Adsorption kinetics, capacity and mechanism of arsenate and phosphate on a bifunctional TiO2–Fe2O3 bi-composite

Fe/Ti co-pillared clay for enhanced arsenite removal and photo oxidation under UV irradiation

“…After 60 min, the adsorption capacity barely changed, indicating the attainment of equilibrium. The adsorption rate in this study is consistent with previous work for arsenic adsorption onto mixed oxide TiO 2 -Fe 2 O 3 bi-composites [31]. The rapid adsorption in the beginning can be attributed to the greater concentration gradient and more available sites for adsorption [10].…”

“…A pseudo-second-model for the kinetic data suggested that the adsorption process might be caused by chemisorption. Previous studies also reported that the pseudo-second-order model correlates well with the experimental data for As(III) on Mn-Al mixed oxide [37], As(V) on TiO 2 -Fe 2 O 3 bicomposite [31], and As(V) on Al 13 -modified montmorillonite [13]. It is likely that oxy-anions are immobilized by forming a mixture of surface complexes between arsenic and Fe-Ti/MMT.…”

Removal of arsenate by cetyltrimethylammonium bromide modified magnetic nanoparticles

“…The positively charged CTA + (cationic part of CTAB) present on the surfaces of Fe 3 O 4 could attract the negatively charged As(V) anions and thus CTA-As(V) complex would be formed. The total adsorption capacity of Fe 3 O 4 @CTAB is found to be 23.07 mg g −1 , which is more than four times of Al 13 -modified montmorillonite (5.008 mg g −1 ) [35], about three times of iron-impregnated tablet ceramic adsorbent (8.49 mg g −1 ) [36], and around two times of TiO 2 Fe 2 O 3 bi-composite (12.14 mg g −1 ) [37]. The adsorption capacity of Fe 3 O 4 @CTAB for As(V) is similar to iron(III) oxide coated ethylenediamine functionalized multiwall carbon nanotubes (23.47 mg g −1 ) [38], yet the cost of Fe 3 O 4 @CTAB is less.…”

Dual-Enhanced Photocatalytic Activity of Fe-Deposited Titanate Nanotubes Used for Simultaneous Removal of As(III) and As(V)

“…It has previously been established that −OH groups play a major role in As(V) adsorption, with complexation the adsorption mechanism. [46][47][48] Figure S10 in the Supporting Information illustrates the difference between the two main complexation processes: bidentate complexation does not introduce -OH groups whereas monodentate complexation replaces a single -OH by two -OH groups from As(V). For adsorption of As(V) by Fe-TNTs, the -OH percent further increased to 32.5% after adsorption, suggesting monodentate complexation of As(V) must have occurred in the adsorption process.…”