Accepted Manuscript Molecular mechanism of anionic dyes adsorption on cationized

ACCEPTED MANUSCRIPT
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and stirred for 3 h to acheive the cationized rich husks cellulose (CRHC). The product 
was filtered and washed with a large amount of anhydrous ethanol to remove the 
unreacted N, N-dimethyl-1-octadecylamine, and washed with 0.1 mol L
-1
NaOH 
solution and 0.1 mol L
-1
HCl solution to adjust the solution pH values around 7, and 
then rinsed with a large amount of water to obtain the pure cationized rice husks 
cellulose (CRHC), dried in a vacuum oven at 60°C. 
2.3 Chemical composition analysis 
The chemical composition of Rice husks (RH), delignified rice husks (RHD), 
and bleached rice husks (RHC) was determined according to the ASTM and TAPPI 
standard methods for different components of products [19]. The cellulose contents 
were accessed according to TAPPI standard T203 OS-61, the hemicellulose contents 
were accessed according to ASTM standard ASTM D 1104-56, while the lignin 
content was measured according to TAPPI standard T222 OS-83. The silica ash 
content was determined using the thermogravimetric analysis (TGA) data. During the 
process of rice husks burning, the cellulose and lignin are decomposed and removed, 
the residual rice husks ash usually contains almost over 95% of amorphous silica [20]. 
Rice husk ash can be left in an amorphous form with a combustion temperature of up 
to 900 °C. Based on this, the composition of silica ash was obtained at temperatures 
900 
℃ as the residual ashes at this point can be attributed to the silica ash [21].
2.4 Characterization 
The functional groups and chemical structure of rice husks (RH), rice husks 
cellulose (RHC) and cationized rice husks cellulose (CRHC) were evaluated by FTIR 
spectroscopy using a Nicolet iS 50 spectrophotometer (Thermo Fisher Scientific, 
USA) at wavelength range of 4000~400 cm
-1
with resolution of 0.09 cm
-1
. The crystal 
structures were performed using X-ray diffraction (XRD) on an X-ray diffractometer 
(DX-2700A, Dandong Haoyuan Instrument Co., Ltd. China) with 5 °/min scanning 
rate at room temperature in the range of 2θ=5~45 °. The microstructures and surface 
morphologies were examined by a S-3400N scanning electron microscope (Hitachi, 

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