Iminodiacetic acid functionalized magnetic peanut husk for the removal of methylene blue from solution: characterization and equilibrium studies.

A novel adsorbent PN-Fe3O4-IDA was developed by the chemical modification of magnetic peanut husk with iminodiacetic acid (IDA) and its efficacy for the sequestration of cationic dyes assessed using methylene blue (MB) as a model. This modification process enhanced the adsorption capacity of peanut husk as an adsorbent for dye sequestration and at the same time greatly minimized the adverse effects associated with its use in the pristine state. Results from the batch adsorption studies indicated that the uptake of MB onto PN-Fe3O4-IDA increased with MB concentration, contact time, temperature and pH whereas it decreased in the presence of some common salts. The pseudo-second-order kinetic model was observed to best describe the adsorption process which may greatly be influenced by the intra particle diffusion mass transfer. A maximum monolayer adsorption capacity of 43.5 mg g-1 was observed at 313 K according to the Langmuir model. There was good property of regeneration for MB-loaded PN-Fe3O4-IDA. Based on these results, as well as other unique features such as easy separation and preparation under benign environmental conditions, PN-Fe3O4-IDA exhibits great potential for the removal of MB and other cationic pollutants in practical applications with easy separation from solution using external magnet. Graphical abstract.