Papers Published Refreed Journals

Papers Published Refreed Journals

ABSTRACTS

Dr. Yahia A. Alhamed

2000 to 2008

Paper Number 1

(2000)

A. A. A-zahrani and Yahia A. S. Alhamed , Oil Removal from Spent Bleaching clay by Solvent Extraction, J. Environ. Sci. Health, Part A: Toxic/Hazardous Substances & Enviromental Engineering,35(9), 1577-1590 (2000).

ABSTRACT

Solvents screening experiments using a Soxhelt extractor were conducted to determine the best solvents for oil removal from spent bleaching clay. The solvents extracted oil in the following decreasing amount: methylethylketone > benzene-ethanol mixture (1:1 by volume) > acetone > trichloroethylene = dichloromethane > chloroform > petroleum ether > benzene > n-hexane > methanol. Four of the safest solvents, methylethylketone, acetone, petroleum ether and n-Hexane were selected for further studies. Large scale treatment of spent clay with the selected solvents were conducted in a batch stirred reactor. The effect of solvent type, solvent to clay ratio (SCR), time of extraction and extent of mixing on the percentage of oil extracted (POE) were investigated. The corresponding optimum conditions for the four solvents were: extraction time time = 5 minutes, solvent to clay ratio = 4 to 5, extraction temperature = 25 OC (room temperature) and mixing rate = 150 to 200 RPM. The bleaching efficiency (compaerd to to fresh clay) of the clay deoiled by methylethylketone, acetone, petroleum ether and n-hexane were 77%, 65%, 51% and 27%, respectively

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Paper Number 2

(2002)

Y. A. Alhamed, “Preparation and charactrerization of activated carbon from dates stones”, The 6th Saudi Engineering Conference, King 14 – 17 December 2002, King Fahd University of Petroleum & Minerals, Dhahran, Saudi Arabia. Proceedings, Volume 2, Chemical engineering, p 441 – 450..

ABSTRACT

In this paper, the results of a laboratory scale study about the preparation of activated carbon from dates' stones using the physical activation method are presented. The preparation method entails the impregnation of the dried and crushed stones with an activating agent such as ZnCl2 followed by carbonization at high temperatures. The effects of carbonization temperature (500 to 700 OC) carbonization time (0.5 to 3 hours) and, weight ratio of zinc chloride to dry stones (2:1, 1:1 and, 0.5:1) on the quality of activated carbon obtained were investigated to determine the optimum operating conditions. The quality of the Activated Carbons (AC) produced was assessed by their ability for methylene blue removal from aqueous solutions. Characteristics of selected samples of the AC, such as specific surface area, solid density and phenol adsorption isotherm were measured.

Based on methylene blue adsorption experiments and economical considerations, it was concluded that the optimum operating conditions tested for production of activated carbon from date's stones are: carbonization time = 0.5 hour; temperature of carbonization = 600OC; and, zinc chloride to wood ratio = 2:1. In addition, it was found that carbons with specific surface area in excess of 1100 m2/g were obtained. Considering phenol adsorption, the study showed that the best conditions which produce carbons with good phenol adsorption capacity are, carbonization temperature = 700 OC, carbonization time = 1.5 hours and R = 2:1. Compared to Commercial AC, carbons prepared in this study were slightly inferior with respect to phenol adsorption. Nevertheless, it was shown that activated carbon with good characteristics can be obtained from dates’ stone.

Key words: Activated carbon, activation, dates’ stones, phenol adsorption

ملخص

في هذه الورقة نقدم نتائج بحث معملي لتحضير الكربون النشط من نوى التمر بإستخدام طريقه التنشيط الفيزيائي.وتشتمل طريقه التحضير على تحميل النوى المجفف والمجروش بعامل منشط مثل كلوريد الزنك ثم بعد ذلك يتم تفحيمه عند درجات حرارة مرتفعه ثم يتم إزالة العامل المنشط بواسطة الأحماض مثل حمض الهيدروكلوريك .لقد تم دراسة تأثير درجه الحراره ( 00 5 إلى 700 م5 ) وزمن التفحيم (5و0 إلى 3 ساعات ) ونسبة كلوريد الزنك إلى النوى المجفف (5و0: 1 ، 1 :1 ، 2: 1) على نوعيه الكربون الناتج وذلك لتحديد الظروف المثلى لعمليه التصنيع . ولقد تم تقييم نوعيه الكربون بناء اَ على مقدرته في إزالة صبغه أزرق المثيلين من المحاليل المائية.كما تم تعيين خواص الكربون لأخرى لبعض العينات المنتجة مثل المساحةالسطحيةوكثافة الكربون الصلب ومقدرته غلى أد مصاص الفينول.وبناءا على قياس أد مصاص أزرق المثيلين فأنه وجد أن أفضل الظروف هي التفحيم لمدة نصف ساعة عند درجه حرارة00 6 م5 واستخدام نسبه من كلوريد الزنك إلى النوى تبلغ 2 :1.بالأضافه إلىذلك فقد ثم الحصول على عينات كربون ذات مساحة سطحيه أكثر من 00 11 م2 /جم.وعند الأخذ بالاعتبار عمليه ادمصاص الفينول فقد وجد أن أفضل الظروف هي درجه حرارة تفحيم تبلغ 00 7 م5 ولمده ساعة ونصف ونسبه كلوريد الزنك إلى النوى تبلغ 2: 1 وبالمقارنة مع الكربون النشط التجاري فأن الكربون المحضر في المختبر أظهر كفاءة أقل في أدمصاص الفينول.ولكن على الأقل لقد تم إثبات أمكانية الحصول على كربون نشط بمزايا جيده من نوى التمر.

Paper Number 3

(2002)

ABSRACT

Regeneration of spent bleaching clay used in edible oil refining in Saudi Arabia was studied using solvent extraction, boil-off method and calcination. The Solvent extraction method entails the removal of the oil using solvents. The effect of the solvent type, solvent to clay ratio (SCR), and extraction time on the percent of oil extracted (POE) and clay activity was investigated. The boil-off method entails the removal of oil by treatment with a boiling aqueous solution of sodium hydroxide under total reflux in the presence of NaCl. The effects of NaOH and NaCl concentrations, water to clay ratio (WCR) and time of reaction on POE and clay activity was investigated. Calcination entails the removal of the oil by heating at high temperatures. The effect of calcination temperature and time was investigated. The spent clay regenerated using either of these methods at optimum conditions was further activated by treatment with HCl or H2SO4. The effect of acid concentration and reaction time on clay activity was investigated.

It was found that calcination without acid treatment is sufficient to restore most of the clay activity. Boil-off method produces a clay with very low activity and further acid treatment enabled complete restoration of the activity of the clay. MEK was found to be the best solvent with respect to the activity of the deoiled clay. Further treatment of the clay deoiled using MEK with acids restored the activity of the clay.

Key Words: bleaching clay, regeneration, edible oils, calcination, acid treatment, solvent extraction.

الملخص

تم في هذا البحث دراسة أعاده تنشيط طينه التبيض المستهلكه والتي تم أستخدامها في تكرير زيوت الطعام بالمملكه العربيه السعوديه بأستخدام المذيبات والغليان في محلول قاعدي والمعالجه الحراريه. عند أستخدام المذيبات تتم عمليه التنشيط عن طريق أزاله الزيت من الطينه. وقد تم دراسة تاثير نوع المذيب ؛ ونسبة المذيب إلى الطينة وزمن الاستخلاص على نسبه الزيت المستخلصه ونشاطية الطينه.وتتضمن طريقه أعادة النشاطيه بالغليان أزالة الزيت من الطينه المستهلكه بغليها في محلول هيدروكسيد الصوديوم وكلوريد الصوديوم وقد تمت دراسة تاثيرات تركيز كل من هيدركسيد الصوديوم وكلوريد الصوديوم ونسبة الماء إلى الطينه ومدة الغليان على كميه الزيت المستخلصه ونشاطية الطينه المسترجعه. أما بأستخدام الطريقه الثالثة (المعالجه الحراريه) فيتم أعاده تنشيط الطينه بإزالة الزيت منها عند درجات حراره عاليه وقد تمت دراسة تأثير درجات الحراره ومده التسخين على نشاطيه الطينة وفي كل من الحالات ثم زيادة نشاطية الطينه التي تم إزالة الزيت منها عند الظروف المثاليه بمعالجتها بحامض الكبريتيك أو الهيدرو كلوريك ولقد تم دراسة تأثير تركيز الحمض وزمن التفاعل على درجة نشاطية الطينة .

ولقد وجد من هذه الدراسة أن المعالجه الحرايه كافيه لاستعاذه معظم نشاطية الطينه بدون المعالجه بالاحماض التي كان لها تأثير ضئيل في زيادة نشاطية الطينه.وعند المعالجه بالغليان في محلول قاعدي ثم الحصول على الطينه ذات نشاطية منخفضه وقد أستعاده كامل نشاطيتها بعد المعالجه بالاحماض .

وفي حاله المعالجه بالمذيبات فقد وجد أن نشاطية الطينه تعتمد على المذيب المستخدم وكان ميتيل ايثيل الكيتون أفضل المذيبات بالنسبه لنشاطية الطينه التي تم الحصول عليها.علماًُ بأن الطينة استعادت كامل نشاطيتها بعد المعالجه الاضافيه بالاحماض.

Paper Number 4

(2006)

Yahia A. Alhamed, Effect of Preparation Conditions on the Characteristics of Activated Carbon Produced by ZnCl2 Activation. Alexandria Engineering Journal, Volume 45, No 6, 739 – 756, 2006.

ABSTRACT

The effect of preparation conditions (carbonization temperature (CT), carbonization time (Ct) and, weight ratio of activator (ZnCl2) to dry stones (R)) on the structural and adsorptive characteristics of activated carbon (AC) produced from Talh tree trunks (Acacia Asak) was investigated.Adsorption data for methylene blue (MB) and benzene were fitted to a Freundlich-type isotherm (X = k Cen). The unit capacity (k) and the heterogeneity factor (n) were determined. The most influential factor was found to be R where high values of R produced AC with abundant mesoporous structure especially at high CT and low Ct. A combination of low R, high CT and large Ctproduces AC with lower surface area most probably due to pore widening which resultsfrom the collapse of the walls of the micropres.For benzene, n did not change significantly with preparation conditions and its adsorption strongly depended on the available surface area associated with meso and micropore volumes. For MB, n changed with preparation conditions. This may indicate a change in the affinity between MB and the carbon surface resulting from a change in the surface chemistry of the carbon and/or a change in the pore size distribution with preparation conditions.

Key words:Activated carbon, Activation, Adsorption, Carbonization

الملخص العربي

في هذا التقرير يتم أستعراض تاثير ظروف التحضير(درجة حرارة الكربنة و زمن الكربنة و نسبة المنشط (كلوريد الزنك) الى النوى الجاف) على تركيب و خواص الأدمصاص للكربون النشط المنتج من جذوع شجر الطلح. و في ضو ءهذه الدراسة تبين ان أدمصاص أزرق الميثيلين و البنزين يمكن تمثيله بأستخدام معادلة فروندليتش (X = k Cen ) و تم استخدام هذه المعادلة لحساب سعة الوحدة (k) و معامل عدم التجانس (n). وقد وجد أن أهم العوام المؤثرة على خواص الكربون هي نسبة المنشط (كلوريد الزنك) الى النوى الجاف. حيث لوحظ أن أن إستخدام نسبة عالية من المنشط بالنسبة الى نوى التمرالجاف ينتج عنه كربون يحتوي نسبة عالية من المسامات دون المجهرية و بالخصوص أذا تم التحضير عند درجات حرارة مرتفعة و أوقات كربنة قصيرة. كما وجد أن الجمع بين نسبة منخفضة من المنشط مع درجات حرارة منخفضة وو قت كربنة طويل يؤدي الى إنخفاض المساحة السطحية للكربون و يمكن تعليل ذالك بحصول أنهيار في جدران المسامات دون المجهرية و تكون مسامات أكبر. و بالنسبة للبنزين فأن قيمة n لم تتغير كثيرا مع ظروف التحضير و أعتمد أدمصاص البنزين بشكل رئيسي على المساحة السطحية المتوفرة. ومن جهة أخرى فأن n بالنسبة أزرق المثيلين تتغير بشكل كبير مع ظروف التحضيرمما يعني تغير طبيعة التجاذب بين سطح الكربون و أزرق المثيلين نتيجة لتغير كيمياء السطح للكربون أو تغير في توزيع حجم المسامات مع أختلاف ظروف التحضير

Paper Number 5

(2006)

Yahia A. Alhamed Activated Carbon from Dates' Stone by ZnCl2 Activation, Journal of KingAbdulazizUniversity: Engineering Sciences, Volume 17, No 2, 75-98, 2006.

ABSTRACT

A study of the effect of preparation conditions on the yield and quality of activated carbon (AC) produced from dates’ stones was made using zinc chloride as an activator. The optimum conditions for AC production was evaluated based on the determination of various adsorption parameters of methylene blue (MB) and phenol. Using MB as an adsorbate it was found that the optimum ratio of activator to dates’ stones (R) is 2. The maximum unit capacity for MB was 148 mg/g at carbonization time (Ct) = 1 hour and carbonization temperature (CT) = 600 OC and the corresponding yield was 32%. Milder conditions (Ct = 0.5 hr and CT = 500OC) produced AC with maximum adsorption capacity of 286.3 mg/g with a yield of 31%.

Using phenol as an adsorbate it was found that the optimum value of R = 0.5. The maximum unit capacity for phenol was 19 mg/g at Ct = 3 hours and CT = 600 OC and AC yield of 47.3%. On the other hand milder conditions (Ct = 0.5 hr and CT = 500OC) were required to produce AC with maximum capacity for phenol removal of 75.0 mg/g and AC yield of 64.6%.

KEYWORDS: Activated carbon, phenol adsorption, activation, dates’ stones, dates’ pits

المستخلص. تم في هذا البحث دراسة تأثير ظروف التحضير على مردود و وعية الفحم النشط المنتج من نوى التمر باستخدام كلوريد الزنك كمنشط. وقد تم تحديد الظروف المثلى لإنتاج الفحم النشط بناءا على تحديد معاملات الأمتزازالمختلفة لأزرق الميثيل و الفينول وعند استخدام أزرق الميثيل كمادة ممتزة وجد أن أفضل نسبة من المنشط إلى نوى التمر هي 2. وتم الحصول على أعلىقيمة لسعة الوحدة لأزرق الميثيل (148مجم أزرق الميثيل لكل جرام من الفحم النشط) عند زمن تفحيم مقداره ساعة واحدة و درجة حرارة كربنة 600 م0 وكان المردود في هذه الظروف 32%. ومن الناحية الأخرى فإن ظروفاً أقل حدة (زمن كربنة = 0.5 ساعة و درجة حرارة كربنة = 500 م0 ) ساعدت على انتاج فحم نشط بسعة قصوى مقدارها 286.3 مجم أزرق الميثيل لكل جم من الفحم النشط بمردود مقداره 31%.

وعند استخدام الفينول كمادة ممتزة وجد أن أفضل قيمة لنسبة المنشط الى نوى التمر هي 0.5. وتم الحصول على أعلى قيمة لسعة الوحدة للفينول (19 مجم فينول لكل جرام من الفحم النشط) عند زمن كربنة = 3 ساعات و درجة حرارة تفحيم = 600 م0 وكان المردود في هذه الظروف 47.3%. ومن ناحية أخرى فإن ظروفاً أقل حدة (زمن كربنة = 0.5 ساعة و درجة حرارة كربنة = 500 م0 ) ساعدت على أنتاج فحم نشط بسعة قصوى مقدارها 75.0 مجم فينول لكل جم من الفحم النشط بمردود مقداره 64.6%.

Paper Number 6

(2007)

S. A. Nosier, Y. A. Alhamed, and H. A. Alturaif, Enhancement of copper cementation using ceramic suspended solids under single phase flow, Separation and purification technology, 52, 454-460 (2007).

Abstract

Rate of Cu++ removal from waste solution by cementation on zinc rod was studied under single phase flow. Suspended ceramic particles wereused to enhance the rate of cementation of Cu++. The cementations process was studied under different conditions of superficial liquid velocitiesand different ratios of suspended solid to liquid (X). It was found that the rate of Cu++ removal increases with increasing superficial liquid velocityand increase in liquid to solid ratio. The dependence of cementation rate on both superficial liquid velocity and the concentration of ceramicsuspended solids confirmed that the diffusion controlled nature of the reaction. Mass transfer study of the process has revealed that the data can berepresented by the following equation:

J = 2.76Re−0.5211X0.5233

where 761 < Re < 1726, 0.0087 < X < 0.0218 and Sc = 1526.

Keywords: Wastewater; Cementation; Copper removal; Mass transfer; Single phase flow; Suspended solids

Paper Number 7

(2007)

S. A. Nosier, Y. A. Alhamed, A. A. Bakry, and I. S. Mansour, Forced Convection Solid-Liquid Mass Transfer at a Surface of Tube Bundles under Single Phase Flow Chem. Biochem. Eng. Q. 21 (3) 213–218 (2007).

Solid-liquid mass transfer characteristics of in-line tube bank were investigated by measuring the rate of diffusion-controlled dissolution of copper surface in dichromate solution. Variables studied were the number of rows in the tube bank, physical properties

of the solution, and flow rate of the solution. The data were correlated for the conditions:

937 < Sc < 1300, 173 < Re < 385, 1 < N < 5, by the equation

Sh = 2.68 Re0.465 Sc 0.33 N–0.35 + 35.35.

The addition of Polyox WSR 301 as a drag reducing agent leads to a decrease in the

mass transfer coefficient, which ranged from 49 to 83 % depending on the mass fraction

of the polymer, number of tube bundles and the liquid flow rates.

Paper Number 8

(2007)

Y. A. Alhamed, Phenol removal using granular activated carbon from dates’ stones, Bulgarian Chemical Communications, accepted fro publication, 2007

ABSTRACT

Granular activated carbon (GAC) was produced from dates’ stones (DS) by chemical activation method using ZnCl2 as activator. The effects of preparation conditions [Carbonization temperature (CT) = 500, 600 and 700 OC), carbonization time (Ct) = 1 and 3 hours) and R the ratio of activator to dry dates’ stones = 0.5 or 2] on the structural properties, yield, particle size distribution, and phenol removal ability of the produced GAC was explored. Phenol adsorption data for GACs prepared at different conditions were fitted to Freundlich and Langmuir equations. The structural characteristics of the produced GACs were determined from nitrogen adsorption isotherms measured at its boiling point.

The results of this study had shown that a GAC with surface area as high as 1215 m2/g can be obtained using DS as a raw material. Mainly microporous GAC is obtained using R = 0.5 while mesoporous GAC is obtained using R = 2 regardless of carbonization time and temperature. Fruendlich equation fitted the adsorption data of phenol on GAC better than Langmuir equation in the range of the concentrations investigated. Maximum adsorption capacity of 103 mg/g was obtained at optimum conditions of: CT = 700 OC, Ct = 3 hours and R = 0.5.

The GAC yield varied between 39 to 45.8%. The yield gradually decreased with increasing carbonization time and carbonization temperature. At R = 0.5, the particle size distribution of the produced GAC was similar to the original dates’ particles, while for R = 2, a considerable amount of fines (less than 0.3 mm) are obtained.

Laboratory scale packed bed adsorption experiments have shown an increase in breakthrough and saturation times with increasing bed height, decreasing the flow rate (at given bed height) however resulted not only in increase of breakthrough time but also in the broadening of the breakthrough curve, thus indicating that pore diffusion could be the controlling mechanism.

Paper Number 9

(2008)

Y. A. Alhamed, Phenol removal using granular activated carbon from date’s stones by H3PO4 activation, Jpurnal of Environmental Protection an decology, accepted for publication, Vol 9, 2008

ABSTRACT

Granular activated carbon (GAC) was produced from dates’ stones (DS) by chemical activation using H3PO4 as activator. The effects of preparation conditions [Carbonization temperature (CT) = 500, 600 and 700oC, carbonization time (Ct) = 1 and 3 hours and R the ratio of activator to dry dates’ stones = 0.5 and 2] on the yield, particle size distribution, and phenol removal ability of the produced GAC was explored. A better fitting of the phenol adsorption data was achieved using the Freundlich isotherm equation compared to Langmuir adsorption equation.

The optimum conditions selected based on phenol adsorption are: CT = 600oC,Ct = 3hr and R =0.5 with maximum adsorption capacity of phenol = 75.32 mg/g. The yield of GAC under these conditions was 49.1% with 80% of the produced GAC particles are between 1.2 to 2.18 mm.

Laboratory scale packed bed adsorption experiments could be very well fitted using a dispersed plug flow model especially for the combination of low flow rate and long bed models. Under different conditions, however, deviations from this model were observed at longer operating times where pore diffusion seems to be the controlling mechanism.

Paper Number 10

(2008)

Ahmed Arafat and Yahia Alhamed,Catalytic activity of mesoporous catalysts in Freide;-Crafts Benzylation of benzene.Journal of Porous materials, Accepted: 26 June 2008.

Abstract Different samples of metal-incorporated MCM-41 were prepared and used as catalysts in Friedel–Craft’sbenzylation of benzene. The catalytic performance wasevaluated by off-line GC analysis. Fe-MCM-41 exhibitedexcellent activity, the sample with Si/Fe ratio = 10 showed90% conversion with 95% selectivity towards diphenylmethanewithin a few minutes. Generally, the activityper Fe-site was an order of magnitude higher for thesamples containing a combination of Fe2O3 nano-particlesand isolated Fe3+ sites. A synergy of two catalytic centers(particles and isolated sites) is proposed to explain the highperformance of the highly loaded samples. The catalyticperformance of Fe-MCM-41 was superior to other metalcontainingMCM-41 (e.g. Ga, Sn, and Ti) catalysts, orother Fe-containing mesoporous materials (e.g. Fe-HMS).

Keywords Mesoporous _ Fe-MCM-41 _ Friedel–Crafts _Benzylation _ Catalysis

Paper Number 11

(2008)

Yahia A. Alhamed and Hisham S. Bamufleh, Sulfur removal from model diesel fuel using granular activated carbonfrom dates’ stones activated by ZnCl2, Fuel 88 (2009) 87–94.

Samples of granular activated carbon (GAC) were produced from dates’ stones by chemical activationusing ZnCl2 as an activator. Textural characteristics of GAC were determined by nitrogen adsorption at77 K along with application of BET equation (Brunauer, Emmett and Teller) for determination of surfacearea. Pore size distribution and pore volumes were computed from N2 adsorption data by applying thenonlinear density function theory (NLDFT). FT-IR spectra of GAC samples were also obtained to determine

the functional groups present on the surface. GAC samples were used in desulfurization of a model dieselfuel composed of n-C10H34 and dibenzothiophene (DBT) as sulfur containing compound. More than 86% ofDBT is adsorbed in the first 3 h which gradually increases to 92.6% in 48 h and no more sulfur is removedthereafter. The adsorption data were fitted to both Freundlich and Langmuir equations to estimate theadsorption parameters. The optimum operating conditions for GAC preparation based on high adsorptioncapacity are Tcarb = 700 _C, hcarb = 3.0 h and R = 0.5. Moreover, the efficiency of sulfur removal by GAC isreduced when applied to commercial diesel fuel. Finally, linear regression of experimental data was ableto predict the critical pore diameter for DBT adsorption (0.8 nm) and validating the reported impact ofaverage pore diameter of activated carbon on the adsorption capacity.