Adsorption studies of β-naphthol by untreated and treated activated carbon [optimizing of adsorption by central composite design (CCD)]

In the present work the adsorption of aromatic compound, namely beta-naphthol (BN) by two granular activated carbons, one untreated and the other treated with HNO3 carried out under controlled conditions. The effects of experimental parameters on adsorption process such as pH, contact time and adsorbent dosage have been investigated. Experimental design methodology was applied to optimize the removal of beta-naphthol. The effect of various experimental parameters was investigated using five-level three-factorial central composite design (CCD). The relationship between the parameters and the response for model optimization was found and optimum conditions were obtained by CCD. In the optimum conditions obtained by response surface modeling, 100% BN was adsorbed on the carbons. Treatment with HNO3 led to a decrease in the point of zero charge and the adsorption capacity ( (max)) of the activated carbon. The adsorption capacity of the carbons was determined using Freundlich and Langmuir homogenous equation. The variation of the model parameters with the solution pH was also studied. The fitted parameters obtained from both models showed the (max) value decrease with increasing of pH.