Chemical Engineering Journal, Vol.371, 1-6, 2019
Understanding the adsorption mechanism of phenol and 2-nitrophenol on a biopolymer-based biochar in single and binary systems via advanced modeling analysis
In this paper, the adsorption of phenol and 2-nitrophenol on a biopolymer-based biochar in single and binary systems was investigated at 298-328 K and pH 5. Experimental results indicated that the adsorption capacities of phenol were significantly reduced from single to binary systems compared to those obtained for 2-nitrophenol. This experimental evidence suggested an antagonistic effect between both adsorbates generating an inhibitive adsorption. In terms of modeling analysis, the single and binary adsorption isotherms were well reproduced by monolayer and competitive monolayer statistical physics models, respectively. These two models showed that phenol and 2-nitrophenol molecules have been mainly docked with an inclined and horizontal positions in single and binary systems, respectively. A detailed analysis of the number of captured phenol (n(1)) and 2-nitrophenol (n(2)) molecules per site in the binary systems demonstrated that its corresponding evolution varied with a completely inverse way thus corroborating the inhibition effect between phenol and 2-nitrophenol molecules. The monolayer and competitive monolayer models were used to estimate two adsorption energies to characterize the single and binary adsorption mechanisms. The analysis of the energetic parameters suggested that the adsorption process was a physisorption. The interpretation of all monolayer and competitive monolayer model parameters provided new insights that contributed to understand the single and binary adsorption mechanisms of phenol and 2-nitrophenol molecules on tested adsorbent.