Stabilization and destabilization of hematite suspensions by neutral and anionic polyacrylamide

Article Article scientifique Article Stabilization and destabilization of hematite suspensions by neutral and anionic polyacrylamide eng 1999 author Zhang Jie 715037 author Huguenard Clarisse 100582 author Scarnecchia Carmela 112716 author Menghetti René 30073 author Buffle Jacques 24673 49-63 10.1016/S0927-7757(98)00700-6 0927-7757 http://linkinghub.elsevier.com/retrieve/pii/S0927775798007006 Polyacrylamide (PAM) and its hydrolysis products are widely used flocculants in water treatment. These relatively flexible polymers may also serve as models for certain natural organic matter rich in carboxyl groups in aquatic systems. We studied the aggregation kinetics of hematite in the presence of neutral and hydrolyzed polyacrylamide (HPAM) at low hydrolysis ratios (τ=0.4–8.2%). Electrophoretic mobility measurements revealed that HPAM, even at very low degree of hydrolysis (0.4% and 2.5%), could reverse the surface charge of hematite. However, no flocculation was observed for neutral and HPAM with τ=0.4 and 2.5%, even at the zero point charge (ZPC). This clearly demonstrates the strong steric repulsion between the polymer layers whose hydrodynamic thickness was comparable to the particle size. For polymer chains containing more charged groups (⩾6.1%), flocculation indeed took place. The maximum rate occurred near the ZPC, indicating the importance of the charge neutralization mechanism. There was no indication of the involvement of polymer bridging in the present systems. Charge neutralization Colloidal stability Hematite Hydrodynamic thickness PCS Polyacrylamide Steric stabilization Dewey 540 40 Département de chimie minérale, analytique et appliquée 145 false Colloids and surfaces. A, Physicochemical and engineering aspects 151 1-2 c4e9ff09-82b3-4db4-9bb2-c682fe3ab736 Article (Published version) Restricted J.Zhang_Stabilization.pdf 534484 application/pdf restrictedAccess Faculté des sciences / Section de chimie et biochimie / Département de chimie minérale, analytique et appliquée

Title	Published in	Access level	OA Policy	Year	Views	Downloads

Stabilization and destabilization of hematite suspensions by neutral and anionic polyacrylamide	Colloids and surfaces. A, Physicochemical and engineering aspects			1999	524	1

Archive ouverte UNIGE

Zhang, Jie