Recovery of orthophosphate ions from aqueous solutions using La/GO composites

Autor: Shan-Shan Chu, 朱珊姍
Rok vydání: 2019
Druh dokumentu: 學位論文 ; thesis
Popis: 107
Graphene oxide (GO)/Lanthanum oxide (La2O3) composites (abbreviated as La/GO) were employed as adsorbents to study the removal of orthophosphate (PO43-) from industrial effluents. The effects of different adsorbents and composite ratio for PO43-adsorption was first investigated. The adsorption performance under various water quality factors and the adsorption/desorption operations were then studied. La/GO showed the best performance on PO43- adsorption as compared to other adsorbents. The adsorption amounts of PO43- were 49.94 and 148.44 mg/g with initial concentrations of 50 and 200 mg/L, respectively. The adsorption amounts of PO43- increased as the solution ionic strength increased but decreased as the solution pH value decrease probably due to the increase of H+ which enhances the surface positively charged surface of La/GO. In the alkaline conditions, the adsorption amounts of PO43- decreased probable because of the competitive adsorption between PO43- and OH-. In the temperature experiments, PO43- is easily adsorbed in the high temperature indication that adsorption process is endothermic. From the results of Langmuir model, adsorption of PO43- to La/GO surface is s monolayer adsorption. Thermodynamics indicate that adsorption process is spontaneous. Desorption results indicated adsorbed PO43- on La/GO could be readily desorbed by NaOH solution and could be employed in the cyclic recovery with adsorption/desorption of PO43- from wastewater. In summary, the La/GO composites possess good performance for adsorption/desorption of PO43-and possibly become promising adsorbents for PO43- recovery in wastewater treatment of high-tech industrial effluents.
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