Recovery of phosphate from aqueous solutions using calcined eggshell as an eco-friendly adsorbent
authors Santos, AF; Arim, AL; Lopes, DV; Gando-Ferreira, LM; Quina, MJ
nationality International
journal JOURNAL OF ENVIRONMENTAL MANAGEMENT
author keywords Phosphorus; Phosphate; Adsorption; Calcined eggshell; Fixed-bed; Germination index
keywords PHOSPHORUS REMOVAL; WASTE-WATER; ADSORPTION; KINETICS; THERMODYNAMICS; MEMBRANE; SORPTION; METALS; MODELS; LEAD
abstract Phosphorus scarcity has become a significant issue in the European Union (EU) during 21st Century, due to its relevance as an irreplaceable macronutrient for life, and because of the total dependency of EU regarding imports. This work aims to evaluate the phosphorus recovery by adsorption in batch and fixed-bed column, using a thermally modified eggshell as an adsorbent. The screening phase revealed that calcined eggshell at 700 degrees C (CES700) is the most suitable material compared with the other thermally modified eggshells tested. Thus, CES700 was characterized regarding the specific surface area, pore volume, zero-point charge pH, total dissolved solids and organic matter. The influence of pH and adsorbent dosage was investigated in batch conditions. Langmuir-Freundlich model described the equilibrium data and the maximum adsorption capacity was about 39 mg P-PO4/g. The kinetics follows a pseudo-first order model, with constants between 0.063 and 0.224 min(-1). Fixed-bed studies indicated that increasing fluid superficial velocity and feed concentration led to an early saturation of the adsorbent. Yoon-Nelson, Thomas and Bohard-Adams empirical models properly adjusted the breakthrough curves with R-2 >= 0.98. Germination tests using CES700 loaded with phosphate revealed a germination index of 120 and 124% to 48 and 72 h, respectively. CES700 is statically better than the other tested materials, which opens the possibility of its use as fertilizer. This study showed that the developed material, CES700, can be applied in batch or fixed-bed processes to recover phosphate ions from liquid effluents, and the loaded adsorbent has potential to be further used as fertilizer.
publisher ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
issn 0301-4797
year published 2019
volume 238
beginning page 451
ending page 459
digital object identifier (doi) 10.1016/j.jenvman.2019.03.015
web of science category Environmental Sciences
subject category Environmental Sciences & Ecology
unique article identifier WOS:000464296400048
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journal analysis (jcr 2017):
journal impact factor 4.005
5 year journal impact factor 4.449
category normalized journal impact factor percentile 80.372
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