Surface and pore structure of deoiled acid‐and heat‐treated spent bleaching clays

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De-oiled spent bleaching clay was activated either by acid treatment followed by heat activation or by heat activation alone at temperatures between 200 and 800°C. The surface area of the heat-activated clay attained a maximal value of ~120 m 2 g -1 at temperatures between 400 and 500°C while the acid-heat-treated clay attained maximal surface area of 140 m 2 g -1 . The adsorption capacities of chromium [Cr(VI)] for both series studied increased as the activation temperature increased until 300°C and decreased again at higher temperatures. At lower pH, more than 95 % of the Cr(VI) was absorbed in a solution with initial concentration of 1 mg L -1 per gram of adsorbent activated at 300°C. The adsorption patterns followed Freundlich's isotherms. Two maximal values of adsorption capacities of nickel [Ni(II)] were observed at activation temperatures of 200 and 500°C for acid-treated samples, whereas these were at 200 and 700°C for the nonacid-treated samples. The amount of Ni(II) adsorbed increased with the pH of the solution for all samples studied. The maximal adsorption capacities of the adsorbents in solution containing initial Ni(II) concentration of 5 mg L -1 per 0.5 g of adsorbent and at pH 6 were found to be 44 and 42%, respectively, for the acid-treated sample activated at 500°C and for the nonacid-treated sample activated at 700°C. They all obeyed both the Langmuir's and Freundlich 's isotherms. Paper no. J9750 in JAOCS 78, 831-835 (August 2001). Removal of Ni(II) (%)Activation temperature (°C) FIG. 4.Percentage removal of nickel [Ni(II)] as a function of activation temperature for acid-treated samples. Conditions: Ni(II) concentration, 5 ppm; adsorbent dosage, 0.5 g L -1 ; temperature, 30°C; ◆ pH 2, ■ pH 4, ▲ ▲ pH 5, ▲ pH 8, ✕  pH 9, • pH 11.

Section: Resultsmentioning

confidence: 86%

“…This method of disposal causes environmental concern because of their pyrolytic nature and also the possibility of the leaching of the oil into the surrounding water resources. While efforts to reduce the loss of oil and to minimize clay dosage in the refining process continue, the possibility of recycling the clay has been studied and reviewed (10,11).…”

mentioning

confidence: 99%

Adsorption of chromium(VI) and nickel(II) ions on acid‐ and heat‐activated deoiled spent bleaching clay

Seng

Lee

Liew

2001

Self Cite

“…Ng et al [10] used a Soxhlet extractor and supercritical CO 2 at 60°C and 300 bar to deoil the clay. The clay was then heat treated at 400°C in a muffle furnace in the air and treated with 20% H 2 SO 4 .…”

Section: Introductionmentioning

confidence: 99%

“…Al-Zahrani and Daous [9], deoiled the SBC with EMK and activated the clay by calcination at 500°C. Ng et al [10] used a Soxhlet extractor and supercritical CO 2 at 60°C and 300 bar to deoil the clay. The clay was then heat treated at 400°C in a muffle furnace in the air and treated with 20% H 2 SO 4 .…”

Section: Introductionmentioning

confidence: 99%

Regeneration and Reutilization of Oil‐Laden Spent Bleaching Clay via in Situ Transesterification and Calcination

Boey

Ganesan

Maniam

2011

Landfill bound waste from the oil palm industry, spent bleaching clay (SBC) containing significant amounts of adsorbed crude palm oil (CPO) has the potential to be used for biodiesel production. In this study, SBC was subjected to ultrasound-aided in situ transesterification with a co-solvent to convert the oil into methyl esters (biodiesel). Optimized reaction conditions used were 5.4 wt% KOH, methanol to oil mass ratio of 5.9:1 and 1:1 mass ratio of co-solvent (petroleum ether or ethyl methyl ketone) to SBC. The remaining bleaching clay was calcined at 500°C for 30 min and reutilized for bleaching. Absence of -CH absorption peaks in the FTIR and TGA-FTIR analysis of regenerated clays shows the regeneration efficiency of the method. In situ transesterification and heat regeneration helped to restore pores without adversely affecting the clay structure. The use of ethyl methyl ketone (EMK) as the co-solvent in the in situ transesterification process produced clay with better bleaching qualities.

“…Whereas efforts to reduce the loss of oil and dosage of clay for the refining process continue, the possibility of recycling the clay has been studied (3,5,6); the first step in recycling is the efficient extraction of the oil. Hexane extraction has been used in the past for the recovery of oil from spent clay (7).…”

mentioning

confidence: 99%

Solvent efficiency for oil extraction from spent bleaching clay

Lee

Seng

Liew

2000

Self Cite

Various alcohols and hydrocarbons were used as solvents to extract the residual oil in spent bleaching clay from palm oil refining. The content of oil and minor components in the spent clay was >40% by weight. The efficiencies of extraction by the polar alcohols, except for methanol, were higher but with a slower initial rate than the nonpolar hydrocarbons. The free fatty acids contents, the Totox values (anisidine value + 2 × peroxide value), and the color of the alcohol-extracted oil were also higher than that by the hydrocarbons resulting in poorer quality oils. All the extracted oils, irrespective of the solvent used, have poorer quality than crude palm oil. However, for regeneration of the residual spent clay, the polar alcohols should be more suitable as more of the impurities are removed.