Sorption Isotherms Research Papers - Academia.edu (original) (raw)

Pineapple puree and juice of 11 to 12 °Brix were used to obtain pineapple powder using oven-drying technique. Addition of maltodextrin in treatments 2 and 4 yielded good quality powder, however addition of sugar and maltodextrin in... more

Pineapple puree and juice of 11 to 12 °Brix were used to obtain pineapple powder using
oven-drying technique. Addition of maltodextrin in treatments 2 and 4 yielded good quality powder,
however addition of sugar and maltodextrin in treatments 1 and 3 resulted to sticky product which was
processed to pineapple leather. Treatment 2 composed of pineapple puree and maltodextrin resulted to
significantly higher powder recovery compared with treatment 4 which composed of pineapple juice and
maltodextrin. The solubility of pineapple powder improved as maltodextrin concentration is increased
from 40.00 % to 60.00 %.Addition of maltodextrin also reduced stickiness of the final product. An instant
pineapple powder of 5.47 and 5.33 % moisture content could be produced by oven-drying.This level of
moisture content will prohibit bacterial growth in the pineapple powder but may have mold or yeast
growth with increase storage period at environments with high humidity. Molds were observed on the
17th day at 89.00 % relative humidity as exhibited by the moisture sorption isotherm data. This suggests
that appropriate packaging with moisture barrier is recommended for pineapple powder. This study
showedthat by using appropriate ratio of juice, puree, and maltodextrin and appropriate oven drying
conditions, a good oven-dried pineapple powder could be obtained.

A method for simultaneous determination of the diffusion and sorption properties of cement-based materials is presented. It is a gravimetric method where one small specimen is exposed to stepwise changes in relative humidity while its... more

A method for simultaneous determination of the diffusion and sorption properties of cement-based materials is presented. It is a gravimetric method where one small specimen is exposed to stepwise changes in relative humidity while its mass is being measured. As sorption in cement-based materials is slow, the change in relative humidity to the next level is made before final equilibrium has been reached on the previous level. Approximate final (equilibrium) levels are found by extrapolation using an exponential equation, and a factor is applied to correct for the fact that the sorption step does not start at equilibrium conditions. A correction for external mass transfer resistance is also included. The method can be used in desorption as well as absorption mode. Measurements of two materials are presented and compared with the results obtained using conventional methods.

In recent years interest in new microbiological methods for wastewaters purification of heavy metal has increased. Cr (VI) sorption was investigated for non-pigmented yeast Saccharomyces cerevisiae 1968, Candida krusei 61t, Williopsis... more

In recent years interest in new microbiological methods for wastewaters purification of heavy metal has increased. Cr (VI) sorption was investigated for non-pigmented yeast Saccharomyces cerevisiae 1968, Candida krusei 61t, Williopsis californica 248, pink-pigmented Rhodotorula mucilaginosa 1776, R. aurantiaca 1198, R. aurantiaca 1195, Rhodotorula sp.4 and black yeast Cryptococcus sp. WT. The use of tested yeast as biosorbents for Cr (VI) offers a potential alternative to existing methods for chromium decontamination or recovery from the environment. The sorption isotherms obtained in these experiments for non-living yeast biomass showed that the maximal sorption capacity (Q max) was 1100 and 1000 µmol·(g sorbent)-1 for Rhodotorula sp.4 and R. mucilaginosa 1776, respectively. In the case of living biomass, the highest maximal uptake capacity was found for yeasts C. krusei 61t and W. californica 248. These cultures also demonstrated the high sorption affinity, which makes them especially efficient biosorbents at low concentrations of hexavalent chromium. Some cultures of pigmented yeasts sorbed Cr (VI) better for non-living biomass, than living biomass. In general, non-pigmented yeasts were more tolerant to hexavalent chromium than tested pigmented strains. The high efficiency of hexavalent chromium elution was shown with 0.1N EDTA.

Background and objectives: Some of heavy metals such as copper (Cu) and manganese (Mn) are toxic and represent as hazardous pollutants due to their persistence in the environment. Heavy metals can be introduced into soils and aqueous... more

Background and objectives:
Some of heavy metals such as copper (Cu) and manganese (Mn) are toxic and represent as hazardous pollutants due to their persistence in the environment. Heavy metals can be introduced into soils and aqueous environment by natural processes or anthropogenic activities. They are non-degradable in nature and highly toxic to plants, animals and human beings. Various methods exist for the removal of heavy metal ions from solution, such as filtration, chemical precipitation, ion exchange and sorption by activated carbon and others. Discarded tires are an interesting and inexpensive medium for the sorption of heavy metals. There has been little research on heavy metal sorption into tire rubber in competitive systems. Therefore the present study was conducted to assess the sorption behavior of Cu and Mn on different size of tire rubber in a competitive system.
Materials and methods:
The finely ground discarded tire rubber with three sizes including 0.088-0.125, 0.177-0.250 and 0.353-0.500 mm were prepared from Yazd Tire Company in Iran. A batch experiment was conducted by adding of 200 mg of ground tire to 10 ml of Cu+Mn aqueous solution of the desired concentration (10 to 50 mg L-1). After 24h, supernatant was separated by filtration and analyzed for remaining Cu and Mn by atomic absorption spectroscopy technique.
Results: Sorption of Cu and Mn on tire rubber increased with increasing of metal concentration from 0 to 50 mg L-1. The greatest sorption of Cu (1088.9 mg Kg-1) was found at the smallest tire rubber size (0.088-0.125 mm) and decreased by 35% when the largest size (0.353-0.500 mm) was used. At the highest concentration, sorption of Cu was restricted by Mn competition. In the whole range of studied metal concentrations, Mn occupied the least sorption sites of tire rubber. The sorption of Mn was not affected by tire rubber size and was restricted by Cu competition. Based on average, the experimental data were fitted in Langmuire (R2=0.94) better than Freundlich one (R2=0.87), showing monolayer sorption of Cu and Mn on discarded tire rubber. The values of maximum sorption capacities calculated from the fitted Langmuir equation showed that Cu sorption was higher than Mn. There was an increase in the qm values of Mn when the tire rubber diameter decreased. In this study, separation factor (RL) was used to predict if an adsorption system is favorable or unfavorable. In all cases, the values of RL were between 0 and 1, pointing to the favorable sorption of Cu and Mn on three size of rubber.
Conclusion:
Results clearly showed that ground discarded tire rubber (especially, the smallest size) are an effective adsorbent for the removal of Cu and Mn in competitive system. The equilibrium sorption isotherm of Cu and Mn onto discarded tire rubber is well described by the Langmuir and Freundlich models, but the Langmuir model fits the experimental data better than the Freundlich model.