Facile fabrication of magnetic phosphorylated chitosan for the removal of Co(II) in water treatment: separation properties and adsorption mechanisms.

Magnetic phosphorylated chitosan composite (P-MCS), an excellent adsorbent for Co(II), was synthesized in this experiment via a facile fabrication. Its removal efficiency was improved by optimizing pH, contact time, and initial concentration. The adsorption isotherms and kinetic models of Co(II) by P-MCS followed the Langmuir model and the pseudo-second-order model, respectively. However, the rate of adsorption was also affected by intragranular diffusion. The maximum adsorption capacity was 46.1 mg g-1 for Co(II). The results of spectroscopic analysis also indicated that good adsorption performance of Co(II) mainly depends on surface chelation between functional groups and metal ions. The saturation magnetic susceptibilities of P-MCS and P-MCS-Co were 22.29 emu g-1 and 18.18 emu g-1, respectively. The excellent magnetic properties of P-MCS enabled the easy achievement of solid-liquid separation via the use of an external magnetic field. In complex aqueous solutions, K+, Na+, Ca2+, and Mg2+ have less influence on P-MCS adsorption Co(II), but the adsorption capacity on Co(II) is still good. This study shows the feasibility of using P-MCS to treat wastewater containing Co(II).