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Chromate Sorption on Metal Ions Doped Goethite Α-Feooh

Thesis Info

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Author

Khan, Sadullah

Program

PhD

Institute

University of Peshawar

City

Peshawar

Province

KPK

Country

Pakistan

Thesis Completing Year

2010

Thesis Completion Status

Completed

Subject

Chemistry

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/746/1/1855S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676725721554

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Goethite (α-FeOOH), being a model adsorbent, has a very highly reactive surface. Therefore, it is considered to be an efficient adsorbent in soil systems and plays an important role in controlling the mobility of trace contaminants, like Pb, Ni, Cu, Cr, As, Cd, Co, Zn, and Cu etc. Being the most abundant iron oxide mineral in almost all the soil types, many researchers have focused, recently, on the sorption properties of metal doped goethite, not only due to its greater resemblance with natural goethite, but also for its possible use as an adsorbent in water purification technology. In line with this trend of research, the present study reports the characterization of Pb, Ni and Cu-doped goethite and their adsorption properties for chromate with stepwise comparison to pure goethite. Further, characterization and chromate adsorption properties of microcrystalline and amorphous phases of copper/iron mixed oxides, are also a part of this study. All the solid samples, used in the present investigation, are prepared according to a well known procedure reported in the literature. The amounts (%) of Pb 2+ , Ni 2+ , Cu 2+ ions doped in goethite samples were 0.38, 0.25 and 0.32, while the microcrystalline goethite and amorphous phases of copper/iron mixed oxides contained 6.27 and 11.31% Cu 2+ ions respectively. All these solids are characterized for Surface Area, pH of Point of Zero Charge (pH pzc ), XRD, TG-DTA, TEM/SEM and FTIR analyses. XRD and TEM/SEM analyses of all the goethite samples suggest the solids to be crystalline and doping of the metal ions have only slightly affected the unit cell parameters of the crystals. TG-DTA analyses reveal that all the goethite samples exhibit similar thermal behavior with a distinct peak for the degradation of doped metal hydroxides, present in the solid matrix.. Furthermore, an increase in the concentration of Cu in the precipitate results in the formation microcryastalline goethite and amorphous phase of copper/iron mixed oxide with a marginal increase in the surface area and pH pzc of the resultant solid phases. xDissolution study of goethite in KNO 3 and 303K suggest that goethite and its metal doped counterparts are quite stable in the pH range 4-7. In all the solid samples dissolution is maximum at the lowest pH of 3 and decreases with the increasing pH. Dissolution of pure goethite is inhibited by increasing the concentration of chromate, while in the metal-doped goethites, it has no effect on their dissolution. The amorphous and microcrystalline mixed oxides of copper/iron also observed to follow the dissolution behavior of metal doped goethites. Adsorption studies of chromate suggest that doping of metal ions increases the chromate adsorption capacity of goethite from 62.8 to 72.2% for Pb, from 61.4 to 82.92% for Ni and from 64.4 to 84.5 for Cu doping in it. The adsorption studies carried out at pH 3, 5 and 7 suggest that the adsorption of chromate is maximum at low pH values and decreases with increasing pH by all the solid samples used here. The effect of temperature is, however, different for different samples. In case of Pb and Cu-doped goethite, an increase in temperature decrease the adsorption capacity of the solid, while for all the other samples adsorption capacity is observed to increase. The amorphous copper/iron mixed oxide sample has been found to be the best adsorbent for chromate of all the solids used in the present investigation. The values of isosteric heat of adsorption, calculated from the Clausius Clapyron Equation, are positive for Ni doped goethite and negative for Cu and Pb-doped goethite. In case of amorphous phases of copper/iron mixed oxides these values are also found to be positive. The values of isosteric heat of adsorption for chromate adsorption by all the solids are consistent with the effect of temperature determining the endothermic/exothermic nature of the surface reactions. Langmuir equation is applicable to the data under all the experimental conditions. The constants of this model calculated for the adsorption of chromate by all the xisolids coincide well with the adsorption capacity of the respective solids obtained from the experimental data. TEM/SEM analyses suggest that doping of foreign elements in the iron oxide structure, not only increases the sizes of the solid particles, but also increase their surface roughness. Theses changes in the solid particles result in an increase in the surface area, H + /OH - ions adsorption capacity and hence increase the net surface positive charge. These changes collectively increase the adsorption capacity of the doped solids. FTIR analyses suggest that all the goethite samples show bands at 636, 793 and 894cm -1 which are the characteristic bands of goethite and are due to OH bending vibrations. Similarly, the goethite samples show bands at 1383 and 833cm -1 for NO 3 - moiety, which either disappear or present with reduced intensity after chromate adsorption. Thus, all the experimental findings suggest that chromate is adsorbed by all the solid samples through innersphere complexation at pH 5 and 7 by replacing OH - , NO 3 - and CO 3 2- anions from the surfaces. However, at the lowest pH of 3, some outersphere complexes of chromate are also formed on the surface of solids.
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سید اختر علی تلہری

سید اختر علی تلہری
سید اختر علی صاحب فن شاعر اور نکتہ سنج ادیب تھے، اردو اور فارسی زبان و ادب پر استادانہ نظر تھی، عربی اور انگریزی سے بھی واقف تھے، ساری عمر درس و تدریس اور تالیف و تصنیف میں گذری، ان کے تلامذہ کا دائرہ بہت وسیع ہے ان کی تربیت نے بہت سے شاعر و ادیب پیدا کردیے، ان کا کلام اور مضامین رسالوں میں نکلتے رہتے تھے، معارف میں بھی ان کی غزلیں شائع ہوتی تھیں، عرصہ ہوا معارف میں ہندوستان کے عربی شعرا پر ایک مبسوط مضمون شائع ہوا تھا، اتفاق سے اس میں کسی شیعہ شاعر کا ذکر نہ تھا، تلہری صاحب نے مجھ کو شکایت کا خط لکھا میں نے جواب دیا کہ اس میں میرا قصور نہیں ہے مضمون جس شکل میں آیا تھا میں نے شائع کردیا، اگر آپ شیعہ شعرا پر لکھ بھیجیں تو اس کو بھی شائع کردیا جائے گا، چنانچہ یہ مضمون انھوں نے لکھ کر بھیجا اور وہ شائع ہوا، مضامین کے علاوہ مستقل علمی و ادبی تصانیف بھی ان کی یاد گار ہیں، آج کل شاعروں اور ادیبوں کی کمی نہیں، ان کی تعداد روز افزوں ہے اس سے نظم و نثر دونوں کا دامن بہت وسیع ہوگیا ہے لیکن فنی مہارت اور علمی و ادبی بصیرت مفقود ہوتی جاتی ہے۔ تلہری مرحوم کی وفات سے ایک صاحبِ علم و ادب اور صاحبِ فن شاعر اٹھ گیا۔ اﷲ تعالیٰ ان کی مغفرت فرمائے۔ (شاہ معین الدین ندوی، مئی ۱۹۷۱ء)

اسلامی ریاست میں داخلی استحکام کے لیے مرکز اور صوبوں کے تعلقات

There is a dire need of an experienced and authoritative mechanism in the polity of Islām in order to run the affairs of the state in a benefiting manner. This mechanism divides the state into different regions and provinces so as to carry out the affairs of the state in an organized way. These provinces must be founded on some administrative basis, not on racial, lingual or regional grounds. It is necessary that these units are autonomous as far as authority and power is concerned. It will help eradicate parochial differences and strengthen integrity of a country. It is essential to keep up and safeguard the freedom and the rights of these units. We can get our desired objectives, if legal and constitutional safeguards are meted out to these administrative units of the state. According to ‘Allāmah Ibn Khaldūn’s point of view, it is imperative to strengthen a state instead of expanding it. There must be small but integrated autonomous units of the state. Such division helps these units to progress and prosper. The golden principle of power distribution is in vogue in all eras, although its structure has been different and varied. In this article, we are going to view the structure of distribution in the perspective in an Islamic state

The Study of Genetic Diversity in Relation to Leaves Morphological and Biochemical Adaptations of Mulberry Genotypes Grownin Muzaffarabad, Azad Jammu and Kashmir, Pakistan

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