Cigdem Ozer

Removal of methylene blue from aqueous solutions using phosphoric acid activated carbon produced from hazelnut husks

In this study, activated carbon (HHPAAC) was prepared from hazelnut husks using phosphoric acid activation and characterized by some physicochemical analyses. Surface area and zero point charge of pH (pHPZC) were found to be 770 m2 g−1 and 4.5, respectively. Removal of methylene blue (MB) from aqueous solution was performed using a batch technique for determination of the effects of initial pH, contact time, dosage, and temperature. Adsorption of MB was elevated with increasing pH and temperature. The equilibrium data were analyzed by Langmuir and Freundlich equations, and it was found that the data were reasonably well represented by the former with an adsorption capacity of 204 g kg−1. Change in Gibbs free energy (ΔG), entropy (ΔS), and enthalpy (ΔH), were also calculated. Adsorption kinetics were pseudo-second order.

Enhanced Adsorption of Hexavalent Chromium Ions on Polyamine Polyurea Polymer: Isotherm, Kinetic, Thermodynamic Studies and Batch Processing Design

In the present study, polyamine polyurea polymer was employed for adsorption of Cr(VI) ions from aqueous solution. Adsorption studies were carried out to examine the effects of parameters such as pH, contact time, initial concentration of Cr(VI), and temperature. Optimum pH value and the contact time of the system were found to be 2.5 and 240 minutes, respectively. Thermodynamic parameters that calculated with the results of temperature studies showed the adsorption processes have exothermic, reversible, and spontaneous nature. The compared isotherm data clarified that Cr(VI) adsorption onto polyamine polyurea polymer (PPP) was proper with Langmuir isotherm with maximum adsorption capacity of 135.1 mg g−1. Pseudo-second-order kinetic model was found to be descriptive for the kinetic mechanism of Cr(VI) adsorption onto PPP. Single-stage batch adsorber was designed using equilibrium data for removal of Cr(VI) at various solutions. Consequently, the PPP has been found to be effective adsorbent for removal of Cr(VI) from water media. GRAPHICAL ABSTRACT