I want to find pH ZPC of a biowaste material for its potential use as adsorbent.
did you try any method? electrophoresis, AFM or any else... perhaps electrophoresis is the easiest way if you have device. just prepare a range of solutions with different pHs. then measure Zeta Potential of the particles in each. by plotting the pH vs Zeta you will find it.
Thank you for showing interest. I don't have this device. Kindly suggest a simple method which can be executed on simple devices such as pH meter or such simple equipments.
You could try to use pH titrations at different ionic strength to determine the surface charge and PZC (in this case actually the point of zero salt effect PZSE) of your material. If you perform the titrations at for example 0.01, 0.05 and 0.1 molar ionic strength (e.g. NaClO4) the pH where all titration curves cross would be your PZSE. When doing this you should keep in mind the potential dissolution of your material which could also affect pH and hence make this experiment more difficult.
You can find more info on the potentiometric titrations in the attached paper
"Potentiometric titrations as a tool for surface charge determination" by Lützenkirchen et al.
http://hrcak.srce.hr/file/138013
i think the easy way using the zeta potential by preparing the several pH solution. the amount of material to water as mg/vol = 0.01 (0.05 mg of material/ 5 ml water) and then adjust the pH from 2 to 6 using drops of the HCL and from 7 to 11 using NaOH (leave about 1 hour after mixing for equilibrium). finally, measure by zeta and then plot between zeta value versus pH , the cut line with X line (ZERO ZETA) you can take as pH ZPC.
with regards
The pH of zero point charge (pHzpc) plays an important role in the adsorption process:
[I]The Bio waste (BW) is collected. It is reduced in its size by mechanical grinding to obtain uniform size of material by sieving through -18+52 (B.S.S.) mesh.
[II]Wash with distilled water and keep it dipped in dilute HCl (0.1 N) for 24 hrs so that the final washing should show no further change in pH.
[III] Dry it by keeping it in an oven at 70- 72C ; cool and store in an air tight container.
.[IV] pHzpc is determined by the Rivera-Utrilla et al method. [Journal of Chemical Technology and Biotechnology, vol. 76, no. 12, pp. 1209–1215, 2001] as follows :
[a] 50 mL of a 0.01 M NaCl solution was placed in a 100 mL flask. The pH was then adjusted to successive initial values between 2 and 12, by using either NaOH s or HCl (0.1 N) containing 0.15 g of dry BW.
[b] After a contact time of 24 h, final pH was measured and plotted against the initial pH. The pH at which the curve crosses the line pH (final) = pH (initial) is taken as the pHzpc
Dear Harminder
You can use Zeta potential to determine the isoelectric charge, or you can use the procedure bellow for the same purpose:
A fixed weight of 0.2g of the activated carbon samples were introduced
into a set of 100ml of 0.1M KNO3 solutions where the initial pH was adjusted from 2 to 11 by
addition of either HNO3 or NaOH. Suspended solids in the solutions were allowed to equilibrate
for 24 hours in a shaker at room temperature (22±1 oC). After equilibration the pH final was
measured again and the difference between initial and final pH was plotted against pHinitial.
Here are some ref.
1. The synthesis and characterization of microporous, high surface area activated carbon from palm seeds. Energy Sources, Part A: Recovery, Utilization and Environmental Effects, 36(1), 93-103.
2. Cobalt and zinc removal from aqueous solution by chemically treated bentonite. Environmentalist, 27(3), 357-363.
Thank you for this information. I will definitely use one of these options.
you can prepare buffer solutions of different pH's (pHinit)and add a fixed weight of biomass material to it (0.1g). After shaking for 2 hours measure (pHfinal). Plot the relation between pH (x-axis and (pHfinal -pHinit) (y-axis) . The intercept of X axis is the pH of zero charge
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