Investigation of heavy metal removal from water using natural absorbent volcanic tuff (Aksaray/Selime)

In this study, three different heavy metals (Cr3,6+, Ni2+, Zn2+) removal of the prepared the aquatic environment with natural adsorbent volcanic tuff were studied. Volcanic tuff taken from Selime/Aksaray and used as adsorbent. In addition to adsorption isotherms and the work of thermodynamics, factors affecting adsorption efficiency were investigated such as mixing time, quantity of adsorbent, adsorbent particle size, mixing speed, pH, ambient temperature for each heavy metal. For Cr3+ optimum mixing time 45 min, quantity of adsorbent 0.50 g, adsorbent particle size 230 mesh was found. For Ni2+ optimum mixing time 30 min, quantity of adsorbent 0.75 g, adsorbent particle size 120 mesh was found. For Zn2+ optimum mixing time 15 min, quantity of adsorbent 0.75 g, adsorbent particle size 120 mesh was found. Also for each heavy metal was determined optimum pH value 5 and optimum mixing speed 250 rev/min and ambient temperature 25C. Cr6+ ion cannot be adsorbed by volcanic tuff. Freundlich and Langmuir adsorption isotherms, adsorption kinetics (for pseudo first order and pseudo second order) and thermodynamics (∆H, ∆G, ∆S) were determined from by each heavy metal. According to experimental results the most appropriate isotherm and kinetic model were determined Langmuir isotherm model and pseudo second degree equation. qe (mg/g) and KL (L/mg) values were calculated respectively 19.37 and 9.23 for Cr3+, 16.63 and 36.23 for Ni2+, 18.93 and 384.62 for Zn2+. ∆H and ∆S values were calculated respectively -58.45 kJ/mol and 0.25 kJ/molºK for Cr3+, 79.87 kJ/mol and 0.29 kJ/molºK for Ni2+, -41.01 kJ/mol and 0.17 kJ/molºK for Zn.