title: Characteristics of activated carbon and carbon nanotubes as adsorbents to remove annatto (norbixin) in cheese whey.
abstract: Removing annatto from cheese whey without bleaching has potential to improve whey protein quality. In this work, the potential of two activated carbon products and multiwalled carbon nanotubes (CNT) was studied for extracting annatto (norbixin) in aqueous solutions. Batch adsorption experiments were studied for the effects of solution pH, adsorbent mass, contact duration, and ionic strength. The equilibrium adsorption data were observed to fit both Langmuir and Freundlich isotherm models. The thermodynamic parameters estimated from adsorption isotherms demonstrated that the adsorption of norbixin on three adsorbents is exothermic, and the entropic contribution differs with adsorbent structure. The adsorption kinetics, with CNT showing a higher rate than activated carbon, followed the pseudo first order and second order rate expressions and demonstrated the significance of intraparticle diffusion. Electrostatic interactions were observed to be significant in the adsorption. The established adsorption parameters may be used in the dairy industry to decolorize cheese whey without applying bleaching agents.
authors: Department of Food Science and Technology, University of Tennessee in Knoxville , Knoxville, Tennessee 37996, United States.
authors: Yue
authors: Y
authors: Zhang
authors: Kang
authors: K
authors: Pan
authors: Qixin
authors: Q
authors: Zhong
mesh_terms: D000327:Adsorption; D031212:Bixaceae / Q000737:chemistry*; D002338:Carotenoids / Q000737:chemistry*; D002606:Charcoal / Q000737:chemistry*; D002611:Cheese / Q000032:analysis*; D005503:Food Additives / Q000737:chemistry*; D005524:Food Technology / Q000379:methods*; D007700:Kinetics; D008894:Milk Proteins / Q000737:chemistry*; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010936:Plant Extracts / Q000737:chemistry*; D000067816:Whey Proteins
chemical_list: D005503:Food Additives; D008894:Milk Proteins; D037742:Nanotubes, Carbon; D010936:Plant Extracts; D000067816:Whey Proteins; D002606:Charcoal; D002338:Carotenoids; C054041:annatto