Detection of efficiency of microwave-enhanced sludge treatments by dielectric measurements

Microwave irradiation is a promising pre-treatment method for sludge stabilisation, but there are few studies focusing its effect on organic matter solubility and biodegradability of wastewater and sludge originated from the food industry. In our research, microwave irradiation was applied standalone and in combination with alkaline treatment to enhance the solubilisation and biodegradation of organic matter content of meat industry wastewater and municipal sludge, respectively. The energy efficiency was investigated, as well. Dielectric measurement is a suitable method to detect physicochemical changes, therefore our research work covered the determination of dielectric properties of the investigated materials. Our experimental results have revealed that the lower power and energy intensity microwave-alkaline treatments were the most efficient pre-treatment process from energetically aspects to increase the organic matter solubility and biodegradability of wastewater and sludge. Furthermore, a strong linear correlation was found between the dielectric constant and the indicators of the solubility of organic matter (SCOD/TCOD) and aerobic biodegradability (BOD/COD) in both treated materials, respectively. Our results show that the dielectric measurements can be applied for detection of physicochemical changes, predict the improvement of biodegradability, and considered as a promising method to estimate the efficiency of sludge pre-treatment methods.

Structural, impedance, dielectric and optical characteristics of Cd- substituted Zn (1-x) CdxO nanoparticles at low temperatures

Nanocrystalline Cd substituted ZnO nanoparticles with common formula Zn (1-x) CdxO (x = 0%, 3%, 6%, and 10%) were fabricated by a co-precipitation technique. X-ray diffraction (XRD) and scanning electron microscopy (SEM) was used to investigate the microstructures and morphology of synthesized nanoparticles at room temperature. The outcome of the x-ray diffraction (XRD) study supports the existence of wurtzite crystal structure for ZnO, and Cd substituted ZnO samples conformed that substituted Cd ions are catching up Zn site. The morphological assessments of the fabricated nanoparticles indicated that the nature of the nanoparticles is a slightly hexagonal and mostly spherical shape with size ranges 46-55 nm. The electric impedance of the samples was measured in a wide range of frequency 100Hz–2MHz at different temperatures (140 K-260 K) using an LCR meter. It was observed that the dielectric constants (ἐ), (ε´´), loss tangent (tanδ), and ac conductivity of pure and Cd substituted ZnO nanoparticles depended on frequency. The calculations of dielectric measurement showed that the parameters (ἐ), (ε´´), loss tangent (tanδ) decreased with the increase in frequency. But the ac conductivity enhanced with the frequency, whereas the values of the above parameters increased with the temperature rise. The dielectric parameters are also found to improve with the increase in Cd concentrations. The correlated barrier-hopping (CHB) model dominated in ac conductivity. The reduction in the bandgap was also observed with Cd concentration.

The specifics of quasi-optical measurements in the submillimetre waveband

The paper investigates the influence of the electromagnetic field and standing wave structure in a quasi-optical waveguide on the dielectric measurement results and gives recommendations on the layout of measuring circuits.

Dielectric response of nitrogen in soil amended with chicken litter biochar and urea under Oryza sativa L. cultivation

Unbalanced utilization of nitrogen (N) rice not economically viable neither is this practice environmental friendly. Co-application of biochar and urea could reduce the unbalanced use of this N fertilizer in rice cultivation. Thus, a field study was carried out to: (i) determine the effects of chicken litter biochar and urea fertilization on N concentration in soil solution of a cultivated rice (MR219) using dielectric measurement at a low frequency and (ii) correlate soil dielectric conductivity with rice grain yield at maturity. Dielectric response of the soil samples at 20, 40, 55, and 75 days after transplanting were determined using an inductance–capacitance–resistance meter HIOKI 3522-50 LCR HiTESTER. Selected soil chemical properties and yield were determined using standard procedures. The dielectric conductivity and permittivity of the soil samples measured before transplanting the rice seedlings were higher than those for the soil samples after transplanting. This was due to the inherent nitrogen of the chicken litter biochar and the low nitrogen uptake at the transplanting stage. The soil N response increased with increasing measurement frequency and N concentration. The permittivity of the soil samples was inversely proportional to frequency but directly proportional to N concentration in the soil solution. The estimated contents of N in the soil using the dielectric conductivity approach at 1000 Hz decreased with increasing days of fertilization and the results were similar to those of soil NH4+ determined using chemical analysis. The conductivity measured within 1000 Hz and 100,000 Hz correlated positively with the rice grain yield suggesting that nitrogen concentration of the soil can be used to estimate grain yield of the cultivated rice plants.

A Dual-Band Non-destructive Dielectric Measurement Sensor Based on Complementary Split-Ring Resonator

A dual-band non-destructive dielectric constant sensor based on the complementary split ring resonators is presented. The resonators for both bands use the complementary split ring structure of different sizes. Numerical simulation demonstrates that the resonating frequency and quality factor is dependent on the variation of dielectric constant and loss tangent, making it a potential structure for dielectric measurement. To search for the optimal thickness for measurement, parametric study is conducted and the retrieval expressions are obtained for both bands. The measured results indicate an accuracy of 1.5% in comparison with the data in the literature. In addition, the effect of air gap has been analyzed, showing that it is an important error source and eliminating such effect can improve the measurement accuracy.

The State of Starch/Hydroxyapatite Composite Scaffold in Bone Tissue Engineering with Consideration for Dielectric Measurement as an Alternative Characterization Technique

Hydroxyapatite (HA) has been widely used as a scaffold in tissue engineering. HA possesses high mechanical stress and exhibits particularly excellent biocompatibility owing to its similarity to natural bone. Nonetheless, this ceramic scaffold has limited applications due to its apparent brittleness. Therefore, this had presented some difficulties when shaping implants out of HA and for sustaining a high mechanical load. Fortunately, these drawbacks can be improved by combining HA with other biomaterials. Starch was heavily considered for biomedical device applications in favor of its low cost, wide availability, and biocompatibility properties that complement HA. This review provides an insight into starch/HA composites used in the fabrication of bone tissue scaffolds and numerous factors that influence the scaffold properties. Moreover, an alternative characterization of scaffolds via dielectric and free space measurement as a potential contactless and nondestructive measurement method is also highlighted.

Effect of Cd2+ Substituted Nickel Ferrite oxide (Ni1-xCdxFe2O4) on Magnetic, Dielectric and Structural Properties

The effect of cadmium (Cd2+) substituted at the NiFe2O4 nano materials were this nano material synthesized by auto-combustion technique. The structural analysis confirms that the samples are polycrystalline nature with spinel cubic crystal symmetry. The effect of Cd2+ contains on lattice constants which obeys Vegard's law. The morphological analysis shows that the highly porous structure with spongy like surface morphology. The observed absorption infrared spectra confirm that the exhibits the nano ferrite materials. The magnetic properties measurements reveal that the saturation of magnetization decreases with an increase in constituent Cd2+ in nickel ferrous oxide. The Cd2+ ions present in A-site and Fe3+ are distributed in both tetrahedral and octahedral sites of spinel lattice. The DC measurement shows that the semiconducting behaviour of the prepared Ni1-xCdxFe2O4. The increase in Cd2+ constituent in the nickel ferrite with decrease curie temperature. The dielectric measurement of all samples shows the usual dielectric dispersion with frequency. The impedance spectroscopy analysis suggests grain interior contribution in the conduction process.

Dielectric Properties of Modified Lead Zirconate Titanate

In this paper, the dielectric properties of modified i. e. alkali doped lead zirconate titanate Pb(Zr1- xTix)O3 has been studied. The composition Pb1-x (La1-zDz)x (Zry Ti1-y)1-x/4 O3;where x = 0.10, y = 0.70, z = 0.0, 0.1, 0.2, and 0.3, D= Na, K and Li has been prepared by conventional mixed oxide method at a temperature of 11000C. Dielectric constant and dielectric loss measurement of the sintered pellets has been measured. Dielectric measurement shows that the dielectric constant decreases with an increase in temperature. The results show that the dielectric loss is very small and decreases with frequency above 300°C. The increase in the dielectric constant observed at high temperatures and low frequencies is explained in the paraelectric state.