Overview
Nurhidayanti and Riyadi modeled cadmium adsorption onto a combined chitosan and coffee-ground activated-carbon adsorbent. This is in-scope remediation evidence because it measures cadmium removal from industrial wastewater; it is not coffee occurrence evidence and should not be used as a food or beverage concentration source.
Key numbers
The introduction reports a preliminary cadmium concentration of 1.15 mg/L in wastewater from one Bekasi Regency textile-industry sample. The same passage gives the Indonesian wastewater quality standard for cadmium as 0.05 mg/L. The results section reports that the best tested treatment, chitosan plus 1.4 g coffee-ground activated carbon, reduced cadmium to 0.07 mg/L.
Figure 3 reports cadmium-removal efficiencies across the adsorbent-mass series:
| Chitosan plus coffee-ground activated carbon mass | Cd removal efficiency |
|---|---|
| 0.6 g | 74.57% |
| 0.8 g | 81.87% |
| 1.0 g | 85.54% |
| 1.2 g | 91.85% |
| 1.4 g | 94.35% |
The one-way ANOVA for cadmium concentration reported p = 8.28x10-9, F calculated = 599.17, and F table = 5.32. The ANOVA for percent removal reported p = 1.01x10-8, F count = 569.43, and F table = 5.32.
The source gives the following isotherm parameters in Table 1:
| Model | Parameter 1 | Parameter 2 | Parameter 3 | R2 |
|---|---|---|---|---|
| Langmuir | KL = 34.3610 | Qm = 0.7546 | RL = 2.468 | 0.9954 |
| Freundlich | KF = 0.1529 | 1/n = -3.6465 | not reported | 0.9521 |
| Dubinin-Raduskevich | qmD-R = 3.5333 | epsilon = 7x10-9 | not reported | 0.9042 |
| Temkin | bT = 0.0053 | B = 0.0249 | not reported | 0.9653 |
The abstract states a Langmuir correlation coefficient of 0.9970, while Table 1 and the results prose report 0.9954. The page preserves the table value in the numerical table and records the discrepancy here.
Table 2 reports the kinetic fits:
| Model | k | qe | R2 |
|---|---|---|---|
| Pseudo first order | 28.615 h-1 | 7.4775 mg.g-1 | 0.9503 |
| Pseudo second order | 2.1482 g.mg-1.h-1 | 0.0415 mg.g-1 | 0.9971 |
| Elovich | 194.9 mg.g-1 | not reported | 0.9693 |
| Weber Morris / intra-particle diffusion | 336.12 mg.g-1 | 8.0635 g.mg-1.h-1 | 0.9833 |
The results prose prints the Elovich constant as 149.9 mg.g-1, while Table 2 prints 194.9 mg.g-1. The table value is used above and the internal mismatch is retained as a verification caveat.
Table 3 reports thermodynamic parameters for cadmium adsorption onto the chitosan and coffee-ground adsorbent:
| Temperature as printed by source | Delta Go (J/mol) | Delta Ho (kJ/mol) | Delta So (kJ/mol.K) |
|---|---|---|---|
| 298 | -1476.592 | 0.3467 | 3.5296 |
| 318 | -2593.167 | 0.3467 | 3.5296 |
| 328 | -3698.187 | 0.3467 | 3.5296 |
| 338 | -4811.776 | 0.3467 | 3.5296 |
The table header says “Temperature (oC)” even though 298, 318, 328, and 338 are Kelvin-like values. The source unit label is not converted here.
Methods (brief)
The study was conducted at PT. Tuv Nord Indonesia and Pelita Bangsa University from June to December 2022. Materials included chitosan, cadmium solution, ZnCl2, HCl, NaOH, and spent coffee grounds from coffee shops. All treatments and measurements were carried out in triplicate.
The authors state that preliminary wastewater testing, adsorbent preparation, and the biosorbent cadmium-removal experiments were completed in 2021; this paper focuses on the isotherm, kinetic, and thermodynamic data analysis. The paper fits Langmuir, Freundlich, Dubinin-Raduskevich, and Temkin isotherms and pseudo-first-order, pseudo-second-order, Elovich, and Weber-Morris kinetic models. SEM-EDX characterization of the chitosan plus 1.4 g coffee-ground adsorbent reported 74.30% carbon, 18.29% oxygen, 0.88% sodium, 0.34% magnesium, 2.99% tin, 0.51% zirconium, 0.53% copper, 0.46% zinc, 0.46% chlorine, 0.42% potassium, 0.34% phosphorus, 0.27% calcium, 0.15% silicon, and 0.06% aluminum.
Related evidence
Update history
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