title: Preparation of bioinorganic fertilizing media by adsorption of humates on glassy aluminosilicates.
abstract: Surface-modified expanded perlite was synthesized using humic substances from the Megalopolis peaty lignite. Adsorption is efficient and increases at higher temperatures and lower pHs. The preparation can be carried out under mild conditions leading to an eco-friendly, bioinorganic material useful as soil conditioner and biofertilizer. Six adsorption models were applied; the Klotz, Freundlich and Redlich-Peterson isotherms fit more successfully to the experimental data. The obeying of the theoretical models was correlated with the heterogeneity and non-uniform distribution of the adsorption sites, host-guest attraction forces as well as the formation of self-assembled aggregates and self-organized multilayers of humic substances onto the aluminosilicate adsorbent, consistent with changes in micromorphology. Thermodynamic quantities revealing distinct physicochemical characteristics of the adsorption phenomena, i.e., enthalpy, entropy and free energy change, were calculated. Desorption experiments and cultivation of microorganisms demonstrated that perlite may act successfully as host material for microbial populations upgrading the humic-loaded perlite for soil applications.
authors.affiliation: Inorganic Chemistry Laboratory, Department of Chemistry, University of Athens, Panepistimiopolis 157 71, Athens, Greece. chassapis@chem.uoa.gr
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Chassapis
authors.forename: Maria
authors.initials: M
authors.lastname: Roulia
authors.forename: Evangelia
authors.initials: E
authors.lastname: Vrettou
authors.forename: Anastassios
authors.initials: A
authors.lastname: Parassiris
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D000538:Aluminum Silicates / Q000737:chemistry*; D015169:Colony Count, Microbial; D005308:Fertilizers; D005898:Glass / Q000737:chemistry; D006812:Humic Substances; D006863:Hydrogen-Ion Concentration; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide / Q000737:chemistry*; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology
chemical_list: D000538:Aluminum Silicates; D005308:Fertilizers; D006812:Humic Substances; D012987:Soil; C003076:Perlite; C049037:aluminosilicate; D012822:Silicon Dioxide; D000537:Aluminum Oxide