Influence of Ph and Dispersant Sodium Hexametaphosphate in Rheology of Suspension of the Clay From Icoaraci-Pará-Amazonia

Abstract

Handmade pottery production is one of the most important economic activities at the District of Icoaraci in the state of Para, Northern Brazil. Aiming to add value to products manufactured in that region as well as to increase its productivity, mineralogical and chemical characteristics of the clay were studied, such as the influence of pH in rheology of clay suspensions according to Van Raij and Peechmethodology to determine the zero point of charge (ZPC-pH) of those suspensions. The results demonstrated that potassium nitrate (KNO3) can be used as an indifferent electrolyte of clay suspensions, suspension particles are dispersed at pH values over 3.8, and lower viscosity values are obtained, which improves clay processing. At the natural value of pH clay suspensions can be easily processed by adding sodium hexametaphosphate as dispersant at the concentration of 2.2 %, considered to be the ideal concentration of that dispersant in clay suspensions.