Adsorption performance of Fe(III) modified kapok fiber for As(V) removal from water.

[Display omitted] • Fe-Kapok has been made by easy hydrothermal method. • Fe-Kapok showed Fe positive impact for As (V) removal. • High and fast As (V) adsorption. • Fe-Kapok could be regenerated and reused several times. Arsenic (As) is one of the most toxic metals for human health. In the present work, kapok fibers were modified using iron Fe(III) to enhance As(V) adsorption and then characterized using Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The impacts of pH, dose of adsorbent, contact time, initial concentration, temperature, and coexisting ions on the adsorption of As(V) onto Fe-modified kapok fiber (Fe-kapok) surfaces were investigated. The results showed that the adsorption process fit more to the Langmuir isotherm equation and pseudo second kinetic equation, thus demonstrating that the adsorption was an endothermic, spontaneous, monolayer chemisorption process with some disorder at the solid/solution interface. The adsorption process was controlled by the film diffusion step, and the maximum adsorption capacity of Fe-kapok was calculated to be approximately 367 µg/g. Further study showed that after 8 adsorption/desorption cycles with 1 regeneration cycle, Fe-kapok was still able to remove 45% of the arsenic (100 µg/L) present in the water. A notable negative impact on the removal of As(V) from water was linked to the concentrations of SO 4 2- and PO 4 3- in the water. [ABSTRACT FROM AUTHOR]