The effect of mechanical grinding on the mesoporosity of steam-activated palm kernel shell activated carbons

Background: Palm kernel shell activated carbon (OPSA) produced by steam gasification at high temperatures generally results in high surface areas of 1146 to 1600 m2 g−1, attributed to the high volume of micropores (0.43 to 0.56 cm3 g−1). The mesoporosity of naturally occurring activated carbons is observed to increase with decreasing particle size. Mechanical grinding was therefore performed to investigate its effect on the mesoporosity and microporosity of OPSA. Results: Mechanical grinding had a strong effect on mesopore volume and average pore diameter, with an increase in mesopore volume from 47 to 66% as particle size decreases. Interestingly, no significant effect on the micropore fraction was observed in ground OPSA particles. Conclusions: The mechanically ground OPSA particles possessed dual adsorption capabilities due to the high microporosity and moderate mesoporosity contained in the structures. This results in interesting porosity behaviour of palm kernel shell activated carbons and the potential to provide materials of distinct sorption capacities with minimal treatment

Deoiling efficiency for oil extraction from spent bleaching clay and the quality of recovered oil

The disposal and reuse of spent bleaching clay (SBC) from the palm oil processing industry is a problem of growing importance. Although today the only practical way of removing SBC is by disposal, extraction with organic solvents is a well-known method of deoiling contaminated SBC. Various hydrocarbon solvents are used as solvents to extract the residual oil in SBC. In this study, SBC was deoiled by hexane extraction. The content of oil and minor components in SBC was more than 40% by weight. All the extracted oils, irrespective of the solvent used, had poorer quality than crude palm oil (CPO). The outcome of the study showed that the amount of extracted oil using the conventional Soxhlet extraction method was higher than by batch extraction. However, for extraction of the residual SBC using the batch method, a SBC to solvent ratio of 1:7 should be more suitable as more of the impurities are removed. The aim of this study was for a complete separation of the residual oil from SBC. The oil and SBC were analyzed and tested. The results show that SBC still had an activity approximately 80% that of fresh bleaching clay

Robust Entanglement in Atomic Systems via Lambda-Type Processes

It is shown that the system of two three-level atoms in $\Lambda$ configuration in a cavity can evolve to a long-lived maximum entangled state if the Stokes photons vanish from the cavity by means of either leakage or damping. The difference in evolution picture corresponding to the general model and effective model with two-photon process in two-level system is discussed.Comment: 10 pages, 3 figure

Regeneration and characterization of spent bleaching clay

Spent bleach­ing clay (SBC), a solid waste gen­er­ated from the palm oil refin­ery, may be recy­cled rather than being sim­ply dis­posed off in land­fills. The aim of this research was to inves­ti­gate the heat regen­er­a­tion of SBC and to eval­u­ate the per­for­mance of the heat-treated SBC in bleach­ing crude oil. Two types of SBC were used, i.e. (a) acid-activated clay, and (b) nat­ural clay. Two types of regen­er­a­tion processes were per­formed, i.e. (a) sol­vent extrac­tion fol­lowed by heat treat­ment, and (b) direct heat treat­ment. Heat treat­ment was con­ducted in a box fur­nace at tem­per­a­tures rang­ing from 400°C to 800°C. Red colour indices of oils were used to deter­mine the regen­er­a­tion effi­ciency. Spent bleach­ing clay pro­duced by the direct heated-regenerated spent bleach­ing clay (HRSBC) yielded a higher regen­er­a­tion effi­ciency than the deoiled-heated-regenerated spent bleach­ing clay (DHRSBC) pro­duced by sol­vent extrac­tion and heat treat­ment. This is because mois­ture, impu­ri­ties and dirt were more com­pletely removed by direct heat­ing than by sol­vent extrac­tion. Spe­cific sur­face area, total pore vol­ume and aver­age pore size of SBC were mea­sured using the nitro­gen adsorption-desorption method. The results show that the HRSBC at 500°C pos­sessed a higher spe­cific sur­face area and total pore vol­ume and gave a bet­ter bleach­ing effi­ciency than HRSBC at 400°C and 800°C. All the regen­er­ated SBC sam­ples were meso­porous material

Linear atomic quantum coupler

In this paper, we develop the notion of the linear atomic quantum coupler. This device consists of two modes propagating into two waveguides, each of them includes a localized and/or a trapped atom. These waveguides are placed close enough to allow exchanging energy between them via evanescent waves. Each mode interacts with the atom in the same waveguide in the standard way, i.e. as the Jaynes-Cummings model (JCM), and with the atom-mode in the second waveguide via evanescent wave. We present the Hamiltonian for the system and deduce the exact form for the wavefunction. We investigate the atomic inversions and the second-order correlation function. In contrast to the conventional linear coupler, the atomic quantum coupler is able to generate nonclassical effects. The atomic inversions can exhibit long revival-collapse phenomenon as well as subsidiary revivals based on the competition among the switching mechanisms in the system. Finally, under certain conditions, the system can yield the results of the two-mode JCM.Comment: 14 pages, 3 figures; comments are most welcom

Dark States and Interferences in Cascade Transitions of Ultra-Cold Atoms in a Cavity

We examine the competition among one- and two-photon processes in an ultra-cold, three-level atom undergoing cascade transitions as a result of its interaction with a bimodal cavity. We show parameter domains where two-photon transitions are dominant and also study the effect of two-photon emission on the mazer action in the cavity. The two-photon emission leads to the loss of detailed balance and therefore we obtain the photon statistics of the cavity field by the numerical integration of the master equation. The photon distribution in each cavity mode exhibits sub- and super- Poissonian behaviors depending on the strength of atom-field coupling. The photon distribution becomes identical to a Poisson distribution when the atom-field coupling strengths of the modes are equal.Comment: 15 pages including 7 figures in Revtex, submitted to PR

Porosity characteristics and pore developments of various particle sizes palm kernel shells activated carbon (PKSAC) and its potential applications

The adsorption behaviour and the micro- and mesopore size distributions of commercial palm kernel shell activated carbons (PKSAC) and other commercial activated carbon are characterized. The results showed that PKSAC are predominantly microporous materials, where micropores account 68–79% of total porosity. On the other hand, commercial activated carbons: Norit SX Plus, Calgon 12×40, and Shirasagi “A” activated carbons contained high mesopore fraction ranging from 33 to 52%. The analysis showed that the degree of mesoporosity of PKSAC is increased steadily with the decrease of particle size. This is due to the presence of channels interconnect the smaller pores in the interior of smaller particle size PKSAC. The smaller size PKSAC particle that is highly mesoporous has preformed better on the adsorption of larger molecules such as methylene blue. On the other hand, bigger size PKSAC particle has better performance on the adsorption of smaller adsorbates such as iodine

Deoiling and regeneration efficiencies of spent bleaching clay

Problem statement: Disposal and reuse of Spent Bleaching Clay (SBC) from palm oil processing industry is a problem of growing importance. The residual oil in the SBC can be recovered using hexane as solvent. Approach: In this study, the effect of different solid to solvent ratio on the deoiling efficiency of SBC samples from palm oil refinery and palm kernel refinery were studied. The amount of extracted oil and deoiling efficiency for both types of SBC increases as the solid to solvent ratio is decreased. Results: All the extracted oils, irrespective of the amount of solvent used, have poorer quality than crude oil and may be difficult to be refined to good quality and stability. Conclusion: The deoiled SBC treated using different solid to solvent ratio gave almost similar regeneration efficiency i.e., about 80% for bleaching of CPO and not more than 30% for bleaching of CPKO