Rhamnolipids as Effective Green Agents in the Destabilisation of Dolomite Suspension

Abstract

In this paper, we describe an application of mono- and dirhamnolipid homologue mixtures of a biosurfactant as a green agent for destabilisation of a dolomite suspension. Properties of the biosurfactant solution were characterised using surface tension and aggregate measurements to prove aggregation of rhamnolipids at concentrations much lower than the critical micelle concentration. Based on this information, the adsorption process of biosurfactant molecules on the surface of the carbonate mineral dolomite was investigated, and the adsorption mechanism was proposed. The stability of the dolomite suspension after rhamnolipid adsorption was investigated by turbidimetry. The critical concentration of rhamnolipid at which destabilisation of the suspension occurred most effectively was found to be 50 mg·dm−3. By analysing backscattering profiles, solid-phase migration velocities were calculated. With different amounts of biomolecules, this parameter can be modified from 6.66 to 20.29 mm·h−1. Our study indicates that the dolomite suspension is destabilised by hydrophobic coagulation, which was proved by examining the wetting angle of the mineral surface using the captive bubble technique. The relatively low amount of biosurfactant used to destabilise the system indicates the potential application of this technology for water treatment or modification of the hydrophobicity of mineral surfaces in mineral engineering.

Evaluation of the Effect of Polyethylenimine on Boron Adsorption by Soil Minerals

“…Based on the data from Figure 2 and Table 1, the unmodified clay mineral suspensions, characterized by finer particle sizes, display greater stability than the gibbsite suspension, with kaolinite being the most stable among them. Turbidimetric studies further support this finding [41–43] …”

“…PEI seems to function as a flocculant. The extended polymer chains can create interparticle bridges between adjacent particles in this scenario [41] . This is also reflected in the optical microscope images (Figure 1C), where floccules of mineral particles are clearly visible after the addition of PEI, particularly in the case of kaolinite.…”

“…Turbidimetric studies further support this finding. [41][42][43] Adding a cationic polymer either completely changes the zeta potential to positive (in the case of clay minerals) or increases its positive value (gibbsite). This indicates the effective adsorption of the polymer on the surface of mineral particles.…”

Biosurfactants: An Overview of Their Properties, Production, and Application in Mineral Flotation

“…Legawiec et al [168] investigated how the biosurfactant rhamnolipid (RL) produced by Pseudomonas aeruginosa influences bubble adhesion to model surfaces with varying levels of hydrophobicity. The attachment time of a single bubble to solid surfaces with contact angles ranging from 6 to 80 • was assessed at RL concentrations from 0 to 500 mg•dm −3 at pH 5 (non-ionic) and pH 10 (anionic).…”

The Role of Biomodification in Mineral Processing

“…Legawiec et al [73] used mono and dirhamnolipid mixtures for dolomite destabilisation. At the critical micelle concentration (CMC) of 50 mg/dm 3 , the most effective destabilisation of the suspension was observed, indicating its possible application as a depressant in mineral processing.…”