Preparation of carboxymethyl salix wood powder as a superadsorbent for removal of methylene blue from wastewater

Novel adsorbents for the efficient removal of dye molecules from wastewater are of great interest, but very challenging to prepare. Herein, we report a simple method for the preparation of novel carboxymethyl salix wood powder (CSWP) as a superadsorbent for the removal of methylene blue from wastewater. The CSWP was prepared by treatment of salix wood powder (SWP) with a NaOH solution followed by carboxymethylation with monochloroacetic acid. The CSWP was characterized using a series of techniques such as scanning electron microscopy (SEM), BET analysis, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The CSWP has a porous morphology with improved specific surface area and pore volume. The successful carboxymethylation of SWP with monochloroacetic acid was confirmed by the FTIR and XRD analyses. The effects of the concentration of NaOH solution, carboxymethylation temperature and carboxymethylation time on carboxymethylation of salix wood powder (SWP) and adsorption capacity of CSWP were also studied. The CSWP treated with 20% NaOH solution followed by modification with monochloroacetic acid at 60 °C for 2 h showed the highest adsorption capacity. The adsorption capacity of CSWP for MB was as high as 1908 mg g−1, which is much higher than that of SWP (257 mg g−1) and is overwhelmingly above almost all of the state-of-the-art adsorbents based on natural biomass.