Simultaneous removal of Methylene Blue and Direct Blue 71 with Pb(II) ions from multi-component systems: application of the multi-component Langmuir model

This study aims to investigate the simultaneous removal of Methylene Blue (MB), Direct Blue 71 (DB71), and Pb(II) ions, which are frequently found together at high concentrations in different industrial wastewaters, such as textile, paper, leather, paint, and plastic manufacturing waste- waters. The simultaneous removal of Pb(II) ions with MB and DB71 from binary mixtures was investigated by the adsorption method. Magnetic halloysite nanotubes-alginate (MHNTs-ALG) hybrid beads were used to remove these components from the binary adsorption media. For this purpose, a magnetic property was gained to halloysite nanotubes using the “co-precipitation method”. Magnetic halloysite nanotubes (MHNTs) were composited with alginate (ALG) biopoly - mers through the “extrusion dripping method”. The adsorption capacities and efficiency of these synthesized MHNTs-ALG hybrid beads were investigated according to their anionic and cationic pollutant content in binary mixtures, and the synergistic and antagonistic effects of these compo- nents on each other were investigated by comparing them according to single systems. The compatibility with the multi-component Langmuir adsorption model for binary systems was examined using equilibrium adsorption data, and the values of the constants showing the adsorption capacity and affinity were calculated. In binary mixtures of Pb(II)-MB, the maximum amounts of Pb(II) and MB adsorbed per unit adsorbent weight calculated from the multi-component Langmuir model were 248.46 mg/g ( q Pb, m ) and 946.92 mg/g ( q MB, m ), respectively. The maximum adsorption capacities of Pb(II) and Direct Blue 71 from binary systems were determined as 203.14 mg/g ( q Pb, m ) and 118.96 mg/g ( q DB71, m ), respectively. The co-presence of Pb(II) and MB was concluded to cre- ate a synergistic effect compared to the adsorption of Pb(II) ions alone and an antagonistic effect compared to the adsorption of MB alone. The co-presence of Pb(II) and DB71 was observed to form a synergistic effect compared to the individual presence of Pb(II) ions and an antagonistic-synergistic mixed effect compared to the individual presence of DB71.