جستجوی مقالات مرتبط با کلیدواژه « isotherm model » در نشریات گروه « پزشکی »

Phenol is one of organic pollutants in industrial effluent and it is toxic to human and environment, so it must be removed before being discharged to environment. Therefore, the purpose of this study was investigating adsorption of phenol from aqueous solutions by sorghum and canola and determination of adsorption isotherms and kinetics
This study was performed in the laboratory at batch scale. The canola and sorghum plants were collected and were dried in the oven at 105AWT IMAGE in 24h and were sieved in 18-30 inches mesh. The variation of pH, dose of adsorbent, contact time, and concentration of phenol were investigated. Different models of isotherms and the rate of adsorption reaction were analyzed by comparing the coefficient (R2) of determination.
The results indicated that by increasing contact time and dose of adsorbent, adsorption amount will increase for both adsorbents, however the adsorption rate remains constant after 75 and 90 for sorghum and canola, respectively. Also adsorption rate remains constant for adsorbent doses higher than 5 g/L. The results showed that phenol removal was highest at a solution pH =3 and an initial phenol concentrantion of 10 mg/L. In these conditions, removal rate for sorghum and canola biomass was equal to 99.1 and 92.4 percent, respectively. The Langmuir equation model and pseudo- second order kinetics provided the best fit for the experimental data to both adsorbents.
Overall, the sorghum and canola plants can be used as effective absorbents to treat the aqueous solution containing phenol.

Chromium, found in many industrial effluents, is one of most important heavy metal with health and environmental risks. Therefore, the aim of this study is to survey the effect of Cr (VI) removal by using Cyperus rotundus Weed biomass. This empirical study was done in lab scale. The variation of pH, dose of adsorbent, contact time, and concentration of chromium were investigated. The adsorption data was explained by adsorption isotherms and kenitics.The residual concentration was analyzed by spectrophotometer in maximum wavelength of 540 nm. It was determined that the pH value of 3, contact time of 60 min, adsorbent dosage of 4 g/L and Cr (VI) concentration of 10 mg/L were the optimum conditions for adsorbents. The most Cr (VI) removal efficiency of 99% was obtained for Cystoseira indica biomass in optimum conditions. The equilibrium data is best fitted on Langmuir isotherm and the adsorption kinetic model follows pseudo-second model. The maximum capacity of adsorption was 10.12 mg/g. The results revealed that by using Bio-absorption the removal of Cr+6 can be done quickly and effectively.

◦Bisphenol A is classified as a toxic and priority hazardous compound; it is required to be degraded prior to discharging the contaminated streams to the environment. Therefore, the purpose of this study is investigation of Bisphenol A adsorption by biomass agricultural waste Rice straw.
Material and This study was performed in laboratory at batch scale. The effects of different parameters including contact time, pH, Bisphenol A initial concentration and biomass dosage were studied for removal of Bisphenol A. All experiments were repeated triplicate and then adsorption isotherms and kinetics of different models were analyzed by comparing the coefficient of determination. The concentration of Bisphenol A was measured by HPLC.
The results indicated that by increasing of contact time and dose of adsorbent the amount of bisphenol adsorption increases, so that by increasing contact time from 10 to 75 min, the adsorption increased from 38.3% to 96.9% and by increasing adsorbent dosage from 1 to 5 gr/L adsorption increased from 35.5% to 94.9%. The adsorption was increased by decreasing of initial concentration of bisphenol A and the pH of 3 was the best for bisphenol A removal. The adsorption data was best fitted to the Freundlich isotherm and pseudo-second order kinetic model. The Langmuir equation and pseudo- second order model showed the best fit for the experimental data
The results showed that the agricultural waste Rice straw can be used as a high efficiency and inexpensive adsorbent for treatment of industrial effluent.