Meso- and macroporous silica-based arsenic

Overview

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Key numbers

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oxides,5,24 carbon nanotubes,5,24,25 and nanoparticles ically and chemically stable under adsorption test conditions.
considered. In this framework, iron oxide NPs can be grown removal from 15% w/w iron oxide-based mesostructured (15Fe-
stable at acidic pH, and preventing the leaking and the aggre- inuence in batch tests. The iron oxide-SBA-15 composite has
in composites with TiO2,50 CoFe2O4,36 MnO2,37 CuO,38 and Pluronic 123 (P123), hydrochloric acid (37% w/w), sodium
Fe2O3.39 Mesostructured silica has also been applied for water acetate (NaAc, 99% w/w), sodium sulfate (99.2% w/w), and
remediation with several organic functional groups, especially toluene (99.7% w/w) were purchased from VWR International
thiol40–43 and amino functionalities,44–49 revealing high perfor- S.r.l. Acetic acid (HAc, 99.8% w/w) and tetraethyl orthosilicate
mance and easy regeneration. In addition, macroporous silica (TEOS, 98% w/w) were purchased from Aldrich. 3-Amino-
(macroporous ordered siliceous foams, MOSF)51–61 has been propyltriethoxysilane (APTES, 97%), ethanol (96% w/w), iron(III)
used as a support, sometimes coupled with mesopores.62,63 The nitrate nonahydrate (98% w/w), and n-hexane (97% w/w) were
ingoing water as a potential column material. Indeed, despite ments, arsenic(V) standard solution (10 000 mg mL1 As in 10%
blockage and uneven distribution within the pores, aﬀecting ppb, specic resistance of 0.741 mS cm1) was used.
1.65 mL of APTES (97%) was added to the mixture and stirred at
a 15 mL test tube together with 2 mL of nitric acid 20% w/w, and
The plotted data qt vs. Ct was then tted by the pseudo-rst using a PerkinElmer STA 6000, in the range 25–850 C, with
the adsorption data in the p/p0 range 0.05–0.17.31 Total pore
where K0 and K00 are the psuedo-1st order and pseudo-2nd order volume was calculated at p/p0 ¼ 0.875, while mean pore diam-
(4 mL) 4 mL of water and 1 mL of a 20% w/w nitric acid was NaOH to modify the pH from 2 to 9. The scattering cell
spheroidal particles with sizes in the 150–1000 nm range are
based circularity factor of around 0.5 for both samples (Table
of SBA15 is conrmed by the distinct step in the range 0.6–0.8 p/ Fe2O3 NPs in the two most common crystalline phases, hema-
Table 1 Surface area (SBET), pore volume (PV), calculated pore diameter by density functional theory (DFT) ﬁt method (Dp (DFT)) and Barrett–
composites, an attempt was carried out taking into account the walls were not aﬀected (Table 1). The presence of a bimodal
is the primary phase (60–70%), and both phases are in the form SBA15 can be justied due to the presence of small NPs instead
matrix, as evidenced by TEM. The presence of maghemite is also to 219 m2 g1 (Fig. 1d and Table 1).
HRTEM image reported in Fig. S8.†72,73,86–88 SE-SEM (Fig. S4†) and image analyses (Fig. S5 and Table S1†)
primary component (70–80%), as conrmed by the tentative and MOSF aer the deposition of Fe2O3 are shown in Fig. 3a and
Table S2†). The results suggest for both samples, the presence The honeycomb architecture of the macropores of the MOSF
content in the nal sorbent is 15% w/w, as assured by the
component (60–80%) in the form of very small NPs (3–6 nm),
Table S4 and Fig. S11†) revealed a higher adsorption capacity at Radushkevich models are not suitable, while the best tting is
probably as a consequence of the interplay of more reactive SBA15 (0.96 instead of 0.98) samples, meaning that more than
literature, the eﬀect of the size of NPs on the As(V) adsorption for rst points in Fig. 5 in all experimental curves (range of Ce
CHN analyses permitted us to evaluate 2.5% of NH2 groups and Among the tested adsorbents, better performances for the
water, while the second one, of about 10% weight loss and also other authors have reported a qm act (qm of the active phase)
z3450 cm1, H–O–H bending mode at z1630 cm1), and the that mesostructured materials are more suitable to disperse
range (pH 3–9), as indicated by the zeta potential vs. pH the APTES groups. Indeed, for the iron oxide modied silica,
in Table S5† (Fig. S15† for the corresponding pH values). The SBA15 and APTES-SBA15 sorbents in the contact time range
data were tted by diﬀerent isotherm models, as indicated in 10–1140 min (initial As(V) concentration 10 mg L1) (Table S6†).
the experimental section (Table 2): Langmuir (eqn (2)), The qt vs. t plots (Fig. 6a) were tted with the pseudo 1st and 2nd
testing only 40% of arsenic is removed. The pseudo 1st order increasing initial arsenic concentration. This behavior suggests
(ki) of almost one order of magnitude higher (Table 3). and under all adsorption conditions (from 23 to 107 mg L1)

Methods (brief)

as the most promising sample for As(V)-removal. The amino-functionalized SBA15 adsorbent (3-
adsorbent platform. Nevertheless, the role of the diﬀerent Synthesis of SBA-15. The SBA-15 sample was synthesized
Synthesis of MOSF. The MOSF sample was synthesized ðC0 Ce ÞV
work.72,73 2.0 g of dried silica sample (120 C for 48 h in air) was In the Freundlich isotherm model (eqn (3)), KF is the
analyzed by ICP-OES. The model is used to diﬀerentiate between physisorption
ðC0 Ct ÞV ethanol dispersion of the sample on a 200-mesh carbon-coated
Autosorb iQ MP from Quantachrome Instruments. The samples
t 1 t from Malvern. An 8 mm3 sample was applied to a glass plate
qt K qe2 qe2 with the sample dispersion unit (SDU) with low energy. The
Germany). For this purpose, the samples were xed with
double-sided adhesive carbon tape on an aluminum pin sample
optical emission spectrometry (ICP-OES) using an iCAP 7400 were carried out with an acceleration voltage of 6 keV at
(1 mg L1), Fe (1 mg L1); standard 7: As (0.5 mg L1); standard the data. The sample was prepared by suspending the
8: As (0.1 mg L1); standard 9: As (0.05 mg L1). To each sample composites (5 mg mL1) in distilled water and adding HCl and
The sorbent samples were characterized by small-angle and
structure COD ID used for the renement is 1 010 369.84 Wall TEM, and SEM. The SA-XRD patterns of the bare SBA15 sample
contrary, the bare MOSF sample featured a type II isotherm
SBA15, and about 150 mm for the MOSF sample, with a number-

Implications

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Update history

The five most recent substantive edits to this page, classified major (evidence or structure moved), correction (a published value or statement was wrong and has been fixed), or minor (narrative rewritten without changing the underlying evidence). Each description is derived from what the edit did to this page; the linked commit is the authoritative record, routine regeneration passes are excluded, and the full version history lives in git. When DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.

Commit	Date	Change	Description
b01ec52c	2026-08-04	major	2 sections added
d49e450f	2026-08-03	major	5 sections added; narrative text revised