Thermal behaviors, combustion mechanisms, evolved gasses, and ash analysis of spent potlining for a hazardous waste management

An unavoidable but reusable waste so as to enhance a more circular waste utilization has been spent potlining (SPL) generated by the aluminum industry. The combustion mechanisms, evolved gasses, and ash properties of SPL were characterized dynamically in response to the elevated temperature and heating rates. Differential scanning calorimetric (DSC) results indicated an exothermic reaction behavior probably able to meet the energy needs of various industrial applications. The reaction mechanisms for the SPL combustion were best described using the 1.5-, 3- and 2.5-order reaction models. Fluoride volatilization rate of the flue gas was estimated at 2.24%. The SPL combustion emitted CO₂, HNCO, NO, and NO₂ but SO_x. The joint optimization of remaining mass, derivative thermogravimetry, and derivative DSC was achieved with the optimal temperature and heating rate combination of 783.5°C, and 5 °C/min, respectively. Interaction between temperature and heating rate exerted the strongest and weakest impact on DSC and remaining mass, respectively. The fluorine mainly as the formation of substantial NaF and CaF₂ in the residual ash. Besides, the composition and effect of environment of residual solid were evaluated. The ash slagging tendency and its mineral deposition mechanisms were elucidated in terms of turning SPL waste into a benign input to a circular waste utilization.     

A study on the potential sources of air pollutants observed at Tjörn,Sweden

The Potential Source Contribution Function (PSCF) receptor model combines both chemical and meteorological information. In this study, PSCF was employed to identify the potential source emission regions for aerosol compositions measured at Tjörn, Sweden (58.01 °N, 11.36 °E). PSCF was for the first time applied on a European scale. One hundred and fifty-two four-day air parcel backward trajectories were combined with concentrations of sixteen elements determined in 33 coarse and fine aerosol samples. The observations were made between February 17 and March 26, 1985. The modeling results of the heavy metals V, Pb, Zn, and As are presented and compared with available emission inventory data. A number of known industrialized regions in the former USSR and Europe are found of high potential to be the emission source areas. These areas are in good agreement with the known emission information. The PSCF maps of total sulfur, Non-Seasalt-Sulfur (N.S.S.) and chlorine are also presented. High potential regions in the Arctic area exist in the PSCF map for total sulfur wheres they do not occur in that for N.S.S.     

Adsorption kinetics of methyl violet onto perlite

This study examines adsorption kinetics and activation parameters of methyl violet on perlite. The effect of process parameters like contact time, concentration of dye, temperature and pH on the extent of methyl violet adsorption from solution has been investigated. Results of the kinetic studies show that the adsorption reaction is first order with respect to dye solution concentration with activation energy of 13.2 kJ mol(-1). This low activation energy value indicates that the adsorption reaction is diffusion controlled. The activation parameters using Arrhenius and Eyring equations have been calculated. Adsorption increases with increase of variables such as contact time, initial dye concentration, temperature and pH.     

Effects of whole spine alignment patterns on neck responses in rear end impact

Objective: The aim of this study was to investigate the whole spine alignment in automotive seated postures for both genders and the effects of the spinal alignment patterns on cervical vertebral motion in rear impact using a human finite element (FE) model.

Methods: Image data for 8 female and 7 male subjects in a seated posture acquired by an upright open magnetic resonance imaging (MRI) system were utilized. Spinal alignment was determined from the centers of the vertebrae and average spinal alignment patterns for both genders were estimated by multidimensional scaling (MDS). An occupant FE model of female average size (162 cm, 62 kg; the AF 50 size model) was developed by scaling THUMS AF 05. The average spinal alignment pattern for females was implemented in the model, and model validation was made with respect to female volunteer sled test data from rear end impacts. Thereafter, the average spinal alignment pattern for males and representative spinal alignments for all subjects were implemented in the validated female model, and additional FE simulations of the sled test were conducted to investigate effects of spinal alignment patterns on cervical vertebral motion.

Results: The estimated average spinal alignment pattern was slight kyphotic, or almost straight cervical and less-kyphotic thoracic spine for the females and lordotic cervical and more pronounced kyphotic thoracic spine for the males. The AF 50 size model with the female average spinal alignment exhibited spine straightening from upper thoracic vertebra level and showed larger intervertebral angular displacements in the cervical spine than the one with the male average spinal alignment.

Conclusions: The cervical spine alignment is continuous with the thoracic spine, and a trend of the relationship between cervical spine and thoracic spinal alignment was shown in this study. Simulation results suggested that variations in thoracic spinal alignment had a potential impact on cervical spine motion as well as cervical spinal alignment in rear end impact condition.     

Status of Cadmium Concentration in Soil and Vegetable Irrigated with City Effluent

Cadmium is a toxic and carcinogenic element[1].In the1950s and 1960s,cadmium intoxication was considered to bestrictly an occupational disease.It was not until recognition of thecontribution of cadmium exposure to the etiology of Itai-itai dis-ease.It is …     

Degradation of the herbicide imazapyr by Fenton reactions

The degradation of the herbicide imazapyr has been carried out by three advanced oxidation processes involving iron ions as catalysts: Fentons reagent, photo-Fenton and electro-Fenton. We show that all processes are rapid and efficient. The kinetic rate constant was found to be k=5.4×10⁹ M^–1 s^–1. The mineralization of imazapyr is almost complete using the photo-Fenton and electro-Fenton processes.     

Analysis of short chain chlorinated paraffins in sediment samples from the Czech Republic by short-column GC/ECNI-MS

Top layer sediment samples from the Czech Republic were analyzed to obtain the preliminary information about contamination of the region by chlorinated paraffins. Sediment samples from three locations with different industrial discharges were taken over the period of 2 years. The analysis was performed by short-column gas chromatography-electron capture negative ion mass spectrometry (SCGC/ECNI-MS). Short chain chlorinated paraffin sediment concentrations varied between 24.00 and 45.78 ng g(-1) (dry weight, d.w.) in the Kosetice area, 16.30-180.75 ng g(-1) (dry weight) in the Zlín area and 4.58-21.57 ng g(-1) dry weight in the Beroun area. Highly chlorinated undecanes prevailed in the samples. On the basis of these results, more detailed studies should be conducted to determine the magnitude and extent of chlorinated paraffin contamination in these regions.     

Investigation of acute toxicity and the effect of 2,4-D (2,4-dichlorophenoxyacetic acid) herbicide on the behavior of the common carp (Cyprinus carpio L., 1758; Pisces,Cyprinidae)

A 96-h LC(50) values of 2,4-D [(2,4-dichlorophenoxy)acetic acid], a common contaminating agricultural herbicide, were determined on the adult common carp (Cyprinus carpio L., 1758; Pisces, Cyprinidae). The study was conducted in two stages using 130 carp. The data obtained were statistically evaluated by the use of the EPA computer program based on Finney's Probit Analysis Method and a 96-h LC(50) value for C. carpio L., 1758 was found to be 63.24 mg/l in a static bioassay test system. 95% lower and upper confidence limits for the LC(50) were 55.03 and 71.92 mg/l, respectively. Water temperature was 17+/-1 degrees C. Behavioral changes of the above mentioned species were examined for various herbicide concentrations.