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Microwave and conventional heating were employed to synthesize micro-sized hematite powder from hydrous ferrous sulfate, a by-product in the process of titanium pigment manufacture. The TG/DTG analysis was used to study thermal behavior of the industrial ferrous sulfate. Therefore the temperature which was significant to product was defined. The calcination experiments were carried out to assess the effect of calcination temperature covering three different temperatures (650°C, 750°C and 850°C, respectively). X-ray powder diffraction (XRD) was used to characterize the structure of the product, while the scanning electron microscopy (SEM) was utilized to characterize the morphology of the product. Microwave calcination process resulted in a mixture of hematite and minor magnetite while a considerable amount of magnesium sulfate was detected with the conventional calcination process. The transformation from periclase to magnesium was discussed during the calcinations as well. The conventional heating resulted in porous product while the microwave heating resulted in smaller particle size.

Single-crystal diborate KSbOB2O5 has been prepared under a high temperature molten-salt method and its structure has been determined by single crystal X-ray diffraction analysis. The diffraction pattern shows strong main reflections and weak satellite reflections, clearly indicating a modulated structure. Using the four-dimensional superspace formalism for aperiodic structures, its reflections could be indexed as orthorhombic superspace group Pmn21(0β0)s00 with the modulation vector q = 5/12b*, and then the structure solution and refinement reached a final commensurately modulated model that was refined extremely well and did not show any unusual features. On the other hand, the powder sample of KSbOB2O5 was synthesized by the high-temperature solid-state reaction method, and the powder X-ray diffraction pattern fits very well with the simulated from the single-crystal data. In addition, photoluminescence properties of diborate KSbOB2O5 activated by 4.5 mol% Dy3+ have been studied, indicating an extraordinary phenomenon that the red emission at around 635 nm (4F9/2→6H11/2) is much stronger than the yellow emission at around 581 nm (4F9/2→6H13/2). [ABSTRACT FROM AUTHOR]

The dielectric properties of petroleum coke at five temperatures between 20 to100∘C, covering different moisture content levels at 2.45 GHz, were measured using an open-ended coaxial probe dielectric measurement system. The effects of drying temperature, duration of drying, and sample mass on the moisture content and dehydration rate of petroleum coke was assessed utilizing the response surface methodology. The dielectric constant, loss factor, and loss tangent were all found to increase nearly linearly with increase in moisture content. Three predictive empirical models were developed to relate the dielectric constant, loss factor, and loss tangent of petroleum coke as a linear function of moisture content from 3–10%. An increase in temperature between 20 to100∘Cwas found to increase the dielectric properties. The penetration depth was observed to increase linearly with decrease in moisture content in the range of 3 to 10%. A predictive empirical model was developed to calculate penetration depth for petroleum coke. Two mathematical models were established and analyzed using RSM to describe the relationship between the microwave drying conditions and the responses, moisture content, and dehydration rate. Statistical analysis with response surface regression showed that microwave drying temperature, duration of drying, and sample mass were significantly related to moisture content and dehydration rate. Based on the RSM analysis, the optimum process conditions were estimated to be a microwave drying temperature of75∘C, drying duration of 10 sec, and sample mass of 60 g, with the resultant moisture content being 0.34 at a dehydration rate of 2.94 g/min. [ABSTRACT FROM PUBLISHER]

Abstract: This paper reports detailed investigation on the influence of microwave irradiation on the cobalt oxalate (Co(C2O4)·2H2O):cobalt oxide (Co3O4) systems in different mass ratio. The analyses of the spectra attenuation and relative frequency shift showed that Co(C2O4)·2H2O had weak capability to absorb microwave irradiation, while Co3O4 had good capability to absorb microwave irradiation. The ability to absorb microwave irradiation was also assessed based on the temperature raise of the system exposed to microwave irradiation. The capability to absorb microwave irradiation of Co(C2O4)·2H2O increased with an increase of ratio Co3O4 in system. [Copyright &y& Elsevier]

Single-crystal diborate KSbOB2O5 has been prepared under a high temperature molten-salt method and its structure has been determined by single crystal X-ray diffraction analysis. The diffraction pattern shows strong main reflections and weak satellite reflections, clearly indicating a modulated structure. Using the four-dimensional superspace formalism for aperiodic structures, its reflections could be indexed as orthorhombic superspace group Pmn21(0β0)s00 with the modulation vector q = 5/12b*, and then the structure solution and refinement reached a final commensurately modulated model that was refined extremely well and did not show any unusual features. On the other hand, the powder sample of KSbOB2O5 was synthesized by the high-temperature solid-state reaction method, and the powder X-ray diffraction pattern fits very well with the simulated from the single-crystal data. In addition, photoluminescence properties of diborate KSbOB2O5 activated by 4.5 mol% Dy3+ have been studied, indicating an extraordinary phenomenon that the red emission at around 635 nm (4F9/2→6H11/2) is much stronger than the yellow emission at around 581 nm (4F9/2→6H13/2). [ABSTRACT FROM AUTHOR]

Single-crystal diborate KSbOB2O5 has been prepared under a high temperature molten-salt method and its structure has been determined by single crystal X-ray diffraction analysis. The diffraction pattern shows strong main reflections and weak satellite reflections, clearly indicating a modulated structure. Using the four-dimensional superspace formalism for aperiodic structures, its reflections could be indexed as orthorhombic superspace group Pmn2₁(0β0)s00 with the modulation vector q = 5/12b*, and then the structure solution and refinement reached a final commensurately modulated model that was refined extremely well and did not show any unusual features. On the other hand, the powder sample of KSbOB2O5 was synthesized by the high-temperature solid-state reaction method, and the powder X-ray diffraction pattern fits very well with the simulated from the single-crystal data. In addition, photoluminescence properties of diborate KSbOB2O5 activated by 4.5 mol% Dy(3+) have been studied, indicating an extraordinary phenomenon that the red emission at around 635 nm ((4)F(9/2) → (6)H(11/2)) is much stronger than the yellow emission at around 581 nm ((4)F(9/2) → (6)H(13/2)).

The work relates to assessing the ability of the microwave for dehydration of large amount of waste hydrous ferrous sulfate generated from the titanium pigment process industry. The popular process optimization tool of response surface methodology with central composite design was adopted to estimate the effect of dehydration. The process variables were chosen to be power input, duration of heating and the bed thickness, while the response variable being the weight loss. An increase in all the three process variables were found to significantly increase the weight loss, while the effect of interaction among the parameters were found to be insignificant. The optimized process conditions that contribute to the maximum weight loss were identified to be a power input of 960 W, duration of heating of 14 min and bed thickness of 5 cm, resulting in a weight loss of 31.44%. The validity of the optimization process was tested with the repeat runs at optimized conditions.