H2 SO4 charring modiﬁcation due to cross-linking reaction of betel nut cellulose, thereby creating suitable complexation sites for

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:

H2 SO4 charring modiﬁcation due to cross-linking reaction of betel nut cellulose, thereby creating suitable complexation sites for
BaCrO4 precipitate (WHO, 0.05 mg/L) using charred BNW (CBNW). The negative value of ΔG◦ evaluated for all the temperatures
notably reduced Cr(VI) uptake capacity of CBNW. More than 98% of adsorbed Cr(VI)
est concentration of Cr(VI) levels as 0.05 mg/L in drinking water (9, biosorption research for Cr(VI) removal is carried out in batch mode
barium chloride solution. g/L by using 0.56 mmol/L (29.54 mg/L) of Cr(VI) solution. The samples
mg/L) was prepared by dissolving 1.415 g of K2 Cr2 O7 in a 500 mL 𝑊
range of 0 to 80◦ using an X-ray diﬀraction spectrometer (Rigaku Co., of Cr(VI) solution (150 mg/L i.e., 2.89 mmol/L) at pH 2 and agitated
the stable pink color complex when 1,5 diphenyl carbazide was mixed pared to HCl and NaCl. NaOH desorbed 99.72% whereas it was only
34.21%) even using 5M HCl, thus further optimization was carried out
( 𝑛 2) suitable for the adsorption reaction if it is amorphous compared to crys-
tion reactions. FTIR analysis allows for the observation of various active adsorption as shown in Fig. 3(b). This can be reasonably attributable
CBNW also provides suitable moiety for complexation (Scheme 1). With
CBNW as shown in Fig. 3(a). Cr(VI) loaded CBNW shows intense peaks not suitable. So, the eﬀect of other biosorption parameters was in-
0.97% of chromium in the sample of Cr(VI) loaded CBNW together with pens quickly, and the adsorption equilibrium is reached within 45 to
64.75% of carbon and 34.28% of oxygen provides direct evidence that 60 minutes. The fast uptake of Cr(VI) may be due to quick exposure of
the biosorbent (34). Fig. 4 shows the % sequestration of Cr(VI) onto models. The exact equation of pseudo-ﬁrst-order, pseudo-second-order,
biosorption percentage of Cr(VI) ions (less than 50% even at optimum Pseudo-ﬁrst-order (PFO) model
ter modiﬁcation or charring (>97%). The % sequestration of Cr(VI) was 𝑞𝑡 = 𝑞𝑒 1 − 𝑒−𝑘1 𝑡 (10)
all three biosorbents. The high sequestration % of Cr(VI) onto CBNW 2.303
1. Although the non-modiﬁed BNW sequestered around 50% of Cr(VI)
H2 CrO4 which was hardly adsorbed onto CBNW reasonably causing the and Fig. 5(d). The correlation regression coeﬃcient for PFO ranges
= 20 mL, Cr(VI) concentration = 0.45 mmol/L, shaking time = 24 hrs, and
the tested pHs as shown in Table 1. The Cr(VI) uptake capacity de- by equations (15) and (16) (38, 39).
(d) intra-particle diﬀusion (IPD) plots. Condition: solid liquid ratio = 1 g/L, pH = 2, Cr(VI) ion = 0.45 mmol/L, shaking time = 24 hrs, and temperature = 298 ±
equations can be used to express the nonlinear and linear forms of the are listed in Table 2. The experimental Cr(VI) adsorption capacity is in
Table 1. Kinetics parameters evaluated for the adsorption of Cr(VI) using CBNW at diﬀerent pH.
Table 2. Investigated isotherm parameters for the adsorption of Cr(VI) using CBNW.
Table 3. Comparisons of maximum adsorption capacities of CBNW for Cr(VI) investigated in this study with other biosorbents reported in the literature.
Table 4. Estimated thermodynamic parameters for the adsorption of Cr(VI) using CBNW.
tively. The evaluated thermodynamic parameters are listed in Table 4.
tration. Condition: volume of solution = 10 mL, Cr(VI) concentration = 0.56
set by WHO (0.05 mg/L) using only 0.6 g/L of CBNW at pH 2 whereas also other co-existing ions such as zinc, sulfate, chloride, phosphate,
Fig. 9. Eﬀect of interfering ions for the removal of Cr(VI) from water using CBNW. Condition: interfering ions = 0 to 200 mg/L, weight of CBNW = 40 mg, volume
of solution = 20 mL, pH = 2, Cr(VI) concentration = 0.015 mmol/L, shaking time = 24 hrs, and temperature = 298 ± 2K.
cationic species such as zinc and sodium ions are negligible because 3 mmol/L of BaCl2 solutions. The result shows that only 68.34% of
the biosorption process. Monovalent nitrate anions caused moderate 87.76% at 0.5 mmol/L whereas the recovery reached 98.17% by using
concentration, with 1M NaOH solution achieving over 96% desorption. of BaCrO4 is high as compared to BaCl2 (61).
CBNW. Condition: Cr(VI) concentration = 0.083 mmol/L, weight of CBNW =
of this ﬁgure that the CBNW removed greater than 97% of Cr(VI) even to the existence of reductive functional groups on the CBNW surface, a
increasing repeated cycles and reached 87% at the 5th cycle. The reason boxyl or hydroxyl groups. Therefore, the biosorbent investigated in this
However, the adsorption of Cr(VI) is higher than 87% even after the
5th cycle whereas desorption was higher than 95% in all the cycles.

Methods (brief)

chu. The waste biomass of A. catechu (betel nut) was collected from the
barium chloride solution. g/L by using 0.56 mmol/L (29.54 mg/L) of Cr(VI) solution. The samples
1. Materials and method shaker. After stirring at pre-determined intervals of time, the samples
the samples (SEM, JEOL model JSM 5900). X-ray diﬀractograms were 2.3.2. Desorption experiment of Cr(VI) from Cr(VI)-CBNW
in the samples before and after sorption were determined by an atomic as Cr(VI) loaded CBNW and abbreviated as Cr(VI)-CBNW henceforth.
glass column having a 0.8 mm internal diameter. For this, the column Fig. 1. Analysis of various functional groups in the sample of BNW, CBNW and
a peristaltic pump and eﬄuent samples were collected using the frac- changes/modiﬁcations to other active groups that may be involved in
To investigate the reproducibility and validation of collected data, linking condensation reaction of betel nut cellulose with the aid of
0.97% of chromium in the sample of Cr(VI) loaded CBNW together with pens quickly, and the adsorption equilibrium is reached within 45 to
of organic compounds from the CBNW (modiﬁed sample) was negligi- 𝑞 𝑡 𝑘2 𝑞 𝑒 2 𝑞 𝑒
Zheng, Eﬀective removal of Cr(VI) using 𝛽-cyclodextrin–chitosan modiﬁed biochars metals from wastewater, Bioresour. Technol. 98 (2007) 2243–2257.

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