Adsorption of arsenic ions on Brazilian sepiolite: Effect of contact time, pH, concentration, and calorimetric investigation

• Published in: Journal of colloid and interface science Vol. 346; no. 1; pp. 178 - 187
• Main Authors: Guerra, Denis L., Batista, Adriano C., Corrêa da costa, Paulo C., Viana, Rúbia R., Airoldi, Claudio
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01-06-2010; Elsevier
• Subjects: Adsorption; Arsenic; Arsenic - chemistry; Brazil; Calorimetry; Chemistry; Clay (material); Colloidal state and disperse state; Dynamical systems; Exact sciences and technology; General and physical chemistry; Hydrogen-Ion Concentration; Ions - chemistry; Magnesium Silicates - chemistry; Porous materials; Sepiolite; Surface chemistry; Surface physical chemistry; Surface Properties; Time Factors; Calorimetry; Arsenic; Adsorption; Sepiolite; Clay; Scanning electron microscopy; Adsorption isotherm; Glass; Ions; NMR spectrometry; Nitrogen; Porous material; Thermodynamics; Dynamics; pH; Aqueous solution; Adsorbent; Room temperature; Functional group
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2010.02.041

This investigation reports the use of original and modified sepiolite as alternative absorbents. The compound 2-aminomethylpyridine was anchored onto Amazon sepiolite surface by heterogeneous route.
The original sepiolite clay mineral has been collected from Amazon region, Brazil. The compound 2-aminomethylpyridine (AMP) was anchored onto Amazon sepiolite surface by heterogeneous route. The natural (SPT) and modified (SPT
AMP) sepiolite samples were characterized by elemental analysis, SEM, N
2 adsorption, and nuclear magnetic nuclei of
29Si and
13C. The well-defined peaks obtained in the
13C NMR spectrum in the 0–160
ppm region confirmed the attachment of organic functional groups as pendant chains bonded into the porous clay. The ability of these materials to remove As(V) from aqueous solution was followed by a series of adsorption isotherms at room temperature and pH 4.0. The maximum number of moles adsorbed was determined to be 7.26
×
10
−2 and 11.70
×
10
−2
mmol
g
−1 for SPT and SPT
AMP, respectively. In order to evaluate the clay samples as adsorbents in dynamic system, a glass column was fulfilled with clay samples (1.0
g) and it was fed with 2.0
×
10
−2
mmol
dm
−3 As(V) at pH 4.0. The energetic effects caused by metal cations adsorption were determined through calorimetric titrations. Thermodynamics indicated the existence of favorable conditions for such As(V)–nitrogen interactions.