Adsorption performance of chitosan Schiff base towards anionic dyes: Electrostatic interaction effects

In this paper, an electropositive adsorbent, salicylaldehyde-chitosan Schiff base (SCSB), was prepared via chitosan modification. The results showed that SCSB exhibited electrostatic adsorption on anionic dyes with a better adsorption performance than chitosan, corresponding to 24.75% and 79.80% removal rate of methyl orange (MO), respectively. Furthermore, the positive charge from the C = N was not strong enough to counter the electron-donating effect of salicylaldehyde, the MO removal rates of 0.5SCSB, 1.0SCSB, and 1.5SCSB were 79.80%, 69.02% and 59.60%, respectively. In the pH test, the imine group (C = N) hydrolysis showed a greater impact on charges changing than the amino group (-NH2) hydrolysis.

Automated summary

In this study, an electropositive adsorbent SCSB was successfully prepared via chitosan modification, showing better adsorption performance than chitosan and a potential for applications. The removal rate of SCSB was correlated with the electron-donating effect of salicylaldehyde, and the hydrolysis of the imine group had a greater impact on charges changing in the pH test.