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Register a new userDecreasing of Phosphate Concentration in Aqueous Solutions by Using a New Adsorbent: Gatite, Comparison with Alumina and Hydrotalcite
خفض تركيز أيونات (شوارد) الفسفات في أوساط مائية، باستعمال مادة مازة جديدة هي الغاتيت المصطنع؛ و مقارنة النتائج مع كل من الألومينا و الهيدروتالسيت الطبيعيين
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محمد مهاب مراد( باحث )
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تتناول هذه الدراسة نتائج خفض تركيز أيونات الفسفات من المياه التي تحوي هذه الأيونات بتراكيـز عالية، و ذلك باستعمال الغاتيت و مقارنتها مع نتائج استعمال كل من الألومينا و الهيدروتالسيت. تبين نتائج استعمال الألومينا، الغاتيت المحضر مخبرياً، و الهيدروتالسيت (HT اختصاراً) أن الوصول إلى التـوازن الكيميائي كان سريعاً باستعمال الهيدروتالسيت؛ نتج أن كلتا المادتين الغاتيت المصطنع، و الهيدروتالـسيت المحمى إلى درجة حرارة 500 °سلسيوس (س°) قد سلكا سلوكاً مرضياً. كذلك فإن إزالة الفسفات تكون عظمى عند 5=pH .درس تأثير وجود الأيون المشترك، فأظهر تأثيراً إيجابياً في فعالية الامتزاز. وجـد أن للهيدروتالسيت المعالج بالدرجة 500 س° استطاعة امتزاز أعظمية بلغت ما يقارب 150 مـغ أيـون فوسفات لكل واحد غرام من المادة المستعملة الهيدروتالسيت (المادة الصلبة)، في حين أبدت مادة أكسيد الألمنيوم أقل فعالية.
This study illustrates, and compares the results of the removal of phosphate ions from aqueous solutions by using substances that have affinity to these ions, i.e., these ions have relatively a high adsorbing tendency toward these substances. Three different adsorbing substances were used, they are alumina, synthesized gatite, and hydrotalcite (abbreviation: HT). The results showed that chemical equilibrium was achieved quickly in the case of HT. Regarding the relative adsorbing ability of these three substances toward phosphate, and its removal from aqueous solutions, it was found that both synthesized gatite, and ignited HT at 500°C were both effective. The removal of phosphate ions was maximum at pH=5. Ionic strength showed a positive effect on the adsorption efficiency. The maximum adsorbing ability of these two adsorbing materials was about 150 mg PO3 -4-P per gram of the adsorbing HT; whereas the minimum efficiency was for aluminum oxide.
References used
Aguilar, M.I., Saez, J., Llorens, M., Soler, A. and Ortuno, J.F., 2002. Nutrient removal and sludge production in the coagulation–flocculation process. Water Res., 36: 2910-2919
Akay, G., Keskinler, B., Cakici, A. and Danis, U., 1998. Phosphate removal from water by red mud using crossflow microfiltration. Water Res., 32(3): 717-726
Chitrakar, R., Tezuka, S., Sonoda, A., Sakane, K., Ooi, K. and Hirotsu, T., 2006. Selective adsorption of phosphate from seawater and wastewater by amorphous zirconium hydroxide. J. Colloid Interf. Sci., article in press
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Some samples of alumina supporting with sulfate ions and molybdenium were
prepared by impregnation method. Supported samples were calcinated at 550°C for 6h.
Presence of sulfate ions and molybdenium lead to decreasing of the specific surface area o
f
alumina, and in the ease of molybdenium the decreasing value was higher. The total pore
volume was decreased with the pore size was increased. XRD patterns showed that the
incorporation of sulfate ions and molybdenium did not affect crystalin structure of
alumina. FTIR spectra showed the bonding between sulfate ionsmolybdenium
and
alumina. The TG-DTA studies showed that the losses mass was decreased when the sulfate
ions and molybdenium were incorporated, sulfate ions and molybdenium oxide
decomposed at ~700°C and ~800°C respectively .
In this work the process of removal of zinc ions from aqueous solutions was studied using natural Syrian zeolite. Two samples were used: natural zeolite Z and modified zeolite with NaCl solution Z-Na. The removal percentage of zinc ions vs. time was
determined using differential initial concentrations of Zn+2: 50,100,200,300,400 mg/L. The contact time was determined and it was 360 min. The removal of Zn+2 ions as a function of temperature and pH have been studied. It was found the increasing of removal percentage by increasing temperature and increasing when pH increasing up to ~7,then the precipitation of zinc hydroxide accurse. The Langmuire adsorption isotherm equation used to calculate the maximum sorption capacity and it was 21.7 and 28.5 mg/g for Z and Z-Na respectively. Results indicate a significant potential for the natural and modified zeolite as an adsorbent/ion-exchange materials for heavy metal removal.
In this search, the removal of copper and lead ions from aqeous solutions by flotation had
been studied, and the effect of various factors on the removal process.
The study showed that the removal of copper and lead ions was increased by increasing
the
value of the solution pH up to pH = 8 and the removal rate was 80%.
At pH = 10 precipitation of the ions was obtained in the form of hydroxides.
The removal ratio of both ions is increased by increasing the flow of the air within the
solution to reach 98% for copper and 97% for lead at the flow of Q = 1000 ml/min and
then the removal rate decreases to 60% with increasing airflow to Q = 1500 ml/min.
The initial concentration values affect the removal process and the increase in the removal
ratio was shown by increasing the initial concentration. The removal rate of copper ions
was 50 % at the initial concentration of C0 = 50 mg / l to 98% at C0 = 100 mg / l. While the
lead removal rate was 61 % at the initial Concentration C0 = 50 mg/l to 97% at
concentration C0 = 100 mg / l.
studied the elimination of lead using natural zeolite by studding the the best
conditions to removal lead in a system with two phase: liquid (contaminated water with
lead)-solid (natural zeolite), correlation of the following factors: time of mixin
g phase,
granular size of solid phase, change of pH values, concentration of the calcium element as
a competitor element for the available sites for occupation on the solid phase, the ratio V/m
represents the size of the aqueous phase to the mass of the solid phase and concentration of
lead element.
On the other hand, the possibility of using natural zeolite as a template for storaging
dangerous materials such as lead, has been studied by changing water quality, pH and
temperature.
The results of this research show that and under the following experimental
conditions: time of mixing=4hour, mix of granular size of solid phase, pH< 8,
concentration of calcium = 20 ppm,V/m=100 and concentration of lead = 1000 ppm , the
rate of lead removal range from 60% to 99%.
On the other hand, the results of this research show that changing water quality has
no impact on the ability of natural zeolite for storaging lead as a hazardous waste, while
pH changes have minor effects on this ability of retention and an effect for the high
temperatures on the template was also observed.
Transfer learning based on pretraining language models on a large amount of raw data has become a new norm to reach state-of-the-art performance in NLP. Still, it remains unclear how this approach should be applied for unseen languages that are not c
overed by any available large-scale multilingual language model and for which only a small amount of raw data is generally available. In this work, by comparing multilingual and monolingual models, we show that such models behave in multiple ways on unseen languages. Some languages greatly benefit from transfer learning and behave similarly to closely related high resource languages whereas others apparently do not. Focusing on the latter, we show that this failure to transfer is largely related to the impact of the script used to write such languages. We show that transliterating those languages significantly improves the potential of large-scale multilingual language models on downstream tasks. This result provides a promising direction towards making these massively multilingual models useful for a new set of unseen languages.
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