Understanding of the flocculating performance in varying salinity solutions of Chi-g-CPAM and CPAM
Colloids and Surfaces A: Physicochemical and Engineering Aspects(2024)
Abstract
In this work, the adsorption performance of a novel chitosan-based flocculant (Chi-g-CPAM) and a cationic flocculant (CPAM) onto the kaolinite surface as well as the interaction mechanisms have been investigated by settling tests, atomic force microscopy (AFM) and quartz crystal microbalance with dissipation (QCM-D). When the KCl concentration of the solution altered from 1 mM to 100 mM, the settling rate of kaolinite suspension using CPAM deteriorated from 2.73 m/h to 1.97 m/h. However, the Chi-g-CPAM exhibited salt resistance as the settling rate changed slightly from 2.34 m/h to 2.44 m/h. From the QCM-D results, the Delta f of CPAM onto silica sensor changed from - 3.6 Hz to - 33.6 Hz and -Delta D/Delta f x 10(6) increased from 0.167 to 0.223, confirming that the CPAM layer adsorbed on the silica surface was thicker and more dissipative in 100 mM KCl solution. Meanwhile, the Delta f of Chi-g-CPAM onto silica sensor changed from - 14.3 Hz to - 33.9 Hz. The conformation of Chi-g-CPAM layer changed slightly as the -Delta D/Delta f x 10(6) increased from 0.174 to 0.186. From the AFM measurements in 1 mM and 100 mM KCl solution, the distance of adhesion forces between the silica probe and CPAM expanded from approximately 20 nm to around 50 nm, and the adhesion force changed from 1.9 nN +/- 0.1 nN to 21.3 nN +/- 0.1 nN. The interaction forces with a long range (similar to 100 nm) maintained at about 3 nN between the silica probe and Chi-g-CPAM. Such difference was mainly attributed to the steric hindrance effect originating from the shorter molecular chain of Chi-g-CPAM. In 100 mM KCl solution, the CPAM molecules with long chains had a more coiled conformation than Chi-g-CPAM, which resulted a train -like flat adsorption conformation and larger adhesion, and formed a loose and thick polymer layer of CPAM in high salinity. The insights into the flocculating performance in varying salinity solutions of CPAM and Chi-g-CPAM will contribute to the molecular design of chitosan-based flocculants for efficient wastewater treatment.
MoreTranslated text
Key words
Flocculants,Chi-g-CPAM,Interfacial interaction,Salinity,Conformation
AI Read Science
Must-Reading Tree
Example
![](https://originalfileserver.aminer.cn/sys/aminer/pubs/mrt_preview.jpeg)
Generate MRT to find the research sequence of this paper
Chat Paper
Summary is being generated by the instructions you defined