Comparison of adsorption capacity of different adsorbents for heavy metals ions

The aim of the study was to investigate the usability of drunk tea waste and gey and brown clayscollected from Erzurum region as an adsorbent in removing metal ions such as Zn(II), Cd(II), Pb(II)and Cu(II). Although, approximately 150.000 tones dry tea is manufactured per year in Turkey, it isunderstood that just 30.000 tones of the manufactured tea is wasted.Tea consist of polyphenols, lignin, tanen and organic compounds in cellulose structure. Therefore,it is thought that it could be used as an adsorbent. The drunk tea waste, firstly washed with pure thanwith heated pure water at 70-80 oC until having a colourless extract. It is dried in oven at 110 oC thanused as an adsorbent. Grey and brown Erzurum clays were used after meshing thorough differentsized meshes. The effect of treatment time, mixing speed, amount of adsorbent, particular size, ionicstrength, single ionic adsorption, pH, temperature and concentration of Zn(II), Cd(II), Pb(II) and Cu(II)on adsorption capacity were investigated.After determining the optimum adsorption conditions for these adsorbents, disorption of these ionswas also investigated.The concentrations of Zn(II), Cd(II), Pb(II) and Cu(II) adsorbed on desopted from drunk tea wasteand Erzurum clays was determined by DPP-ASV method.The optimum adsorption conditions for Zn(II), Cd(II), Pb(II) and Cu(II) on drunk tea waste werefound as 30 minutes treatment time, 500 rpm mixing speed, 1.00 g adsorbent, 1000 mesh particularosize, pH 5.00 and 30 C temperature. The adsorption capacity of drunk tea waste in optimumconditions was 15.66 mg Zn(II)/g; 18.83 mg Cd(II)/g; 22.53 mg Pb(II)/g and 21.51 mg Cu(II)/g.The optimum adsorption conditions for Zn(II), Cd(II), Pb(II) and Cu(II) on grey Erzurum clay werefound as 10 minutes treatment time, 500 rpm mixing speed, 1.00 g adsorbent, 1000 mesh particularosize, pH 4.00 and 30 C temperature. The adsorption capacity of drunk tea waste in optimumconditions was 16.40 mg Zn(II)/g; 16.77 mg Cd(II)/g; 18.74 mg Pb(II)/g and 19.38 mg Cu(II)/g.The optimum adsorption conditions for Zn(II), Cd(II), Pb(II) and Cu(II) on brown Erzurum clay werefound as 15 minutes treatment time, 500 rpm mixing speed, 1.00 g adsorbent, 1000 mesh particularosize, pH 6.00 and 20 C temperature. The adsorption capacity of drunk tea waste in optimumconditions was 12.93 mg Zn(II)/g; 13.05 mg Cd(II)/g; 17.80 mg Pb(II)/g and 17.40 mg Cu(II)/g.The desorption of adsorbed Zn(II), Cd(II), Pb(II) and Cu(II) from drunk tea waste in 0.1 M HNO3were 68.69 %, 44.41 %, 56.36 % and 53.42 % respectively, from grey Erzurum clay in 0,1 M HCI were97.14 %, 65.18 %, 65.61 % and 68.50 % respectively and from brown Erzurum clay in 0.1 M HCI were64.65 %, 64.80 %, 51.53 % and 48.84 % respectively.These results show that these adsorbents can be used to remove metal ions from the Gediz river.The changes on adsorbents surface were investigated by taken SEM photographs of surfacesbefore and after adsorption.Key words: Adsorption, heavy metals, desorption, DPP-ASV, Erzurum clay, drunk tea waste,SEM.