Powder Technology, Vol.302, 207-214, 2016
Dual function magnetic hydroxyapatite nanopowder for removal of malachite green and Congo red from aqueous solution
In this study, the removal of both cationic dye (malachite green) and anionic dye (Congo red) by magnetic Sr5xBa3x(PO4)(3)(OH)/Fe3O4 nanopowder (namely SBPF) from aqueous solution was investigated. Variables influencing the adsorption capacity, such as solution pH, temperature, adsorbent dosage, adsorption time, and initial concentration, were systematically investigated. The adsorption process is pH and temperature dependent The adsorption for MG and CR can be described by pseudo-first-order and pseudo-second-order kinetic model, respectively. The adsorption behaviors fit quite well with the Langmuir model for both dyes with the maximum adsorption capacity of 526 mg g(-1), for MG and 417 mg g(-1) for CR Thermodynamic analysis revealed that the adsorption processes were spontaneous and exothermic Physical forces, hydrogen bonding, and ionic interaction are responsible for binding of the dyes with SBPF. The used SBPF nanopowder could be regenerated effectively and recycled for five cycles without a significant loss of adsorption ability. Moreover, the adsorbent can be applied to remove MG and CR in different water matrices. (C) 2016 Elsevier B.V. All rights reserved.