Recovery of Chlorella biomass using Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles: Isotherm and thermodynamic characteristics of adsorption

Harvesting microalgae by centrifugation and filtration is very costly, affecting technical and economical feasibility of downstream processing of algal biomas to bioproducts. Flocculation is a potential technique for recovery of algae biomass. Particularly, flocculation using magnetic nanoparticles offers high separation efficiency due to their high surface area and magnetic properties. I
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Recovery of Chlorella biomass using Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles: Isotherm and thermodynamic characteristics of adsorptionCite this paper: Vietnam J. Chem., 2023, 61(S3), 116-125 Research ArticleDOI: 10.1002/vjch.202300068 Recovery of Chlorella biomass using Fe3O4 and Fe3O4@SiO2 magnetic nanoparticles: isotherm and thermodynamic characteristics of adsorptionDo Thi Cam Van1, Lam Van Toan2, Nguyen Thi Phuong Dung2,3, Tran Dang Thuan4*, Dinh Thi Cuc4, Dang Thi Mai4, Pham Thi Mai Huong5, Pham Thi Thanh Yen5 1 HaUI Institute of Technology, Hanoi University of Industry (HaUI), 298 Cau Dien, Bac Tu Liem, Hanoi 11900, Viet Nam 2 Graduate University of Science and Technology, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam 3 Department of Applied Science, University of Transport Technology, 54 Trieu Khuc, Thanh Xuan, Hanoi, Viet Nam 4 Institute of Chemistry, Vietnam Academy of Science and Technology (VAST), 18 Hoang Quoc Viet, Cau Giay, Hanoi 10000, Viet Nam5 Faculty of Chemical Technology, Hanoi University of Industry (HaUI), 298 Cau Dien, Bac Tu Liem, Hanoi 11900, Viet Nam Submitted February 19, 2023; Revised May 2, 2023; Accepted July 21, 2023Abstract Harvesting microalgae by centrifugation and filtration is very costly, affecting technical and economical feasibilityof downstream processing of algal biomas to bioproducts. Flocculation is a potential technique for recovery of algaebiomass. Particularly, flocculation using magnetic nanoparticles offers high separation efficiency due to their high surfacearea and magnetic properties. In this work, the synthesized magnetic nanoparticles including Fe 3O4 and Fe3O4@SiO2 wereused to harvest C. sorokiniana TH01 from aqueous suspension. The effects of pH, adsorbent dosage, algal biomassconcentration, temperature and reaction time on harvesting performance were investigated. It was revealed that theoptimal C. sorokiniana TH01 harvesting conditions for Fe3O4 were pH of 5, adsorbent dosage of 0.5 g/L, biomassconcentration of 2-2.5 g/L, temperature 25oC and reaction time 20-30 min. For Fe3O4@SiO2, the optimal conditions werepH of 7, adsorbent dosage of 0.6 g/L, with the same biomass concentration, temperature and reaction time as Fe3O4. Underthe optimal conditions, Fe3O4 and Fe3O4@SiO2 can be regenerated up to three cycles with harvesting efficiency tillremained over 55%. Adsorption of C. sorokiniana TH01 on Fe3O4 and Fe3O4@SiO2 exhibited the best fitness withLangmuir isortherm with R2 and maximal adsorption capacity estimated of 0.995 and 6.55 g/g and 0.9971 and 9.53 g/g,respectively. Thermodynamics study revealed that an adsorption of C. sorokiniana TH01 on Fe3O4 and Fe3O4@SiO2 wasexothermic process. Furthermore, XRD, EDS, SEM, TGA and FT-IR data confirmed the successful binding of microalgaecells on surfaces of Fe3O4 and Fe3O4@SiO2. The super-magnetization intensities (> 22 emu/g) of the synthesized materialsdemonstrated an excellent separation capability with external magnetic devices. Keywords. Chlorella, magnetic particles, flocculation, isotherm, thermodynamics .1. INTRODUCTION lipids, carbohydrates, chlorophylls, carotenoids and other bioactive compounds (astaxanthin, lutein, etc.)Microalgae are regarded as the third generation of which are promising precursors for production ofbiomass feedstock for biofuels production.[1,2] pharmaceutical, cosmesceutical, food/feed andMicroalgae can be grew in different aqueous energy.[4,5] Most of microalgae are phototrophicenvironments such as artificial, industrial, domestic strains which need light as an energy source for theirand agricultural wastewaters in nonarable lands.[3] growth. Due to limitation of photon transfer inParticularly, microalgae can accumulate high content microalgal culture, phototrophic microalgae generallyof multiple secondary metabolites such as proteins, achieve maximal dry cell weight of bellow 5-10 g/L,[6]116 Wiley Online Library © 2023 Vietnam Academy of Science and Technology, Hanoi & Wiley-VCH GmbH 25728288, 2023, S3, Downloaded from https://onlinelibrary.wiley.com/doi/10.1002/vjch.202300068 by Readcube (Labtiva Inc.), Wiley Online Library on [01/05/2024]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons LicenseVietnam Journal of Chemistry Tran Dang Thuan et al.leading to dewatering and concentration of biomass polyaluminium chloride and polyacrylamide.[35]become challenging and costly. Various harvesting Fraga-García et al. (2018) studied separation oftechnologies for recovery of microalgae biomass have Scenedesmus ovalternus and Chlorella vulgaris usingbeen developed and applied such as centrifugation,[7] bare iron oxide nanoparticles.[36] Fu et al. (2021) usedfiltration (membrane-based technologies),[8-10] magnetic particles synthesized by co-precipitation of ...