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Nowadays concerns regarding fossil fuel resources depletion as well as environmental issues attributed to CO2 accumulation in the atmosphere force communities toward utilizing biomass as a substitute fuel source which is environmentally secure and renewable. Pyrolysis bio-oil from biomass comprises varieties of undesirable oxygenate and heavy compounds and has to be treated before feeding to bio-refineries. Catalytic biomass pyrolysis vapor upgrading presently seems to be a techno-economical process toward production of fuel-like components. However, selection of stable and productive catalyst(s) to yield desirable chemicals with low coke formation is a great challenge. The three most important classes of catalysts comprising microporous zeolites, mesoporous catalysts and metal based catalysts are utilized for vapor phase bio-oil upgrading. This study offers a comprehensive review on catalytic biomass pyrolysis vapor upgrading by emphasizing particularly on catalyst types and properties, coke formation over catalysts and catalytic process conditions.

International audience; Today, the price of glycerol has dramatically dropped due to its oversupply from biodiesel production as well as oleochemical industry. Thus, it is essential to develop processes to transform bioglycerol into commercially valued products which is important to ensure sustainability in the biodiesel and oleochemical industries. One possibility is to transform it in propanediols, which have numerous applications such as food additives, raw material in pharmaceutical and cosmetic industries. In this paper, methods of conversion of glycerol into 1,3-propanediol are reviewed and discussed in detail.

The inevitably low value of bioglycerol has led to extensive investigations on glycerol conversion to value-added chemicals. This review focuses on the industrially important catalytic esterification of glycerol with oleic acid attributable to its high commercial value. Conventionally, the catalytic esterification of long-chain fatty acids with glycerol is operated at extreme operating conditions (homogeneous acid catalyst, high temperature, and intensive vacuum system). Because of these, rational design of reliable solid acid catalysts for water-sensitive esterification process is needed in order to enhance existing process condition. Up until now, the recent development of efficient and environmentally benign catalysts for esterification of glycerol with oleic acid has not been captured in any review. Therefore, the current literatures of catalytic esterification of glycerol with oleic acid and their affecting parameters are primarily discussed in this review. This review has shown that the hydrophobicity surface of catalysts is vital to boost up the reaction activity of polar glycerol and immiscible phase behavior of reactants. In addition, the concluding remarks for catalyst selectivity of glycerol monooleate, dioleate, and trioleate synthesis are presented. The paper also highlights the research gaps and future direction of this important research field.

Wastewater-based microbial fuel cell is a promising green technology that can potentially be used to treat recalcitrant wastewater such as textile wastewater through in situ Fenton oxidation while generating net positive energy. One of the main features of this technology is the use of membranes for isolating the cathode chamber for in situ H2O2 production (thus in situ Fenton oxidation). The challenges in this technology include membrane fouling and resistance, pH splitting, oxygen diffusion, substrate crossovers, effect of Fenton's reagents and high cost of commercially available membranes. Therefore, this paper critically analyzes each challenge in detail to access their direct or indirect effects on the overall performance. Exploration of new materials and modifications of existing materials has produced cost-efficient and reliable membranes. However, their application in in situ Fenton oxidation has not been demonstrated. It is concluded that the use of membranes with high hydrophilicity, small pore size and materials enriched with sulfonated groups is suitable for in situ H2O2 production in the cathode chamber. Moreover, use of cleaning agents such as H2O2 or H2SO4 recovers the membrane performance for in situ H2O2 production. Thus, it offers a green technology because in situ H2O2 can be used for membrane cleaning and energy produced can be used for aeration of the cathode chamber.

Highly reactive phenolic compounds of pyrolysis bio-oil are recognized as a major cause of the unpleasant properties of this biofuel. Catalytic hydrodeoxygenation of phenolic compounds of bio-oil is an efficient technique for improving the quality of bio-oil. Dual function catalysts consisting of metal and acid sites are usually used for transformation of bio-oil/bio-oil model compounds to high value hydrocarbons. Metal and acid sites are generally involved in hydrogenation/hydrodeoxygenation and dehydration/hydrocracking/dealkylation/alkylation reaction mechanisms, respectively. In this work, the product selectivity of hydrogenation of phenol, o-cresol, m-cresol and guaiacol was investigated over combined catalysts of Pd/C with zeolite solid acids of HZSM-5 (Si/Al of 30, 50 and 80) and HY (Si/Al of 30 and 60). Catalytic activity and product distribution in the hydrogenation process were affected by the density and strength of zeolite acid sites. HZSM-5 (30) with only weak acid sites showed lower cyclohexane selectivity compared with HZSM-5 (50) and HZSM-5 (80) which had both weak and strong acid sites. HY (30) and HY (60) containing only strong acid sites favored production of cycloketones.

The efficiency of phenol degradation via Fenton reaction using mixture of heterogeneous goethite catalyst with homogeneous ferrous ion was analyzed as a function of three independent variables, initial concentration of phenol (60 to 100 mg /L), weight ratio of initial concentration of phenol to that of H2O2 (1: 6 to 1: 14) and, weight ratio of initial concentration of goethite catalyst to that of H2O2 (1: 0.3 to 1: 0.7). More than 90 % of phenol removal and more than 40% of TOC removal were achieved within 60 minutes of reaction. Two separate models were developed using artificial neural networks to predict degradation percentage by a combination of Fe3+ and Fe2+ catalyst. Five operational parameters were employed as inputs while phenol degradation and TOC removal were considered as outputs of the developed models. Satisfactory agreement was observed between testing data and the predicted values (R2 Phenol = 0.9214 and R2TOC= 0.9082).

Advanced oxidation processes (AOPs) are commonly used for treating recalcitrant wastewater with varying degree of efficiency, depending on several operating parameters. In this review, a comparative study among selected AOPs integrated with ultraviolet (UV) (UV/Fenton, UV/H2O2, UV/O-3, UV/TiO2, UV/persulfate, UV/H2O2/O-3, and UV/TiO2/H2O2) was conducted. The cost implication, changes in kinetics, changes in reaction rates, and effects of various parameters such as type of contaminants, pH, catalyst loading concentration of oxidants, and type of UV light are explained and concluded in this paper. From this review, it is concluded that UV-integrated AOPs are efficient for wastewater treatment. However, a few aspects must be considered including process scale-up, kinetics of combined processes, reactor configuration, modeling of a system, and optimization of operating parameters to enhance the process efficiency.

Zeolites are the most common catalysts used for atmospheric deoxygenation of biomass pyrolysis derived feedstocks. The catalytic performance of the zeolite and the yield of deoxygenation greatly depend on the nature of the feedstock. Lignin is the most difficult part of biomass to be deoxygenated and lignin derived phenolic compounds cause rapid deactivation of zeolites. The main purpose of this research was to study the origin of zeolite deactivation in atmospheric deoxygenation of phenolic compounds. Phenol and m-cresol were selected as model compounds for lignin. In order to investigate their effect on zeolite deactivation, catalytic conversion of a mixture of methanol with m-cresol or phenol and a mixture of m-cresol with phenol were carried out over HBeta and Fe/HBeta, respectively. Co-feeding phenol or m-cresol with methanol caused high deactivation of HBeta and significant reduction in the aromatics yield. Meanwhile, these phenols had low reactivity over HBeta. Catalytic performance was enhanced by iron impregnation on zeolite, and Fe/HBeta could considerably convert m-cresol into aromatic hydrocarbons through hydrogenolysis. However, this catalyst was not efficient for deoxygenation of phenol. Strong adsorption of phenol molecules on zeolite acid sites resulting in high formation of coke was the main source of zeolite deactivation which was attenuated by an increase in reaction temperature.

The carbon modified silica adsorbents were prepared by synthesizing and modifying zeolite Y type with activated carbon. This paper reports on effects of activated carbon loadings on the methane and nitrogen adsorption, structure and properties of carbon modified zeolite Y. With the increase in activated carbon loadings, the surface area, pore size and pore volume of the activated carbon loaded zeolite Y adsorbent decreased. The intensity of the diffraction patterns of zeolite Y decreased after the activated carbon was loaded. With increasing activated carbon loadings, the intensity of diffraction peaks decreased. Adsorption capacity of nitrogen (N2) was smaller than adsorption capacity of methane (CH4) by using activated carbon modified silica. When activated carbon loadings 30% wt.%, adsorption capacity of methane and nitrogen was 12.9317 wt.% and 12.6115 wt.%, these were caused by difference in molecular weight. The molecular weight of nitrogen is bigger than molecular weight of methane.

A generally applicable stoichiometric and kinetic model was developed for the polymerization of dimer fatty acids with ethylenediamine in the presence of phosphoric acid as catalyst. Rate equation used is based on second order and the temperatures are between 405 and 475 K with mixing rate of 75 rpm. The parameters of the rate equations are determined using nonlinear regression analysis. Comparison of the model predictions with the experimental data show that the approach is useful in predicting the polymerization kinetic. Equilibrium constant changes from 2.432 to 17.765. Frequency factor and activation energy for forward rate constant are 362306102.681 kg mol −1 min −1 and 83.24 kJ mol −1 , respectively. The equilibrium constant is independent of temperature with frequency factor and activation energy values of 17317.97 and 28.65 kJ mol −1 , respectively.

A generally applicable stoichiometric and kinetic model was developed for the polymerization of dimer fatty acids with ethylenediamine. The rate equations were second-order before 90% conversion and were used between 405 and 475 K. The parameters of the rate equations were determined with nonlinear regression analysis. A comparison of the model predictions and the experimental data showed that the approach was useful in predicting the polymerization kinetics. The equilibrium constant changed from 3.175 to 7.311. The frequency factor and activation energy for the forward rate constant before 90% conversion were 2,716,894 kg mol−1 min−1 and 66.7 kJ mol−1, respectively. The equilibrium constant was independent of the temperature at frequency factor and activation energy values of 74.4 and 9.7 kJ mol−1, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2504–2513, 2004

A series of experiments were conducted to investigate the effect of activation temperature on pore development of activated carbon produced from palm shell. Activation of the samples was carried out at 800, 850 and 900 °C for different durations ranging from 10 to 180 min. The samples were characterized using N2 adsorption for evaluation of micropores and the mercury intrusion technique for mesopore and macropore analysis. Within the range of activation temperatures studied, high burn-off products derived from high activation temperatures tend to have larger micropore development. However, an increase in the activation temperature has no remarkable effect on mesopore and macropore development. © 2002 Society of Chemical Industry

In this study, activated carbons (ACs) wereprepared from tea leaves by using a two-stage self-generated atmosphere method. The process was done by semi-carbonizing the precursor at 300 °C for 1 h, followed by the impregnation of the resulting char at 85 °C for 4 h and finally activation at 500 °C for 2 h. The semi-carbonised samples were impregnated with different ratios of zinc chloride (ZnCl2) and their physicochemical effect was studied. The prepared ACs underwent several aspects of both, chemical and physical characterizations, such as the percentage of yield, moisture content, ash content, pH, porosity, adsorption capacity of 2,4-dichlorophenol (2,4-DCP), surface area, porosity, morphology and surface chemistry studies. It was found that sample AC2, with an impregnation ratio of 2:1 was the best AC produced in this study. The maximum Brunauer, Emmett and Teller surface area of AC2 was found to be 695 m2/g. Langmuir, Freundlich and Temkin isotherm models were used to examine the experimental isotherms while the kinetic data was analyzed using the pseudo-first-order, pseudo-second-order and intraparticle diffusion kinetic models. The 2,4-DCP adsorption isotherm results complied well to the Langmuir isotherm for the equilibrium data while the adsorption kinetic data fitted well to the pseudo-second order model, indicating that chemisorption by valency forces via the sharing (covalent bond) or exchanging of electrons between the AC and the 2,4-DCP molecules were mainly responsible for the adsorption process. From these findings, it is concluded that tea leaves can be used as a low cost precursor for the removal of 2,4-DCP in aqueous medium.

In this study, different parameters for the preparation of activated carbon were investigated for their yield and CO2 capture capabilities. The activated carbon was prepared from Oil Palm Empty Fruit Bunch (OPEFB) via a 2-step physical activation process. The OPEFB was pyrolyzed under inert conditions at 500 °C and activated via CO2. A 2-factorial design was employed and the effects of activation temperature, activation dwell time and gas flow rate on yield and CO2 capture capabilities were compared and studied. The yield obtained ranged from between 20 – 26, whereby the temperature was determined to be the most significant factor in influencing CO2 uptake. The CO2 capture capacity was determined using Temperature Programmed Desorption (TPD) technique. The CO2 uptake of EFB activated carbon achieved was between 1.85 – 2.09 mmol/g. TPD analysis has shown that the surface of AC were of basic nature. AC was found to be able to withhold the CO2 up to 663°C before maximum desorption occurs. The surface area and pore size of OPEFB obtained from BET analysis is 2.17 m2 g-1 and 0.01 cm3 g-1. After activation, both surface area and pore size increased with a maximum observed surface area and pore size of 548.07 m2 g-1 and 0.26 cm3 g-1. Surface morphology, functional groups, pore size and surface area were analyzed using SEM, FT-IR, TPD and BET.

Polytetrafluoroethylene (PTFE) is among the most common binders used in the fabrication of an electrode, which is used for various electrochemical applications such as desalination, water purification, and wastewater treatment. In this study, the amount of the binder was varied at 10, 20, 30, and 40 wt% of the total mass of palm shell activated carbon (PSAC). The PSAC was used as the active material and carbon black was used as the conductive agent. The effect of different amounts of binder was observed by evaluating the electrochemical characteristics of the electrode through cyclic voltammetry (CV) and potentio electrochemical spectroscopy (PEIS). The CV analysis was employed to determine the geometric area normalised electrode double layer capacitance, CE , and the electrode reaction of the prepared electrode. Meanwhile, the common redox probe, ferro/ferricyanide in 0.5 M NaCl, was employed to estimate the electron transfer resistance through PEIS. The electrochemical characterisation proved that the optimum amount of PTFE was 20 wt% for the 4:1 ratio of active material to conductive agent. On increasing the amount of the binder to 30 wt% and 40 wt%, the estimated value of CE decreased and remained almost equivalent. Adding more than 30 wt% of binder resulted in pore blockage and reduced the available active site on the PSAC electrode. In addition, the electron transfer resistance of the prepared electrode was found to be in the range of 4-5 Ωcm2.

The present situation reveals the dependence on fossil fuels, which is seriously accountable for two major impediments: (i) global warming due to increasing atmospheric carbon dioxide (CO2) and (ii) the alarming consumption of energy assets. The reduction of green CO2 in terms of producing solar fuels would be an expedient accomplishment to resolve both problems, simultaneously. The review classifies different categories of photocatalysts applied in foregoing photocatalytic CO2 conversion processes with detailed information concerning operating conditions, preparation techniques and physical properties of catalysts, radiation sources, and selectivity. The categories are concentrated on metal oxides, sulfides, phosphides, and p-type and nonmetal oxide semiconductors. In addition, their modification by doping co-metals, noble metals, transition metals and non-metals for visible light response is emphasized. Besides, for harnessing solar fuel, the recent prospect and advancement of novel sensitized catalysts by dye elements, phthalocyanines and quantum dots (QDs) are also highlighted in this review. This technology needs more efficient solar active catalysts to increase production rates as well as selectivity. The recent scenario indicates that massive prospects and opportunities still exist in this area for further investigation on catalyst selection.

This study investigates the effects of different parameters such as biomass composition, moisture content, particle size, heating rate, temperature, inert gas, reactor system, and catalyst on the production of hydrogen gas (HG) and other gases (OGs) such as CO2, CO, CH4, C2H6, and so on. The reformation of OGs into H2 via the shift reaction significantly increases the total HG formation during biomass pyrolysis. Biomass raw material is capable of producing different proportions of HG at different temperatures because the raw material structure varies from one material to another. It is very puzzling that the formation of HG and total gas (TG) could either increase or decrease with moisture and this result varied between researchers. Smaller particles are more suitable than larger ones in terms of HG and TG formation. Additionally, longer residence times and higher temperatures favor good HG yield while the heating rate is a function of heat flux and particle size of biomass fuel is supposed to increase the pyrolytic gases and properties. Moreover, the heating rate would play a smaller role on the process when the system is introduced with inert gas and if the purpose is to maximize the production of TGs, secondary reactions such as thermal cracking, re-polymerization, and re-condensation should be maximized because the inert gas removes the volatiles from the pyrolysis environment. Therefore, the ultimate product of biomass conversion is dependent on the reactor design and type of feedstock in the presence of appropriate catalysts.

The mineralisation kinetics of petroleum refinery effluent (PRE) by Fenton oxidation were evaluated. Within the ambit of the experimental data generated, first-order kinetic model (FKM), generalised lumped kinetic model (GLKM), and generalized kinetic model (GKM) were tested. The obtained apparent kinetic rate constants for the initial oxidation step ( ), their final oxidation step ( ), and the direct conversion to endproducts step ( ) were 10.12, 3.78, and 0.24 min−1 for GKM; 0.98, 0.98, and nil min−1 for GLKM; and nil, nil, and >0.005 min−1 for FKM. The findings showed that GKM is superior in estimating the mineralization kinetics.

Simulation of fluidized bed reactor (FBR) was accomplished for treating wastewater using Fenton reaction, which is an advanced oxidation process (AOP). The simulation was performed to determine characteristics of FBR performance, concentration profile of the contaminants, and various prominent hydrodynamic properties (e.g., Reynolds number, velocity, and pressure) in the reactor. Simulation was implemented for 2.8 L working volume using hydrodynamic correlations, continuous equation, and simplified kinetic information for phenols degradation as a model. The simulation shows that, by using Fe3+and Fe2+mixtures as catalyst, TOC degradation up to 45% was achieved for contaminant range of 40–90 mg/L within 60 min. The concentration profiles and hydrodynamic characteristics were also generated. A subsequent scale-up study was also conducted using similitude method. The analysis shows that up to 10 L working volume, the models developed are applicable. The study proves that, using appropriate modeling and simulation, data can be predicted for designing and operating FBR for wastewater treatment.

Several batches of chars were prepared from palm shell by carbonization in a flow of nitrogen using a fixed-bed reactor. Palm shell was carbonized at temperatures of 500, 600, 700, 800 and 900 °C for 1 h to study the effects of carbonization temperature on char yield and its porosity. The prepared chars were characterized for the micropore volume using CO2 adsorption while the meso- and macropore volumes were analyzed using a mercury porosimeter. The char yield was around 25% and is comparable with yields reported from other lignocellulosic materials. The results show that carbonization temperature has a significant effect on the micro- and mesopore volumes. However, it has negligible effect on the macropore volume. © 2001 Society of Chemical Industry

A series of experiments have been conducted to study the effects of carbonization temperature on pore development in palm shell activated carbon. Activation of char prepared at 500, 800 and 900°C was performed at 820°C in a fluidized bed reactor. Activated carbon prepared from high temperature char had a significant amount of micropore volume. For all carbonization temperatures investigated, both micropore and macropore volumes showed maximum values at intermediate carbon burn-off. Only a small amount of mesopore was developed in the initial stage of activation. However, as the level of burn-off increased, a rapid development in mesopore was observed. No clear pattern was demonstrated on the effects of carbonization temperature on the development of mesopore and macropore volumes.

Activated carbons (ACs) prepared from apple pulp and apple peel with phosphoric acid as an activation agent under microwave radiation were investigated. The effects of microwave radiation power and time on the adsorption capacities of the ACs were studied. The optimum AC preparation condition was identified by comparing the MB adsorption capacities of the produced ACs. The obtained results show that the microwave radiation power and time had strong effects on the adsorption capacities. Relative to conventional heating methods, microwave-prepared ACs showed higher BET surface areas and mesopore volumes after a shorter activation time due to differences in the type of heat transfer between these two methods. The N2 adsorption isotherms at −196°C and SEM and FTIR results were used to characterize the properties of the prepared ACs. The N2 adsorption results revealed BET surface areas of 1552 m2/g and 1103 m2/g for apple-peel and apple-pulp-based AC, respectively.

Production of hydrogen has been widely practiced to produce a CO2-neutral green fuel that can substitute for fossil fuel. One of the alternative ways in producing such fuel is to utilize biomass by the hydrolysis process. In this study the effects of reaction times (10 to 70 min), reaction temperatures (180 to 260 °C ), and biomass to water mass ratio (1:1 to 1:9) were evaluated relative to the hydrolysis of palm shell particles in a low temperature (below 300 °C) hydrolysis process. Palm shell biomass was hydrolyzed in distilled water, and the gaseous products (bio-syn gas) generated were comprised of H2 and CO2, with small amounts of carbon monoxide and methane.

In order to achieve the biodiesel central policy of protecting the environment, replacing petroleum diesel and protecting and/or creating jobs, a good understanding of biodiesel history is essential. This is because consumers always tend to buy cheap rather than “green“ fuels. Moreover, it is more difficult for a new technology to dislodge one that has reached societal standard. The more the popular technology is used, the more it improves; becoming less expensive due to wider market potentials. Petrodiesel has become the “lifeblood“ of our economy. It would be almost impossible to find a commercial product today that does not consume diesel fuel during its production and distribution [1-4]. Therefore, the aim of this chapter is to provide an overview on the history and motivation, successes, challenges and prospects of biodiesel as source of energy. This will provide a global outlook in making biodiesel an economical and eco-friendly alternative to petroleum diesel.

The mineralisation of remazol black B (RBB) was studied at concentrations ranging from 20-1000 mgL(-1). The work was aimed at investigating the Fenton-like peroxidation of RBB at a concentration typically obtained in Batik cottage industries. Other response parameters were degradation and colour removal efficiencies. The parameters that were measured included total organic carbon (TOC), chemical oxygen demand (COD) as well as absorbance for mineralisation, degradation and colour. To optimise the process, the interaction effects of several controlling variables on the treatment process were examined using dispersion matrix-optimal design and response surface analysis. Four specific variables: initial dye concentration (Dye)o; the molar ratio of oxidant to dye organic strength (H2O2):(COD); the mass ratio of the oxidant to the catalyst (H2O2):(Fe3+) and reaction time (t(r)), were observed. Three reduced empirical models, one for each response, were developed for describing the treatment process. For 20, 510 and 1000 mgL(-1), the optimum %TOC reduction and oxidation times were 44% for 95 min, 52% for 52.5 min and 68% for 10 min corresponding to 67, 81 and 75% COD reduction, respectively. The optimum COD reduction and oxidation times were 89% for 95 min, 91% for 10 min and 84% for 95 min for concentrations of 20, 510 and 1000 mg L(-1), respectively. For all concentrations, total colour removal was achieved. A comparison of the results obtained in this study with literature values for traditional Fenton, photo-Fenton and photo-Fenton-like oxidation indicated that the TOC reduction obtained using the Fenton-like process was satisfactory.

The literature on the use of Fenton oxidation in wastewater treatment has established the method as one of the most effective and suitable methods for recalcitrant wastewater treatment. It is an advanced oxidation process (AOP) that utilises the highly reactive hydroxyl radical (•OH) to aggressively and non-selectively destroy organic contaminants. The Fenton oxidation possesses environmental and economic benefits coupled with effective mineralisation of most wastewater organics. Broadly, the Fenton oxidation encompasses three types of oxidation routes for the production of •OH: (i) through the use of Fenton reagents alone, termed classical Fenton oxidation (CFO), (ii) assisted by means of UV (photo-Fenton), or (iii) electron beams (electro-Fenton). However, this review is limited to CFO, which involves the catalytic decomposition of hydrogen peroxide (H2O2) by suitable transition metals to generate •OH. Despite the many advantages of the CFO process, there are issues related to operational parameters and the final treated wastewater, the most notable being pH modulation, the presence of the catalyst and the cost of the oxidant (H2O2). Furthermore, sludge generation constitutes an apparent drawback to the utilisation of this technology. This paper attempts to review the highlighted limitations and presents researches and advances reported in the literature addressing these issues.

Surface of activated carbon can be functionalized with amine groups to enhance their capacity for CO 2 adsorption. Amine functionalized solid sorbents were prepared by anchoring two types of amine compounds, namely ethylenediamine (EDA) and 2-chloroethylamine hydrochloric acid (CEA) on the surface of palm shell based activated carbon (PSAC). Samples of PSAC were first oxidized by nitric acid using three different available setups to ensure about creation of a significant amount of oxygen containing groups on the surface. At the second stage, the best oxidized sample was modified by anchoring EDA and CEA on the surface to produce a superior CO 2 adsorbent. Several quantitative and qualitative methods were used to characterize the prepared samples: Nitrogen adsorption at 77K, proximate and ultimate analysis and temperature programmed desorption (TPD). Moreover, CO 2 adsorption study was carried out using CO 2 adsorption isothermal profile at 30°C and temperature-programmed (TP) CO 2 adsorption test. All modified samples had a lower surface area than the virgin PSAC. The best modified sample presented an increase of 45% in CO 2 capture capacity at 100°C. On the other hand, on the basis of unit surface area, CO 2 capture capacity of amine modified samples was much higher, compared to the parent sample. Furthermore, the modified samples showed a less dependency of their CO 2 capacity on temperature indicating chemisorption of the adsorbate on the PSAC surface.

The biodegradable oil absorption resin (B-PEHA) was prepared by suspension polymerization, and its preparation was confirmed by Fourier transform infrared analysis. The oil absorption capacities of the prepared B-PEHA were: chloroform 30.88, toluene 19.75, xylene, 18.78, THF 15.96, octane 11.43, hexane 9.5, diesel oil 12.80, and kerosene 13.79 g/g. The biodegradation of the prepared B-PEHA was also investigated by determination of reduced sugar produced after enzymatic hydrolysis, thermogravimetric analysis, and incubation with Aspergillus niger. The biodegradation of B-PEHA was ~18%.

The low-cost activated carbon was prepared from Palm shell an agricultural waste material, by combination of chemical and physical activation with phosphoric acid and CO2, respectively for adsorption of methane. Central composite design (CCD) was applied to study the influence of activation temperature, chemical ratio of phosphoric acid to palm shell and physical activation time on the amount of methane adsorption. A quadratic model was developed for adsorption of methane using Design-Expert software. Physical activation time was found to have the most effect on the methane adsorption capacity of produced activated carbon.

The effects of polyethyleneimine (PEI) impregnation on the Pb(2+) adsorption kinetics of palm shell-activated carbon and pH profile of bulk solution were investigated. Adsorption data were fitted to four established adsorption kinetics models, namely, pseudo-first-order, pseudo-second-order, Elovich equation and intraparticle diffusion. It was found that PEI impregnation at 16.68 and 29.82 wt% PEI/AC increased the Pb(2+) uptake rate while the opposite was observed for PEI impregnation at 4.76 and 8.41 wt% PEI/AC. The increased uptake rates were due to higher concentration of PEI molecules on the surface of clogged pores as well as varying pore volumes. The adsorption kinetics data fitted the pseudo-second-order model better than the pseudo-first-order model, implying chemisorption was the rate-controlling step. The bulk solution pH generally showed an increasing trend from the use of virgin to PEI-impregnated activated carbon.

In this study, the kinetics of adsorption of Pb(II) from aqueous solution onto palm shell-based activated carbon (PSAC) were investigated by employing ion selective electrode (ISE) for real-time Pb(II) and pH monitoring. Usage of ISE was very appropriate for real-time adsorption kinetics data collection as it facilitated recording of adsorption data at very specific and short time intervals as well as provided consistent kinetics data. Parameters studied were initial Pb(II) concentration and agitation speed. It was found that increases in initial Pb(II) concentration and agitation speed resulted in higher initial rate of adsorption. Pseudo first-order, pseudo second-order, Elovich, intraparticle diffusion and liquid film diffusion models were used to fit the adsorption kinetics data. It was suggested that chemisorption was the rate-controlling step for adsorption of Pb(II) onto PSAC since the adsorption kinetics data fitted both the pseudo second-order and Elovich models well.

Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst was developed to provide an alternative solution for homogeneous Fenton oxidation. Iron Zeolite Socony Mobile-5 (Fe-ZSM-5) was synthesized using a new two-step process. Next, the catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis and tested against a model wastewater containing the azo dye Acid Blue 113. Results showed that the loading of iron particles reduced the surface area of the catalyst from 293.59 to 243.93 m2/g; meanwhile, the average particle size of the loaded material was 12.29 nm. Furthermore, efficiency of the developed catalyst was evaluated by performing heterogeneous Fenton oxidation. Taguchi method was coupled with principal component analysis in order to assess and optimize mineralization efficiency. Experimental results showed that under optimized conditions, over 99.7% degradation and 77% mineralization was obtained, with a 90% reduction in the consumption of the developed catalyst. Furthermore, the developed catalyst was stable and reusable, with less than 2% leaching observed under optimized conditions. Thus, the present study proved that newly developed catalyst has enhanced the oxidation process and reduced the chemicals consumption.

A series of experiments were conducted to compare the pore development in palm-shell and coconut-shell-based activated carbons produced under identical experimental conditions. Carbonization and activation processes were carried out at 850 degrees C using a fluidized bed reactor. Within the range of burn-off studied, at any burn-off, the micropore and mesopore volumes created in palm-shell-based activated carbon were always higher than those of coconut-shell-based activated carbon. On macropore volume, for palm-shell-based activated carbon, the volume increased with increase in burn-off up to 30% and then decreased. However, for coconut-shell-based activated carbon, the change in macropore volume with burn-off was almost negligible but the absolute macropore volume decreased with burn-off.

This study investigates the effects of different parameters such as biomass composition, moisture content, particle size, heating rate, temperature, inert gas, reactor system, and catalyst on the production of hydrogen gas (HG) and other gases (OGs) such as CO2, CO, CH4, C2H6, and so on. The reformation of OGs into H2 via the shift reaction significantly increases the total HG formation during biomass pyrolysis. Biomass raw material is capable of producing different proportions of HG at different temperatures because the raw material structure varies from one material to another. It is very puzzling that the formation of HG and total gas (TG) could either increase or decrease with moisture and this result varied between researchers. Smaller particles are more suitable than larger ones in terms of HG and TG formation. Additionally, longer residence times and higher temperatures favor good HG yield while the heating rate is a function of heat flux and particle size of biomass fuel is supposed to increase the pyrolytic gases and properties. Moreover, the heating rate would play a smaller role on the process when the system is introduced with inert gas and if the purpose is to maximize the production of TGs, secondary reactions such as thermal cracking, re-polymerization, and re-condensation should be maximized because the inert gas removes the volatiles from the pyrolysis environment. Therefore, the ultimate product of biomass conversion is dependent on the reactor design and type of feedstock in the presence of appropriate catalysts.

The present situation reveals the dependence on fossil fuels, which is seriously accountable for two major impediments: (i) global warming due to increasing atmospheric carbon dioxide (CO2) and (ii) the alarming consumption of energy assets. The reduction of green CO2 in terms of producing solar fuels would be an expedient accomplishment to resolve both problems, simultaneously. The review classifies different categories of photocatalysts applied in foregoing photocatalytic CO2 conversion processes with detailed information concerning operating conditions, preparation techniques and physical properties of catalysts, radiation sources, and selectivity. The categories are concentrated on metal oxides, sulfides, phosphides, and p-type and nonmetal oxide semiconductors. In addition, their modification by doping co-metals, noble metals, transition metals and non-metals for visible light response is emphasized. Besides, for harnessing solar fuel, the recent prospect and advancement of novel sensitized catalysts by dye elements, phthalocyanines and quantum dots (QDs) are also highlighted in this review. This technology needs more efficient solar active catalysts to increase production rates as well as selectivity. The recent scenario indicates that massive prospects and opportunities still exist in this area for further investigation on catalyst selection.

As solid oxide fuel cells (SOFCs) are highly nonlinear systems, a single linear controller cannot perform satisfactorily over a wide range of operating conditions of the processes. This work studies multilinear-model predictive control of a tubular SOFC. The objective is to control the fuel cell outlet voltage over a wide range of operating conditions by manipulating inlet fuel pressure (flow rate). A first-principles model of an ammonia fed-tubular solid oxide fuel cell is used for the controller design. The model accounts for diffusion, inherent impedance, transport (momentum, heat and mass transfer), electrochemical reactions, activation and concentration polarizations, and the ammonia decomposition reaction. The servo and regulatory performances of the multimodel predictive controller (MMPC) are compared with those of a single-model predictive controller (SMPC) and a proportional-integral (PI) controller. For small load changes, the MMPC, SMPC, and PI controller all provide zero offset, and the MMPC yields the best closed-loop performance. However, for large load changes, the SMPC and PI controller fail to provide zero offset; under these two controllers the closed-loop system with the large load changes is unstable.