Recent advances in hexavalent chromium removal

Overview

This source page is a mechanical bulk-ingest record for a PDF in the research-pulls corpus. It preserves source-level identity, routeable product/analyte scope, and exact extracted numeric lines for later human or fresh-context audit. It does not derive HMTc thresholds, percentiles, or brand-by-brand comparisons.

Key numbers

The worker extracted the full PDF text with layout preservation twice and compared extraction hashes before commit. The following lines are copied from numeric/table-bearing regions of the PDF and retain the source units and wording where legible:

have been used as building blocks of other adsorbents in area. Promising Cr(VI) removal eﬃciency of 70% from water
composite manufacturing. As high as 539.53 mg g1 adsorption solution having a salinity of 20 000 ppm adjusted to pH 7 was
tists to investigate their potential application in the elimination and 103% from lake, rain, and river water were reported for
99.94% removal eﬃciency was obtained63 while 3 g L1 adsor- 3. Toxicity of chromium
reported using the two plant species ranged from 54% (Phrag- groups is paramount for optimal performance.
mites australis) to 70% (Helianthus annuus).85 A simple conver- 4.2.1. Synthetic polymer-based adsorbents. Recently, the
cavities mimicking the shape, charge, size, and functionality of water with a limit of detection (CLOD ¼ 3Sb/m) of 0.29 ng mL1.
nanomaterials can be accessed from ref. 42. pH ranged from 2.5–5 due to electrostatic attraction between
been utilized as supports for numerous applications.68–70 In range of 1.0–6.0, and when the pH exceeds 7, CrO42 is formed
achieved 92% Cr removal eﬃciency within 70 min that was
photocatalysis.161 The composite adsorbed 80% Cr(VI) recent studies have reported three mechanisms all taking place
species of Cr(VI) over the pH range (1–14), where at pH ¼ 3.0 for electrostatic attraction of chromate anions to the adsorbent’s
4.4. Re-usability of hexavalent chromium adsorbents polypyrrole was reported.162 As shown in Table 1, the sand-
presented in Table 1, it is clearly shown that some chromium
popular.15,23,30,65,158,167 The choice of the desorbing agent used in adsorption capacity values (Table 2). However, in our opinion,
these groups and HCrO4.148 In Table 1, the number of repeated adsorption as well as shaking versus stirring; all these give
use shown indicate the minimum re-usability experiments diﬀerent adsorption capacities. Table 2 depicts the diﬀerent
Table 1 Re-usability of adsorbents for removal of Cr(VI) from aqueous solutions
AC of Cornulaca monacantha 5 89% adsorption eﬃciency Desorption was carried out 173
ZnO tetrapods and AC based 3 Cr removal eﬃciency > 90% Washed with 0.1 mol L1 65
AC modied with micro- 4 Cr removal eﬃciency > 75% Washed with HCl solutions 174
Nanocomposite adsorbent 5 >80% adsorption eﬃciency Washed with deionized 64
Tetraethylenepentamine 5 30 (% removal exceeded 100 mL of NaCl (1 M)/ 177
functionalized alginate 80%) ethanol (98%) solution
percentage removal of the pollutant is minimal (20%) while the ported in Table 2 show that researchers are now able to develop
60 mg L1 was removed (20%) and 240 mg L1 concentration of progress indeed. However, biomass adsorption capacities are
Table 2 Comparison of adsorption capacities from various adsorbents for Cr(VI)
while the adsorption capacity decreases. Adsorption rate also examples include eggshell powder,189 orange peels,190 coﬀee
by approximately 30% aer the third adsorption/desorption carried out. Functionalization could be achieved by cross-
consecutive biosorption of Cr(VI) and Orange II onto 2640-2.

Methods (brief)

from environmental samples. Amongst the removal techniques reported in the literature, adsorption
avalent chromium (Cr(VI)) from environmental samples have aqueous solutions.1,2 A plethora of adsorbents of diﬀerent
compounds in environmental samples include seepage or Some adsorbents are used as scaﬀolds to generate new mate-
X-ray spectroscopy and X-ray photon electron spectroscopy removal. Cellulose modied with b-cyclodextrin and quaternary
lyte as a template during synthesis resulting in a polymer with were evaluated with real samples, tap water, lake water and river
cavities mimicking the shape, charge, size, and functionality of water with a limit of detection (CLOD ¼ 3Sb/m) of 0.29 ng mL1.
acid mine drainage water sample compared to its control (non- adsorption capacities and selectivity with their materials. This
tion.15,16,29,30 Atomic absorption spectroscopy can be used to
how the prepared adsorbent will perform in real-world samples
between positively charged adsorbent surface groups and include removal of Cr(VI) from water samples using m-
as rock wool.4 The application of these adsorbents in water solution with atomic absorption spectroscopy does indicate the
reported adsorbents in real samples such as industrial waste- nanoparticle, and silica are known for their high surface area
chromium removal from water, Int. J. Biol. Macromol., plasma mass spectrometry, Talanta, 2019, 195, 173–180,
58 R. Bhatt, B. Sreedhar and P. Padmaja, Chitosan in situ studies by X-ray and neutron scattering, Chem. Soc.
human urothelial cells, Toxicol. Appl. Pharmacol., 2016, solution using functionalized poly (GMA-co-EGDMA)-gra-
of Cr(VI) from environmental samples, Pure Appl. Chem., Aspergillus niger, Water Res., 2005, 39, 533–540, DOI:
Cr(VI) in water samples, Talanta, 2017, 162, 345–353, DOI: 57–66, DOI: 10.1016/j.biortech.2013.12.037.
111 N. M. Rane, S. V. Admane and R. S. Sapkal, Adsorption of j.powtec.2019.06.020.

Implications

This page makes the source discoverable for category-level evidence routing. Values remain source-native and should be used only with the stated matrix, species, basis, geography, and censoring context from the paper. The page does not convert total mercury to methylmercury or use total arsenic as inorganic arsenic.

Wiki pages this source may touch

Verification notes

Identity check: DOI, raw handle, candidate cite-key, and SHA-256 were compared against existing wiki/sources/ pages before creation.
Full-PDF read: pdftotext -layout was run on the full PDF twice; extracted text hashes matched before the page was written.
Numeric verification: numeric/table-bearing lines were selected mechanically from the verified extraction and preserved without unit conversion or rounding.
Brand firewall: the worker skips PDFs when extracted numeric lines appear brand/manufacturer-sensitive; this page contains category-level or species-level evidence only.
HMTc firewall: no threshold, percentile, pass/fail, clean/dirty, or certification math is stated.

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