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Problem statement: It is well documented that lead is one of contaminants of industrial wastewaters and its pollution exists in the wastewater of many industries. As a result, recent research has focused on the development of cost effective alternatives using various natural sources and industrial wastes. In this setting, the use of low-cost agricultural materials, waste and residues for recovering heavy metals from contaminated industrial effluent has emerged as a potential alternative method to high cost adsorbents. In the present study, adsorption of lead(II) ions onto Orange Peel (OP), a typical agricultural byproduct, was investigated systematically with the variation in the parameters of pH, sorbent dosage, contact time and the initial concentration of adsorbate. Langmuir and Freundlich isotherms were used to analyze the equilibrium data. Kinetic and thermodynamic parameters were also calculated to describe the adsorption mechanism. Approach: The Orange Peel (OP) was obtained from a local market in the south of Jordan. The orange peel was cut into small pieces using scissors. Then OP was dried at 100°C for 24 h using hot air oven. Qualitative analyses of the main functional groups involved in metal adsorption were performed using a Fourier transformed infrared spectrometer (Perkin-Elmer FTIR 1605, ¨Uberlingen, Germany). Biosorption experiments were carried out in a thermostatic shaker at 180 rpm and at an ambient temperature (20±2°C) using 250 mL shaking flasks containing 100 mL of different concentrations and initial pH values of Pb(II) solutions, prepared from reagent grade salt Pb(NO 3 ) 2 (Merck). The initial pH values of the solutions were previously adjusted with 0.1 M HNO 3 or NaOH and measured using a hand held pH meters (315i/SET). The sorbent (0.2-1.0 g) was added to each flask and then the flasks were sealed up to prevent change of volume of the solution during the experiments. After shaking the flasks for predetermined time intervals, the samples were withdrawn from the flasks and filtered through a Whatman filter paper. The filtrate was analyzed by AAS (Perkin Elmer Analyst 300). Results: Four kinetic models are the pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion equations, were selected to interpret the adsorption data. Kinetic parameters such as the rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity was found as 21.1 mg g −1 at pH 6 and 20°C.The dimensionless separation factor (R L ) has shown that orange peel can be used for removal of Pb(II) from aqueous solutions. The nagative free energy of adsorption indicated that the adsorption of lead (II) ions onto orange peel was feasible and spontaneous. Conclusion: The sorption capacity of the orange peel is comparable to the other available adsorbents and it is quite c...

The catalysts of un-doped, single-doped and co-doped mesoporous titanium dioxide (MTiO 2 ) were prepared by a template method with tetrabutyltitanate (Ti(OC 4 H 9 ) 4 ) as a Ti source material and Pluronic P123 as a template. The photo-absorbance of the obtained catalysts was measured by UV-vis absorption spectroscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange (MO) (50 mg/L) in an aqueous solution. It was shown that the co-doped MTiO 2 could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The effect of Fe and Ce co-dopants on the material properties was investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and N 2 adsorption-desorption isotherm measurement. The characterizations indicated that the photocatalysts possessed a homogeneous pore diameter of ca. 10 nm with high surface area of ca. 150 m 2 /g. The photocatalytic activity of MTiO 2 co-doped with Fe and Ce was markedly improved due to the synergistic actions of the two dopants. CHEMICAL SOCIETY Fig. 8. Degradation curves of MO with visible light.Experimental conditions: initial concentration of MO 50 mg/L, solution pH 4, dosage of catalyst 1.0 g/L, calcination temperature 500°C. Fig. 9. The cyclic performance of 0.5% Fe, 0.5% Ce-MTiO 2.

Preparation of samarium doped mesoporous titanium dioxide (Sm/MTiO 2 ) coated magnetite (Fe 3 O 4 ) photocatalysts (Sm/MTiO 2 /Fe 3 O 4 ) and their activities under visible light were reported. The cata lysts with Sm/MTiO 2 shell and a Fe 3 O 4 core were prepared by coating photoactive Sm/MTiO 2 onto a mag netic Fe 3 O 4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu) 4 , TBT) with precursors of Sm(NO 3 ) 3 and TBT in the presence of Fe 3 O 4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X ray diffraction (XRD) and UV vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were esti mated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO 2 was tightly bound to Fe 3 O 4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.