Ordered mesoporous carbons and their corresponding column for highly efficient removal of microcystin-LR

Abstract

Highly effective removal of toxic pollutant microcystins from water sources is achieved by employing ordered mesoporous carbons prepared from the surfactant-templating method as adsorbents. For the first time, a systematic study into the static and dynamic adsorption behaviours of ordered mesoporous carbons towards microcystin-LR (MC-LR) is demonstrated. Firstly, by adopting different mesoporous carbons with various mesostructures, textures and surface chemical properties for batch adsorption, definite relationships between the adsorption performance of MC-LR and properties of adsorbents are established. Among all the samples, the mesoporous carbon (MCS/C) obtained from a mesoporous silica–carbon composite after removing the silica component exhibits an unprecedented adsorption capacity of ∼526 mg g⁻¹, due to its unique bimodal mesopores of ∼2.8 and 5.8 nm, a high surface area of 1680 m² g⁻¹, a large pore volume of 1.67 cm³ g⁻¹ and two-dimensional (2D) straight mesopore channels. A comprehensive understanding of dynamic adsorption behaviour shows that this mesoporous carbon possesses a 30-fold higher adsorption capacity compared with powdery activated carbon at a high flux of 120 L m⁻² h⁻¹. Finally, two pollutants, Rhodamine B and phenol, are mixed with MC-LR for competitive adsorption onto the mesoporous carbon MCS/C. It is found that the total amount of removal pollutants increases sharply to ∼700 mg g⁻¹. Considering all the advantages, the ordered mesoporous carbon MCS/C shows a promising potential for practical waste water treatment, especially for large toxin microcystin removal.