Synthesis of a novel Fe–Mn binary oxide‐modified lava adsorbent and its effect on ammonium removal from aqueous solutions

Abstract

Ammonium is strongly related to eutrophication and a key control of eutrophication in aquatic systems, especially in agricultural runoff. In this study, a novel Fe-Mn binary oxide-modified lava (FMML) granular adsorbent was synthesized for ammonium removal from aqueous solutions by co-precipitation method. The kinetic data were described by pseudo-second-order kinetic model well and intraparticle diffusion had effects on ammonium adsorption. For pH between 4.0 and 10.0, the adsorption efficiency was >80%, and its optimum was recorded at pH 7.0. FMML exhibited strong ammonium adsorption selectivity under the single presence of cations like Na + , K + , Ca 2+ , and Mg 2+ . The optimum adsorbent dose and particle size were 4 g/L and 3-5 mm, respectively, for an aqueous solution containing 10 mg/L of ammonium under normal conditions (298 K and pH 7.0). Furthermore, the adsorption process was endothermic, following both the Langmuir (R 2 > 0.98) and Freundlich (R 2 > 0.96) models. Compared with other adsorbents, the FMML can be prepared following a simpler protocol. After 30 times of adsorption-regeneration cycle, the FMML also had a relatively high ammonium adsorption capacity; hence, we see it as a prospective adsorbent for ammonium adsorption from aqueous solutions. © 2019 Water Environment Federation • Practitioner points• Fe-Mn binary oxide-modified lava with Fe/Mn ratio 3:1 was prepared using co-precipitation method. • Adsorption maximum of modified lava was 20.8 mg/g (298 K and pH 7.0). • Adsorption was sensitive to changes in adsorbent dose, particle size, and pH. • Inorganic cations decreased ammonium adsorption in order of Na + > K + > Ca 2+ > Mg 2+ . • Mechanisms for ammonium removal by FMML include diffusion, electrostatic attraction, oxidation, and complexation reaction.

Editorial

“…This issue of Water Environment Research features 12 illuminating articles describing a range of studies of immediate relevance to water/wastewater professionals. The far‐reaching issue of nutrient removal was approached from several different angles, including evaluations of physicochemical adsorption using novel adsorbents comprised of naturally derived/recycled materials such as metal‐amended lava (Sadeghi Afjeh, Bagheri Marandi, & Zohuriaan‐Mehr, 2020) and biochar composites (Zhao et al, 2020). Naga Babu, Srinivasa Reddy, Suresh Kumar, Ravindhranath, and Krishna Mohan (2020) also employed biochar for contaminant adsorption from wastewater, with a focus on the removal of inorganic aluminum and fluoride using a combination of experimental results and factorial statistical modeling.…”