Reuse of Spent Bleaching Earth of the Edible Oil Factory to Reduce Pollution from Aqueous Solutions

Merikhy, Arezoo (2016) Reuse of Spent Bleaching Earth of the Edible Oil Factory to Reduce Pollution from Aqueous Solutions. Masters thesis, university of Mohaghegh Ardabili.

Text (استفاده¬ی مجدّد از خاک رنگبر مستعمل کارخانه¬ی روغن نباتی در کاهش آلایندگی از محیط¬های آبی) Arezoo Merikhy.pdf Download (704kB)

Abstract

In this research, regeneration of Spent Bleaching Earth (SBE), a waste from vegetable oil refinery plant, was carried out using thermal and organic solvent extraction methods to reduce its environmental hazards. To find the optimum time and temperature of carbonization, themally regeneration experiments were carried out based on full factorial design and results were analyzed and optimised using response surface methodology (RSM). In solvent extraction method, n-Hexane and Acetone were used as non-polar and polar organic solvents to desolve remnant oil and non-polar and polar organic compounds in SBE, respectively. The regenerated samples were investigated in terms of morphology, elemental analysis, and chemical structure with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and Fourier transform infrared spectroscopy (FTIR), compared to Bleaching Earth (BE), respectively. The regenerated samples were used as adsorbents for the removal of Methylene Blue (MB) dye, a model pollutant, from aqueous solution in a batch mode. In this step, the effects of pH of the solution, adsorbent dose, mixing time, and MB initial concentration as well as the isotherms and kinetics studies were investigated. The results revealed that RSM can be used as an appropriate and cost-effective alternative for conventional method to optimizate the time and temperature of carbonisation. In conventional method, samples were regenerated at different temperatures and times, then the time and temerature of the carbonization were optimized based on characterization tests for each of the studied samples. Sequentionally extracted SBE with n-Hexane and Aceton was the most similar sample to BE, and based on the results of studying the samples regenerated separately with the aforementioned solvents, Acetone was better than n-Hexane. The batch adsorption studying results reveal that the applied regeneration methods by converting SBE into an efficient adsorbent for water/wastewater treatment could overcome the environmental problems caused by disposal of SBE. Maximum adsorption capacities obtained from Toth isotherm model at pH=5±0.1 were 138.7 mg g-1 for BE, 108.6 mg g-1 for n-Hexane and Acetone extracted SBE, 88.96 mg g-1 for Acetone extracted SBE, 72.07 mg g-1 for n-Hexane extracted SBE and 53.34 mg g-1 for thermally regenerated SBE.

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