Investigation on the Flocculating Activity of Some Cactus Extracts for Crystal Violet Dye Removal

In this study, the flocculating activity of three cactus extracts—cactus juice (CJ), lyophilized powder (LP) and oven-dried powder (DP)—was appraised to treat a synthetic crystal violet dye solution. The highest color and turbidity removals were gained using the powdered cactus extracts over the juicy one. Interestingly, important dye removal exceeding 60% was found using LP as flocculant, thanks to its significant carbohydrates content. Wherefore, two polysaccharide extracts were isolated and characterized in order to identify the main flocculating active agent, which is an arabinogalactan. Accordingly, dye uptake is likely occurred via adsorption-charge neutralization mechanism. Therefore, application of cactus extracts as bio-flocculants is highly recommended to ensure a clean, efficient and sustainable water treatment approach.