Phosphate adsorption characteristics of ‘nanoclay’ separated from Indonesian volcanic tuffs

From an Indonesian volcanic tuff taken from parent material layer of Andisols profile, it was separated ‘nanoclay’ fraction <200 nm particle size. The exhibits pH-dependent charge characteristic due to the presence allophane in tuff. Therefore, can be utilized as a natural anionic adsorbent since its separation process conditioned proceed at pH <4.0. This study aims compare phosphate adsorption characteristics positively charged based on Langmuir, Freundlich, Brunauer-Emmett-Teller (BET), and Dubinin-Radushkevich (D‒R) isothermal models. using US Patent No. US2010/0187474 A1 procedure that modified this with addition HCl treatment. results showed after 48 h equilibration, application Langmuir D‒R model resulted capacity (qe para-meter) 460.78 (two-sites) 439.66 mg.g-1 (heterogeneous sites), respectively, while BET Freundlich respectively first adsorptive (qmono parameter) 111.11 (multilayers) constant (1/n 0.28. later indicated studied high-quality value 0.1-0.5). Limitations advantages each were discussed. However, best performance term linear equations highest R2 values obtained.