Dear Members:
I want to find out the surface charge on the surface of algae. I have read that pH titration may be useful for measuring the surface charge on algal cells. If you have detailed method, I would like to share with.

Marinephyco said:

Dear Members: I want to find out the surface charge on the surface of algae. I have read that pH titration may be useful for measuring the surface charge on algal cells. If you have detailed method, I would like to share with.

Abstract for presentation at Chemeca 2005

Influence of coagulant dose and pH on surface charge of Microcystis implications for coagulation

Mr Torbjorn van Heeswijck, School of Chemical Engineering, University of Adelaide, Australia
Steve Amos, School of Chemical Engineering, University of Adelaide, Australia
Dr David Lewis, School of Chemical Engineering, University of Adelaide, Australia
Dr Uwe Kaeding, United Water International, Australia
Coagulation processes are largely governed by destabilising the surface charge on a particle such that they may agglomerate, and are easily removed. Insufficient coagulant addition results in less than optimal removal, whilst excess coagulant can restabilise the suspension at an increased chemical cost.
The ability of chemical coagulants aluminium sulphate and ferric sulphate to bring about charge neutralisation of Microcystis algal cells was investigated using a zeta meter. Algae cultures were diluted to a concentration of 106 cells/mL in tap water, buffered media or with filtered pond effluent and then dosed with between 2 and 30 mg/L coagulant. After a 20 s period of rapid mixing the dosed algae was exposed to an electric potential of 100 V in the zeta meter and velocity measurements for individual algae cells were recorded over a 7 minute period. The zeta potential was calculated at 30 second intervals and plotted against time after coagulant addition.
Charge reversal of algae displayed time dependent behaviour, as previously shown by Chow et al. Increased coagulant dose resulted in zeta potential reduction or charge reversal in all media, in agreement with previous work. Charge reversal was achieved at lower coagulant doses in buffered media than in tap water or raw water. For all media, pH was found to be a significant factor in charge neutralisation, with enhanced coagulant performance occurring at optimal pH levels. Charge neutralisation was significantly hindered at low pH levels in raw water. This is attributed to the presence of dissolved organic content in the raw water

thanks for posting that mariamaria