الفهرس 
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Abstract
1- Summary:
Over the last periods of times, the contamination of water resources by the heavy metal ions has steadily been increased as a result of over population and expansion of industrial activities. Because the toxicity of heavy metals and their serious threat to the human health and ecological systems, an intensive care and research efforts are continuing to find and develop cheaper treatment technologies which are appropriate to a variety of industrial simulations. Currently, the adsorption technique is believed to be a simple and very effective technique for the treatment of water and wastewater where success of the technique is depending largely on the efficient of adsorbents and thier development.
In our study two different types of solid waste materials namely; burnt brine sludge (BBS) and non burnt brine sludge (NBBS) as cheaper and very low cost adsorbents were used for the removals of the heavy metal ions Pb+2, Cd+2 and Cu+2 from their aqueous solutions.
The heavy metal salts used in this study were; Cu(NO3)2•3H2O (MW: 241.6, purity: 99% and produced by Central Drug House (p) LTD laboratory reagent), Cd(NO3)2•4H2O (MW: 308.48 and purity: 99% and produced by Central Drug House (p) LTD laboratory reagent) and Pb(NO3)2•6H2O (MW: 331.21 and purity: 99% and produced by Alpha Chemika laboratory reagent). The burnt brine Sludge (BBS) and non burnt brine sludge (NBBS) used in this investigation produced by the chemical treatment for the brine solution to produce ultra pure brine solution for the electrolysis in the electrolytic cells in the production of chlorine and caustic soda (El Naser Intermediate Chemicals Plant in El Giza Egypt). burnt brine sludge BBS was dried at 110 °C and compressed for nearly 300 bar to be sure of complete drying for 48 hours, crushed, fired at different temperatures (500°C) for 2 hours and then quenched in air. The non burnt brine sludge waste (NBBS) are grinded to a fraction size less than 300 μm then dried at 110°C for 2 hrs before use.
The two solid wastes are used having mineralogical, geochemical and textural characterizations were carried out by using X-ray fluorescence spectrometer (XRF), X-ray diffraction (XRD), nitrogen gas adsorption and scanning electron microscopy (SEM).
The batch experiments were carried out at temperature dgree of room tempreature by addition of known weight of adsorbent 0.5 g to a 100 ml glass stoppered conical flask on a rotary shaker at 200 rpm containing 50 ml individual nitrate solutions of Pb+2, Cd+2 or Cu+2 100 mg/l in distilled water.
The effect of firing temperature (only for BBS), contact time, initial pH value of the solution, adsorbent dose, leaching effect of the heavy metal ions and the competitive effect of the heavy metal ions (mixing groups of Pb+2-Cd+2, Pb+2-Cu+2 and Pb+2-Cd+2-Cu+2at different initial concentrations) on the efficiency of the removal process were investigated.
Various kinetic models were used in order to understand the mechanism of the adsorption process like; pseudo-first-order and pseudo-second-order. Besides, for determining the maximum adsorption capacity of adsorbate, affinity and selectivity for ions, two equilibrium isotherms namely; Langmuir and Freundlich were examined.
2- Conclusions:
from the obtained results, the main conclusions can be summarized as follows:
A. Non Burnt Brine Sludge (NBBS):
1- XRD analysis indicated that the main phase composition of NBBS was quartz and magnisum hydroxide calcium carbonate calcium silicate hydrates (Tobermorite) and the minor phase was calcium oxide and calcium silicates (wollastonite).
2- The N2 adsorption-desorption isotherm of NBBS was shown Type II (monolayer-multilayer adsorption). The NBBS showed surface area 25.02 m2/gm with total pore volume 0.048 cc/gm.
3- The microstructure investigation of NBBS by using SEM displayed the presence of many pore sites, cracks and different shaped objects on the surface with EDX spectrum which was identified the major elements of crystals; Ca and Si.
4- The removal efficiency increased the heavy metal ions with increasing the contact time. By the two stages were distinguished during adsorption process. About 91% for Cd+2 and nearly 97% for Pb+2 and 86 % for Cu+2 were adsorbed within the first 12 hrs. After 24 hrs, the rate of removal becomes constant and equilibrium state has been reached for the heavy metal ions. According to the obtained results, ptimum contact time was fixed at 12 hrs.
5- An increase of Pb+2, Cd+2 and Cu+2 ions uptake was
observed with increasing the initial solution pH (range 5- 9). It reached to about 98 - 100% at pH 9. To ensure the highest removal of metal ions by the sorption process and reduce ions precipitation, the selected normal pH of synthetic solution was 5, as an optimum pH value.
6- Increasing NBBS adsorbent mass will led to increase the adsorption effeciency of the heavy metal ions that could be attributed to the availability of larger surface area and more adsorption sites. The optimum dose for the heavy metal ions removal was chosen as 0.5 gm with removal efficiency of 100%.
7- The leaching percent of Pb+2, Cd+2 and Cu+2 ions increased considerably by increasing the time and the intial metal ions concentration will decreased from the surface of adsorbent with very small extent.
8- The competitive adsorption effect of the heavy metal ions was showed that the high affinity of NBBS towards Pb+2 adsorption does not change whatever the mixture of the heavy metal ions which are present in the aqueous solutions as well as the initial concentration applied. For
Cd+2 and Cu+2 in the binary and tertiary mixtures with Pb+2, increasing the initial concentration cause a decrease in their removal percentage.
9- The removals efficiency percentage of the heavy metals ions we are studying is found to be in the order Pb+2 > Cd+2 > Cu+2 in the tertiary mixtures. This order is matching with their order of ionic radii and the hydration energy for each ion.
10- The adsorption kinetics for Pb+2, Cd+2 and Cu+2 ions are fine approximated and described by the pseudo-second-order model with an agreement between qe calculated and qe experimental and high correlation coefficient (R2= 0.99).
11- NBBS exhibited the high max adsorption capacity for Pb+2 125.2 mg/g in comparison with Cu+2 and finally with Cd+2 (18.63 and 8.09 mg/g, respectively).
B. Burnt Brine Sludge (BBS):
1- XRD analysis indicated that the main phase composition of BBS, burned at 500 °C, were the quartz and illite phases while the albite phase appears only for (BBS) sample fired at 500°C.
2- The N2 adsorption-desorption isotherm of (BBS), after thermal treatment at 500°C show Type II (monolayer-multilayer adsorption) which distinguish the presence of large numbers of pores and more open mesopores. The BBS fired at 500°C showed high surface area (61.92 m2/g) compared with sample without firing (22.61 m2/g).
3- Microstructure investigation of BBS fired at 500°C using SEM displayed the presence of quartz and illite phases for all samples with the appeared of albite phase as small fibers in BBS fired at 500°C.
4- The removal percent of Cd+2 and Cu+2 ions are increased with the increasing of firing temperature up to 500°C (98 and 99%, respectively) and then stay constant. While Pb+2 removal was nearly 100% at all the firing temperatures. BBS Fired at 500°C degree was chosen as the optimum for the removal of heavy metal ions.
5- The removal efficiency of ions increased with increasing the contact time. Two stages were distinguished during adsorption process. About 93 and 99 % of Cd+2 and Cu+2 respectively were adsorbed within the first stage. This high removal percentage could be related to the high diffusion rate of the adsorbate ions from the bulk of the solution to the adsorbent surface. Whereas Pb+2 showed removal percentage close to 100% that could be related to precipitation of Pb+2 due to increasing pH of the solution. According to the obtained data, 4 hrs was chosen as an optimum contact time.
6- An increase of Pb+2, Cd+2 and Cu+2 ions uptake was observed with increasing the initial solution pH (range 2- 11). It reached to 92, 93 and 96 %, respectively, at PH = 9. To ensure the highest removal of metal ions by the sorption process and reduce ions precipitation, the normal pH of synthetic solution 5, was selected as an optimum initial pH value.
7- Increasing BBS mass will led to increase the adsorption process of the heavy metal ions that could be attributed to the availability of larger adsorption sites and more surface area by increasing the adsorbtion effeciency and the adsorbent dose. The optimum dose for the heavy metal ions removal was chosen as 2 gm with the removal efficiency of about 99%.
8- The leaching percent of Pb+2, Cd+2 and Cu+2 ions increased considerably by increasing the time the heavy metal ions concentration decreased with very small extent in the adsorbate surface.
9- The competitive adsorption effect for the heavy metal ions expressed that the high affinity of BBS towards Pb+2 adsorption does not change whatever the heavy metal ions present in the mixture as well as the initial concentration we started. For Cd+2 and Cu+2 in the binary and tertiary mixtures with Pb+2, increasing the initial concentration will cause a decrease in their removal percentage from aqueous solutions.
10- The removal efficiency percentage of heavy metals ions under study is found in order Pb+2 > Cd+2 > Cu+2 in the tertiary mixtures. This trend matches with the order of their ionic radii and the hydration energy for every ion and the normal pH of synthetic solution 5, was selected as an optimum pH The adsorption kinetics of Pb+2, Cd+2 and Cu+2 ions are best approximated by the pseudo-second-order model with an agreement between qe experimental and qe calculated and high correlation coefficient (R2= 0.99).
11- BBS exhibited high max adsorption capacity for Pb+2 28.7 mg/g comparing with Cd+2 then Cu+2 (11.2 and 8.9 mg/g, respectively).
C. General Conclusions:
The different solid wastes (BBS and NBBS) used in this study have the following behavior:
1. The chemisorption is the main process of sorption, where the adsorption kinetics of the heavy metal ions is best approximated and described by the pseudo-second-order model.
2. The two solid wastes showed the highest removal effeciency for Pb+2 ion, because of precipitation process.
3. In the tertiary mixtures, the removal efficiency of the heavy metal ions followed the order Pb+2 > Cd+2 > Cu+2, which agrees with the order of their ionic radii and the hydration energy.
4. The optimum conditions for each solid waste and at initial concentration mixture of each ion 450 ppm, removal efficiency of solids waste follow order; BBS > NBBS agree with increasing specific surface area.