title: Clinoptilolite-based mixed matrix membranes for the selective recovery of potassium and ammonium.
abstract: A clinoptilolite-based mixed matrix membrane (MMM) was developed and studied for the selective recovery of ammonium and potassium. Adsorption of sodium (Na(+)), potassium (K(+)) and ammonium (NH4(+)) was investigated with single salt and equimolar salt solution under static and dynamic conditions. Furthermore, the adsorption capacity of clinoptilolite was investigated when embedded in the MMM and in clay form. Two conditioning methods were compared: HCl and NaCl. Conditioned clinoptilolite with NaCl gave higher static adsorption capacities than with HCl which alters the chemical structure of clinoptilolite. The adsorption of Na(+) was not detected in the static adsorption experiments and results showed that Na(+) adsorbed during the conditioning process it was exchanged by K(+) and NH4(+).The clinoptilolite embedded in MMM reduced the porosity of the MMM so the highest adsorption capacity was reached when the amount of polymer was the lowest: 30 wt% polymer and 70 wt% clinoptilolite. The application of MMM in a dead-end filtration cell (dynamic adsorption) resulted in higher adsorption capacities compared to static conditions and comparable results between synthetic solutions and diluted urine samples. This indicates that MMM is a suitable method for the recovery of K(+) and NH4(+) directly from a diluted urine matrix. The desorption (recovery) of K(+) and NH4(+) from MMM was higher using water at 60 °C than using an acidic treatment.
authors.affiliation: Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands; Wetsus, European Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8911 MA Leeuwarden, The Netherlands.
authors.forename: A
authors.initials: A
authors.lastname: Casadellà
authors.affiliation: Wetsus, European Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8911 MA Leeuwarden, The Netherlands.
authors.forename: P
authors.initials: P
authors.lastname: Kuntke
authors.affiliation: Wetsus, European Centre of Excellence for Sustainable Water Technology, P.O. Box 1113, 8911 MA Leeuwarden, The Netherlands.
authors.forename: O
authors.initials: O
authors.lastname: Schaetzle
authors.affiliation: Department of Polymer Chemistry, Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands. Electronic address: k.u.loos@rug.nl.
authors.forename: K
authors.initials: K
authors.lastname: Loos
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds / Q000302:isolation & purification* / Q000652:urine; D006801:Humans; D008567:Membranes, Artificial; D011188:Potassium / Q000302:isolation & purification* / Q000652:urine; D014865:Waste Disposal, Fluid / Q000379:methods*; D017641:Zeolites / Q000737:chemistry*
chemical_list: D064751:Ammonium Compounds; D008567:Membranes, Artificial; C083175:clinoptilolite; D017641:Zeolites; D011188:Potassium
keywords: Adsorption capacity; Clinoptilolite; Mixed matrix membrane; Nutrient recovery; Sodium removal