Health risk assessment of heavy metals in dust particles precipitated on the screen of computer monitors.

Dust is an important factor to indoor pollution that contains suspended particles and heavy metals. Since today, use of computer has become an essential part of human life. Therefore, this study aimed to compare the amount of heavy metals deposited on CRTs and LCDs and their risk assessment. Ten dust samples for each type of monitor were collected from CRT and LCD screens in accordance with the standard OSHA ID-125 and ID-206, wet filter wipe method. Concentrations of Pb, Hg, Cd, Cr, and Cu were measured by inductively coupled plasma-optical emission spectrometer. Exposure and risk assessment of these elements were estimated using USEPA's exposure parameters. The average concentrations of heavy metals in the dust on CRTs (0.82 mg/kg) were higher than LCD screens (0.69 mg/kg). Cr with 62.824% and Hg with 0.849% had the highest and lowest average concentration in both types of monitors. The non-carcinogenic risk and carcinogenicity indexes of CRT monitors were 0.0009, and 3.94 × 10-11 and for LCD monitors were 0.0008 and 2.94 × 10-11. In both monitors, ingestion is the main route to exposure with heavy metals. The average concentration of heavy metals in CRT dust. HI values for studied metals in dust of CRTs and LCDs were less than safe limit of 1. Because RI < 10-4, cancer risk of studied elements in dust can be ignored.

Data of adsorption of Basic Blue 41 dye from aqueous solutions by activated carbon prepared from filamentous algae.

For this data article the adsorption of Basic Blue 41 (BB 41) dye by activated carbon derived from filamentous algae (AAC) of available in agriculture waste as cheap adsorbents were examined. Activated carbon has been widely used as an adsorbent regard to its massive specific surface area, high porosity, reusability and thermal stability for the removal of pollutants from effluent. These filamentous algae grow widely in irrigation streams, causing decreasing speed of water flow and are not even eaten by livestock so are considered agricultural wastes. They can be used as precursors for activated carbon preparation and as adsorbent for the dye removal. The data of initial dye concentration (50-200 mg//L), pH of dye solution (3-9), adsorbent dosage (0.25-2 g/L), and contact time (5-200 min), were assessed. The structure of AAC was characterized by X-ray diffraction and Fourier transforms infrared spectroscopy. Activated carbon with a 94% removal of dye at concentration of 100 mg/L, pH 9, and adsorbent dose 1 g/L after 90 min. The data of isotherms and Kinetics indicated that the experimental data are fitted to Langmuir and second-pseudo-order models. Under the optimum conditions, maximum adsorption capacity of the AAC in Langmuir model enhanced to amount of 125 mg/g. According to the experimental data, filamentous algae are a suitable raw material for activated carbon production.

Bisphenol A removal from aqueous solutions using novel UV/persulfate/H2O2/Cu system: optimization and modelling with central composite design and response surface methodology.

BACKGROUND: Bisphenol A is a high production volume chemical widely used in manufacturing polycarbonate plastics and epoxy resins used in many industries. Due to its adverse effects on human health as an endocrine disruptor and many other effects on the various organs of the human body as well as aquatic organisms, it should be removed from the aquatic environments. This study aimed to mineralisation of BPA from aquatic environments by application of novel UV/SPS/H2O2/Cu system and optimization and modelling of its removal using central composite design (CCD) from response surface methodology (RSM). METHODS: CCD from RSM was used for modeling and optimization of operation parameters on the BPA degradation using UV/SPS/HP/Cu system. Effective operation parameters were initial persulfate, H2O2, Cu2+ and BPA concentration along with pH and reaction time, all in three levels were investigated. For analysis of obtained data ANOVA test was used. RESULTS: The results showed that a quadratic model is suitable to fit the experimental data (p < 0.0001). Analysis of response surface plots showed a considerable impact of all six selected variables which BPA and Cu2+ initial concentrations have been the highest and the least impact on the process, respectively. F-value of model was 54.74 that indicate significance of the model. The optimum values of the operation parameters were determined. The maximum removal of BPA was achieved 99.99 % in optimal conditions and in that condition TOC removal was about 70 %. Finally, validation and accuracy of the model were also evaluated by graphical residual analysis and the influential diagnostics plots. The higher relevance between actual and predicted values demonstrated the validation and applicability of the obtained equation as the model. CONCLUSIONS: According to the results, UV/SPS/HP/Cu system is an effective process in degradation and mineralisation of BPA and CCD methodology is a convenient and reliable statistical tool for optimizing BPA removal from aqueous solutions.