Abstract
A novel composite adsorbent of Fe loaded biomass char (Fe-BC) was fabricated to treat phosphorus in water. Fe-BC was prepared by a procedure including metal complex anion incorporation and precipitation with the pyrolysis char of corn straw as supporting material. The abundant porous structures of the as-prepared sample can be easily observed from its scanning electron microscopy (SEM) images. Observations by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses show that inorganic nanoiron oxides deposited in the composite could be amorphous hydrous iron oxideα-FeOOH. Adsorption of phosphate onto the Fe-BC composite and its precursor (BC) from aqueous solutions were investigated and discussed. The equilibrium adsorption data of phosphate was described by Langmuir and Freundlich models, and Langmuir isotherm was found to be better fitted than Freundlich isotherm. The maximum phosphate adsorption capacity for phosphate of Fe-BC was as high as 35.43 mg/g, approximately 2.3 times of BC at 25°C. The adsorption kinetics data were better fitted by pseudo-second-order model and intraparticle diffusion model, indicating that the adsorption process was complex. The Fe-BC composite has been proved as an effective adsorbent of phosphate from aqueous solutions owing to its unique porous structures and the greater Lewis basicity of theα-FeOOH.
Highlights
Phosphorus is considered as the main culprit of lake eutrophication [1]
Adsorption isotherms and the kinetics of phosphate adsorption on the composite adsorbents were compared with its precursor and some similar absorbents from literature; the results show that the synthesized Fe loaded biomass char (Fe-Biomass char (BC)) is a promising absorbent for phosphate with remarkably high adsorption capacity
The BC sample with very high BET surface area (434.7 m2/g) and narrow pore size distribution (Figure 1), its average pore diameter is about 3.5 nm
Summary
Phosphorus is considered as the main culprit of lake eutrophication [1]. Excess phosphorus will stimulate the algal blooms, causing deterioration of water quality [2]. Human activities dramatically increased the loads of phosphate in environment and its cycling rate on Earth, such as the production and application of a plenty of detergents, agricultural pesticides, and fertilizers [3]. The increased amount of phosphorus in water bodies poses greater potentials to the occurring of eutrophication. High effective methods for the removal of phosphate from wastewater need to be established. The difficulties of excessive sludge handling and cost of added chemical materials would hinder its widespread application. Other effective phosphorus removal techniques such as ion exchange and electrodialysis encountered difficulties of complicated management and high cost. Adsorption has been regarded as one of the most effective and economical methods for the removal of phosphorus. Numerous studies have been conducted for this purpose, such as activated alumina [4, 13], metal oxide hydroxides [14,15,16,17,18,19,20,21], hydrotalcite [22], palygorskite [23, 24], zeolite [13, 25,26,27], slag [28,29,30,31] and layered double hydroxides
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