Para-nitrophenol adsorbed on bone char synthesized from cow bones has been studied.The Langmuir Freundlich and Sips models were applied to the equilibrium data to describe the adsorption process.The Langmuir model bes...Para-nitrophenol adsorbed on bone char synthesized from cow bones has been studied.The Langmuir Freundlich and Sips models were applied to the equilibrium data to describe the adsorption process.The Langmuir model best described the adsorption process with R^2=0.919;and maximum adsorption capacity,qmax of 365.76 mg/g.Batch kinetic studies conformed to pseudo-second-order indicating that several mechanisms may be involved in the process and gave a value of 2.5×10^4 g/mg/min for the rate constant for the sorption ofp-nitrophenol on bone char.The values of thermodynamic parameters,free energy≈-22.0 kJ/mol,enthalpy-20.2 kJ/mol and entropy 5.34 J/K mol for the adsorption of p-nitrophenol on bone char showed that the adsorption was spontaneous and exothermic.展开更多
This study evaluates the characteristic levels,sources and risk of human exposure to polycyclic aromatic hydrocarbons(PAHs)in indoor dusts from electronic repair workshops in southern Nigeria.The dust samples were col...This study evaluates the characteristic levels,sources and risk of human exposure to polycyclic aromatic hydrocarbons(PAHs)in indoor dusts from electronic repair workshops in southern Nigeria.The dust samples were collected by gentle sweeping with a brush and dustpan,and subsequently dried and extracted with hexane/dichloromethane by ultrasonication.The extracts were purified on a silica gel/alumina column,and then analysed for their PAH content by means of gas chromatography-mass spectrometry.The concentrations of PAHs in the electronic repair workshop dusts ranged between 205 and 2963 mg kg1.The compositional patterns indicate the dominance of 5-and 3-ring PAH homologues.The estimated benzo[a]pyrene carcinogenic(BaPTEQ)and mutagenic(BaPMEQ)potency concentrations ranged from 67 to 401 mg kg^-1 and 56.5e277 mg kg^-1 respectively.The non-cancer risk(hazard index,HI)arising from human contact with PAHs in the electronic repair workshop dusts were less than one for all human subject age groups indicating that there is no considerable non-cancer risk.The cancer risk values for the ingestion and dermal contact routes were greater than the acceptable risk of 10^-6,which suggests that there is a considerable cancer risk associated with unconscious ingestion and dermal contact with dust particles from these electronic repair workshops.The isomeric ratios for the PAHs in the dust samples and principal component analysis suggest that combustion of biomass and vehicular emissions were responsible for the presence of PAHs in the electronic repair workshop dusts.展开更多
文摘Para-nitrophenol adsorbed on bone char synthesized from cow bones has been studied.The Langmuir Freundlich and Sips models were applied to the equilibrium data to describe the adsorption process.The Langmuir model best described the adsorption process with R^2=0.919;and maximum adsorption capacity,qmax of 365.76 mg/g.Batch kinetic studies conformed to pseudo-second-order indicating that several mechanisms may be involved in the process and gave a value of 2.5×10^4 g/mg/min for the rate constant for the sorption ofp-nitrophenol on bone char.The values of thermodynamic parameters,free energy≈-22.0 kJ/mol,enthalpy-20.2 kJ/mol and entropy 5.34 J/K mol for the adsorption of p-nitrophenol on bone char showed that the adsorption was spontaneous and exothermic.
基金BSM acknowledges the support from the University of KwaZulu-Natal and National Research Foundation of South Africa(NRF).
文摘This study evaluates the characteristic levels,sources and risk of human exposure to polycyclic aromatic hydrocarbons(PAHs)in indoor dusts from electronic repair workshops in southern Nigeria.The dust samples were collected by gentle sweeping with a brush and dustpan,and subsequently dried and extracted with hexane/dichloromethane by ultrasonication.The extracts were purified on a silica gel/alumina column,and then analysed for their PAH content by means of gas chromatography-mass spectrometry.The concentrations of PAHs in the electronic repair workshop dusts ranged between 205 and 2963 mg kg1.The compositional patterns indicate the dominance of 5-and 3-ring PAH homologues.The estimated benzo[a]pyrene carcinogenic(BaPTEQ)and mutagenic(BaPMEQ)potency concentrations ranged from 67 to 401 mg kg^-1 and 56.5e277 mg kg^-1 respectively.The non-cancer risk(hazard index,HI)arising from human contact with PAHs in the electronic repair workshop dusts were less than one for all human subject age groups indicating that there is no considerable non-cancer risk.The cancer risk values for the ingestion and dermal contact routes were greater than the acceptable risk of 10^-6,which suggests that there is a considerable cancer risk associated with unconscious ingestion and dermal contact with dust particles from these electronic repair workshops.The isomeric ratios for the PAHs in the dust samples and principal component analysis suggest that combustion of biomass and vehicular emissions were responsible for the presence of PAHs in the electronic repair workshop dusts.
