ABSTRACT
Background: Co[II] constitutes a part of vitamin B12, hence, it is necessary for human health. However, at concentrations higher than the permissible limits, humans and animals suffer adverse chronic effects. It is necessary to reduce the concentration to a permissible level. In the present study, pre-purification and thermal modification of chicken's feather increased their porosity and they were used to adsorb Co[II] ions from aqueous solutions
Methods: Chicken feather was procured from a slaughter house, washed with detergent and dried at laboratory temperature. To increase the porosity and remove the organic pollutants attached to the feather, feathers were heated in the oven for 1 hour at 165 degree C. Some batch experiments were conducted to optimize the parameters affecting the adsorption process, such as solution pH, initial concentration of Co[II] and contact time, at a constant agitating speed and temperature
Results: The pH[zpc] of chicken's feather granules obtained was 5.3. The results showed that a time of 60 minutes, pH value of 9 and initial concentration of 10 mg/l were the optimum conditions for Co[II] removal by the adsorption process. Increasing the initial concentration of Co[II] from 10 to 50 decreased the removal efficiency from 52% to 26%. The pseudo-first order kinetic model provided the best correlation [R[2] = 0.998] for adsorption of Co[II] on chicken's feather granules
Conclusion: The increase in electrostatic repulsion forces between positive charges of Co[II] ions decreased the removal efficiency at higher concentrations of Co[II] ions. The maximum efficiency of Co[II] adsorption was obtained at pH= 9, which is higher than the pH[zpc] of the adsorbent
ABSTRACT
Background: Solvents, which are widely used in industry, are able to dissolve another substance for creating a solution. Solvents have various effects on human health based on their type and chemical composition
Methods: This was a cross-sectional study to investigate the harmful effects of solvents on wood painters in Yazd city. To achieve information, a census questionnaire was prepared and distributed among wood painters. The studied parameters include the mean score of knowledge, attitude, and practice of wood painters about harmful effects of dyes and solvents on body according to age, work experience, education, hours worked per day, and smoking. The data of survey were analyzed by Chi-square test and T-test in SPSS
Results: The average age and work experience of wood painters were 29 and 7.5 years, and the age of 25 years and work experience of 5 years had the highest frequency among them. Analysis of data indicated that 71.8% of people had middle school and lower education level, 68.3% was married, 31.7% was single, and 37.5% was smoking. Average working hours were 8 hours in day
Conclusion: Results show that attitudes had significant correlation with education level and different age groups. None of the studied parameters were not significant correlation with performance. Also, there was significant correlation between knowledge with experience