Overview
Ahuja and colleagues tested iron-oxide nanoparticles and chitosan-coated iron-oxide nanoparticles for removal of arsenite and arsenate from aqueous solutions intended to model arsenic-contaminated groundwater treatment. This is remediation evidence: it reports adsorbent-dose, pH, and isotherm findings for As(III) and As(V), but it does not measure arsenic occurrence in a consumer product, food ingredient, or market water sample.
Key numbers
Batch experiments used initial As(III) and As(V) concentrations of 0.125 mg/L. The abstract reports maximum arsenic removal of 99.9% at pH 7.0 and room temperature, using 0.4 g/L IONPs or 0.6 g/L Ch-IONPs. The conclusion frames this dose against average Brahmaputra floodplain arsenic concentrations of approximately 100 micrograms/L from reviewed literature.
Table 1 reports pH-dependent removal percentages:
| pH | As(III) IONP | As(III) Ch-IONP | As(V) IONP | As(V) Ch-IONP |
|---|---|---|---|---|
| 4.0 | 66.92% | 82.40% | 86.72% | 45.92% |
| 5.0 | 99.90% | 87.84% | 89.28% | 88.36% |
| 6.0 | 99.90% | 93.92% | 99.80% | 95.48% |
| 7.0 | 99.90% | 99.90% | 99.90% | 97.84% |
| 8.0 | 99.90% | 87.80% | 99.90% | 85.40% |
| 9.0 | 99.90% | 76.96% | 94.68% | 79.64% |
Table 2 reports dose-dependent removal percentages for 5, 10, 15, 20, 30, 40, and 50 mg adsorbent doses in 50 mL arsenic solution:
| Dose | As(III) IONP | As(III) Ch-IONP | As(V) IONP | As(V) Ch-IONP |
|---|---|---|---|---|
| 5 mg | 65.00% | 47.64% | 79.00% | 60.32% |
| 10 mg | 75.40% | 59.16% | 87.90% | 72.16% |
| 15 mg | 77.20% | 86.24% | 88.40% | 75.12% |
| 20 mg | 99.90% | 99.90% | 88.08% | 99.90% |
| 30 mg | 99.90% | 99.90% | 99.90% | 99.90% |
| 40 mg | 99.90% | 99.90% | 99.90% | 99.90% |
| 50 mg | 99.90% | 99.90% | 99.90% | 99.90% |
The authors report maximum adsorption capacities of 213.25 micrograms/g for As(III) on IONPs, 118.67 micrograms/g for As(III) on Ch-IONPs, 239.50 micrograms/g for As(V) on IONPs, and 116.33 micrograms/g for As(V) on Ch-IONPs. Freundlich isotherm correlation was reported as R2 = 0.96, compared with Langmuir R2 = 0.87. The conclusion states that As(V) removal was approximately 20% higher than As(III) removal and that IONP removal efficiency was 1.5 times higher than Ch-IONPs.
Methods (brief)
IONPs were synthesized by co-precipitation from FeCl3.6H2O and FeSO4.7H2O, heated to 55 degrees C, adjusted to pH 10 with NH4OH, centrifuged, washed with distilled water and ethanol, and oven-dried for 12 h. Ch-IONPs used FeCl3.6H2O and FeCl2.4H2O mixed with chitosan in acetic-acid solution, adjusted to pH 6.9, treated with NH4OH after dry nitrogen at 80 degrees C, centrifuged, washed, and dried.
pH experiments added 50 mg adsorbent to 50 mL NaAsO2 or NaHAsO4 solution at 0.125 mg/L, adjusted pH from 4.0 to 9.0, and shook samples for 60 min. Dose experiments held pH at 7.0 and varied adsorbent dose from 5 to 50 mg per 50 mL. Particle morphology was assessed by FESEM; XRD showed magnetite peaks at diffraction angles 35.246, 42.831, 53.128, and 74.530.
Related evidence
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.
| Commit | Date | Change | Description |
|---|---|---|---|
| b01ec52c31 | 2026-08-04 | major | 1 section added |
| 3171d069e3 | 2026-08-02 | major | 1 section added |
| 90a2f9a38e | 2026-07-30 | major | 1 section added and 1 removed; narrative text revised |
| eaa8eeeedf | 2026-07-27 | major | 1 section added |
| 50de6ab217 | 2026-07-27 | minor | Narrative text revised |