Author
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Laird, David |
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Submitted to: Managing Irrigation Induced Erosion and Infiltration with Polyacrylamide Co
Publication Type: Abstract Only Publication Acceptance Date: 5/6/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: The objective of this research was to evaluate bonding mechanisms between clay mineral surfaces and both cationic and anionic polyacrylamides (PAM). A flocculation index was used to quantify the interaction between PAM and both Ca- and Na-forms of kaolinite, illite, and quartz. The cationic PAM was highly effective for flocculating all three minerals regardless of the electrolyte concentration or saturating cation. Under basic (pH = 9.4-11) conditions, the cationic PAM was only slightly less effective than under neutral (pH = 5-6) or acidic (pH = 3.4) conditions. Positive charge functional groups on the cationic PAM are believed to bond directly with negative surface charge sites on the mineral surfaces. The effectiveness of anionic PAM as a flocculent varied with mineralogy (kaolinite > illite >> quartz). The anionic PAM was much more effective under acidic conditions than basic conditions and with Ca-clays than Na-clays. The results suggest that cation bridging (PAM-Ca-clay) is the major bonding mechanism between anionic PAM and clay mineral surfaces. However, direct bonding between negative functional groups on the PAM and positive charge sites on lateral edges of clay particles, and hydrogen bonding between amide groups on the PAM and hydroxyl surfaces of kaolinite, may also occur. |
