Analyse comparative des techniques d’élimination d’un colorant alimentaire

Abstract

The main objective of this Master's thesis was to evaluate and compare the efficiency of two treatment methods for the removal of Patent Blue V (E131) dye extracted from a real

pharmaceutical form, Biocalyptol syrup. The two studied techniques are adsorption on an eco- friendly activated carbon prepared from date pits (DPAC) and coagulation-flocculation using

aluminum sulfate. UV-Visible spectrophotometric analyses performed at the maximum wavelength λmax = 640 nm demonstrated that both processes achieved high decolorization performances, exceeding 91%. Kinetic tracking of the adsorption showed an ultra-fast rate, capturing approximately 90% of the dye within the first 10 minutes. The data perfectly followed the pseudo-second-order model (R2 = 1), confirming an irreversible chemisorption mechanism with zero desorption. At equilibrium, the modeling indicated an excellent fit with the Langmuir isotherm (R2 = 1), validating a homogeneous monolayer coverage with a maximum adsorption capacity of 0.8396 mg/g. In parallel, coagulation-flocculation trials with aluminum sulfate confirmed an efficient and reproducible decolorization, dropping the residual absorbance to minimal values between 0.0187 and 0.0235 due to charge neutralization mechanisms. Although both methods exhibit very close decolorization performances, the adsorption technique on DPAC stands out as the most advantageous solution for this type of effluent. It valorizes an abundant local agricultural by-product in Algeria and constitutes a clean green engineering process that permanently traps the pollutant without requiring expensive industrial reagents and without generating complex secondary chemical sludge to treat.