The ion flotation of copper, nickel, and cobalt using the biosurfactant surfactin

Abstract

Heavy metal contaminated waters are a significant environmental hazard, which require novel treatment methodologies. Further, the metals which might be recovered from these streams have significant intrinsic value, if they can be collected and concentrated. This work demonstrates, for the first time, the use of surfactin, an environmentally benign biosurfactant, for the flotation of metal ions (Cu2+, Ni2+, and Co2+). Surfactin, at a molar ratio of 1:3, has been shown to float 75.2%, 94.7%, and 98.2% of initial 100 $$\mu$$ μ M solutions of copper nickel and cobalt, respectively. Increasing the gas flow rate modifies the float by increasing the carryover of water into the overflow. A pH of 5 was found to be ineffective (due to surfactin precipitation), while a pH of 10 was less effective than pH 7, likely due to the ionic speciation of the metals in solution tending to hydroxyl precipitates at a high pH. This work demonstrates an opportunity for the recovery of metals (at low concentrations) using biosurfactant-based froth flotation.

Optimized Feeding Strategies for Biosurfactant Production from Acetate by Alcanivorax borkumensis SK2

“…This group of molecules has diverse chemical structures, represented by fatty acids, glycolipids, lipopeptides, lipoproteins, phospholipids, and polymeric biosurfactants [3]. The diverse compositions of these structures yield a range of biological and physicochemical attributes, including the effective reduction in surface tension, low critical micelle concentrations, the chelation of metal ions, bioactivity, and remarkable stability [2,4]. Biosurfactants play a vital role in enabling microorganisms to utilize hydrophobic substrates but also can contribute to the virulence of pathogens like Pseudomonas aeruginosa [5,6].…”

“…While A. borkumensis can degrade a wide range of hydrocarbons (C 5 -C 32 ), its hydrophilic substrate range is limited to acetate, propionate, and pyruvate due to the absence of key enzymes and transporters responsible for sugar utilization [14,15,18]. It can use NH 4 + or NO 3 − as nitrogen sources, with NO 3 − converted to NH 4 + under ATP consumption [14]. A. borkumensis produces various storage compounds using n-alkanes and hydrophilic substrates as carbon sources at a high carbon-to-nitrogen (C/N) ratio [19,20].…”

High-quality physiology of Alcanivorax borkumensis SK2 producing glycolipids enables efficient stirred-tank bioreactor cultivation

“…These molecules exhibit various structural elements, including fatty acids, phospholipids, glycolipids, lipopeptides, lipoproteins, and polymeric biosurfactants ( Desai and Banat, 1997 ). Their structural diversity contributes to various biological and physicochemical properties such as low critical micelle concentrations (CMC), strong surface tension reduction, metal ion chelation, bioactivity, and high tolerance to unfavorable pH values, temperatures, and ionic strengths ( Santos et al, 2016 ; Schlebusch et al, 2023 ). In nature, biosurfactants play a crucial role in facilitating the utilization of hydrophobic substrates by microorganisms and can also contribute to the virulence of pathogens by facilitating cell lysis, as reported for Pseudomonas aeruginosa ( Van Delden and Iglewski, 1998 ; Tripathi et al, 2018 ).…”

A review of the application of nanoparticles as collectors in ion flotation

“…Ion flotation, precipitative flotation, sorptive flotation, dissolved air flotation, and foam fractionation are types of flotation methods (Rubio et al, 2002;. Precipitative flotation or sorptive flotation may be ineffective at dilute ion concentrations, producing large amounts of hazardous sludge (Schlebusch et al, 2023). However, at dilute ion concentrations, ion flotation produces small sludge volumes and requires low equipment costs Saleem et al, 2019;Mondal et al, 2021;Schlebusch et al, 2023).…”

“…Precipitative flotation or sorptive flotation may be ineffective at dilute ion concentrations, producing large amounts of hazardous sludge (Schlebusch et al, 2023). However, at dilute ion concentrations, ion flotation produces small sludge volumes and requires low equipment costs Saleem et al, 2019;Mondal et al, 2021;Schlebusch et al, 2023). Ion flotation was described by Sebba in 1959.…”