Leaching behavior of chromium in chrome shaving generated in tanning process and its stabilization

In this study, leaching properties and pollution potential of chromium in chrome shaving (CS), which is a solid residue of leather industry, containing 2.27% Cr were investigated and thermal stabilization procedure was applied to the CS for chromium immobilization. For this purpose, firstly, effects of the liquid/solid ratio, contact time, pH and sequential extraction on the leaching behavior of chromium in the CS were studied. It was determined that the CS-caused chromium pollution is a hazardous material for environment. Thermal stabilization procedure was applied to the CS in the temperature range of 250-500 degrees C for the chromium immobilization. Effective stabilization of chromium in the CS was achieved by heating of CS at 350 degrees C under CO(2) atmosphere. Leaching experiments were also carried out with the samples obtained from the stabilization process and the results compared with that of the CS. Also, TCLP test method was applied to the samples to determine pollution potentials and discharge situations of the CS and its stabilization products. While the chromium concentrations in the test solutions of all samples stabilized thermally at above 350 degrees C were below the USEPA regulatory limit of 5 mg/l, the concentration of chromium leached out from the CS was 30-fold bigger than the USEPA regulatory limit.     

News or social media? Socio-economic divide of mobile service consumption

Reliable and timely information on socio-economic status and divides is critical to social and economic research and policing. Novel data sources from mobile communication platforms have enabled new cost-effective approaches and models to investigate social disparity, but their lack of interpretability, accuracy or scale has limited their relevance to date. We investigate the divide in digital mobile service usage with a large dataset of 3.7 billion time-stamped and geo-referenced mobile traffic records in a major European country, and find profound geographical unevenness in mobile service usage—especially on news, e-mail, social media consumption and audio/video streaming. We relate such diversity with income, educational attainment and inequality, and reveal how low-income or low-education areas are more likely to engage in video streaming or social media and less in news consumption, information searching, e-mail or audio streaming. The digital usage gap is so large that we can accurately infer the socio-economic status of a small area or even its Gini coefficient only from aggregated data traffic. Our results make the case for an inexpensive, privacy-preserving, real-time and scalable way to understand the digital usage divide and, in turn, poverty, unemployment or economic growth in our societies through mobile phone data.     

Technical demand response potentials of the integrated steelmaking site of Tata Steel in IJmuiden

Power generation from intermittent renewable energy sources in northwest Europe is expected to increase significantly in the next 20 years. This reduces the predictability of electricity generation and increases the need for flexibility in electricity demand. Data on demand response (DR) capacities of electricity-intensive consumers is limited for most countries. In this paper, we evaluate the DR potential that can be provided to the Dutch national grid by the integrated steelmaking site of Tata Steel in IJmuiden (TSIJ). TSIJ generates electricity from its works arising gases (WAGs). The DR potentials are evaluated by using a linear optimisation model that calculates the optimal allocation of WAGs of TSIJ in case of a call for DR by the transmission system operator. The optimisation is done subject to the technical constraints of the WAG distribution network, WAG storage capacities, the on-site demand for WAGs and the ramp-up rate of the power plant that runs on WAGs. Results show that TSIJ can supply 10 MW for two programme time units (equal to 15-min period in the Netherlands) of positive DR capacity (demand reduction) with an availability rate of 97%. This is not sufficient for participating in the current emergency capacity programs in the Netherlands, which require at least 20 MW for longer than one programme time unit. Tata Steel can provide 20 MW DR capacity with an availability rate of 65%. The negative DR capacity (demand increase) of Tata Steel in IJmuiden is found to be 20 MW supplied for three programme time units and four programme time units with doubling of blast furnace gas storage capacities.     

Ligand exchange based paraoxon imprınted QCM sensor

In the present work, a paraoxon imprinted QCM sensor has been developed for the determination of paraoxon based on the modification of paraoxon imprinted film onto a quartz crystal combining the advantages of high selectivity of the piezoelectric microgravimetry using MIP film technique and high sensitivity of QCM detection. The paraoxon selective memories have formed on QCM electrode surface by using a new metal–chelate interaction based on pre-organized monomer and the paraoxon recognition activity of these molecular memories was investigated. Molecular imprinted polymer (MIP) film for the detection of paraoxon was developed and the analytical performance of paraoxon imprinted sensor was studied. The molecular imprinted polymer were characterized by FTIR measurements. Paraoxon imprinted sensor was characterized with AFM and ellipsometer. The study also includes the measurement of binding interaction of paraoxon imprinted quartz crystal microbalance (QCM) sensor, selectivity experiments and analytical performance of QCM electrode. The detection limit and the affinity constant (K_affinity) were found to be 0.06 μM and 2.25 × 10⁴ M^? 1 for paraoxon [MAAP–Cu(II)–paraoxon] based thin film, respectively. Also, it has been observed that the selectivity of the prepared paraoxon imprinted sensor is high compared to a similar chemical structure which is parathion.     

Effect of fuel type on the optimum thickness of selected insulation materials for the four different climatic regions of Turkey

The optimum insulation thickness of the external wall for four various cities from four climate zones of Turkey, energy savings over a lifetime of 10 years and payback periods are calculated for the five different energy types and four different insulation materials. Foamboard 3500, Foamboard 1500, extruded polystyrene and fiberglass as insulation material are selected. In this study, it is calculated the value of the amount of the net energy savings using the P₁–P₂ method. The results show that optimum insulation thicknesses vary between 1.06 and 7.64 cm, energy savings vary between 19 $/m² and 47 $/m², and payback periods vary between 1.8 and 3.7 years depending on the city and the type of fuel. The highest value of energy savings is reached in A?r? for LPG fuel type, while the lowest value is obtained in Ayd?n for natural gas.     

Leaching behavior of pollutants in ferrochrome arc furnace dust and its stabilization/solidification using ferrous sulphate and Portland cement

In this study, dissolution properties under different conditions and pollution potential by toxicity characteristic leaching procedure (TCLP) of arc furnace dust generated in the production of ferrochrome were examined and some stabilization/solidification (S/S) techniques were applied to the dust depending on contaminants determined. Dissolution properties and pollution potentials of all the materials stabilized/solidified were also studied under the similar conditions. It was determined that the metallic components concentrations dissolved from the ferrochrome arc furnace dust (FAFD) except for chromium and zinc were below the detection limits. The chromium concentration dissolved from the FAFD by TCLP was found to be 9.8 mg/l. Portland cement (PC), PC-FeSO(4) and PC-sand-FeSO(4) mixtures for S/S of the FAFD were tested. Although metal ions in the cationic form were stabilized when the PC was only used, Cr(VI) in the sample was not changed depending on PC amount and remained in the soluble chromate form. The stabilization efficiency of Cr(VI) increased by the increasing amounts of PC and FeSO(4). The best S/S of the FAFD was accomplished when the 5 stoichiometric amounts of FeSO(4), 30% PC and 16% sand mixture were used. TCLP leaching results of the samples obtained under the optimum conditions were below the EPA landfilling limits.     

Exergoeconomic analysis and optimization of a solar-assisted heating system for residential buildings

In this study, an exergoeconomic model was developed for analysis and optimization of solar heating systems with residential buildings. The optimum collector area (_Ac$A_{\mathrm{c}}$) and storage volume (V$V$) for solar-assisted heating system in the Elaz??, Turkey (38.7^°N)$(38.7^{°}\mathrm{N})$, weather conditions were obtained using MATLAB optimization toolbox. The energy and exergy losses in each of the components of a solar heating system with seasonal storage were also determined. The results showed that the exergy loss and total cost increased with increasing per house collector area for the trapeze and cylindirical tanks. It was found that the total cost of the cylindrical tank system was higher than that of the other trapeze tank system. The exergy loss at the cylindrical tank was 19.8%, while the exergy loss at the trapeze tank was 8.3%.