Overview
Ebisike and colleagues tested an agricultural-waste-derived chitosan-silica hybrid aerogel as an adsorbent for nickel ions in aqueous solution. This is mitigation and water-remediation evidence: it reports removal efficiency, sorption capacity, kinetic models, and desorption recovery for spiked Ni2+ solutions, but it does not measure a consumer product, ingredient, or market water sample.
Key numbers
The authors report maximum nickel removal of 99.78% at 60 min contact time and pH 3 in the abstract. In the pH experiment, the highest plotted value is described as 99.89% Ni2+ bound at pH 3; the verification note below preserves this abstract-versus-results discrepancy.
Table 1 reports equilibrium sorption capacities for initial Ni2+ concentrations of 10, 20, 50, 75, 100, and 200 mg/L:
| Initial Ni2+ concentration | Reported amount removed |
|---|---|
| 10 mg/L | 4.9750 mg/g |
| 20 mg/L | 9.9550 mg/g |
| 50 mg/L | 24.9450 mg/g |
| 75 mg/L | 37.2550 mg/g |
| 100 mg/L | 48.7000 mg/g |
| 200 mg/L | 85.8400 mg/g |
The conclusion summarizes the same concentration-response range as 4.98-85.84 mg/g when initial nickel concentration rose from 10-200 mg/L. The abstract and conclusion identify the Langmuir model as the best isotherm interpretation and give a maximum monolayer adsorption capacity of 85.84 mg/g. The pseudo-second-order model was reported as the best kinetic fit, with R2 values described as ranging from 0.9 to 1.
For desorption, 0.1 M hydrochloric acid was the best eluent tested and recovered 55.63% of bound nickel ions from the aerogel. The tested eluents were hydrochloric acid, acetic acid, ammonia, and sodium hydroxide at 0.1, 0.05, and 0.01 M.
Methods (brief)
The authors prepared chitosan-silica hybrid aerogel following their prior method and tested Ni2+ sorption in batch experiments. pH was adjusted from 1 to 8 with hydrochloric acid and sodium hydroxide, and the pH-profile suspensions were agitated for 6 h. Contact-time experiments used 10 mL Ni2+ solutions at 10, 20, 50, 75, 100, and 200 mg/L, with aliquots taken at 5, 10, 15, 30, 60, 120, 180, 240, 300, and 360 min. Desorption experiments used 0.02 g sorbent loaded from 10 mL of 50 mg/L Ni2+ solution at pH 3. The PDF does not identify the instrumental method used to quantify nickel in the supernatants.
Related evidence
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