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. 2025 Aug 6;17(8):395.
doi: 10.3390/toxins17080395.

Effectiveness of Kaolinite with and Without Polyaluminum Chloride (PAC) in Removing Toxic Alexandrium minutum

Cherono Sheilah Kwambai  1 , Houda Ennaceri  1   2 , Alan J Lymbery  1   2 , Damian W Laird  1   2 , Jeff Cosgrove  1   2   3 , Navid Reza Moheimani  1   2
Affiliations

Effectiveness of Kaolinite with and Without Polyaluminum Chloride (PAC) in Removing Toxic Alexandrium minutum

Cherono Sheilah Kwambai et al. Toxins (Basel). .

Abstract

Alexandrium spp. blooms and paralytic shellfish poisoning pose serious economic threats to coastal communities and aquaculture. This study evaluated the removal efficiency of two Alexandrium minutum strains using natural kaolinite clay (KNAC) and kaolinite with polyaluminum chloride (KPAC) at three concentrations (0.1, 0.25, and 0.3 g L-1), two pH levels (7 and 8), and two cell densities (1.0 and 2.0 × 107 cells L-1) in seawater. PAC significantly enhanced removal, achieving up to 100% efficiency within two hours. Zeta potential analysis showed that PAC imparted positive surface charges to the clay, promoting electrostatic interactions with negatively charged algal cells and enhancing flocculation through Van der Waals attractions. In addition, the study conducted a cost estimate analysis and found that treating one hectare at 0.1 g L-1 would cost approximately USD 31.75. The low KPAC application rate also suggests minimal environmental impact on benthic habitats.

Keywords: Alexandrium spp.; cost estimate; harmful algal blooms; kaolinite; modified clays; removal rates; seawater; zeta potential.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

Figure 1
Figure 1
Impacts of Alexandrium spp. blooms.
Figure 2
Figure 2
Removal efficiency of A. minutum strains CS-1178 and CS-324/16 with initial cell density of 1.0 × 107 cells L−1. Cultures were treated with 3 different concentrations of KPAC (solid lines) and KNAC (dashed lines) at both pH 7 and 8.
Figure 3
Figure 3
Removal efficiency of A. minutum strains CS-1178 and CS-324/16 with initial cell density of 2.0 × 107 cells L−1. Cultures were treated with 3 different concentrations of KPAC (solid lines) and KNAC (dashed lines) at both pH 7 and 8.
Figure 4
Figure 4
KPAC’s average removal efficiencies of A. minutum cells at a density of 2.0 × 107 cells L−1 at pH 7, along with the corresponding fitted data curve.
See this image and copyright information in PMC

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