الفهرس 
Introduction and Literature reviewOnly 14 pages are availabe for public view
 |  | from | 192 |  |  |
| | | from | 192 | | |
Abstract
Summary
Activated carbons prepared from Cyperus Rotundus were developed in the removal of organic and inorganic pollution from wastewater.
Production of activated carbon derived from Cyperus Rotundus had been demonstrated to be feasible. High surface area activated carbons were obtained by chemical activation with H3PO4 and one step activation which was carried out in a self-generated atmosphere. This study showed that the use of dehydrating agent and the one-step activation process in self-generated atmosphere played a major role in shaping and transforming precursors into activated carbons.
Phosphoric acid was used as a dehydrating agent, produced a very different activated carbons, changing not only the pore structure and morphology of the activated carbon but also giving the sponge-like physical appearance of the precursor itself.
Adsorption tests have been carried out for industrial pollutants (methylene blue) under different experimental conditions. The adsorption of methylene blue was dependent on adsorbent surface characteristics, adsorbent dose, methylene blue concentration and time of contact. The pH of the solution did not have important effect on the extent of adsorption of the dye on activated carbons. The results indicated that the significant decrease on amount of dye removal for example in sample (P450 35%) the removal rate decreased form 97.28% to 65.81% when the initial dye concentration decreased from 100 mg/l to 500 mg/l at constant pH value (2.83). The results showed that: the optimum contact time for methlylene blue removal is 25min. after which equilibrium takes place and the effective adsorbent is 9.75 g/l. from the study of adsorption isotherm, it was found that the data fit well with Langmuir indicating that the high values of R2.
The study was extended to investigate the catalytic efficiency of the as-prepared activated carbon on the removal of inorganic pollutants (Cr6+ and Pb2+) from wastewater.
from the present study, it can be concluded that the activated carbon has a great potential to remove chromium (VI) from wastewater. The percentage removal of Cr (VI) depends on pH of the solution. The increased in pH value, decreased the removal percent and optimum value is 2.3. The results showed also that the optimum adsorbent dose is 10 g/l; the removal efficiency of Cr (VI) in some sample is found to be 99.31% at an initial metal concentration of 250 mg/l at constant pH. It was found that, Cr(VI) removal efficiency on activated carbon increasing with increased the contact time up to 3 hours. The adsorption of Cr (VI) decreases from 97.56 to 85.9% when the initial metal concentration was increased from 20 to1000 mg/l by an absorbent dose of 10 g/l at pH 2.3.
The experimental data correlated reasonably well with Freundlich adsorption isotherms and the isotherm parameters were calculated.
Concerning the adsorption of Pb(II) ion on activated carbons, it was found that the activated carbon samples prepared from Cyperus Rotundus are efficient for the adsorption of Pb(II) ion from aqueous solution. In batch mode studies, the adsorption was found to depend on solution pH. The results show that adsorption of Pb(II) increased at a steady rate as pH increased up to 4.3, attaining a maximum value of around 97.40%, 98.65%, 88.24% and 86.24% for samples P450 35% q, RP 500 35%, P550 65% and P550 35%, respectively. It was also observed that with increasing initial concentrations, the adsorption capacity increases while the percent metal removal decreases.
The adsorption of Pb(II) ion by activated carbons increases with increasing contact time and attained equilibrium at about 3hours. The contact time required for the metal ion is relatively short. This result is interesting because equilibrium time is one of the important considerations for economical wastewater treatment applications.
It was also found that the adsorption of Pb(II) ion increased as the adsorbent dose increases. the results showed that at an adsorbent dose of 10 g/l, the removal efficiency of Pb(II) ion in sample (P450 35%q) is found to be 97.4% at an initial metal concentration of 50 mg/l, pH 5 and 3 hours contact time, while decreased to 75.56% when the dose decreases to 1 g/l.
A comparison of isotherm parameters for two types of isotherm was done to determine the effectiveness of them. The determination of coefficient (R2) had high values at Freundlich models isotherms.