Removal of ammonium from wastewater with geopolymer sorbents fabricated via additive manufacturing

Ceramic-like membranes without sintering via alkali activation of metakaolin, blast furnace slag, or their mixture: Characterization and cation-exchange properties

“…The ammonium concentration in the permeate increased during the first 30 min and stabilized to a value of ~40 mg L -1 corresponding to ~50 % rejection. However, the retentate ammonium concentration was higher than the initial concentration only for the first 30 min, which implies that ammonium was not rejected by the membrane but likely uptaken to the membrane structure via cation exchange (Franchin et al, 2020;Luukkonen et al, 2018bLuukkonen et al, , 2017aSanguanpak et al, 2021). Thus, the low-Ca membrane could be used as an ion-exchange membrane (Xu, 2005).…”

Performance and dynamic modeling of a continuously operated pomace olive packed bed for olive mill wastewater treatment and phenol recovery

“…The pressure drop is impacted by the beads bed thickness (i.e. column height), the bed porosity, as well as the frictional at the surface of the beads (Franchin et al, 2020). This pressure drop across the column increases approximately linearly with breakthrough time (Kratochvil et al, 1998).…”

Open-cell mullite ceramic foams derived from porous geopolymer precursors with tailored porosity

“…Meanwhile, the XRD pattern for the geopolymer sample was also collected. While the characteristic "hump" for the geopolymer gel from the XRD data cannot observed (Figs.S2(a) and S2(b) in the ESM) due to the strong peak for Al 2 O 3 , the typical broad characteristic hump for the MK located in the 2θ range of 2θ = 15°-35° disappeared, providing further evidence for the formation of the geopolymer gel as well[58,65,69]. Figure6(b)shows the open porosity and total porosity of the samples after sintering for different ion-exchange days.…”

“…The alumino-silicate network contains the mobile alkali ions bonded to charge balance sites, which can be replaced by other cations, endowing the material with new functionalities or/and improved properties [21,40]. References [65,66] show that the geopolymer has high affinity for 4 NH  , and the charge balancing Na + cations in the geopolymer aluminosilicate network can be exchanged by 4 NH  with an efficiency close to 100%. After the foam samples with the selected geopolymer formulation were produced, the ion exchange was carried out to obtain alkali-free ceramics by exchanging the alkali ions with ammonium ions.…”