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

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.

Investigation of the role of cell hydrophobicity and EPS production in the aggregation of the marine diatom Cylindrotheca closterium under hypo-saline conditions.

Aggregation of diatoms is of global importance to understand settling of particulate organic carbon in aquatic systems. In this study, we investigate the aggregation of the marine diatom Cylindrotheca closterium during the exponential growth phase under hypo-saline conditions. The results of the flocculation/flotation experiments show that the aggregation of the diatom depends on the salinity.

The role of microplastics in microalgae cells aggregation: A study at the molecular scale using atomic force microscopy.

Plastic pollution has become a significant concern in aquatic ecosystems, where photosynthetic microorganisms such as microalgae represent a major point of entry in the food chain. For this reason an important challenge is to better understand the consequences of plastic pollution on microalgae and the mechanisms underlying the interaction between plastic particles and cell's interfaces. In this study, to answer such questions, we developed an interdisciplinary approach to investigate the role of plastic microparticles in the aggregation of a freshwater microalgae species, Chlorella vulgaris.

Probing the interactions between air bubbles and (bio)interfaces at the nanoscale using FluidFM technology.

Understanding the molecular mechanisms underlying bubble-(bio)surfaces interactions is currently a challenge that if overcame, would allow to understand and control the various processes in which they are involved. Atomic force microscopy is a useful technique to measure such interactions, but it is limited by the large size and instability of the bubbles that it can use, attached either on cantilevers or on surfaces. We here present new developments where microsized and stable bubbles are produced using FluidFM technology, which combines AFM and microfluidics.

Nanoscale Evidence Unravels Microalgae Flocculation Mechanism Induced by Chitosan.

Microalgae are a promising resource for biofuel production, although their industrial use is limited by the lack of effective harvesting techniques. Flocculation consists in the aggregation and adhesion of cells into flocs that can be more easily removed from water than individual cells. Although it is an efficient harvesting technique, contamination is a major issue as chemical flocculants are often used.

Towards a better understanding of microalgae natural flocculation mechanisms to enhance flotation harvesting efficiency.

In microalgae harvesting, flocculation is usually a compulsory preliminary step to further separation by sedimentation or flotation. For some microalgae species, and under certain growth conditions, flocculation can occur naturally. Natural flocculation presents many advantages as it does not require the addition of any flocculants to the culture medium and shows high efficiency rate.

Flocculation-flotation harvesting mechanism of Dunaliella salina: From nanoscale interpretation to industrial optimization.

Dunaliella salina is a green microalgae species industrially exploited for its capacity to produce important amounts of carotenoid pigments. However in low nitrogen conditions in which they produce these pigments, their concentration is low, which results in harvesting difficulties and high costs. In this work, we propose a new solution to efficiently harvest D.

Surface-modified microbubbles (colloidal gas aphrons) for nanoparticle removal in a continuous bubble generation-flotation separation system.

The treatment of nanoparticle (NP) polluted aqueous suspensions by flotation can be problematic due to the low probability of collision between particles and bubbles. To overcome this limitation, the present work focuses on developing an enhanced flotation technique using the surface-functionalized microbubbles - colloidal gas aphrons (CGAs). The CGA generator was adapted to be air flow rate controlled based on the classical Sebba system; thus it could be well adopted in a continuous flotation process.

Analysis of cutting-oil emulsion destabilization by aluminum sulfate.

The destabilization mechanism of the high stable cutting-oil emulsion by aluminum sulfate (Al(SO)) was investigated since it can affect properties of aggregates and following separation units. Al(SO) dosage and pH were key factors in the destabilization. The effective separation occurred when precipitated Al(OH) is dominated at the neutral pH of 6.

High-pH-induced flocculation-flotation of the hypersaline microalga Dunaliella salina.

Natural autoflocculation was not observed in a Dunaliella salina hypersaline culture and the microalgae did not float without destabilization of the algal suspension. High-pH-induced flocculation by sodium hydroxide addition was chosen to induce flotation. Recovery efficiencies greater than 90% and concentration factors of around 20 were reached.

Elimination of TiO₂ nanoparticles with the assist of humic acid: influence of agglomeration in the dissolved air flotation process.

With recent advances in nanotechnology, environmental and health consequences of nanomaterial disposal merit close attention. In the search for environmentally-friendly reagent, this study investigates the use of humic acid (HA) as an assist of dissolved air flotation (DAF) in the TiO₂ nanoparticle (TNP) elimination. To determine mechanisms of TNPs interacting with HA, surface modification experiments were firstly carried out; thereafter, laboratory scaled DAF tests were applied to remove TNPs with HA assisting.

Study of antimutagenic and antioxidant activities of gallic acid and 1,2,3,4,6-pentagalloylglucose from Pistacia lentiscus. Confirmation by microarray expression profiling.

In vitro antioxidant and antimutagenic activities of two polyphenols isolated from the fruits of Pistacia lentiscus was assessed. Antioxidant activity was determined by the ability of each compound to scavenge the free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH*), to inhibit xanthine oxidase and to inhibit the lipid peroxidation induced by H(2)O(2) in K562 cell line. Antimutagenic activity was assayed with SOS chromotest using Escherichia coli PQ37 as tester strain and Comet assay using K562 cell line.