Ön işlemsiz ve CTAB Ön işlemli Şeker Pancarı Adsorbente Tekli Boyarmadde ve Tekli Metal İyonları ile İkili Karışımlarının Adsorpsiyonunun İncelenmesi

Abstract

In textile and leather industry wastewaters, anionic Remazol Black B (RBB) dye and chromate/bichromate ions, which are anionic and contain chromium(VI) ions, coexist at high concentrations. Sugar beet pulp (SBP) is known for its high adsorption capacity for both dyes and heavy metal ions and has been used as an adsorbent. This adsorbent was prepared by direct drying (without pretreatment) and treated with a cationic surfactant, Cetyltrimethylammonium Bromide (CTAB), to enhance its adsorption properties. In this thesis, SBP without pretreatment and SBP treated with CTAB were used as adsorbents for the adsorption of single RBB and single chromium(VI) ions as well as their mixtures. The initial pH effects on the adsorption rate and capacity were investigated in the first part of the thesis for single RBB and single chromium(VI) adsorption using dried, untreated SBP, determining pH 2 as the optimal operating pH for both pollutants. When SBP treated with CTAB was used, the optimal operating pH was found to be pH 8 for RBB and pH 2 for chromium(VI) in the pH range of 2-8.

In the subsequent part of the thesis, the effects of initial pollutant concentration on the adsorption rate and capacity were examined over a range of 25-500 mg/L for single RBB and single chromium(VI) adsorption on dried, untreated SBP at pH 2, which was identified as the optimal pH for both components. Subsequently, for RBB+chromium(VI) mixtures, the initial concentration of one component was kept constant (25, 50, 100, 250, 500 mg/L) while the other component's initial concentration was varied from 25-500 mg/L to study their combined effects on adsorption rate and capacity. The results indicated that increasing the initial pollutant concentration up to 500 mg/L increased the adsorption equilibrium capacity while decreasing the removal efficiency for each single and mixed adsorbate-adsorbent system.

The highest adsorption capacity values in environments containing 500 mg/L single RBB, 500 mg/L single chromium(VI), and 500 mg/L RBB+500 mg/L chromium(VI) were determined as 94.2 mg/g RBB, 49.1 mg/g chromium(VI), and 104.8 mg/g RBB+32.8 mg/g chromium(VI), respectively. The presence of RBB in RBB+chromium(VI) mixtures reduced the adsorption of chromium(VI), whereas the presence of chromium(VI) increased the adsorption of RBB. In the subsequent stages of the thesis, since pH 8 was identified as optimal for RBB and pH 2 for chromium(VI) adsorption on CTAB-treated SBP, the effects of initial pollutant concentrations were studied at these pH values for single RBB, single chromium(VI), and RBB+chromium(VI) mixtures. Similar trends were observed regarding the influence of initial pollutant concentrations on adsorption rate and capacity at both pH 2 and pH 8. At pH 8, the highest adsorption capacity values for environments containing 500 mg/L single RBB, 500 mg/L single chromium(VI), and 500 mg/L RBB+500 mg/L chromium(VI) were 250.1 mg/g RBB, 37.1 mg/g chromium(VI), and 336.5 mg/g RBB+23.3 mg/g chromium(VI), respectively. At pH 2, these values were 56.8 mg/g RBB, 69.0 mg/g chromium(VI), and 89.8 mg/g RBB+34.5 mg/g chromium(VI). Similarly, in RBB+chromium(VI) mixtures, the presence of RBB significantly reduced the adsorption of chromium(VI), while the presence of chromium(VI) increased the adsorption of RBB.

Furthermore, Langmuir Equilibrium Models were applied to each single and mixed adsorbate-adsorbent system to derive model constants. Experimental results showed that surface modification of SBP with CTAB enhanced the adsorption capacity for both RBB and chromium(VI), and in mixed-component adsorption, the adsorption of one component was influenced by the presence of the other. The pH of adsorption was found to be crucial in selecting the adsorbent for these pollutants.