Şeker Pancarı Küspesi Adsorbente Tekli Nikel(II) ve Tekli Krom(VI) İyonlarının ve Eşanlı veya Ardışık Olarak İkili Karışımlarının Adsorpsiyonunun İncelenmesi
Özet
In this thesis, adsorption of single nickel(II) and single chromium(VI) ions and simultaneous or sequential adsorption of their binary mixtures to sugar beet pulp adsorbent were examined in the batch environment.
In the first part of the thesis study, the single adsorption of each metal ion was examined as a function of the initial pH, adsorbent particle size range and initial metal ion concentration, and the optimal working pH value was determined as 2 for chromium(VI) ions and 6 for nickel(II) ions. It has been observed that the adsorption capacity increased and the adsorption efficiency decreased by increasing the initial metal ion concentration up to 250 mg/L for each metal ion in the 710–850 µm particle size range, which is determined as the most suitable grain size range. The highest chromium(VI) adsorption capacity of dried sugar beet pulp adsorbent was 64,8 mg/g at pH 2, and the highest nickel(II) adsorption capacity was 18,6 mg/g at pH 6.
In the next stage of the studies, at pH 2 and 6, the pH values in which each metal ion is best adsorbed, the dried sugar beet pulp adsorbent simutaneous adsorption of the binary mixtures of chromium (VI) and nickel(II) ions was investigated and the concentration of the other metal ion in the fixed metal ion concentration was changed and the common effects of rate and capacity of the adsorption for each metal ion were examined. It was observed that the presence of chromium(II) ions in the environment at both pH values increased nickel(II) ion adsorption dramaticly (synergistic effect), while the presence of nickel(II) ions significantly reduced chromium(VI) adsorption (antagonistic effect). At pH 2, in the absence of nickel(II) ions in the environment, the highest chromium (VI) adsorption capacity of pulp adsorbent was 64,8 mg/g in 250 mg/L initial chromium(VI) concentration, while this value decreased to 11,9 mg/g when 250 mg/L nickel(II) ion was found in the environment at the same chromimium(VI) initial concentration. Again, when there is no chromium(VI) ions in the environment at pH 2, the highest nickel(II) adsorption capacity of pulpe adsorbent in 250 mg/L initial nickel(II) ion concentration was determined as 6,0 mg/g, while in the same initial nickel(II) ion concentration, this value increased to 18,5 mg/g when 250 mg/L chromium(VI) ion was found in the environment. At pH 6, the highest adsorption capacity was obtained as 14,1 mg/g in single chromium (VI) adsorption decreased to 9,2 mg/g in the presence of 250 mg/L nickel(II). Likewise, the highest adsorption capacity was obtained as 18,6 mg/g in single nickel(II) adsorption increased to 42,0 mg/g in the presence of 250 mg/L chromium(VI).
In the later part of the studies, in the sequential adsorption of chromium (VI) and nickel (II) ions to the dried sugar beet pulp adsorbent, at pH 2 and 6, when the adsorption equilibrium was reached at the first metal ion concentration kept constant, the change in the concentration of the second metal ion added to the adsorption environment affected the adsorption of each metal ion. Their joint effects on speed and efficiency were examined. Similar to the results obtained in simultaneous adsorption, it was observed that the presence of chromium(II) in the environment increased nickel(II) adsorption (synergistic effect) at both pH values, while the presence of nickel(II) decreased chromium(II) adsorption (antagonistic effect). For example, at pH 2, in the absence of nickel(II) ions in the environment, the highest chromium(VI) adsorption capacity of the pulp adsorbent is 62,3 mg/g at an initial chromium(VI) concentration of 200 mg/L, while it is 200 mg/L in the adsorption environment. When the single adsorption of nickel(II) ions reached equilibrium, when 200 mg/L chromium(VI) was added to the environment, the chromium(VI) adsorption capacity of the pulp decreased to 8,4 mg/g. At the same pH, the 200 mg/L single nickel(II) adsorption equilibrium capacity changes from 5,7 mg/g, and when 200 mg/L chromium(VI) is added to the environment, the nickel(II) adsorption capacity is positively affected and increases to 15,2 mg/g.
Again, at pH 2, this time in the absence of chromium(VI) ions in the environment, the highest nickel(II) adsorption capacity of the pulp adsorbent was 5,7 mg/g at an initial nickel(II) concentration of 200 mg/L, while chromium(VI) concentration was 200 mg/g in the adsorption environment. When the single adsorption of chromium(VI) ions reached equilibrium, the nickel(II) adsorption capacity of the pulp increased to 10,9 mg/g when 200 mg/L nickel(II) was added to the environment. At the same pH, the adsorption equilibrium capacity of 200 mg/L single chromium(VI) was 62,3 mg/g, and when 200 mg/L nickel(II) was added to the environment, the chromium(VI) adsorption capacity was negatively affected and decreased to 9,3 mg/g.
In the last part of the studies, the compatibility of the adsorption equilibrium with the Langmuir and Freundlich adsorption models in the single adsorption of each metal ion was investigated and it was determined that the Langmuir model describes the adsorption equilibrium better. In the simultaneous and sequential adsorption of chromium(VI) and nickel(II) binary mixtures, the adsorption equilibrium was defined by the Langmuir model, which includes synergistic and antagonistic interactions, and the model constants were found.
The results showed that the adsorption and selectivity of chromium(VI) ions in the presence of nickel(II) ions decreased significantly depending on the concentration of each metal ion studied, that at pH 2, the adsorption of chromium(VI) in the mixture decreased much more, and at pH 6, chromium(VI) adsorption decreased significantly depending on the concentration of each metal ion studied. It was observed that the decrease in adsorption was less, and simultaneous or sequential addition of chromium(VI) ions to the mixture did not affect the adsorption efficiency much. Again, experimental results show that the adsorption and selectivity of nickel(II) ions in the presence of chromium(VI) ions increases significantly depending on the concentration of each metal ion studied, that the initial pH is not very effective in this increase, and that the simultaneous or sequential addition of nickel(II) ions to the mixture increases significantly. It was shown that it did not affect the adsorption efficiency much.
