Point of Zero Charge (PZC)

Working principle & Instrumentation  

PZC instrumentation 

The Point of Zero Charge (PZC or pH

PZC) is a characteristic of a material's surface at which the material carries no net electrical charge. It is a critical parameter in understanding the surface charge behavior of materials, particularly in the context of colloidal systems and adsorption phenomena. It is that value of PH where surface attain neutrality.

The PZC is related to the protonation or deprotonation of functional groups on the material's surface. At the PZC, the concentrations of positively and negatively charged sites are equal, surface attain neutrality, Experimental methods involve determining the pH at which the material exhibits no net charge. This is often done by measuring the zeta potential or by titrating the material. with an acid or a base and monitoring the surface charge In salt addition method first Prepared 600ml 0.1M stalk solution of Sodium nitrate, take 40ml of this solution in fourteen different Erlenmeyer or conanical flasks one by one set the different pH value (1 to 14) of the solution with either adding acid or base drop vice through droper carefully Nitric acid (0.1 M) or Sodium hydroxide (0.1 M) by using a pH meter addjust different pH value from (1 to 14) has been set these are the initial pH (pHi) values then in each flask add desirable composite or material whose pzc want to be determin placed all these flask in orbital shaker and shake at speed of 150 rpm on the orbital shaker at room temperature for 24 hours or set the parameters of your own choice according to sample requirement. After equlibrium filter the contents, and record the pH of beaker containg the filtrate known as final pH (pHf) then find the change in pH by ΔpH=pHi _ pHf then draw the graph against ΔpH and pHi the line intersect or coside on the zero is its PZC.

Sample Preparation Sample preparation depends on the technique used in salt addition method Care fully salt solution prepared 0.1 M adjust their pH (1 to 14 by adding acidc or basic solution drope vice in it) Disperse the cleaned material in each of the prepared solutions. This could involve mixing the material with the solution and allowing it to equilibrate.

Results interpretation The pH below the PZC, the surface is positively charged, and above the PZC, it becomes negatively charged. PZC is crucial for predicting the adsorption behavior of ions and molecules onto a material's surfaces.

Figure PZC graph