The effect of the reaction temperature during the APTES modification of CS beads on RB4 removal was investigated. The experimental data showed that the adsorptive efficiency for the elimination of RB4 was highest at 50 °C (Fig. 3a). When the preparation of CS/APTES beads was conducted at a concentration of 1% APTES and at increasing temperatures ranging from 30 °C to 70 °C, the dye removal percentages increased from 81.4% at 30 °C to a maximum value of 85.96% at 50 °C. The increase in the temperature resulted in an increase in the rate of reaction between CS and APTES. The increase in the temperature accelerated the kinetics of the APTES molecules in aqueous environments and consequently improved the interactions between the functional groups on the surface of the CS beads and the APTES molecules (Zhu, Yang, & Deng, 2009). However, further increases in the temperature (>50 °C) were detrimental to the hydrogen bonds between the CS bead surfaces and the APTES or bonds in the APTES molecules. Therefore, more siloxane linkages could be created by the condensation of the silanol groups (Xue, Zhou, Zhao, Lu, & Han, 2011). As such, 50 °C was selected as the optimal temperature for the subsequent preparation of CS/APTES.