Efficiency of camalote grass residue (Paspalum fasciculatum Willd) in the adsorption of methylene blue

Abstract

Camalote is a perennial grass that reproduces quickly and spontaneously in tropical regions. This grass has no economic use; on the contrary, it is considered a weed. However, it is a good source of cellulose and occurs in abundance. In this regard, the purpose of this work is to take advantage of the Camalote grass as an adsorbent of methylene blue (MB). The adsorption tests were carried out in a batch system, using MB concentrations within the range of 20-100 mg/L. The highest adsorption capacity (qe) was 43 mg/g for the concentration of 100 mg/L of MB at pH 8. For all the concentrations studied, percentage removal values greater than 80% were obtained in a contact time of 30 min. The equilibrium data were correlated with the Langmuir and Freundlich models. The qmax values for the Langmuir isotherm are within the range of 19.79 to 94.51 mg g-1 and b from 0.10 to 0.05 L mg-1. While for the Freundlich isotherm, K values ranging from 3.79 to 5.13 (mgg-1(L mg-1)-1/n and n from 2.6 to 1.27 are obtained, suggesting that in the active sites MB is retained by chemisorption through hydrogen bonds. The results showed that Camalote grass is an efficient and economically viable material for removing dyes from aqueous media.