Effective adsorption of phosphoric acid by UiO-66 and UiO-66-NH 2 from extremely acidic mixed waste acids: Proof of concept
Journal
Journal of the Taiwan Institute of Chemical Engineers
Journal Volume
96
Pages
483-486
Date Issued
2019
Author(s)
Abstract
Streams of waste mixed acids from conventional wet etching processes contain high levels of H 3 PO 4 , which warrant recycling. This investigation is the first to use metal organic framework UiO-66 and UiO-66-NH 2 to adsorb phosphoric acid from waste mixed acids from the world's largest semiconductor foundry, a synthetic HNO 3 [sbnd]H 3 PO 4 [sbnd]HAc mixture, and 85% phosphoric acid. Both UiO-66 and UiO-66-NH 2 have high capacities to adsorb H 3 PO 4 in extremely acidic solutions. The Langmuir adsorption capacities (q max ’s) of UiO-66 for waste mixed acids and a synthetic HNO 3 [sbnd]H 3 PO 4 [sbnd]HAc mixture on UiO-66 at 25 °C are 3360 and 8,510 mg-H 3 PO 4 /g, respectively, and that of 85% phosphoric acid on UiO-66 is 4,790 mg-H 3 PO 4 /g. The q max of UiO-66-NH 2 for phosphoric acid from 25% to 75% waste mixed acids is 4550 mg-H 3 PO 4 /g, which exceeds that of UiO-66. The corresponding P:Zr ratio for adsorbed MOF is in the range 6.2‒13.5, suggesting that the tested MOF crystals are super-adsorbents of phosphoric acid under extremely acidic conditions.
Type
journal article