Invasive Freshwater Macrophyte Alligator Weed: Novel Adsorbent for Removal of Malachite Green from Aqueous Solution

The batch sorption experiments were carried out using a novel adsorbent, freshwater macrophyte alligator weed, for the removal of basic dye malachite green from aqueous solution. Effects of process parameters such as initial solution pH, contact time, adsorbent concentration, particle size, and ion strength were investigated. The adsorbent was characterized by FT-IR. The adsorption of malachite green by alligator weed was solution pH dependent. The adsorption reached equilibrium at 240 min for two particle size fractions. The pseudo-first-order equation, Ritchie second-order equation, and intraparticle diffusion models were tested. The results showed that adsorption of malachite green onto alligator weed followed the Ritchie second-order equation very well and the intraparticle diffusion played important roles in the adsorption process. The Langmuir and Freundlich equations were applied to the data related to the adsorption isotherms and the observed maximum adsorption capacity (q (max)) was 185.54 mg g(-1) at 20A degrees C according to the Langmuir model. The effects of particle size, adsorbent concentration, and ionic strength on the malachite green adsorption were very marked. The alligator weed could serve as low-cost adsorbents for removing malachite green from aqueous solution.