Search

Problem statement: Steel making slag from Electric Arc Furnace (EAF) is an abundant byproduct in Malaysia steel making industry. It has potential to be used for heavy metal removal from contaminated water or waste water. Approach: The aim of this study was to investigate the characteristic and behavior of manganese removal by using EAF slag for efficient metal removal. The removal characteristics of manganese were investigated in term of sorption kinetics and isotherm. The batch adsorption kinetics and isotherm studies were carried out at 28[degrees]C and ten grams of EAF slag was added into 1 L manganese solution of various concentrations of 10, 25, 50, 75, 100 and 120 mg [L.sup.-1]. All these different mixtures were stirred and sampled at various desired times and centrifuged. The supernatant solutions were then collected for chemical analysis. Results: It was found that the EAF slag adsorption kinetics can be described well by the pseudo-2nd order kinetic model with fairly high correlation coefficients. The adsorption process obeyed the Langmuir isotherm model and the maximum uptake of the manganese from the solution is 2.31 mg [L.sup.-1][g.sup.-1] of EAF slag used. Conclusion: From the study, it was concluded that the EAF slag can be an efficient adsorbent to remove manganese from both the solution and waste water. Key words: Electric are furnace slag, manganese, sorption kinetics and isotherm, efficient adsorbent, INTRODUCTION Human activities in achieving development have caused environmental pollution over the past few decades. One of the major concern of pollutant is heavy metals as they are non-degradable and [...]

The adsorption of two reactive dyes, Reactive Black 5 and Reactive Red E, onto palm kernel shell-activated carbon (PKSAC) was studied. The effect of the presence of more than one dye in solution on the equilibrium and kinetics of adsorption was investigated. Equilibrium isotherm models were applied to describe the adsorption capacities of single and binary systems. Adsorption of reactive dyes for single system can be represented by the Freundlich and the Redlich-Peterson models. For binary system, the equilibrium was described successfully by the modified extended Freundlich model. Experimental data showed that competitive adsorption for active sites on the carbon surface resulted in a reduction in the overall uptake capacity of the reactive dyes. The rates of adsorption in single system were found to agree well with the pseudosecond-order kinetic model. Finally, the chemical oxygen demand (COD) of the treated reactive dye solutions from single and binary systems showed that a minimum of 4 g/L dosage of PKSAC was needed to reduce the COD to an acceptable level according to the Water Quality Guidelines and the Pollutant Fact Sheets Guidelines. DOI: 10.1061/(ASCE)EE.1943-7870.0000091 CE Database subject headings: Adsorption; Dyes; Chemical oxygen demand; Equilibrium; Activated carbon.

Problem statement: Earlier work on ohmic heating technique focused on viscous food and foods containing solid particles. In this study, the use of ohmic heating on sterilization of guava juice is carried out. Computational fluid dynamics is used to model and simulate the system. Approach: Investigate the buoyancy effect on the CFD simulation of continuous ohmic heating systems of fluid foods. A two-dimensional model describing the flow, temperature and electric field distribution of non-Newtonian power law guava juice fluid in a cylindrical continuous ohmic heating cell was developed. The electrical conductivity, thermo physical and rheological properties of the fluid was temperature dependent. The numerical simulation was carried out using FLUENT 6.1 software package. A user defined functions available in FLUENT 6.1 was employed for the electric field equation. The heating cell used consisted of a cylindrical tube of diameter 0.05 m, height 0.50 m and having three collinear electrodes of 0.02 m width separated by a distance of 0.22 m. The sample was subjected to zero voltage at the top and bottom of electrodes while electrical potential of 90 volts (AC 50-60 Hz) was set at the middle electrode. The inlet velocity is 0.003 m [sec.sup.1] and the temperature is in the range of 30-90[degrees]C. Results: The simulation was carried with and without buoyancy driven force effect. The ohmic heating was successfully simulated using CFD and the results shows that the buoyancy has a strong effect in temperature profiles and flow pattern of the collinear electrodes configuration ohmic heating. A more uniform velocity and temperature profiles were obtained with the buoyancy effect included. Conclusion: For accurate results, the inclusion of buoyancy effect into the CFD simulation is important. Key word: CFD numerical modeling, 2D ohmic heating, Natural convection, guava juice, INTRODUCTION Ohmic heating is a developing technology with considerable potential for the food industry. The main advantages of ohmic processing are the rapid and relatively uniform heating achieved, together with [...]

Significant quantities of steel slag are generated as waste material or byproduct every day from steel industries. Slag is produced from different types of furnaces with different operating conditions. Slag contains Ferrous Oxide, Calcium Oxide, Silica etc. Physical and chemical properties of slag are affected by different methods of slag solidification such as air cooled, steam, and injection of additives. Several material characterization methods, such as X-ray Diffraction (XRD), Scanned Electron Microscopy (SEM) and Inductive Coupled Plasma (ICP-OES) are used to determine elemental composition in the steel slag. Therefore, slags can become one of the promising materials in various applications such as in transportation industry, construction, cement production, waste water and water treatment. The various applications of steel slag indicate that it can be reused and utilized rather than being disposed to the landfill. This paper presents a review of its applications and utilization.

Globally, considerable effort and resources are being channeled toward controlling the rising threat from pollution and other related impacts from man-made activities, which have detrimental effects on human health and the environment. The presence of some associated gases such as nitrogen oxides and sulfur oxides in the flue gas interfering with the carbon capture processes are responsible for acid rain and ground-layer ozone formation. The wet flue gas desulfurization and the selective catalytic reduction technologies are associated with high investment, production of secondary pollution, poor catalyst durability, and high temperature requirements. In response to these limitations, the development of a hybrid environmental catalyst, especially using activated carbon, carbon-coated monolith, and metal oxides, is desirable. For a catalyst to be competitive, it must be cost-effective with enhanced sorption capacity, regenerability, and be safe for disposal. Some of the recent methods for dispersing the metal oxides on the supports and the simultaneous removal of sulfur oxides and nitrogen oxides were enumerated in this review and the possible ways for improvement have been presented. [ABSTRACT FROM AUTHOR]

Slag, a by-product of steelmaking industries, has invaluable potentials for various environmental applications. Slag is generally produced in different types of furnaces working under various operating conditions and contains alumina, calcium oxide, silica and so on. Physical and chemical properties of a typical slag dictate the distinct methods of slag solidification including air cooling, steam introduction and injection of additives. Owing to this uniquely-widespread range of properties, slags are being increasingly considered attractive materials in a broad range of applications. They are widely used in transportation industry, construction, and cement manufacturing as well as wastewater and water treatment. This makes slag an important substitute for natural resources, leading to significant minimization in natural resource utilization. This paper walks through a comprehensive essay of steelmaking slag retained in a wide range of furnaces, their modifications and their applications alike. [ABSTRACT FROM AUTHOR]

Carbon-coated monoliths (CCMs) were chemically modified by sodium hydroxide (NaOH) and ammonia aqueous solution (NH3) in order to enhance phenol adsorption. The adsorptive performance of phenol onto CCM-NaOH and CCM-NH3was comparatively evaluated by batch mode. Experiments were carried out by varying pH, contact time, and initial adsorbate concentration. The optimum molarities for modification were 1.5 M NaOH and 2 M NH3solutions. The basicity groups of modified CCM were 0.198 and 0.339 mmol g−1for CCM-NaOH and CCM-NH3by Boehm titration method, respectively. The presence of basic groups (O–H and NH3) was also confirmed by FT-IR. The studies showed optimum phenol adsorption, at pH 4 for both adsorbents. As compared to unmodified CCM, the CCM-NH3and CCM-NaOH enhanced phenol uptake by 16.5 and 9.7%, respectively. The maximum equilibrium adsorption capacities were 51.29 ± 0.7 mg g−1for CCM-NaOH and 54.45 ± 0.7 mg g−1for CCM-NH3in the range of concentration 50–350 mg L−1. The equilibrium adsorption data for CCM-NaOH and CCM-NH3was fitted to both Langmuir and Freundlich models. Kinetic studies of both modified CCMs showed better applicability of pseudo-second-order kinetics model. The regeneration studies showed a 26% drop in adsorption capacity after four cycles for CCM-NH3. [ABSTRACT FROM PUBLISHER]

Acid Red 57 (AR57) has been successfully removed from aqueous solution by adsorption on our synthesized mesoporous carbon-coated monolith (MCCM). For the first time, a powerful artificial neural network (ANN) model has been developed to predict the removal efficiency of AR57 on MCCM. Three critical parameters in adsorption systems, that is, solution’s initial pH, initial dye concentration, and contact time were incorporated in the ANN model in order to optimize the observed adsorption process. Langmuir and Freundlich adsorption models were then fitted to the adsorption data to estimate the adsorption capacity. It was concluded that Langmuir isotherm was best-fitted to the data showing a maximum monolayer adsorption capacity of 1,162.7 mg/g. The pseudo-first-order and pseudo-second-order kinetic models were subsequently tested to evaluate the kinetics of the adsorption process. It was revealed that the adsorption kinetics could be better represented by the pseudo-second-order model. A comparison was finally drawn between ANN and pseudo-second-order kinetic models. Based on the error analyses and determination of coefficients, ANN was the more appropriate model to describe the studied adsorption process. [ABSTRACT FROM PUBLISHER]

The adsorptive performance of phenol, 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) onto carbon-coated monolith (CCM) was comparatively evaluated by batch mode. Experiments were carried out by varying pH, contact time, initial adsorbate concentration and reaction temperature. Regeneration performance of CCM was also assessed. The studies showed optimum 2,4-DCP adsorption, followed by 4-CP and phenol at pH 5. The adsorption equilibration time for phenol, 4CP, 2 and 4-DCP were 600, 470 and 400 min, respectively. The equilibrium adsorption capacities were increased 13.1–37.6 mg/g for 50–250 mg/L (phenol), 51.9–93.7 mg/g for 250–450 mg/L (4-CP) and 84.3–117.5 mg/g for 400–600 mg/L (2,4-DCP), respectively. The adsorption at different temperatures was monolayer as depicted by linear and non-linear isotherm models. Kinetic studies showed better applicability of pseudo-second-order kinetics model. The adsorption increases with increase in reaction temperature from 30 to 50°C showing endothermic adsorption process. Desorption and regeneration studies showed optimum phenol recovery with ethanol with 12.9% loss in adsorption after four consecutive cycles. [ABSTRACT FROM PUBLISHER]

Wastewater produced from stone industry of Iran causes serious environmental problems associated with slurry disposal. In traditional method, many ponds are required for clarifying. The use of filtration and addition of chemicals enhance the efficiency of operation as well as saving laborer cost. The polymer bridging mechanism is responsible for flocculation of suspended particles. It was found that the increase of rapid mix velocity reduced the residual turbidity substantially except for the dosage of 0.2 mg of polymer. The addition of polymer was able to enhance flocs strength. For higher dosages of polymer, a direct relationship between increasing rapid mix velocity and reduction of turbidity was observed. The values of aggregation rate constant Kapp were calculated to evaluate the effects of rapid mix velocity and dosage of polymer on residual turbidity. The maximum value of Kapp = 7.2 x 10-3 was obtained for the rapid mix velocity 200 rpm and dosage of polymer 1 mg/l. [ABSTRACT FROM AUTHOR]

The oil content of the flesh of mesocarp has direct relationship with color bands red, green and blue. By running intensive experiments, it was found that oil content correlated with the red color band, with a regression value of 0.86. The finding of this study may be useful for determining the ripeness of oil palm for harvesting and for the use in the operation and control of continuous steriliser in palm oil mill. [ABSTRACT FROM AUTHOR]

Chlorine is a liquefied gas, and is stored in large quantities for use in the chemical industry or in water treatment (e.g. the chlorination of swimming-pool water). Chlorine is highly toxic and if released accidentally has the potential to kill or injure people in the vicinity of the storage tank. A geographic information system (GIS) is used to determine the impact of the release of chlorine from a tank in the area surrounding a swimming-pool at the University Putra Malaysia (UPM). Spatial impact is determined using GIS software (GeoMedia Professional 5.1). Spatial analysis and buffering command are performed to locate affected residential areas near the UPM swimming-pool. The findings mean that the affected residential area and its population can be evacuated more quickly and smoothly. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) have the potential to act as a catalyst support in many sciences and engineering fields due to their outstanding properties. The CNT-coated monolith was synthesized over a highly active Ni catalyst using direct liquid injection chemical vapor deposition (CVD). The aim was to study the optimum condition for synthesizing CNT-coated monoliths. The Taguchi method with L9 (34) orthogonal array design was employed to optimize the experimental conditions of CNT-coated monoliths. The design response was the percentage of carbon yield expressed by the signal-to-noise (S/N) value. The parameters including the mass ratio of Ni to citric acid (Ni:CA) (A), the injection rate of carbon source (B), time of reaction (C), and operating temperature (D) were selected at three levels. The results showed that the optimum conditions for CNT-coated monolith were established at A1B2C1D2 and the most influential parameter was D followed by B, C, and A. The ANOVA analysis showed the design was significant with R-squared and standard deviation of the factorial model equal to 0.9982 and 0.22, respectively. A confirmation test was conducted to confirm the optimum condition with the actual values of the average percentage of carbon yield deviated 1.4% from the predicted ones. The CNT-coated monoliths were characterized by various techniques such as field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and Raman spectroscopy. [ABSTRACT FROM AUTHOR]