Activated carbon preparation

Production of activated carbon (AC) from agricultural byproducts is a research field that has gained increased interest in recent years because of its potential for the disposal of agro-residues. At the same time, a beneficial byproduct that can be used in a number of environmental applications is produced. This paper surveys the developments in the production processes of AC from agricultural byproducts in the past 7 years from 2005 to 2012 via conventional and microwave heating. Emphasis is placed on the applied methodology and the influences of activating conditions, such as carbonization temperature, retention time, and impregnation ratio. From the review of AC production processes, agricultural wastes produced by a chemical method with microwave heating can be a source of AC with relatively higher surface area than that produced via conventional heating.

To date, microwave energy has been widely developed and applied to almost every field of chemistry. In many cases, microwave technology has proven to remarkably reducing costs, accelerating reaction rates, improving yields and selectively activating. This paper presents a state of art review of microwave technology , its background studies, fundamental chemistry and industrial applications. With the renaissance of activated carbon, there has been a steadily growing interest in this research field. The review provides a summary on recent development in preparation and regeneration of activated carbons. The key advance of introducing microwave energy has been highlighted relative to conventional methods. Moreover, the major drawbacks, challenges with its future expectation are presented and discussed. Conclusively, microwave energy is predicted to be a potentially viable and powerful replacement for fuel technology in various areas, while its progress represents an expanding field in the area of adsorption science.

Pore size distribution a b s t r a c t In this paper, activated carbons with high surface area from carbonized tobacco stems with K 2 CO 3 activation by microwave radiation were investigated. Effects of microwave radiation time and K 2 CO 3 /C ratio on the yield and adsorption capacities of activated carbons were evaluated. Experimental results indicated that the optimum conditions were as follow: microwave power 700 W; microwave radiation time 30 min; K 2 CO 3 /C ratio 1.5:1. Iodine number, amount of methylene blue adsorption and the yield of activated carbon prepared under optimum conditions were 1834 mg/g, 517.5 mg/g and 16.65%, respectively. Surface area, micropore volume and pore size distribution (PSD) of the carbons were determined by the BET, H-K and DFT methods. Results showed that activated carbons had a micropore content about 59.98% and a small number of mesopores and macropores; BET specific surface area and total pore volume were 2557 m 2 /g and 1.647 cm 3 /g, respectively.

The abundant fraction of agricultural waste materials in the environment that poses
disposal challenge could be converted into useful value added products such as activated carbon.
Palm oil shell based carbon was prepared by two step process using K2CO3 as the chemical activant.
The Langmuir surface area, BET surface area and pore volume were 817 m2/g, 707m2/g and
0.31cm3/g. From the FTIR analysis, carbonyls, alkenes and hydroxyls were identified. The SEM
image shows gradual formation of pores due to elimination of volatiles and contaminants.
Carbonization at 800°C for 2 hours and activation at same temperature for 1h has the highest yield
of 23.27%. The proximate and ultimate analysis shows high percentage of carbon and low
percentage of ash which is an indication of a good material for production of porous carbon. The
activated carbon produced showed basic properties suitable for removal of organic contaminants in
aqueous solutions. However, the aim of this study is to produce a green and porous carbon with
controlled pores and surface properties for organic contaminants removal from water and
wastewater.

Production of activated carbon (AC) from agricultural byproducts is a research field that has gained increased interest in recent years because of its potential for the disposal of agro-residues. At the same time, a beneficial byproduct that can be used in a number of environmental applications is produced. This paper surveys the developments in the production processes of AC from agricultural byproducts in the past 7 years from 2005 to 2012 via conventional and microwave heating. Emphasis is placed on the applied methodology and the influences of activating conditions, such as carbonization temperature, retention time, and impregnation ratio. From the review of AC production processes, agricultural wastes produced by a chemical method with microwave heating can be a source of AC with relatively higher surface area than that produced via conventional heating.

This study involves synthesis of two types of the activated carbon from Iraqi zahdy date palm seeds and Iraqi khestawy date palm seeds.
These two types of activated carbon were synthesized using H3PO4 as an activator. Synthesis processes of activated carbon were performed
by chemical activation method. The activity of these materials as adsorbents was investigated by following removal of reactive yellow dye
145 (RYD-145). Kinetics of adsorption and removal of reactive yellow as a model of the polluted dyes were investigated from batch tests.
Different reaction parameters and conditions were investigated, such as amount of loading of activated carbon and duration of the adsorption
process. The point zero charges of the synthesized samples were also calculated. It was found that Iraqi zahdy date palm seeds based
activated carbon was more efficient than Iraqi khestawy date palm seeds in dye removal under the same reaction conditions.

In this study, an activated carbon was prepared from paulownia (P. tomentose) wood by chemical activation with ZnCl 2. Pore properties including surface area, pore volume, pore size distribution and average pore diameter of the activated carbon were determined by N 2 adsorption at 77 K using the BET, t-plot and density functional theory (DFT) methods. The activated carbon had a BET surface area of 2736 m 2 g-1 and total pore volume of 1.387 cm 3 g-1. The use of activated carbon for the removal of methylene blue (MB) from aqueous solutions was investigated in a batch system different pH, initial dye concentrations contact times, temperatures and adsorbent doses. The extent of dye removal decreased with increasing initial MB concentration and increased with increasing contact time, temperature and adsorbent dosage. The equilibrium data were analyzed by the Langmuir and Freundlich isotherm models. The experimental data for the adsorption of MB dye fit the Langmuir iso-therm model very well and the maximum monolayer adsorption capacity of the activated carbon was determined as 322.58, 384.61, 370.37 mg g-1 for 25, 35 and 45°C, respectively. The adsorption kinetics were found to follow a pseudo-second-order kinetic model. The changes in entropy (∆S°) and heat of adsorption (∆H°) for MB adsorption on activated carbon were positive.

In attempt to compare the removal efficiency and yield of the activated carbon prepared using the conventional and microwave-assisted heating is the focus of this work. Toward this olive stone (a biomass precursor) is activated using the popular activating agent potassium hydroxide. The process optimization exercise is carried out by using the standard full factorial statistical design of experiments (response surface methodology). The activated carbons prepared under the optimized conditions are compared based on the adsorption capacity and yield. The adsorption capacity was found higher using microwave heating as compared with conventional heating. The microwave heating requires significantly lesser holding time as compared to conventional heating method to produce activated carbon of comparable quality, with higher yield. The BET surface area of carbon using microwave heating is significantly higher than the conventional heating. Although the mesopore surface area of carbon is not vary significantly, the activation time, power, and nitrogen gas consumption are significantly lower than the conventional heating rendering that the activation process via microwave is more economical than that via conventional heating. The adsorption isotherm data fitted the Langmuir isotherm well and the monolayer adsorption capacity was found to be 12.0 and 8.42 mg/g for microwave and thermally heated activated carbon, respectively. Regeneration studies showed that microwave-irradiated and thermally heated olive stone could be used several times by desorption with an HCl reagent. Both carbons can be used for the efficient removal of Ni 21 (>99%) from contaminated wastewater.

In this study, a novel continuous reactor has been developed to produce high quality methyl esters (biodiesel) from palm oil. A microporous TiO2/Al2O3 membrane was packed with potassium hydroxide catalyst supported on palm shell activated carbon. The central composite design (CCD) of response surface methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst amount and cross flow circulation velocity on the production of biodiesel in the packed bed membrane reactor. The highest conversion of palm oil to biodiesel in the reactor was obtained at 70 degrees C employing 157.04 g catalyst per unit volume of the reactor and 0.21 cm/s cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. High quality palm oil biodiesel was produced by combination of heterogeneous alkali transesterification and separation processes in the packed bed membrane reactor. (C) 2010 Elsevier Ltd. All rights reserved.

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The effect of pyrolysis conditions on the yield and composition of char from pectin was studied. Pectin is a component of the carbohydrate fraction of biomass-derived materials. The pyrolysis was done at atmospheric pressure under oxidative and non-oxidative (inert) atmospheres and at temperatures ranging from 150 to 5508C. The volatile product was analyzed by gas chromatography/mass spectrometry (GC/MS). The solid product, i.e. char, was characterized by solid-state 13 C nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy. The char was also analyzed for its elemental composition and surface area. The surface morphology of char was studied by scanning electron microscopy (SEM). The results were compared to those from chlorogenic acid (CA), a component of the phenolic fraction of biomass-derived materials. The behavior of pectin was similar to that of CA. For both pectin and CA, the char yield decreased with increasing temperature before leveling-off at ca. 20% of the starting substrate in non-oxidative runs. In oxidative runs, the char yields from both substrates became negligible at 5508C. NMR analysis indicated that the aromatic character of char increased as the pyrolysis temperature increased. The oxygen functionality was progressively lost and the resonance bands corresponding to carbonyl groups mostly disappeared above 3508C. FTIR analysis also suggested the loss of hydroxyl and carbonyl groups from chars at high temperatures. The H/C and O/ C ratios of chars decreased continuously with increasing temperature. The oxidative chars showed characteristics essentially similar to those of the non-oxidative chars. The surface area of char was negligible at low temperatures, but increased dramatically to a maximum of 70 m 2 g 21 at 4508C before decreasing at 5508C. SEM analysis indicated that the pyrolysis of pectin occurred via softening and melting of the substrate followed by bubble formation. At high temperatures, surface etching followed by the appearance of crystal deposition on the char surfaces were also observed. The results are consistent with the analysis of the evolved gases q

Production of activated carbon (AC) from agricultural byproducts is a research field that has gained increased interest in recent years because of its potential for the disposal of agro-residues. At the same time, a beneficial byproduct that can be used in a number of environmental applications is produced. This paper surveys the developments in the production processes of AC from agricultural byproducts in the past 7 years from 2005 to 2012 via conventional and microwave heating. Emphasis is placed on the applied methodology and the influences of activating conditions, such as carbonization temperature, retention time, and impregnation ratio. From the review of AC production processes, agricultural wastes produced by a chemical method with microwave heating can be a source of AC with relatively higher surface area than that produced via conventional heating.

Activity learning is student activities during learning. Active learning is learning that supply and provides an opportunity for students to learn on their own or their activities that have an impact on learning outcomes. The purpose of this study was to describe the activity and student learning outcomes by applying the model of discovery learning. The research sample is Class X MIPA Public High School 1 Piyungan. This type of research is classroom action research consisted of two cycles of cycle 1 and cycle 2. Data collection techniques are using observation sheets and test sheets, As for the data analysis using descriptive analysis. The results of the analysis that studied physics Increased activity class X MIPA Public High School 1 Piyungan with discovery learningon the measurement of physical quantities in the academic year 2019/2020 of the first cycle in the first meeting and the second meeting was increased from 88.5% to 93.0%, i.e. 4.50%. In the second cycle increased from 92.1% to 97.0% there was an increase of 4.90. Improved physics learning outcomes of students of class X MIPA Public High School 1 Piyungan with discovery learning(DL) on the material for measuring physical quantities in the academic year 2019/2020 in cycle I to cycle II from 61% to 77.8% experiencing an increase of 16.8%. Improved learning outcomes show that the application of discovery learningcan be fun and make students interested and interested in learning. Abstrak: Aktivitas belajar merupakan kegiatan yang dilakukan siswa saat pembelajaran. Suatu pembelajaran yang efektif adalah pembelajaran yang menyediakan dan memberi kesempatan kepada siswa untuk belajar sendiri atau aktivitas sendiri sehingga berampak terhadap hasil belajar. Tujuan penelitian ini adalah untuk mendeskripsikan keaktifan dan hasil belajar siswa dengan menerepakan model pembelajaran discovery learning. Sampel penelitian yaitu Kelas X MIPA SMAN 1 Piyungan. Jenis penelitian ini adalah penelitian tindakan kelas yang terdiri dari dua siklus yaitu siklus 1 dan siklus 2. Teknik pengumpulan data yaitu menggunakan lembar observasi dan lembat tes. Sedangkan untuk analasi data menggunakan analisisi deskriptif. Hasil analisis diperoleh bahwa Peningkatan aktivitas belajar fisika siswa kelas X MIPA SMA Negeri 1 Piyungan dengan discovery learning pada pengukuran besaran fisis tahun pelajaran 2019/2020 dari siklus I pada pertemuan pertama dan pertemuan kedua mengalami peningkatan dari 88,5% menjadi 93,0% yaitu 4,50%. Pada siklus II mengalami peningkatan dari 92,1% menjadi 97,0 % ada peningkatan 4,90. Peningkatan hasil belajar fisika siswa kelas X MIPA SMA Negeri 1 Piyungan dengan discovery learning(DL) pada materi pengukuran besaran fisis tahun pelajaran 2019/2020 pada siklus I ke siklus IIdari 61 % menjadi 77,8% mengalami kenaikan 16,8%. Adanya peningkatan hasil belajar menunjukkan bahwa DL yang dilaksanakan dapat menyenangkan dan membuat siswa berminat dan tertarik dalam pembelajaran tersebut.

This study investigates the effect of temperature and impregnation ratio on the physicochemical properties of activated carbon prepared from desiccated coconut residue by chemical activation using potassium hydroxide. Desiccated coconut residue sample was first carbonized at three different temperatures for 1 h at 400, 500 and 600 °C, respectively. The resulting chars were impregnated with KOH at three different impregnation ratio; 1:1, 1:2 and 1:3, respectively and activated under nitrogen atmosphere for 1 h at three different temperatures based on its carbonization temperature. The BET surface area and pore volume was strongly affected by temperature in which increased in temperature caused increased in BET surface are and pore volume. The BET surface area also increased with impregnation ratio but then decreased due to pore widening of activated carbons.

Mangosteen peel is an important source of natural antioxidants. Due to the growing interest in extracting this anti cancer substances from the mangosteen peel, the amount of this lignocellulosic residu has been generated significantly as byproduct. In this research, mangosteen peels (MP) and extraction-waste mangosteen peel (EMP) were used as alternative precusor for production of carbon-based adsorbent for ethylene removal. Steam was used as activating agent to develop carbon pore structure. Pyrolysis process was carried out by heating the mangosteen peels powder (180 μm-355 μm) from ambient temperature up to carbonization temperature of 848 K and kept for 3 hours then followed by heating up to 1123 K and kept for 15 minutes under flowing N 2 and steam. The carbon obtained was characterized in term of its pore structure and ethylene uptake capacity. The results show that porous carbon obtained from pyrolysis of mangosteen peel can be characterized as microporous carbon, whereas porous carbon derived from extraction-waste mangosteen peel was mesoporous carbon. The surface area of 1185 m 2 /g was obtained from pyrolysis of mangosteen peels with carbonization time of 3 hours and pyrolysis temperature of 1123 K, and the surface area of 1067 m 2 /g was obtained from pyrolysis of extraction waste mangosteen peels with carbonization time of 3 hours and pyrolysis temperature of 1123 K. From the ethylene uptake experiment, it was noted that carbon obtained from mangosteen peel (MPC) has higher ethylene adsorption capacity than that of carbon obtained from extraction waste mangosteen peels (EMPC) and that commercial carbon (CC). The ethylene adsorption capacity of MPC, EMPC, and CC are 57.62 cm 3 /g, 40.12 cm 3 /g and 49.89 cm 3 /g, respectively.

Microwave–induced activation process with or without ultrasonic technique was performed to
produce activated carbon from waste cooked tea. This material was activated by using Clorox or
concentrated H2SO4- HNO3 mixture as individual activating agent. Different spectroscopic (FTIR, XRD,
SEM, and AFM) techniques were applied to qualify the resulted properties as results of activation
process and applied activating agent. The qualitative and quantitative analysis with statistical
information of several prepared samples were summarized, discussed, and compared with our
recently published paper that demonstrated the existence of micro- and nano- structural particles.
Our selection of waste cooked tea as a starting material subjected to microwave irradiation or
ultrasonic as eco-friendly activation process beside different chemicals as activating agents with their
spectroscopic results suggested that the prepared activated carbon representing an economically
promising material with wide spectrum of applications.

Carbon brush has been developed for several decades and also indispensable hardware for electric machines in the era of microelectronic.  It is the electromechanical that connect the circuit and to generate an electric motor.  The mineral graphite is always used as a raw material in producing carbon brushes besides the uses of charcoal.  This study is propose to use oil palm shell (OPS) as a waste material that can be recycle and sustainable to produce a carbon pre-cursor.  This research is to minimize the use of graphite or charcoal as a raw material in producing a carbon brushes by replaced an OPS as the raw material and produced a carbon brush for railway application.  Several processes such as crushing, milling, mixing, carbonization and compaction are used in this study to produce the carbon brush.  The formation of carbon (C) had been produced by reaction of combustion in Nitrogen atmosphere with used variety of temperatures (500°C, 550°C, 600°C) to produce carbon pre-cursor.  The carbon brush samples then had been prepared by mixing a copper powder and phenolic with different ratio of mixtures.  The suitable percentages of phenolic that could form a solid cylindrical shape were 15%.  Sample of carbon brush that had been baked at 600°C forming the highest carbon.  In this study, the used of copper powder can procure a better conductivity which the sample can permit current flow through it.  By using 60% of copper powder, the sample produced less porosity which resulted for high density.  Lesser the pores of the carbon brush sample procure low resistivity and high conductivity but the appropriate percentages should be find out in the future to match the specification for railway application.
Keywords: [Carbon brush, Light Rail Transit, Oil palm shell, carbon pre-cursor, copper powder, carbonization, conductivity]

The adsorption of a group of heavy metals namely, Zn 2+ , Ni 2+ , and Cd 2+ onto olive stones activated carbon (OSAC) was carried out in this work. The effects of different reaction parameters, such as the adsorbent dosage, contact time, shaking speed, and initial pH, on pollutant removal efficiency were investigated. Adsorption of Zn 2+ , Ni 2+ , and Cd 2+ was effectively explained by Langmuir and Freundlich isotherms. OSAC efficiently removed 99.03% Zn 2+ , 97.34% Ni 2+ , and 94.88% Cd 2+ at pH 5 and shaking speed 200 rpm. Surface characteristics of the prepared AC were examined by pore structure analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. The Brunauer-Emmett-Teller surface area, total pore volume and average pore diameter of the prepared AC were 886.72 m 2 /g, 0.507 cm/g, and 4.22 nm, respectively. The equilibrium data of the adsorption were fitted well to the Langmuir and the highest value of adsorption capacity (Q) on the OSAC was found for Zn 2+ 11.14 mg/g, followed by Ni 2+ 8.42 mg/g and Cd 2+ 7.80 mg/g. A pseudo-second-order model sufficiently described the adsorption kinetics, which indicated that the adsorption process was controlled by chemisorption. The results revealed that the OSAC has the potential to be used as a low-cost adsorbent for the treatment of wastewaters contaminated with heavy metals.

The removal efficiencies of Cu 2þ , Cd 2þ , Ni 2þ , Pb 2þ , Fe 2þ , and Zn 2þ from aqueous solution with olive stone activated carbon (OSAC) were investigated in this paper. Central composite design method was used to optimize the preparation of OSAC by chemical activation using potassium hydroxide (KOH) as chemical agent. The optimum conditions obtained were 715 C activation temperature, 2 hours activation time, and 1.53 impregnation ratio. This resulted in removal of 99.25% Cu 2þ , 94.98% Cd 2þ , 99.08% Ni 2þ , 99.33% Pb 2þ , 99.41% Fe 2þ , and 99.17% Zn 2þ , as well as 73.94% OSAC yield. The surface characteristics of the activated carbon (AC) prepared under optimized condition were examined by pore structure analysis, scanning electron microscopy, and Fourier transform infrared spectroscopy. The Brunauer-Emmett-Teller (BET) surface area, total pore volume, and average pore diameter of the prepared activated carbon were 886.72 m 2 /g, 0.507 cm 3 /g, and 4.22 nm, respectively. The equilibrium data of the adsorption was well fitted to the Langmuir and the highest value of adsorption capacity (Q) on the OSAC was found for Fe 2þ (57.47 mg/g), followed by Pb 2þ (22.37 mg/g), Cu 2þ (17.83 mg/g), Zn 2þ (11.14 mg/g), Ni 2þ (8.42 mg/g), and Cd 2þ (7.80 mg/g). The prepared OSAC can be used for efficient removal of metals from contaminated wastewater.

Landfilling used tires which are generated each year in the United States is increasingly becoming an unacceptable solution. A better approach, from an environmental and economic standpoint, is to thermally reprocess the tires into valuable products such as activated carbon, other solid carbon forms (carbon black, graphite, and carbon fibers), and liquid fuels. In this study, high surface area activated carbons (>800 m2/g solid product) were produced in relatively high yields by pyrolysis of tires at up to 900 C, followed by activation in CO2 at the same temperature. The surface areas of these materials are comparable with those of commercial activated carbons. The efficiency of the activation process (gain in specific surface /loss in mass) was greatest (up to 138 m2/g original tire) when large pieces of tire material were used ( about 170 mg each). Oxygen pretreatment of tires was found to enhance both the yield and the surface area of the carbon product. High-pressure treatment of tires at low temperatures ( < 400 C ) is an alternative approach if the recovery of carbon black or fuel oils is the primary objective.

This study briefs about the conditions for preparation of activated carbons from pectin, citrulline, and cellulose rich Annona squamosa shell (custard apple shell) using phosphoric acid (H 3 PO 4 ). The influence of time, temperature, and impregnation ratio on the yield were studied on the preparation of activated carbon by conventional i.e. normal stirring method (CAC), microwave assisted (MAC), and sunlight assisted synthesis (SAC). Also, the characteristics of all the three carbons were determined and found to have high surface areas using Brunauer-Emmett-Teller analysis. The prepared activated carbons were optimized for lead (Pb 2+ ) and cadmium (Cd 2+ ) uptake from aqueous solution and further the same was used to treat industrial effluent. The Langmuir isotherm was used to correlate equilibrium data of the adsorption of Pb 2+ and Cd 2+ by the prepared activated carbons.

Three series of activated carbon have been prepared by heat treatment of peach stones impregnated with solutions of phosphoric acid, in order to analyze the effect of phosphoric acid on the yield, bulk density and porosity of the resultant activated carbons. The analysis of the adsorption isotherms of N2 at 77 K. CO2 at 273 K and n-C4H10, at 273 K shows that the amount of phosphorus introduced into the material. Xp. is the main factor conditioning the porosity and pore size distribution of the activated carbon. In general terms, the increase in Xp leads to an increase in the volumes of micro and mesopores of the carbon. Furthermore, there is a noticeable similarity between the volume of micropores and the volume occupied by the P2O5·.xH2O in the interior of the peach stones. This suggests that the microporosity is mainly caused by the phosphoric acid remaining in the impregnated material, which inhibits the contraction of the material during carbonization. On the other hand. it is suggested that the mesoporosity of the activated carbon, which is large only when the concentration of phosphoric acid is high, is mainly caused by the hydrolysis of the lignocellulosic material and subsequent partial extraction of some of its components during impregnation.

Carbons were prepared from resins synthesised using the phenolic precursors phenol, para methylphenol, para ethylphenol, para n-propylphenol, para isopropylphenol and 3,5-dimethylphenol. Loss of phenolic OH from these materials was followed using solid-state nuclear magnetic resonance. The surface areas of the carbons were determined using N2 and CO2 adsorption. No significant differences in the loss of phenolic OH were observed. Under the same carbonisation conditions, the para alkyl phenols gave carbons with wide micropores, while the phenol and 3,5-dimethylphenol gave carbons with narrow micropores. Grinding the cured resins prior to carbonisation was found to significantly increase the surface area of the carbons obtained, with the microporous surface area increasing rapidly with a fall in particle size, without a significant increase in burn-off. Higher carbonisation temperatures widened the micropore size distribution, as shown by fitting the CO2 adsorption isotherm with the Dubinin–Astakhov equation. The ability to change the carbon micropore structure obtained from a simple, well defined precursor, has many potential applications in carbon molecular sieves, catalyst supports and the investigation of adsorption processes.

SiO 2 /TiO 2 composites were synthesized by adding Degussa P25 TiO 2 to a liquid sol that was catalyzed by HNO 3 and HF acids. Various composites were synthesized by altering the mass loading of TiO 2 and concentration of HF added to the liquid sol before gelation. The resulting materials were characterized by SEM, nitrogen adsorption-desorption, streaming potential, XRD, diffuse reflectance and TiO 2 surface area analyses. Approximate characteristics include an isoelectric point of 3, TiO 2 particle size of 30 nm, and a band gap energy of 3.2 eV. Small variations in these properties were noted for the different composites. Physical characteristics were largely affected by HF concentration and TiO 2 loading. Nitrogen adsorptiondesorption isotherms were type IV for all materials and exhibited trends of decreased pore volume with an increase in TiO 2 loading and an increase in pore diameter with increased HF concentration. Surface areas of the composites ranged from 167 to 630 m 2 /g. Available TiO 2 surface area of the composite was also dependent upon TiO 2 loading and increased as the mass composition of TiO 2 increased but was not largely affected by HF concentration.

This study investigated the potentiality of residual oil fly ash as a precursor of activated carbon (AC). Fly ash samples were activated by physical activation method, i.e. with CO 2 flow at 950˚C for 2 h. Samples were characterized by BET, SEM, FTIR, and XRD techniques. The produced AC developed a high surface area (269.013 m 2 /g). The synthesized AC was then examined as an adsorbent for Cu(II) and Pb(II) removal from aqueous solutions. The effect of solution pH, initial solution concentration, and contact time were studied. Results of batch experiments for precipitation (in absence of AC) showed that removal of both Cu(II) and Pb(II) ions by precipitation was occurred at pH 6 and increased at pH 7 with removal values of 52.5 and 88.1%, respectively. On another hand, higher removal efficiency of metal ions by adsorption (in presence of AC) was achieved with increased solution pH levels. Adsorption values of 72.7 and 78.5% were achieved at pH 5 for Cu(II) and Pb(II), respectively. Complete removal (99 and 99.3% for copper and lead, respectively) of both metals was achieved at pH 7 (adsorption and precipitation). The maximum equilibrium time of adsorption was found to be 30 min for the two metal ions. Kinetics studies revealed that the adsorption of Cu(II) and Pb(II) onto AC followed the pseudo-second-order kinetics and the adsorption equilibrium data were well fitted to Langmuir isotherm model.

Synthetic activated carbons were prepared by phosphoric acid activation of a styrene-divinylbenzene copolymer in an air atmosphere at various temperatures in the 400-900 8C interval. The carbons were characterized by elemental analysis, cation-exchange capacity measurement, infrared spectroscopy, potentiometric titration, copper adsorption from solution and physical adsorption of N at 2196 8C and CO at 0 8C. It was shown that, similarly to synthetic phosphoric acid activated 2 2 carbons obtained in argon, the synthetic carbons activated with phosphoric acid in air possess an acidic character and show considerable cation-exchange properties. The contribution of oxygen-containing surface groups along with phosphoruscontaining groups to CEC is higher for carbons obtained in air. Three types of surface groups were identified on carbons prepared at temperatures up to 600 8C, and four types on carbons prepared at higher temperatures. These groups were assigned to 'super-acidic' (pK,0), phosphorus-containing (pK51.1-1.2), carboxylic (pK54.7-6.0) and phenolic (pK58.1-9.4) groups. The cation-exchange capacity was at a maximum for the carbon prepared at 800 8C. Copper adsorption by synthetic phosphoric acid activated carbons obtained in air at temperatures lower than 800 8C is higher than for similar carbons obtained in argon. The increase is due to additional formation of oxygen-containing surface groups. Calculated copper binding constants revealed the importance of phosphorus-containing and carboxylic groups for adsorption of copper from aqueous solution. All carbons show a multimodal pore size distribution including simultaneously micropores and mesopores, but the porous texture is not a prime factor in determining the cation-exchange capacities of these carbons. Synthetic phosphoric acid activated carbons show a greater development of porosity when obtained in air as compared to carbons carbonized in argon.  properties of carbons obtained by phosphoric acid activa-0008-6223 / 03 / $ -see front matter 

A series of experiments was conducted to study the catalytic effects of the stainless-steel reactor material and activated carbon (AC) on the decomposition of methane for production of hydrogen. Additionally, the effects of the methane flow rate, amount of AC, decomposition temperature, and particle size on methane conversion, initial decomposition rate and deactivation time were determined in a fixed bed reactor. The reactor wall seriously affected the methane decomposition when the temperature was higher than 850 • C. The activity of the AC increased with the increase in methane decomposition temperature (775-850 • C), and changing the particle size (135-1095 m) did not have a significant effect. The initial rate of methane decomposition showed an inverse and non-linear relationship with increasing weight of AC due to the dilution of methane by the produced hydrogen. However, the method of changing the volume hourly space velocity, i.e., by changing either the AC weight at a constant methane flow rate or the methane flow rate at a constant AC weight, did not cause differences in the measured AC initial activity. Various measurements on the AC at the beginning and end of the experiment revealed that methane decomposition occurs mainly within AC micropores.

In this study, the recycling possibility of residual oil fly ash (ROFA) towards preparing activated carbon and its application in environmental remediation through adsorbing Cu (II) and Pb (II) ions from aqueous solutions were investigated. Activated carbons were prepared using two different physical activation methods such as under steam flow at 950 0C, and combined steam and CO2 flow at 850 0C for 2 hours. Characterization of activated carbons was done by BET surface area method, scanning electron microscopy (SEM), Fourier transform infra-red spectroscopy (FTIR), and X-ray diffraction technique (XRD). Combined gasification increased the surface area of ROFA particles quite higher (110.89 to 423.09 m2/g) than only steam activation (275.07 m2/g). Development of microporosity was also achieved during the treatments and it increased from 0.043 cc/g (raw ash) to 0.325 in steam activated samples, and 0.078 in combined gas activated samples. FTIR analysis showed the presence of aromatic, ester, and hydroxyl functional groups on the ROFA surface after the treatment while XRD examination confirmed its carbonaceous and amorphous nature. pH 5 was found optimum for the adsorption studies at which the removal efficiencies were >71% for Cu (II) and >80% for Pb (II), while the concentration was 25 ppm for both metals. The Langmuir isotherm model was found statistically significant for both Cu (II) (R2 > 0.95) and Pb (II) (R2 > 0.99). ROFA has been successfully recycled in this work and the activated carbons might be considered for industrial applications.

Keywords
Residual oil fly ash, Activated carbon, CO2 activation, Steam activation, Fly ash, Physical activation.

In this study, a novel continuous reactor has been developed to produce high quality methyl esters (biodiesel) from palm oil. A microporous TiO 2 /Al 2 O 3 membrane was packed with potassium hydroxide catalyst supported on palm shell activated carbon. The central composite design (CCD) of response surface methodology (RSM) was employed to investigate the effects of reaction temperature, catalyst amount and cross flow circulation velocity on the production of biodiesel in the packed bed membrane reactor. The highest conversion of palm oil to biodiesel in the reactor was obtained at 70°C employing 157.04 g catalyst per unit volume of the reactor and 0.21 cm/s cross flow circulation velocity. The physical and chemical properties of the produced biodiesel were determined and compared with the standard specifications. High quality palm oil biodiesel was produced by combination of heterogeneous alkali transesterification and separation processes in the packed bed membrane reactor.

This paper presents the feasibility of removal of heavy metal ions of iron (Fe), Zinc (Zn) and Copper (Cu) from aqueous solutions by using a low cost natural adsorbent produced from Groundnut Shells (Arachis hypogaea). Batch adsorption experiments were carried out to determine the effect of contact time, adsorbent dosage and temperature on the adsorption processes. The functional groups and the surface properties of the activated carbon were determined using FTIR and SEM. The equilibrium, kinetics and thermodynamics studies of the sorption process were also carried out. The Heavy metal ion adsorption equilibriums were attained at 120 minutes of the contact time, and it was described by the Langmuir and Freundlich adsorption isotherms. Adsorption data obtained from the equilibrium studies suggests that the activated carbon produced fits better into the Freundlich Isotherm (R2 > 90) and that the adsorption of Cu and Fe ions are best described by the pseudo-second order kinetic model (R2>94), which indicate that the adsorption mechanism is chemisorption and adsorption of the Zinc ions are better described by the first-order kinetics (R2>88) implying Zn ions undergo physisorption. From the values of thermodynamic parameters (ΔHo, ΔSo, and ΔGo), it was evident that adsorption of Fe and Cu ions followed exothermic process and were spontaneous at lower temperatures (-ΔHo values and - ΔSo values).  Adsorption of Zn ions followed endothermic process and it is non spontaneous (+ΔHo values and - ΔSo values). The FTIR result proved the existence of some essential functional groups like hydroxyl (OH) on the activated carbon which have been proven to aid adsorption The SEM analysis revealed the micro-porous structure of the Activated Carbon to be elongated in shape. Therefore, the Activated Carbon produced from the groundnut shells is more efficient for the adsorption of Cu and Fe than adsorption of Zn ions.

Coupled with the highly voluminous wastewater – palm oil mill effluent (POME) – usually produced during the palm oil processing, there are also abundant solid wastes such as empty fruit bunch (EFB) from the industry which could be converted to value added products such as low cost adsorbents like activated carbons. These adsorbents could well fit into low budget treatment process integration with better sustainability if improved. In this study, the EFB-based powdered activated carbon (PAC) was produced in a two-way step; carbonization and thermal activation (pyrolysis) to be applied in the treatment of biotreated POME (BPOME). The pyrolysis was carried out at 900 °C and steam flow rates of 2.0 mL/min, 4.0 mL/min, 6.0 mL/min, 8.0 mL/min and 10.0 mL/min for 15 min activation time. Through one-factor-at-a-time (OFAT) method, the 8.0 mL/min steam flow rate was identified as best flow rate because it led to an activated carbon with higher Brunauer–Emmet–Teller (BET) surface area of 882 m2/g coupled with better adsorption efficiency of 95% and 90% removals for Mn and H2S, respectively. This high uptake efficiency is due to, amongst other factors, improved better pore architecture. Moreover, extensive physicochemical characterization of the PAC in terms of, but not limited to Fourier Transform Infra-red (FTIR) spectroscopy, Scanning Electron Microscopy (SEM), particle size and distribution analysis were carried out, and there were indications of characteristic improvements our previous investigation. Optimization studies revealed that 5 g PAC/100 mL BPOME, 200 rpm agitation speed and 60 minutes of sorption time brought about the best removal of both Mn and H2S. Equilibrium studies also revealed that Langmuir isotherm model fitted better with the adsorption data in describing the adsorption behavior.

Three mixture of catering waste was pyrolyzed at 650, 725 and 900 °C and the solid residue (coke) was examined for powdered activated carbon production. For this, the carbon content, iodine number, particle size distribution and scanning electron microscopic images were analysed. Based on the carbon content, these cokes are suitable for activated carbon production, which were 60-85 wt.% (depending on the base material and pyrolysis temperature). The studied cokes showed slightly porous structure with smooth surfaces. Because of this, the iodine number was mostly small (13-30). Based on the grinding experiments, 10 minutes of grinding was found to be optimal. After this grinding time, the reached iodine number of powdered activated carbon was 350-610.

This study involves synthesis of two types of the activated carbon from Iraqi zahdy date palm seeds and Iraqi khestawy date palm seeds. These two types of activated carbon were synthesized using H3PO4 as an activator. Synthesis processes of activated carbon were performed by chemical activation method. The activity of these materials as adsorbents was investigated by following removal of reactive yellow dye 145 (RYD-145). Kinetics of adsorption and removal of reactive yellow as a model of the polluted dyes were investigated from batch tests. Different reaction parameters and conditions were investigated, such as amount of loading of activated carbon and duration of the adsorption process. The point zero charges of the synthesized samples were also calculated. It was found that Iraqi zahdy date palm seeds based activated carbon was more efficient than Iraqi khestawy date palm seeds in dye removal under the same reaction conditions.

SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three out of six sampled trees contained measurable amounts of mineral inclusions which were quantified using image analysis. Based on the variations of mineral content observed between trees and within and between annual rings of the same tree, some hypotheses were formulated concerning the factors involved in the formation of inorganic deposits in oak wood. Their occurrence varies depending on the mineral concerned and seems to be controlled largely by a tree effect. The time of formation appears to coincide with a shifting of the oak wood's functions as a result of heartwood formation processes (inter-annual scale) or changes in leaf phenology and climate (intra-annual scale). In addition, the technical consequences of their presence as well as their effects on wood density measurements through microdensitometry are discussed.

Benzyl alcohol oxidation by molecular oxygen using solid manganese oxide as a catalyst and n-heptane as the solvent was studied in the liquid phase. The catalyst was synthesized by a simple mechanochemical process at room temperature and was characterized by different physical methods. The catalyst was highly active and 100% selective for benzyl alcohol conversion to benzaldehyde. The solid catalyst can be recovered from the reaction mixture by simple filtration and can be re-used. We found n-heptane to be an excellent solvent for the oxidation reaction, and that the catalyst did not leach into solution.