Methylene blue removal by nano-polyacrylonitrile particles: modelling and formulation studies

The kinetic and isothermal studies of the methylene blue (MB) adsorption by nano-polyacrylonitrile (PAN) and nano-hydroximated polyacrylonitrile (HPAN) particles prepared by the precipitation polymerization technique have been performed in this study. The kinetic models of the MB adsorption, namely first-pseudo order, second-pseudo order, and Elovich models have been studied over 75 min. The MB concentration was varied between 10 and 50 mg/L during the study of the MB adsorption isotherms. The Freundlich, Langmuir, Temkin, and Harkins-Jura isotherm models have been used in the study. Moreover, the diffusion controlling step has been determined by testing the adsorption data using the intraparticle and D-W diffusion models. Finally, the formulation conditions, such as alginate concentration, crosslinker concentration, crosslinking time and temperature, and adsorbent amount, with alginate biopolymer, have been studied. The synergetic effect between the alginate and the nano-polyacrylonitrile (PAN) and HPAN particles has been investigated. The calculated distribution coefficient (K-d) values were found to be 6.0 and 12.25 L g(-1) for PAN and HPAN, indicating that the PAN is a suitable adsorbent while the HPAN is an outstanding adsorbent.