Regeneration of Bleaching Clay Waste by Chemical Activation with Chloride Salts

Abstract

Spent bleaching earth (SBE) was regenerated by chemical activation with low cost and low pollution chlorides as activating agents. Under the conditions of activation temperature of 600d egrees C and holding time of 1 h investigated, results show that fresh bleaching earth and regenerated bleaching earth are type IV with hysteresis loops corresponding to type H3 from nitrogen adsorption-desorption isotherms, indicating slit-shaped mesoporous structure. It is also found that the effect of the regeneration treatment studied in the present work on the pore structures and chemical properties of the resulting solids is negligible compared to the fresh bleaching earth. On the other hand, the pore properties of these chemically activated solids are higher than those of the sample regenerated from heat regeneration, but only approximate 45% of surface area are reclaimed. It implies that the carbon residues could be retained within pores and/or clogs the entrance of pores, resulting in a decrease in pore properties.

Adsorption of ethyl violet dye in aqueous solution by regenerated spent bleaching earth

“…The precursor was then impregnated with potassium chloride and finally regenerated in the conditions of constant ramp rate of 10 • C min −1 under N 2 flow of 300 cm 3 min −1 , activation temperature of 600 • C, and holding time of 1 h [5]. The main physical properties are given in Table 1 [5].…”

“…As experimental comparisons, Table 1 also shows the main physical properties of ABE. Obviously, these adsorbents are characteristic of mesoporous structures, showing that the sample possesses a major peak of pore (slit) widths at about 4.0 nm and a majority of the pores in a broad range at widths of 3.0-20.0 nm [5]. H 2 SO 4 and NaOH were used to adjust initial pH value of aqueous solution.…”

“…In order to conservatively utilize this natural resource, Taiwan's Environmental Protection Administration (EPA), in cooperation with the Ministry of Economic Affairs (MOEA), has mandated a regulatory system for its reuse/recycling under the authorization of the newly revised Waste Disposal Act since 2002 [2]. In our previous studies [3][4][5][6], SBE was regenerated by the thermal, chemical, and physical activation methods. The maximum total pore volume of the regenerated SBE (RSBE) obtained by the chemical method was close to 120 m 2 g −1 , which is equivalent to over 60% of ABE's property based on its total pore volume.…”

“…RSBE with the optimal properties has been obtained by using the chemical activation as described before [5]. Thus, this work aims at determining the extent of the effects of determining factors such as initial concentration, pH, and temperature on adsorption rate of ethyl violet, and further evaluating the usefulness of pseudosecond-order and intraparticle diffusion models for analyzing the adsorption system between the cationic dye and these clay adsorbents.…”

Influence of Some Intercalations on Activation of Pre-Baked Clay

“…Physical activation with steam to get high micropore 12 and irradiating with gamma rays have been documented in the literature 13 . Activating clay using simultaneous chemical as well as physical activation is extensively reported [14][15][16] . We report on the use of NaOH and KOH as intercalating agents to pre baked clay, separately.…”