This work aimed to investigate the adsorption characteristics, both kinetically and thermodynamic... more This work aimed to investigate the adsorption characteristics, both kinetically and thermodynamically, of Cu(II) and Pb(II) removal from aqueous solutions onto mixed-waste activated carbon, as well as to study the competitive behavior found in mixed heavy metal solution systems. This study shows that activated carbon prepared from mixed waste is an effective adsorbent for the removal of Cu(II) and Pb(II) from aqueous solutions, with the aim of detoxifying industrial effluents before their safe disposal onto water surfaces. The adsorption process was characterized in terms of kinetic and thermodynamic studies. In addition, the influence of presence of Cu(II) and Pb(II) in a competitive system was investigated. The results showed that the maximum adsorption capacities were gained at a pH of 6 with a contact time of 180 min, a metal solution concentration of 300 ppm, and an adsorbent dose of 0.3 g/L. The adsorption process was found to follow a pseudo-first-order kinetic model. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo showed that the sorption process was spontaneous and endothermic in nature. A competitive study demonstrated the applicability of mixed-waste activated carbon to adsorb Cu(II) and Pb(II) from a solution of mixed metals. In addition, the adsorption capacity was found to be as effective as other adsorbents reported in the literature. The developed adsorptive removal procedure was applied for treatment of real wastewater samples and showed high removal efficiency.
Activated carbon was prepared by the copyrolysis of mixed solid wastes (biomass, cartons and poly... more Activated carbon was prepared by the copyrolysis of mixed solid wastes (biomass, cartons and polystyrene) at low carbonization temperatures. The effects of carbonization temperature (200°C, 300°C and 400°C) and chemical activation using different concentrations of a ZnCl2 solution (0.0, 0.5, 1.0 and 2 M) on the yield and adsorption capacity of activated carbon were investigated. The results show that the activated carbon yield is significantly dependent on both the carbonization temperature and the ZnCl2 concentration. The yield increased as the ZnCl2 concentration increased from 0.0 to 2 M and decreased as the carbonization temperature increased from 200°C to 400°C. In conclusion, treating solid wastes with a low carbonization temperature (200°C) followed by chemical activation with 2 M ZnCl2 yielded AC with a high adsorption efficiency.
Environmental science and pollution research international, Jan 4, 2015
Activated carbon was prepared from date pits via chemical activation with H3PO4. The effects of a... more Activated carbon was prepared from date pits via chemical activation with H3PO4. The effects of activating agent concentration and activation temperature on the yield and surface area were studied. The optimal activated carbon was prepared at 450 °C using 55 % H3PO4. The prepared activated carbon was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer, Emmett, and Teller (BET) surface area. The prepared date pit-based activated carbon (DAC) was used for the removal of bromate (BrO3 (-)). The concentration of BrO3 (-) was determined by ultra-performance liquid chromatography-mass tandem spectrometry (UPLC-MS/MS). The experimental equilibrium data for BrO3 (-) adsorption onto DAC was well fitted to the Langmuir isotherm model and showed maximum monolayer adsorption capacity of 25.64 mg g(-1). The adsorption kinetics of BrO3 (-) adsorption was very well represented by the pseudo-first-orde...
Wastes must be managed properly to avoid negative impacts that may result. Open burning of waste ... more Wastes must be managed properly to avoid negative impacts that may result. Open burning of waste causes air pollution which is particularly hazardous. Flies, mosquitoes and rats are major problems in poorly managed surroundings. Uncollected wastes often cause unsanitary conditions and hinder the efforts to keep streets and open spaces in a clean and attractive condition. During final disposal methane is generated, it is much more effective than carbon dioxide as a greenhouse gas, leading to climate change. Therefore, this study describes the possible valorization of two waste streams into activated carbon (AC) with added value due to copyrolysis. High efficiency activated carbon was prepared by the copyrolysis of palm stem waste and lubricating oil waste. The effects of the lubricating oil waste to palm stem ratio and the carbonization temperature on the yield and adsorption capacity of the activated carbon were investigated. The results indicated that the carbon yield depended strongly on both the carbonization temperature and the lubricating oil to palm stem ratio. The efficiency of the adsorption of methylene blue (MB) onto the prepared carbons increased when the lubricating oil to palm stem ratio increased due to synergistic effect. The effects of pH, contact time, and the initial adsorbate concentration on the adsorption of methylene blue were investigated. The maximum adsorption capacity (128.89 mg/g) of MB occurred at pH 8.0.
We describe a comparative study of the concentration of different metals (e.g., Cd, Pb, As, Ni, C... more We describe a comparative study of the concentration of different metals (e.g., Cd, Pb, As, Ni, Cu, Zn, Mn, and Cr) in various parts of wheat plants (e.g., roots, stem, leaves and seeds) collected at several locations in Khyber Pukhtoon Khaw, Pakistan. The wheat crop in these areas was irrigated using different irrigation sources, including rain, tube well, river, and canal. In wheat samples, the concentration of metals was analyzed using an atomic absorption spectrophotometer. Among the various parts of the plant, the roots had the highest levels of heavy metals, followed by the vegetative parts. By comparison, the seeds and grains had the lowest levels of heavy metals. The levels of heavy metals in all of the studied areas were not significantly localized to any particular area. The general order for the accumulation of studied metals in wheat was found to be Mn > Zn > Cu > Ni > Cr > As > Pb > Cd.
Environmental Science and Pollution Research, 2012
(2012). Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cos... more (2012). Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cost adsorbent developed from peanut shell activated with phosphoric acid. Environ Sci Pollut Res.
Numerous studies have been performed on the conversion of individual types of waste into activate... more Numerous studies have been performed on the conversion of individual types of waste into activated carbon (AC). However, this study focused on the evaluation of the simultaneous conversion of different types of wastes (palm, paper, and plastic wastes) into AC via copyrolysis. The tartrazine adsorption capacity onto the produced AC was optimized. The results showed that the carbon content of the AC improved as the calcium hydroxide concentration varied from 0.0 to 2.0 mol L À1. In addition, the volatile matter and ash content were reduced as the concentration of calcium hydroxide was increased from 0.0 to 2.0 mol L À1. The tartrazine adsorption capacity of the prepared AC samples increased as the calcium hydroxide concentration increased from 0.5 to 2 mol L À1 at a carbonization temperature of 400°C for 2 h and a final activation temperature of 500°C for 1 h. Effective adsorption occurred at pH 2. The maximum adsorption capacity (74.9 mg g À1) was obtained with a contact time of 300 min and an initial tartrazine concentration of 150 ppm. The adsorption kinetics of tartrazine were modeled with pseudo-first order, pseudo-second order, and intraparticle diffusion models, which revealed that the tartrazine adsorption onto the AC showed a best fit with the pseudo-second order kinetic model. The thermodynamic parameters DG 0 , DH 0 , and DS 0 indicated that the adsorption of tartrazine onto the AC was spontaneous and endothermic. The values of DG 0 were between À1.3 and À2.3 kJ mol À1 , and the DH 0 and DS 0 values, in the temperature range of 25-50°C, were 9.12 kJ mol À1 and 35.5 J mol À1 K À1 , respectively. In general, the thermodynamic parameters indicate that the adsorption is spontaneous and endothermic.
Maintenance of normal endothelial function is critical to various aspects of blood vessel functio... more Maintenance of normal endothelial function is critical to various aspects of blood vessel function, but its regulation is poorly understood. In this study, we show that disruption of baseline fibroblast growth factor (FGF) signaling to the endothelium leads to a dramatic reduction in let-7 miRNA levels that, in turn, increases expression of transforming growth factor (TGF)-b ligands and receptors and activation of TGF-b signaling, leading to endothelial-to-mesenchymal transition (Endo-MT). We also find that Endo-MT is an important driver of neointima formation in a murine transplant arteriopathy model and in rejection of human transplant lesions. The decline in endothelial FGF signaling input is due to the appearance of an FGF resistance state that is characterized by inflammation-dependent reduction in expression and activation of key components of the FGF signaling cascade. These results establish FGF signaling as a critical factor in maintenance of endothelial homeostasis and point to an unexpected role of Endo-MT in vascular pathology.
This work aimed to investigate the adsorption characteristics, both kinetically and thermodynamic... more This work aimed to investigate the adsorption characteristics, both kinetically and thermodynamically, of Cu(II) and Pb(II) removal from aqueous solutions onto mixed-waste activated carbon, as well as to study the competitive behavior found in mixed heavy metal solution systems. This study shows that activated carbon prepared from mixed waste is an effective adsorbent for the removal of Cu(II) and Pb(II) from aqueous solutions, with the aim of detoxifying industrial effluents before their safe disposal onto water surfaces. The adsorption process was characterized in terms of kinetic and thermodynamic studies. In addition, the influence of presence of Cu(II) and Pb(II) in a competitive system was investigated. The results showed that the maximum adsorption capacities were gained at a pH of 6 with a contact time of 180 min, a metal solution concentration of 300 ppm, and an adsorbent dose of 0.3 g/L. The adsorption process was found to follow a pseudo-first-order kinetic model. Thermodynamic parameters such as ΔGo, ΔHo, and ΔSo showed that the sorption process was spontaneous and endothermic in nature. A competitive study demonstrated the applicability of mixed-waste activated carbon to adsorb Cu(II) and Pb(II) from a solution of mixed metals. In addition, the adsorption capacity was found to be as effective as other adsorbents reported in the literature. The developed adsorptive removal procedure was applied for treatment of real wastewater samples and showed high removal efficiency.
Activated carbon was prepared by the copyrolysis of mixed solid wastes (biomass, cartons and poly... more Activated carbon was prepared by the copyrolysis of mixed solid wastes (biomass, cartons and polystyrene) at low carbonization temperatures. The effects of carbonization temperature (200°C, 300°C and 400°C) and chemical activation using different concentrations of a ZnCl2 solution (0.0, 0.5, 1.0 and 2 M) on the yield and adsorption capacity of activated carbon were investigated. The results show that the activated carbon yield is significantly dependent on both the carbonization temperature and the ZnCl2 concentration. The yield increased as the ZnCl2 concentration increased from 0.0 to 2 M and decreased as the carbonization temperature increased from 200°C to 400°C. In conclusion, treating solid wastes with a low carbonization temperature (200°C) followed by chemical activation with 2 M ZnCl2 yielded AC with a high adsorption efficiency.
Environmental science and pollution research international, Jan 4, 2015
Activated carbon was prepared from date pits via chemical activation with H3PO4. The effects of a... more Activated carbon was prepared from date pits via chemical activation with H3PO4. The effects of activating agent concentration and activation temperature on the yield and surface area were studied. The optimal activated carbon was prepared at 450 °C using 55 % H3PO4. The prepared activated carbon was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric-differential thermal analysis, and Brunauer, Emmett, and Teller (BET) surface area. The prepared date pit-based activated carbon (DAC) was used for the removal of bromate (BrO3 (-)). The concentration of BrO3 (-) was determined by ultra-performance liquid chromatography-mass tandem spectrometry (UPLC-MS/MS). The experimental equilibrium data for BrO3 (-) adsorption onto DAC was well fitted to the Langmuir isotherm model and showed maximum monolayer adsorption capacity of 25.64 mg g(-1). The adsorption kinetics of BrO3 (-) adsorption was very well represented by the pseudo-first-orde...
Wastes must be managed properly to avoid negative impacts that may result. Open burning of waste ... more Wastes must be managed properly to avoid negative impacts that may result. Open burning of waste causes air pollution which is particularly hazardous. Flies, mosquitoes and rats are major problems in poorly managed surroundings. Uncollected wastes often cause unsanitary conditions and hinder the efforts to keep streets and open spaces in a clean and attractive condition. During final disposal methane is generated, it is much more effective than carbon dioxide as a greenhouse gas, leading to climate change. Therefore, this study describes the possible valorization of two waste streams into activated carbon (AC) with added value due to copyrolysis. High efficiency activated carbon was prepared by the copyrolysis of palm stem waste and lubricating oil waste. The effects of the lubricating oil waste to palm stem ratio and the carbonization temperature on the yield and adsorption capacity of the activated carbon were investigated. The results indicated that the carbon yield depended strongly on both the carbonization temperature and the lubricating oil to palm stem ratio. The efficiency of the adsorption of methylene blue (MB) onto the prepared carbons increased when the lubricating oil to palm stem ratio increased due to synergistic effect. The effects of pH, contact time, and the initial adsorbate concentration on the adsorption of methylene blue were investigated. The maximum adsorption capacity (128.89 mg/g) of MB occurred at pH 8.0.
We describe a comparative study of the concentration of different metals (e.g., Cd, Pb, As, Ni, C... more We describe a comparative study of the concentration of different metals (e.g., Cd, Pb, As, Ni, Cu, Zn, Mn, and Cr) in various parts of wheat plants (e.g., roots, stem, leaves and seeds) collected at several locations in Khyber Pukhtoon Khaw, Pakistan. The wheat crop in these areas was irrigated using different irrigation sources, including rain, tube well, river, and canal. In wheat samples, the concentration of metals was analyzed using an atomic absorption spectrophotometer. Among the various parts of the plant, the roots had the highest levels of heavy metals, followed by the vegetative parts. By comparison, the seeds and grains had the lowest levels of heavy metals. The levels of heavy metals in all of the studied areas were not significantly localized to any particular area. The general order for the accumulation of studied metals in wheat was found to be Mn > Zn > Cu > Ni > Cr > As > Pb > Cd.
Environmental Science and Pollution Research, 2012
(2012). Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cos... more (2012). Kinetic, equilibrium isotherm and thermodynamic studies of Cr(VI) adsorption onto low-cost adsorbent developed from peanut shell activated with phosphoric acid. Environ Sci Pollut Res.
Numerous studies have been performed on the conversion of individual types of waste into activate... more Numerous studies have been performed on the conversion of individual types of waste into activated carbon (AC). However, this study focused on the evaluation of the simultaneous conversion of different types of wastes (palm, paper, and plastic wastes) into AC via copyrolysis. The tartrazine adsorption capacity onto the produced AC was optimized. The results showed that the carbon content of the AC improved as the calcium hydroxide concentration varied from 0.0 to 2.0 mol L À1. In addition, the volatile matter and ash content were reduced as the concentration of calcium hydroxide was increased from 0.0 to 2.0 mol L À1. The tartrazine adsorption capacity of the prepared AC samples increased as the calcium hydroxide concentration increased from 0.5 to 2 mol L À1 at a carbonization temperature of 400°C for 2 h and a final activation temperature of 500°C for 1 h. Effective adsorption occurred at pH 2. The maximum adsorption capacity (74.9 mg g À1) was obtained with a contact time of 300 min and an initial tartrazine concentration of 150 ppm. The adsorption kinetics of tartrazine were modeled with pseudo-first order, pseudo-second order, and intraparticle diffusion models, which revealed that the tartrazine adsorption onto the AC showed a best fit with the pseudo-second order kinetic model. The thermodynamic parameters DG 0 , DH 0 , and DS 0 indicated that the adsorption of tartrazine onto the AC was spontaneous and endothermic. The values of DG 0 were between À1.3 and À2.3 kJ mol À1 , and the DH 0 and DS 0 values, in the temperature range of 25-50°C, were 9.12 kJ mol À1 and 35.5 J mol À1 K À1 , respectively. In general, the thermodynamic parameters indicate that the adsorption is spontaneous and endothermic.
Maintenance of normal endothelial function is critical to various aspects of blood vessel functio... more Maintenance of normal endothelial function is critical to various aspects of blood vessel function, but its regulation is poorly understood. In this study, we show that disruption of baseline fibroblast growth factor (FGF) signaling to the endothelium leads to a dramatic reduction in let-7 miRNA levels that, in turn, increases expression of transforming growth factor (TGF)-b ligands and receptors and activation of TGF-b signaling, leading to endothelial-to-mesenchymal transition (Endo-MT). We also find that Endo-MT is an important driver of neointima formation in a murine transplant arteriopathy model and in rejection of human transplant lesions. The decline in endothelial FGF signaling input is due to the appearance of an FGF resistance state that is characterized by inflammation-dependent reduction in expression and activation of key components of the FGF signaling cascade. These results establish FGF signaling as a critical factor in maintenance of endothelial homeostasis and point to an unexpected role of Endo-MT in vascular pathology.
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Papers by Rahmat Ali