a bioreagent

Cellular Adaptation: Culture conditions of R. opacus and bioflotation of apatite and quartz

“…1(a) shows the zeta potential of the microorganism at different pH values. Initially, we observed an isoelectric point (IEP) of approximately 2.8, as found in previous works (Botero et al, 2007(Botero et al, , 2008Mesquita et al, 2003;Merma et al, 2013). According to several authors (Rao and Subramanian, 2007;Natarajan, 2006;Vilinska and Rao., 2008;Faharat et al, 2008;Van Der Wal et al, 1997), this acidic value is related to the higher presence of anionic functional groups compared with cationic groups.…”

“…The cell shape is generally characteristic of each bacterial strain, but this can vary depending on the growth conditions. In previous studies (Mesquita et al, 2003;Merma et al, 2013), it was observed that the R. opacus cells had a "coccus" shape at the lag phase and at the beginning of the exponential phase; however, in the stationary phase, the cells presented a bacillus-shape. Although, the modification of the morphology of the cells occurs along the culture, it was observed that their hydrophobicity did not present any significant change, preserving a contact angle value of approximately 75°.…”

“…Thus, considering that phosphate ores are associated with several gangue minerals, especially quartz, carbonates and silicates, then a detailed bioflotation study of each component is necessary to establish the bioflotation of phosphate ores. One bacteria, quite recently used in mineral bioflotation, is Rhodococcus opacus (Botero et al, 2007;Mesquita et al, 2003;Botero et al, 2008;Merma et al, 2013). It is a Gram positive bacterium with different types of components on their cell-wall, which are primarily polysaccharides, carboxylic acids, lipid groups and mycolic acids, that result in amphoteric behavior (hydrophobic and/or hydrophilic properties) of the bacteria (Mesquita et al, 2003;Natarajan, 2006;Vilinska and Rao., 2008).…”

Bioflotação Seletiva De Hematita Em Relação Ao Quartzo: Cálculo Da Energia De Superfície E Da Adesão Do Bacillus Subtilis

“…E, esses têm sido relatados como modificadores, coletores e/ou depressores benignos, por não serem danosos ao meio ambiente, e ainda, biodegradáveis (CHANDRAPRABHA et al, 2004, CHANDRAPRABHA et al, 2005 CHANDRAPRABHA e NATARAJAN, 2006; Deo e Natarajan, 1998; EL-MIDANY e ABDEL- KHALEK, 2014, GERICKE e GOVENDER, 2011PATRA e NATARAJAN, 2003, 2008MERMA et al, 2013;SANTHIYA et al, 2000;SANTHIYA et al, 2001 As células bacterianas são quimicamente e estruturalmente mais complexas e heterogêneas que partículas sintéticas e isto têm impacto diferente sobre a adesão bacteriana às superfícies (POORTINGA et al, 2002).…”

“…Na Tabela 3.3 apresentam-se os dados mais recentes, extraídos da literatura, SARVAMANGALA e NATARAJAN (2011) Figura 3.8 -Imagens por microscopia eletrônica de varredura da cepa R. opacus aderia às superfícies de apatita (a) e quartzo (b) (MERMA et al, 2013).…”