Zinc is one of the hazardous metals commonly found in municipal solid waste incineration (MSWI) ash, and this study reveals the stabilization mechanisms when sintering zinc-laden ash and ceramic precursors as a waste-to-resource strategy. Using ZnO to simulate the zinc-laden ash and sintering with kaolinite and mullite ce-ramic precursors, both zinc aluminate spinel (ZnAl2O4) and willemite (Zn2SiO4) phases were found in the products under the tested thermal conditions. The results also indicate that kaolinite and mullite precursors exhibit different incorporation behavior, and ZnAl2O4 and Zn2SiO4 were found to be competitive as the Zn-hosting phases in the system. A prolonged leaching test was used to evaluate the leachability of potential product phases in the system. The concentrations of zinc in ZnO and Zn2SiO4 leachates were about two orders of magnitude higher than that in ZnAl2O4 leachate, indicating the preference of forming ZnAl2O4 for zinc stabilization. Furthermore, the alumi-num-rich sludge generated from waterworks could be beneficially used as a material resource to stabilize zinc in this study. The X-ray diffraction (XRD) pattern collected from the 1150 °C and 3-h sintered sample shows the suc-cess of incorporating zinc into the ZnAl2O4 spinel structure with waterworks sludge precursor. The formation of ZnAl2O4 indicates a strong potential for employing aluminum- and silicon-based materials to thermally immobilize zinc and achieve the beneficial use of metal-laden MSWI ash.

A novel electrode design for the in situ generation of ozone in the reaction zone of a tubular reactor is described in this work. The ozone generator uses a porous inner electrode tube in the corona discharge assembly, and the ozone generated around the outer periphery of the porous tube diffuses into the tubular reactor and reacts with the contaminants in the fluid that is being treated. A mathematical model that includes absorption and second order reaction in the film is developed to describe ozonation kinetics of a contaminant dye in the tubular reactor. The model describes the experimental data for dye decolorization, oxidation byproducts, dissolved ozone, and ozone gas concentrations well. Model analysis indicates that the fast dye decolorization reaction occurs partly in the liquid film and partly in the bulk fluid. The model can be used in the selection of appropriate gas-liquid contactors for efficient oxidation of contaminants in effluents.

The silk sericin is the main residue in silk production and it is found to be a low cost and efficient biosorbent. In this study, sericin was characterized with various techniques including SEM (scanning electron microscope), XRD, N2 physisorption, FTIR (Fourier transformed infrared spectroscopy) and XPS (X-ray photoelectron spectroscopy). The nitrogen content of sericin was ca. 8.5 mmol•g?1 according to elemental analysis. Dye adsorption by sericin biosorbent was investigated with the acid yellow (AY), methylene blue (MB) and copper (II) phthalocyanine-3,4′4″4′″-tetrasulfonic acid (CuPc) dyes from water. Sericin displayed large capacity for AY and CuPc adsorption with adsorption capacities of respectively 3.1 and 0.35 mmol•g?1, but it did not adsorbed methyl-ene blue dye. This selectivity is due to the basicity of amide groups in sericin biosorbents.

Microbiologically induced corrosion of concrete (MICC) and its protective coatings has a high economic impact on sewer maintenance and rehabilitation. A better understanding of the micro-organisms and the biogenic acids that are generated in the sewer is essential in controlling the corrosion of concrete pipes and protective coatings. The role of succession of micro-organisms growth in the corrosion of concrete and protective coatings was evaluated in this study. Examination of various sewer pipe materials exhibiting various extents of degradation, including concrete, cement based and epoxy based coating revealed the presence of both organic and biogenic sulphuric acids. This reflects the activity of fungi and the thiobacilli strains. Organism growth and metabolism were strongly related to the substrate pH. Fungi were found to grow and metabolise organic acids at pH from 2.0-8.0. Whilst the thiobacilli strains grew and generated sulphuric acids at pH below 3.0. The successive growth of the organisms provides an important bearing in developing improved strategies to better manage sewers.

Electrochemical treatment of distillery spent wash was carried out using different combinations of aluminum and iron electrodes in batch mode of operation. The spent wash was characterized for various parameters as per standard method of analysis and the treatment results were analyzed in terms of chemical oxygen demand (COD) removal efficiency of the spent wash. The experiments were performed to study the effect of operating parameters such as current density, pH of the spent wash, agitation speed, electrolysis time and the distance between the electrodes on the COD removal efficiency of the spent wash. It was observed that aluminum electrodes were more suitable for treatment of distillery spent wash as compared to iron electrodes. The maximum COD removal efficiency of 81.3% was obtained with Al-Al electrodes at the current density of 0.187 A•cm?2 and pH 3 for an electrolysis time of 2 h.

The feasibility of adsorptive removal of single component organic compound (para-chlorophenol) by Calgon Filtrasorb 400 (F400) carbon was investigated. The Redlich-Peterson equation was found to be the best fit model for describing the equilibrium relationship between the para-chlorophenol adsorption onto F400 carbon. Four adsorption columns with different column geometry and adsorbent particle stratification were used to examine the adsorption kinetics onto F400 carbons. The Bed Depth Service Time (BDST) model was applied and modified to analyse the performance of the columns and the effect of different operating variables. When combining the effects of adsorption efficiency and the associated pressure drop of each type of adsorption columns tested, the carbon stratified tapered column has been determined to be the most efficient engineering option for removing organics, in which the enhancement of the adsorbent bed in terms of longer breakthrough time and higher saturation percentage is the greatest amongst the four types of columns with reasonably small pressure drop across the fixed-bed column.

Interests in charcoal usage have recently been re-ignited because it is believed that charcoal is a much better fuel than wood. The conventional charcoal production consumes a large amount of energy due to the prolonged heating time and cooling time which contribute to the process completing in one to several days. Wood pyrolysis consists of both endothermic and exothermic reactions as well as the decomposition of the different components at different temperature range (hemicellulose: 200-260 °C; cellulose: 240-350 °C and lignin: 280-500 °C). In this study we propose a multistage pyrolysis which is an approach to carry out pyrolysis with multiple heating stages so as to gain certain processing benefits. We propose a three-stage approach which includes rapid stepwise heating stage to a variable target temperatures of 250 °C, 300 °C, 350 °C and 400 °C, slow and gradual heating stage to a final temperature of 400 °C and adiabatic with cooling stage. The multi-stage pyrolysis process can save 30% energy and the processing time by using a first temperature target of 300 °C and heating rate of 5 °C•min?1 to produce a fixed-carbon yield of 25.73% as opposed to the base case with a fixed-carbon yield of 23.18%.

A general research program, focusing on activated carbon fiber cloths (ACFC) and felt for environmental protection was performed. The objectives were multiple: (i) a better understanding of the adsorption mechanisms of these kinds of materials; (ii) the specification and optimization of new processes using these adsorbents; (iii) the modeling of the adsorption of organic pollutants using both the usual and original approaches; (iv) applications of ACFC in industrial processes. The general question was: how can activated carbon fiber cloths and felts be used in air treatment processes for the protection of environment. In order to provide an answer, different approaches were adopted. The materials (ACFC) were characterized in terms of macro structure and internal porosity. Specific stud-ies were performed to get the air flow pattern through the fabrics. Head loss data were generated and modeled as a function of air velocity. The performances of ACF to remove volatile organic compounds (VOCs) were approached with the adsorption isotherms and breakthrough curves in various operating conditions. Regeneration by Joule effect shows a homogenous heating of adsorber modules with rolled or pleated layers. Examples of industrial developments were presented showing an interesting technology for the removal of VOCs, such as dichloromethane, benzene, isopropyl alcohol and toluene, alone or in a complex mixture.

The advantage of using an available and abundant residual biomass, such as lignin, as a raw material for activated carbons is that it provides additional economical interest to the technical studies. In the current investigation, a more complete understanding of adsorption of Cr(VI) from aqueous systems onto H3PO4-acid activated lignin has been achieved via microcolumns, which were operated under various process conditions. The practice of using microcolumn is appropriate for defining the adsorption parameters and for screening a large number of potential adsorbents. The effects of solution pH (2-8), initial metal ion concentration (0.483-1.981 mmol•L?1), flow rate (1.0-3.1 cm3•min?1), ionic strength (0.01-0.30 mmol•L?1) and adsorbent mass (0.11-0.465 g) on Cr(VI) adsorption were studied by assessing the microcolumn breakthrough curve. The microcolumn data were fitted by the Thomas model, the modified Dose model and the BDST model. As expected, the adsorption capacity increased with initial Cr(VI) concentration. High linear flow rates, pH values and ionic strength led to early breakthrough of Cr(VI). The model constants obtained in this study can be used for the design of pilot scale adsorption process.

This study aimed to identify and to analyze characteristics of top-cited articles published in the Web of Science chemical engineering subject category from 1899 to 2011. Articles that have been cited more than 100 times were assessed regarding publication outputs, and distribution of outputs in journals. Five bibliometric indicators were used to evaluate source countries, institution and authors. A new indicator, Y-index, was created to assess quantity and quality of contribution to articles. Results showed that 3828 articles, published between 1931 and 2010, had been cited at least 100 times. Among them 54% published before 1991, and 49% top-cited articles originated from US. The top eight productive institutions were all located in US. The top journals were Journal of Catalysis, AIChE Journal, Chemical Engineering Science and Journal of Membrane Science. Y-index was successfully applied to evaluate publication character of authors, institutions, and countries/regions.

It is well established that hydrogen has the potential to make a significant contribution to the world energy production. In U.S., majority of hydrogen production plants implement steam methane reforming (SMR) for centralized hydrogen production. However, there is a wide lack of agreement on the nascent stage of using hydro-gen as fuel in vehicles industry because of the difficulty in delivery and storage. By performing technological and economic analysis, this work aims to establish the most feasible hydrogen production pathway for automotives in near future. From the evaluation, processes such as thermal cracking of ammonia and centralized hydrogen produc-tion followed by bulk delivery are eliminated while on-site steam reforming of methanol and natural gas are the most technologically feasible options. These two processes are further evaluated by comprehensive economic analysis. The results showed that the steam reforming (SR) of natural gas has a shorter payback time and a higher return on investment (ROI) and internal rate of return (IRR). Sensitivity analysis has also been constructed to evaluate the impact of variables like NG feedstock price, capital of investment and operating capacity factor on the overall production cost of hydrogen. Based on this study, natural gas is prompted to be the most economically and technologically available raw material for short-term hydrogen production before the transition to renewable energy source such as solar energy, biomass and wind power.

In this study, waste tire was used as raw material for the production of activated carbons through pyrolysis. Tire char was first produced by carbonization at 550°C under nitrogen. A two factorial design was used to optimize the production of activated carbon from tire char. The effects of several factors controlling the activation process, such as temperature (850-950 °C), time (2-6 h) and percentage of carbon dioxide (70%-100%) were investigated. The production was described mathematically as a function of these three factors. First order modeling equations were developed for surface area, yield and mesopore volume. It was concluded that the yield, BET surface area and mesopore volume of activated carbon were most sensitive to activation temperature and time while percentage of carbon dioxide in the activation gas was a less significant factor.

This paper reports the effect of several competing anions on arsenate adsorption with maghemite nanoparticles. Sulphate (as SO4), nitrate (as NO3-N), phosphate (as PO4-P) ions and silicate (as SiO2) were studied in dual solution with arsenate. Moreover, the combined effect of ions and other water characteristics were examined with a natural groundwater sample which was spiked with a certain amount of arsenate. Arsenate batch adsorption experiments were carried out with two different kinds of maghemite—a commercially available one and a homemade one using the sol-gel process. Sulphate (≤250 mg•L?1) and nitrate (≤12 mg•L?1) had a negligible effect on the arsenate (0.5 mg•L?1) adsorption at pH 3. However, both phosphate (≤2.9 mg•L?1) and silicate (≤50 mg•L?1) had an adverse impact on arsenate (≤3 mg•L?1) adsorption at pH 7. Phosphate (≤1.5 mg•L?1) showed minimal competition with arsenate (0.5 mg•L?1), while silicate (≤10 mg•L?1) inhibition was insignificant for all studied As(V) concentrations at pH 3. The removal of arsenate from the groundwater sample was as efficient as from laboratory water for 0.5 mg•L?1 As(V) both at pH 3 and pH 7.

In this study, bamboo scaffolding was used to produce activated carbon by carbonization at 600 °C and 900 °C with the purge of nitrogen. The 600 °C char was then further modified chemically by acids and alkalis by reflux for 6 hours. The produced chars were then characterized by nitrogen adsorption isotherm, He pyncometry, pH, elemental analysis and Boehm titration. For most of the chemically modified carbons, the micropore surface areas and volumes have increased compared with the 600 °C char, while the mesopore surface areas and volumes slightly decreased, which may have been due to the dissolving of some of the permeated inorganic matter and oxidizing deposited carbon that blocks the pore openings. For the acidic modified carbons, larger amounts of acidic groups were present in the carbons after being activated by phosphoric acid, phosphoric acid further treated with 2 mol•L?1 nitric acid, and calcium hydroxide. Although carbon treated with 2 mol•L?1 and 5 mol•L?1 nitric acid also produced high acidity, the surface areas and pore volumes were relatively low, due to the destruction of pores by nitric acid oxidation. The reduction of porosity may impair the adsorption capacity.

The objectives of this study are to convert at laboratory scale agricultural residues into activated carbons (AC) with specific properties, to characterize them and to test them in adsorption reactor for tetracycline removal, a common antibiotic. Two new ACs were produced by direct activation with steam from beet pulp (BP-H2O) and peanut hulls (PH-H2O) in environmental friendly conditions. BP-H2O and PH-H2O present carbon content ranged between 78% and 91%, similar BET surface areas (821 and 829 m2•g?1 respectively) and pHPZC values (9.8). Their porosities are different: PH-H2O is mainly microporous (84%) with 0.403 cm3•g?1 of total porous volume, whereas BP-H2O develops a mesoporous volume of 0.361 cm3•g?1 representing 50% of the total porous volume. Two other commercial granular AC carbons (GAC1 and GAC2) were also characterised and used for comparison. The adsorp-tion study is conducted in batch reactors. Two parts can be observed from kinetic decay curves: a very fast concen-tration decrease during the first 12 h, followed by a slow adsorption. An optimal contact time of 120 h is also de-duced from these curves. It is shown as well that adsorption decreases with an increase of pH, indicating that the form preferentially adsorbed is probably the zwitterion form of the tetracycline. From equilibrium isotherms data, two adsorption models have been used: Langmuir and Freundlich. Both of them lead to a very good description of the experimental data. Maximum adsorption capacities deduced from the Langmuir equation follow the sequence: GAC2 (817 mg•g?1)>BP-H2O (288 mg•g?1)>GAC1 (133 mg•g?1)>PH-H2O (28 mg•g?1). In real spring waters spiked with TC (tetracyclines), adsorption isotherms show that the maximum adsorption capacity of BP-H2O is slightly in-creased to 309 mg•g?1 while it is decreased by one third to 550 mg•g?1 in the case of GAC2. This study demon-strates that the production of AC from agricultural residues, at lab-scale, is feasible and leads to genuine activated carbons with different intrinsic properties.

The revolution in information and communication technology has brought huge technical benefits and wealth, but has created a major global problem: the generation of vast amounts of electronic waste, or e-waste through product obsolesce. The challenge in managing e-waste will be in developing sustainable recycling technologies that are able to address the volume and complexity of this waste using cost effective and ecologically sensitive methods. In this study, the capability of microorganism metabolic acids in dissolving the metallic fractions from waste printed circuit boards was examined. Several factors were considered in the examination of the activity of the acids including secondary reactions, solution pH, temperature and the nature of ligands in solutions (or bioacid constituents). The leaching tests were conducted ex-situ, using synthetic organic acids. Leaching was performed for periods of up to 6 h at 70-90 ?C and 1000 r•min?1.

High surface area activated carbons were produced by thermal activation of waste bamboo scaffolding with phosphoric acid. Single component equilibrium dye adsorption was conducted on the carbons produced and compared with a commercially available carbon. Two acid dyes with different molecular sizes, namely Acid Yellow 117 (AY117) and Acid Blue 25 (AB25), were used to evaluate the adsorption capacity of the produced carbons. It was found that the dye with smaller molecular size, AB 25, was readily adsorbed onto the produced carbon, nearly three times higher than a commercially available carbon, while the larger size dye, AY117, showed little adsorption. The experimental data were analyzed using isotherm equations including Langmuir, Freundlich, Tempkin, Toth, Redlich-Peterson and Sips equations. The equilibrium data were then analyzed using five different non-linear error analysis methods.

The analysis on the feedstock pyrolysis characteristic and the impacts of process parameters on pyrolysis outcomes can assist in the designing, operating and optimizing pyrolysis processes. This work aims to utilize both experimental and modelling approaches to perform the analysis on three biomass feedstocks—wood sawdust, bamboo shred and Jatropha Curcas seed cake residue, and to provide insights for the design and operation of pyro-lysis processes. For the experimental part, the study investigated the effect of heating rate, final pyrolysis tempera-ture and sample size on pyrolysis using common thermal analysis techniques. For the modelling part, a transient mathematical model that integrates the feedstock characteristic from the experimental study was used to simulate the pyrolysis progress of selected biomass feedstock particles for reactor scenarios. The model composes of several sub-models that describe pyrolysis kinetic and heat flow, particle heat transfer, particle shrinking and reactor opera-tion. With better understanding of the effects of process conditions and feedstock characteristics on pyrolysis through both experimental and modelling studies, this work discusses on the considerations of and interrelation between feedstock size, pyrolysis energy usage, processing time and product quality for the design and operation of pyrolysis processes.

Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The increased importance of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze drying of aqueous solutions based on publications in the past few decades. The important issues of the process are analyzed.

Due to the high cost of adsorbents and their thermal regeneration in recent years, much research has focused on the search for cheaper adsorbents for treating wastewater from textile industry. The single component adsorption of an acidic dye, Acid Yellow 117, and a basic dye, Methylene Blue, onto several adsorbents—bamboo, waste wood, bamboo char, waste wood char, bamboo activated carbon, wood activated carbon and active carbon F400 were conducted. Based on a Langmuir analysis, the monolayer adsorption capacities were determined. Three of the adsorbents were selected for binary layer adsorption to check the multilayer concept and the potential application for better adsorbent usage. The two cheapest adsorbents, bamboo and wood are compared with the commercial activated carbon F400, and all three systems were successful.

This paper deals with the design of an observer-based nonlinear control for continuous stirred tank reactors (CSTR). A variable structure observer is constructed to estimate the whole process state variables. This observer is basically the conventional Luenberger observer with an additional switching term used to guarantee the robustness against modeling errors. The observer is coupled with a nonlinear controller, designed based on input-output linearization for controlling the reactor temperature. The asymptotical stability of the closed-loop system is shown by the Lyapunov stability theorem. Finally, computer simulations are developed for showing the performance of the proposed approach.

This study is focused on the kinetic characteristics of photocatalytic degradation of gaseous organic compounds on modified titanium dioxide/activated carbon composite photocatalyst (MTA). The MTA, which co-doping with iron (Fe) and nitrogen (N), was synthesized by a sol-gel method, and its photocatalytic performance was investigated under different reaction conditions. The experimental data obtained were tested by the zero, first and second order kinetic model, and the factors affecting the kinetic model were analyzed. It was clearly demonstrated that the experimental data of toluene and acetone on MTA fit quite well with second order kinetic model equation, but the experimental data of formaldehyde fits well with zero order kinetic model equation.

The partial oxidation of methane under periodic operation over Ni/γ-Al2O3 catalyst was investigated in a Pd-membrane reactor. The effects of key parameters such as the inlet composition and the sweeping gas on methane conversion and the hydrogen recovery are numerically established with two periodic input functions. In order to analyze the effect of the inputs modulation, the reaction was performed under low steam to methane ratio at a mod-erate temperature and pressure. It was obtained that to achieve process intensification is to operate the process in a periodic way. The main results show that the periodic input functions can improve the performance of the process compared to the optimal steady state operation. Moreover, there is an optimum amplitude of manipulated inputs leads to a maximum of hydrogen recovery. It is noteworthy that the comparison between the predicted performance via the sinusoidal and the square ways show that the better average performance was obtained with the square way.

The paper presents a 3D numerical simulation of turbulent heat transfer and flow characteristics in con-verging-diverging tubes (CDs) and converging-diverging tubes equipped with twin counter-swirling twisted tapes (CDTs). The effects of Reynolds number (Re 10000-20000), pitch length (P 11.25, 22.5 mm), rib height (e 0.5, 0.8, 1.1 mm), pitch ratio (? 1︰8, 5︰4, 8︰1), gap distance between twin twisted tapes (b 0.5, 4.5, 8.5 mm) and tape number (n 2, 3, 4, 5, 6) on Nusselt number (Nu), friction factor (f) and thermal enhancement factor (η) are investigated under uniform heat flux conditions, using water as working fluid. In order to illustrate the heat transfer and fluid flow mechanisms, flow structures in CDs and CDTs are presented. The obtained results reveal that all geometric parameters have important effects on the thermal performance of CD and CDT, and both CD and CDT show better thermal performance than plain tube at the constant pumping power. It is also found that the increases in the Nusselt number and friction factor for CDT are, respectively, up to 6.3%-35.7% and 1.75-5.3 times of the corresponding bare CD. All CDTs have good thermal performance with η greater than 1 which indicates that the compound heat transfer technique of CDT is commendable for the maximum enhanced heat transfer rate.

Rifapentine, an important antibiotic, was crystallized from methanol solvent in the form of its methanol solvate. The crystal structure of rifapentine methanol solvate belongs to monoclinic, space group P21, with the unit cell parameters of a 1.2278(3) nm, b 1.9768(4) nm, c 1.2473(3) nm, Z 2, and β 112.35(3)°. The parallelepiped morphology was also predicted by Materials Studio simulation program. The influence of intermolecular interaction was taken into account in the attachment energy model. The crystal shape fits the calculated morphology well, which was performed on the potential energy minimized model using a generic DREIDING 2.21 force field and developed minimization protocol with derived partial charges.