Removal of 3-chloroaniline from aqueous solution by treated coffee waste: isotherm modelling and thermodynamic studies

ABSTRACT

3-chloroaniline (3CA) concentrations were measured in aqueous solution by UV/Vis spectrophotometer. Validation of the calibration curve’s linearity, instrumental precision (RSD%), limits of detection and quantification were accomplished. The coefficient of calibration curve (1.0–10.0 mgL⁻¹ 3CA) had a high correlation (R² = 0.9997) and the instrumental precision was in the range (RSD% = 0.50–0.74%, n = 10). The LOD and LOQ from the regression analysis were 0.20 mgL⁻¹ and 0.61 mgL⁻¹, respectively. A treated coffee waste adsorbent was utilised for 3-chloroaniline removal by process of sorption from aqueous solution. The major components of the coffee waste are the hemicellulose, cellulose, and lignin. The temperature effect (25°C, 35°C and 45°C) on sorption was evaluated, with sorption decreasing by increasing of temperature which reached 87%, 75% and 54%, respectively. Isotherms type L were found and associated with monolayer sorption. The parameters of sorption were examined by employing Langmuir, Freundlich and Dubinin-Radushkevich sorption models. The isotherm models of Langmuir and Dubinin-Radushkevich had acceptable correlation coefficients (R² = 0.87–0.88). The Langmuir and Dubinin-Radushkevich sorption capacities of 3-chloroaniline were found to be 44 to 50 mgg⁻¹. The values of separation factor (R_L) were ranging from (0–1) which indicated a favourable sorption. In thermodynamic study the physical sorption process was confirmed by van’t Hoff equation. In addition, the free energy ∆G° (−19.1 kJmol⁻¹) and enthalpy ∆H° (−56.6 kJmol⁻¹) had negative values which suggested that the sorption was spontaneous, and the process was exothermic.

KEYWORDS:

• 3-chloroaniline
• isotherm models
• thermodynamic study
• UV-Vis
• coffee waste

Disclosure statement

No potential conflict of interest was reported by the author(s).

Author contribution

The author (Bandar R. M. Alsehli) planned and designed the experiments; conducted the tests; analyzed the data; provided reagents, materials and methods for analysis and wrote the article.

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.