Opening and blocking the inner-pores of halloysite.

Aggregation and dispersion behaviours of halloysite nanotubes (HNTs) were influenced by pH. The meso- and micro-porosity of halloysite were determined by N2 gas physisorption. The blocking and opening of halloysite nanotube pores with acid, neutral, and base treatment were detected in a micro- and mesoporous matrix of tunable porosity. The inner pores of HNTs were opened with base treatment, but were closed with acid or neutral treatment.