Application of an Alkali Functionalized Material for Treating Pharmaceutical Wastewater Containing Chlorhexidine Gluconate and Cetrimide.

Two different types of mesoporous adsorbents and one microporous adsorbent were used for the adsorption of chlorhexidine gluconate and Cetrimide. Chlorhexidine gluconate and Cetrimide are widely used in antiseptic solutions, mouthwashes, and germicidal hand rinses, etc. Scanning electron microscopy images, N₂ adsorption/desorption isotherms, pore size distribution, Fourier transform infrared spectra and points of zero charge illustrate that significant changes occur on the activated carbon after functionalization with NH₄OH when compared to the precursor granular activated carbon (GAC). The adsorption capacity of the novel alkali functionalized activated carbon (FAC-NH₃) was found to be comparable with the highly expensive mesoporous aluminosilicate MCM-41 for both chlorhexidine gluconate and cetrimide. For a wide concentration range, adsorption with FAC-NH₃ is approximately three times more in comparison to GAC for both compounds. Chlorhexidine gluconate forms surface complexes with the functional groups present in the super microporous FAC-NH₃. This fact is also supported by kinetic studies, where pseudo first-order and second-order models, intra-particle diffusion, and Boyd's plots showed evidences to support chemisorption, on top of pure physical adsorption. [ABSTRACT FROM AUTHOR]