Evaluation of N-terminated siloxanes grafted onto lignocellulose as adsorbent for the removal of phenol red from water

This study reports the chemical modification of lignocellulose (from Kikuyu grass) with N-terminated siloxanes and its utilisation as adsorbent for the removal of phenol red from aqueous media. The stability of the bond between lignocellulose and siloxane was assessed after Soxhlet extraction of unreacted siloxanes in tetrahydrofuran for 5 h, as well as soaking the materials in water for 24 h. Adsorption tests showed the prepared materials to be good candidate for the removal of phenol red (dye) from water, with adsorption capacity from 1.454 to 3.312 mg of phenol red adsorbed per gram of adsorbent. The kinetics of adsorption was found to follow a pseudo-second-order equation indicating chemisorption rather than simple forces of association. The linearised form of adsorption isotherms matched with the Langmuir model.

Keywords
Lignocellulose; N-terminated siloxane; Chemical modification; Phenol red; Adsorption; Kinetics; Isotherms