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Kinetic modeling of adsorption for harmful algal bloom mitigation using predator-derived info-chemical-enhanced adsorbents

  • Sehoon Oh (오세훈, 대학원 환경생태공학과 환경생태공학)

초록/요약

Harmful Algal Blooms (HABs) result from the rapid proliferation of cyanobacteria, such as Microcystis sp. and Anabaena sp., within aquatic ecosystems. Among these, Microcystis aeruginosa is widely recognized as a major contributor to HABs. With the ongoing impact of climate change and global warming, the frequency, intensity, and geographical range of HABs have been escalating worldwide, leading to detrimental effects on ecosystems. HABs obstruct sunlight penetration, deplete dissolved oxygen, and release toxins upon the breakdown of cyanobacterial cells, which significantly disrupts aquatic environments. These toxins can cause the death of fish and other aquatic organisms, posing serious environmental challenges and potential health risks to humans through direct and indirect exposure. This study aims to develop an adsorption-based method for effectively removing harmful cyanobacteria without inducing cell death and to systematically evaluate the adsorption efficiency using isotherm and kinetic models. Specifically, a novel adsorbent, Benzylamine-chitosan-urea-modified-cotton (BCU-m-cotton), was synthesized by functionalizing cotton fibers with info-chemicals, namely benzylamine and urea, secreted by Daphnia magna. This functionalization resulted in a benzylamine-chitosan-urea complex that enables selective and efficient adsorption of cyanobacteria. The adsorption capacity and mechanism of BCU-m-cotton were thoroughly analyzed using various isotherm models (e.g., Langmuir, Freundlich, and Sips) and kinetic models. Results showed that the Sips isotherm model best described the adsorption process, indicating a strong adsorption capacity, while kinetic analysis was shown to follow a pseudo-second-order response. High correlation values (R²) across all models further validated the applicability and reliability of these models in accurately predicting the adsorption behavior of living cyanobacterial cells. To assess the viability of using the adsorbed cyanobacterial biomass as a resource, the biomass was recovered through ultrasonic and sodium hydroxide (NaOH) treatment. Subsequent analysis confirmed its potential for biofuel conversion, indicating that this biomass could serve as a energy source. In summary, this study highlights the effectiveness of an eco-friendly, cyanobacteria-targeted adsorbent inspired by predator-prey interactions, as substantiated by adsorption isotherm and kinetic modeling. Additionally, the promising possibility of converting cyanobacterial biomass into biofuel contributes to the development of sustainable energy solutions and advances carbon-neutral initiatives. These findings support the advancement of efficient cyanobacterial adsorption technologies, while the insights from model application may facilitate precise performance evaluations of cyanobacterial adsorbents, thereby contributing to both environmental and energy objectives.

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목차

1. INTRODUCTION 1
1.1 Harmful algal blooms (HABs) and cyanotoxins 2
1.2 Adsorptionstrategyusinginfo-chemical 4
1.3 Isothermandkineticmodeling 8
1.4 Objective of this study 10
2. Materialsandmethods 12
2.1 Materials and chemical reagents 13
2.2 Identification of effective info-chemicals for controlling cyanobacteria based on natural enemy relationships 14
2.3 Verification of M. aeruginosa removal using selected info-chemicals 14
2.4 Development of adsorbent imitating natural predatorprey relationship between M. aeruginosa and D. magna 14
2.5 Surface functional group characteristic of developed adsorbent 17
2.6 Assessment of M. aeruginosa control efficiency of adsorbents via isotherm, kinetic testing 17
2.7 Surface observation by Field-emission scanning electron microscopy (FE-SEM) 18
2.8 M. aeruginosa biomass recovery by desorption 19
2.9 Biodiesel production and fatty acid analysis 19
3. Resultanddiscussion 21
3.1 Exploration of M. aeruginosa control info-chemicals derived from D. magna 22
3.2 Surface characterization of the adsorbent 27
3.3 Optimization of Surface modification of adsorbents 34
3.4 Isotherms and kinetics of developed adsorbents 36
3.6 FAME analysis of recovered M. aeruginosa biomass 45
4. Conclusion 49
5. Future plan 52
6. Reference 54

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