• Zeta-Meter System(입자 전위차 측정기)

  • 입자 전위차 측정기

    [Model : Zeta-Meter System 3.0+]

Zeta Meter는 정전기적 전하의 영향을 측정하는 기계이다. 입자들은 서로 인접한 것끼리 척력을 작용한다. 한편 Van der waals force와 같은 인력도 작용한다.

콜로이드 용액에 기계적인 교반을 가했을때 충돌한 두 임자가 서로 인력을작용한다면 둘은 뭉치게 되고 점점 더 자라나게 한다. 그러나 만약 서로 척력을 일으킨다면 그 정전기적 힘은 둘 사이의 거리가 짧아질수록 증가하므로 콜로이드 그 상태를 유지하게 된다.

미립자 표면의 전하는 그 콜로이드와 부유용액 간에 전위차(millivolt 단위의 크기로)를 일으키게 되는데 이것이 zeta potential이다. zeta potential은 두 전극 사이에 전압을 걸어주었을 때에 전극 사이에 존재하는 대전된 콜로이드가 움직이는 것을 이용하여 쉽게 측정할 수 있다. 그리고 그 이동속도는 zeta potential에 비례하게 된다. 이러한 현상을 electrophoresis(전기영동)라 한다.

Zeta Potential -125 to +125 millivolts
Electrophoretic Mobility +20 to -20 microns/sec per volt/cm
Specific Conductance 0 to 60,000 micromhos/cm, autoranging
Temperature 5 to 75℃
Concentration 10 to 800,000 mg/l (0 to 80% solids by weight)
Particle Diameter 1.5 to 100 microns (with standard 15x eyepieces)

0.4 to 10 microns (with optional 25x eyepieces)
Sample Size 20 ml minimum (standard cell)

5 ml minimum (low volume cell)
Suspending Medium water or otrganic liquids
Applications Adhesives, Agricultural Chemical, Asbestos, Atomic Energy Beverages, biochemistry, Biomedicine Coal, Dairy Product, Detergents, Dry Power Technology Drystuffs, Emulsions, Fibers Foods, Latex Production, Petrochemicals Petroleum, Photographic Emulsions, Pigment
  • 1. Minerals &Ores (광물, 광석) - Coper, Lead, Zinc and Tungsten
  • 2. Clays & Drillng Fluid - Paper, Adhesives Ointments,Rubber and Synthetics
  • 3. Ceramics : Slip Casting Control
  • 4. Pharmaceuticals
  • 5. Paints
  • 6. Water and Wasterwater Coagulation
  • 7. Paper Making
  • Control of Slip Casting

  • Control of Slip Casting

    Clay suspensions for slip casting must have their viscosity minimized so that they pour readily and release trapped air bubbles easily. The above figure shows the effect of pH on the apparent viscosity and zeta potential of thoria(ThO3). Note that a maximum zeta potential corresponds to a low apparent viscosity.
  • Fluidization of an Antacid Suspension

  • Fluidization of an Antacid Suspension

    Fluidization is an alternative to flocculation. A negatively charged colloidal polyelectrolyte is used as a "fluidizing" agent. The polyelectrolyte adsorbs onto the surfaces of insoluble particles and deflocculates them once the zeta potential exceeds the critical value.This graph illustrates the fluidization of an aluminum hydroxide suspension using carrageenan sodium as the "fluidizing" agent. The drops in zeta potential and viscosity of the suspension correlate quite well with each other and are produced by an increase in the concentration of carrageenan.
  • Zeta Potential Control of Alum Dose

  • Zeta Potential Control of Alum Dose

    There is no single zeta potential that will guarantee good coagulation for every treatment plant. It will usually be between 0 and - 10 mV but the target value is best set by test, using pilot plant or actual operating experience. Once the target ZP is established, then these correlations are no longer necessary, except for infrequent checks. Just take a sample from the rapid mix basin and measure the zeta potential. If the measured value is more negative than the target ZP, then increase the coagulant dose (andvice versa). In this example a zeta potential of -3 mV corresponds to the lowest filtered water turbidity and would be used as the target ZP.
  • Synthetic Size Retention in Papermaking

  • Synthetic Size Retention in Papermaking

    The point of maximum size retention corresponds to a zeta potential of =4, which can be considered the optimum ZP. More positive or more negative values of the zeta potential cause a drop in the percent of size retained. Operating at the optimum value resultsin titanium oxide savings, improved sheet formation, increased wire life, improved sizing, pitch control, and biocide reduction.
  • Determining Point of Zero Charge

  • Determining Point of Zero Charge

    These experiments with alpha-alumina show good correlation between the point of zero charge as determined by zeta potential and the point of maximum subsidence rate. Subsidence rate is measure of the degree of coagulation.