reduction of hexavalent chromium from aqueous

Overview

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• an initial Cr(VI) concentration of 30 ppm, and a contact time of 45 min. The adsorption data were well
• raw hides into stable leather, is typically performed using late 19th century following reports of nasal tumors among
• vegetables or chrome. Chrome tanning with Cr(III) produces so workers exposed to chromium compounds.5
• widely adopted than vegetable tanning.1 However, only 60–70% recognized as an effective technique for Cr(VI) removal from
• of the applied chromium is xed during tanning, while 30–40% wastewater owing to its high selectivity, efficiency, operational
• relatively stable and exhibits low solubility in water; however, it Cr(VI).7 Zeolites, crystalline aluminosilicates composed of SiO4
• $6H2O solution in a 250 mL Erlenmeyer ask (8% w/v) and
• generation of boron-containing residues.21 Additionally, green a Rigaku Ultima diffractometer in the 2q range of 5–50°.
• sodium hydroxide (NaOH) (Supelco), 98% sulfuric acid (H2SO4) Effect of pH. To determine the optimal pH, it was varied
• phenylcarbazide (Sigma-Aldrich) were used. Subsequently, 1 mL of 1000 ppm Cr(VI) solution was transferred
• into six 50 mL volumetric asks. Each solution was then diluted a 30 ppm Cr(VI) solution at pH 1. The adsorption experiments
• with pre-adjusted distilled water to obtain 20 ppm Cr(VI) solu- were conducted at room temperature for varying durations.
• 20 ppm Cr(VI) solution was transferred to a 100 mL beaker, and adsorption kinetics. The adsorption kinetics were studied using
• was added to 25 mL of a 20 ppm Cr(VI) solution at pH 1. The are the rate constants of the pseudo-rst-order and pseudo-
• concentration, it was varied among 10, 20, 30, 40, and 50 ppm.
• zeolite Y/nZVI as a result of Cr(VI) reduction.32 Meanwhile, the
• 10.47 wt% (Fig. 3c). The elemental mapping of zeolite Y/nZVI-Cr
• on numbers, 88.3% of nZVI has a particle size of 80.6 ± 10.8 nm,
• Fig. 2 FTIR spectra of (a) zeolite Y/nZVI-Cr, (b) zeolite Y/nZVI, and (c) and 11.7% has a particle size 330.0 ± 234.5 nm. In addition, the
• hydrogen chromate (HCrO4−) in the pH range of 1–6, which is
• range of 303–343 K. This can be explained by the fact that higher signicantly increase. This is because at the initial contact time,
• 30 ppm, the adsorption capacity decreased. This reduction can An isotherm study was conducted to quantitatively describe the
• increased. Once the surface became saturated with Cr(VI), isotherm parameter are presented in Table 1 and Fig. 11.
• further interactions between Cr(VI) and zeolite Y/nZVI were As shown in Table 1, using the Langmuir isotherm model,
• Fig. 9 Effect of initial concentration on Cr(VI) reduction. onto zeolite Y/nZVI, Table 1 indicates that the Freundlich
• As shown in Fig. 13c, the plot of qt vs. t1/2 does not pass Table 3 Thermodynamic parameters of adsorption on zeolite Y/nZVI
• value (0.3747, Table 2), which lies within the range of 0.1 < Ri < Linear equation (kJ mol−1) (kJ mol−1)
• nZVI proceeds through multiple mass transfer stages. The Table 4 DG° values at 303, 313, 323, and 333 K
• and the adsorbent surface, facilitating mass transfer. temperature range of 313–333 K indicate that adsorption is
• Based on Table 3, a positive DH° value is obtained, which A comparison of the Cr(VI) adsorption capacities of zeolite Y and
• changes (DH°) in the 40–120 kJ mol−1 range indicate whether Cr(VI) adsorption capacity of zeolite Y/nZVI was 7.4-fold higher
• zeolite Y/nZVI. Based on Table 4, negative DG° values in the adsorbents is summarized in Table 5. The green-synthesized
• Table 5 Cr(VI) removal capacities for various adsorbents B/UN.3.LPPM/PT.01.03/2025) using a Penelitian fundamental
• Therefore, the values presented in Table 5 are intended to M. B. Alshammari, in. Emerg. Tech. Treat. Toxic Met. from

Methods (brief)

• synthesized using green tea extract as a reducing agent to samples were sputter-coated with a gold layer containing poly-

Implications

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Wiki pages this source may touch

• Fish — marine, predatory (tuna, swordfish, shark, king mackerel)
• Fish — marine, non-predatory (sardines, anchovies, salmon, cod)
• Chromium

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