Abstract
This work describes the potential of utilizing prepared activated carbon from apricot stones as an efficient adsorbent material for tartrazine (TZ) azo-dye removal in a batch and dynamic adsorption system. The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation. In batch experiments, effects of the parameters such as initial dye concentration and temperature on the removal of the dye were studied. Equilibrium was achieved in 120 min. Adsorption capacity was found to be dependent on the initial concentration of dye solution, and maximum adsorption was found to be 76 mg/g at 100 mg/L of TZ. The adsorption capacity at equilibrium (qe) increased from 22.6 to 76 mg/g with an increase in the initial dye concentrations from 25 to 100 mg/L. The thermodynamic parameters such as change in free energy (ΔG0), enthalpy (ΔH0) and entropy (ΔS0) were determined and the positive value of (ΔH) 78.1 (K J mol−1) revealed that adsorption efficiency increased with an increase in the process temperature. In fixed-bed column experiments, the effect of selected operating parameters such as bed depth, flow rate and initial dye concentration on the adsorption capacity was evaluated. Increase in bed height of adsorption columns leads to an extension of breakthrough point as well as the exhaustion time of adsorbent. However, the maximum adsorption capacities decrease with increases of flow rate. The breakthrough data fitted well to bed depth service time and Thomas models with high coefficient of determination, R2 ≥ 94.
Highlights
Azo-dyes as an aromatic molecular structure compound are generally resistant to light, biodegradation, temperature, ozonation and oxidation
The results revealed that activated carbons with well-developed surface area (774 m2/g) and pore volume (1.26 cm3/g) can be manufactured from apricot stones by H3PO4 activation
The maximum adsorption capacities decrease with increases of flow rate
Summary
Azo-dyes as an aromatic molecular structure compound are generally resistant to light, biodegradation, temperature, ozonation and oxidation. On the basis of the previous discussions, the focus of this research was to evaluate the adsorption potential of the Apricot stone-based activated carbon in removing Tartrazine azo-dye from aqueous solutions through batch and fixed-bed experiments. Batch adsorption experiments were conducted using synthetic aqueous solutions of tartrazine and the effects of initial dye concentration and temperature were investigated. Tartrazine dye supplied by Morgan Chemical Company was used without further purification to prepare all synthetic wastewater solutions. The experiments were conducted by varying the weight of activated carbon and different initial solutions concentration of TZ. Several bed parameters are important for the characterization of any adsorption process They were determined for each column from the breakthrough curves using previously published calculation methods Qtotal m ð4Þ where m (g) is the mass of adsorbent in the column
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