Synthesis of magnetic adsorbents from titanium gypsum and biomass wastes for enhanced phosphate removal.

[Display omitted] • Co-presence of biomass lowered TiG decomposition temperature below 700 °C. • TiG decomposition correlated well with organic volatiles of biomass wastes. • No hazardous gases were released during adsorbent preparation. • GC 10 had high P adsorption (183 mg/g) and perfect magnetic separation property. • P adsorbed on GC 10 was plant-available and could be slowly released. A novel scheme was proposed to prepare magnetic adsorbents by co-pyrolysis of titanium gypsum (TiG) and agricultural biomass wastes for phosphate (P) recovery. Co-presence of biomass wastes could improve TiG decomposition in inert atmosphere to generate magnetic centers and active sites, and P adsorption correlated well with organic volatiles of biomass wastes. The adsorption process evolved from a biomass-controlled process to a TiG-controlled process when increasing the mass ratio of corncob above 10 %. The optimal adsorbent (i.e. GC 10) exhibited higher P adsorption capacity (Q m 183 mg/g) than many previous adsorbents; moreover, it can be magnetically separated from water after P adsorption. Active sites including CaO, CaS and Fe 3 O 4 were deemed as the main factors for P chemisorption and surface precipitation. Most of adsorbed P could be released continuously and slowly by dilute NaHCO 3. These results highlight potential applications of TiG and biomass waste derived adsorbents in P purification and recovery. [ABSTRACT FROM AUTHOR]