wAbstract
@Studies concerning competitive sorption of anions on oxidic materials
eligible to be used as soil amendments are crucial for a better
understanding of the adsorbent's effectiveness and ion mobility/availability
in the environment. This study evaluated mono-/multi-element adsorption
of phosphate and arsenate on aluminum (AMB) and iron mining by-products
(IMB; used for comparison) and measured the effect of pH and thermal
pretreatments on P and As adsorption on AMB and IMB. We also evaluated
whether the desorption of As previously adsorbed on AMB and IMB
increases with the addition of increasing doses of P. For adsorption,
each adsorbent was reacted at selected pHs with solutions containing
As and P individually or in combination. Non-competitive desorption
was performed with 30 mmol L-1 NaCl. Arsenate displacement
was evaluated by reaction of the adsorbents obtaining previously
adsorbed As with P-containing solutions. The competition between
P and As decreased the adsorption of these anions by 2.7 and 23.3,
respectively. Increasing pH decreased adsorption of both As and
P, whereas the thermal pretreatment increased P adsorption by
40 and As adsorption by 15. Phosphate in solution increased
As desorption, with each millimoles per kilogram of adsorbed P
desorbing as much as 2.3}1.1 mmol kg-1 of As.
Keywords: Anions; Adsorption; Displacement; Redmud; Thermal pretreatmentsx
Abbreviations
1. Introduction
2. Materials and methods
3. Results and discussion
@3.1. Characterization
@3.2. Mono- and multi-element adsorption and desorption
@@3.2.1. Comparison between aluminum and iron mining by-products
@@3.2.2. Effect of thermal pretreatment and pH on arsenate and
phosphate adsorption and desorption by aluminum mining by-product
@3.3. Arsenate displacement by phosphate
4. Conclusions
Acknowledgments
References