Adsorption of three chlorinated herbicides on two activated carbons: an example of the effect of surface charge, pore diameter and molecular size on the adsorption process

M. PILA; D. COLASURDO; S. SIMONETTI; G. DODERO; P. ALLEGRETTI; D. RUIZ; S. LAURELLA

Korean Chem. Eng. Res.

The Korean Institute of Chemical Engineers (KICE)

Año: 2023

Two carbonaceous adsorbents CAT and CARBOPAL are here tested for reducingconcentration of the three herbicides in water: 2,4-D (2,4-dichlorophenoxyacetic acid), TCP (2,4,6-trichlorophenol) and metolachlor. Textural and chemical characterization of the adsorbents includenitrogen isotherms, FTIR, titration and thermogravimetric analyzes. Adsorption was studied indiscontinuous adsorption experiments at different pH values. The experimental adsorptionisotherms data were fitted to four theoretical models. Adsorbent characterization reveals that CAThas higher micropore area, lower pore diameter and lower acidity than CARBOPAL. Theadsorption is a second-order process and the isotherms best fitted to Sips model. The efficiency ofthe process depends mainly on the charge of the adsorbate for TCP and 2,4-D, but it depends on thecharge of the surface for metolachlor. Adsorption capacity is higher on CAT for 2,4-D and TCP(small molecules), and it is higher on CARBOPAL for metolachlor (big molecules). Theoreticalcalculations clearly support this assumption.