Bubble functionalization in flotation process improve microalgae harvesting

Demir-Yilmaz, Irem; Ftouhi, Malak Souad; Balayssac, Stéphane; Guiraudx, Pascal; Coudret, Christophe; Formosa-Dague, Cécile

doi:10.1016/j.cej.2022.139349

Cited by 32 publications

(23 citation statements)

References 44 publications

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“…We propose potential mechanisms for the attractive force between hydrophobic AC and Chlorella in water based on literature (Figure 5g). [43][44][45][46][47][48] Micro-nano air film on the surface of hydrophobic AC, influenced by liquid pressure, create a high-energy reaction field. The interfacial collapse triggers the generation of hydroxyl radicals by dispersing the surged chemical potential at the interface.…”

Section: Resultsmentioning

confidence: 99%

3D Monolayer Silanation of Porous Structure Facilitating Multi‐Phase Pollutants Removal

Zhuang

Jiao

et al. 2023

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Activated carbon (AC) is widely used to removing hazardous pollutants from air and water, owing to its exceptional adsorption properties. However, the high affinity of water molecules with the surface oxygen‐containing functional groups can adversely affect the adsorption performance of AC. In this study, a facile and efficient method is presented for fabrication of hydrophobic AC through surface monolayer silanation. Compared to initial AC, the hydrophobic AC improves the water contact angle from 29.7° to 123.5° while maintaining high specific surface area and enhances the removal capacity of multi‐phase pollutants (emulsified oil and toluene). Additionally, the hydrophobic AC exhibits excellent adsorption capability to harmful algal bloom species (Chlorella) (97.56%) and algal organic matter (AOM) (96.23%) owing to electrostatic interactions and surface hydrophobicity. The study demonstrates that this method of surface monolayer silanation can effectively weaken the effect of water molecules on AC adsorption capacity, which has significant potential for practical use in air and water purification, as well as in the control of harmful algal blooms.

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Section: Resultsmentioning

confidence: 99%

3D Monolayer Silanation of Porous Structure Facilitating Multi‐Phase Pollutants Removal

Zhuang

Jiao

et al. 2023

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“…For C. vulgaris CCAP strain, the maximum flocculation efficiency was reached at a concentration of 30 mg/L of POchitosan, which is thus consistent. 20 However, in that case, the flocculation efficiency decreased at higher pH (9), as both cells (C. vulgaris CCAP strain) and PO-chitosan were hydrophilic. Thus, in the next step, the effect of pH was investigated on PO-chitosan meditated flocculation with an optimized POchitosan concentration of 25 mg/L.…”

Section: Po-chitosan Is An Efficient Flocculant At Any Ph For C Vulga...mentioning

confidence: 87%

“…20 In the best conditions, the separation efficiency doubled with PO-chitosan bubbles, demonstrating the efficiency of this flotation process. 20 Thus, our previous results showed the potential of POchitosan to efficiently separate C. vulgaris cells (strain CCAP 211/11B) from their culture medium by using it either as a flocculant or as a surfactant to functionalize bubbles and perform separation through a one-step flotation process. But as we also showed, the efficiency of the molecule is directly correlated to the cell surface properties, especially hydrophobic properties, which raises the question to know if this molecule can in fact be used more generally to harvest microalgae cells with different surface properties.…”

Section: ■ Introductionmentioning

confidence: 86%

“…In our previous study in the case of the CCAP strain, the interactions with functionalized bubbles resulted in much higher adhesion forces (13 nN), and no molecular unfoldings were observed on the force curves, only one peak at the contact point resulting from the dominant hydrophobic interaction between cells and bubbles. 20 To understand the differences between the two C. vulgaris strains, it is important to understand what part of the PO-chitosan molecule is exposed at the surface of the bubbles. Basically, surfactants like PO-chitosan are absorbed on the bubble surface in a way that hydrophobic parts of the molecule stay inside of the bubble, whereas the hydrophilic chitosan backbone is exposed on the bubble surface, as shown in Figure 2c.…”

Section: Isolation and Ultrafiltration Of Extracellular Soluble Algal...mentioning

confidence: 99%

“…AFM experiments in this case showed that in fact, the flocculation mechanism was different from chitosan, as the interaction between this modified chitosan molecule, called polyoctyl chitosan (PO-chitosan), was based on hydrophobic interactions with the cell surface. 20 Another alternative for increasing flotation efficiency is to modify the bubble surface with a molecule that will interact with cells, allowing efficient separation without the need of a flocculation step. This concept was first used for microalgae harvesting in 2008 by the team of Henderson.…”

Section: ■ Introductionmentioning

confidence: 99%

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The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

Demir-Yilmaz,

Pappa,

Lama

et al. 2024

ACS Appl. Bio Mater.

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Microalgae show great promise for producing valuable molecules like biofuels, but their large-scale production faces challenges, with harvesting being particularly expensive due to their low concentration in water, necessitating extensive treatment. While methods such as centrifugation and filtration have been proposed, their efficiency and cost-effectiveness are limited. Flotation, involving air-bubbles lifting microalgae to the surface, offers a viable alternative, yet the repulsive interaction between bubbles and cells can hinder its effectiveness. Previous research from our group proposed using an amphiphilic chitosan derivative, polyoctyl chitosan (PO-chitosan), to functionalize bubbles used in dissolved air flotation (DAF). Molecular-scale studies performed using atomic force microscopy (AFM) revealed that PO-chitosan's efficiency correlates with cell surface properties, particularly hydrophobic ones, raising the question of whether this molecule can in fact be used more generally to harvest different microalgae. Evaluating this, we used a different strain of Chlorella vulgaris and first characterized its surface properties using AFM. Results showed that cells were hydrophilic but could still interact with PO-chitosan on bubble surfaces through a different mechanism based on specific interactions. Although force levels were low, flotation resulted in 84% separation, which could be explained by the presence of AOM (algal organic matter) that also interacts with functionalized bubbles, enhancing the overall separation. Finally, flocculation was also shown to be efficient and pH-independent, demonstrating the potential of PO-chitosan for harvesting microalgae with different cell surface properties and thus for further sustainable large-scale applications.

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Application of microbubble air flotation to harvest Microcystis sp. from agriculture wastewater: The regulation and mechanisms

Ye,

Zhu,

Song

et al. 2024

Biotech & Bioengineering

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The harvesting of microalgae is the main bottleneck of its large‐scale biomass production, and seeking an efficient, green, and low‐cost microalgae harvesting technology is one of the urgent problems to be solved. Microbubble air flotation has been proven to be an effective measure, but the mechanisms of microbubbles‐algal cell attachment are still unclear. In this study, microbubble air flotation was used as a harvesting method for Microcystis cultured in agricultural wastewater. The process mechanism of microbubble air flotation harvesting microalgae in wastewater was fully revealed from three aspects (the design of bubble formation, the adhesion law, and the recovery rate of microalgae under different working conditions). The results show that the length of the release pipe is the main factor affecting the proportion of microbubbles with a particle size of less than 50 μm. In the process of adhesion, when the particle size of microbubbles is 0.6–1.7 times the size of Microcystis, the adhesion efficiency of microbubbles to Microcystis is the highest. Under the conditions of pressure 0.45 MPa, gas–liquid ratio 5%, and release pipe length 100 cm, the harvesting performance of Microcystis was the best. Microbubble air flotation has better harvesting performance (63.5%, collection rate) of Microcystis with higher density. By understanding the mechanism of microbubble flotation, the technical parameters of microbubble flotation for harvesting energy microalgae are optimized to provide support for the development of efficient and low‐cost devices and equipment for collecting microalgae.

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Bubble functionalization in flotation process improve microalgae harvesting

Cited by 32 publications

References 44 publications

3D Monolayer Silanation of Porous Structure Facilitating Multi‐Phase Pollutants Removal

3D Monolayer Silanation of Porous Structure Facilitating Multi‐Phase Pollutants Removal

The Biophysical Properties of Microalgal Cell Surfaces Govern Their Interactions with an Amphiphilic Chitosan Derivative Used for Flocculation and Flotation

Application of microbubble air flotation to harvest Microcystis sp. from agriculture wastewater: The regulation and mechanisms

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