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

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 (R-2 = 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 degrees C, 35 degrees C and 45 degrees 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 (R-2 = 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 increment G degrees (-19.1 kJmol(-1)) and enthalpy increment H degrees (-56.6 kJmol(-1)) had negative values which suggested that the sorption was spontaneous, and the process was exothermic.