Ultrafiltration of Humic Acid Solution: Effects of Self‐dispersible Carbon Black and Cations

Abstract

Effects of carbon black (CB) addition on membrane fouling and rejection of macromolecular humic acids (HA) were evaluated by a stirred‐cell ultrafiltration unit. Stable CB dispersions increased filtration resistances, but enhanced HA rejection by the membranes. Monovalent and divalent ions affected the filtration resistance of CB solution differently; namely, NaCl solution showed a very high resistance due to the concentration of CB in the diffusion boundary layer near the membrane surface, whereas CaCl₂ and MgCl₂ solutions showed only cake resistance. The cake layer containing both CB and HA was more easily removed from the membranes than HA‐cake layer.

Keywords:

• Carbon black
• humic acids
• ultrafiltration
• aggregation
• fouling

Acknowlegdment

This study was partially supported by the 21st century COE‐ Research Project on Sustainable Urban Regeneration provided by the Ministry of Education, Culture, Sports, Science, and Technology (MEXT), of the Japanese Government.