In this study, novel chitosan/FeOnano composite Ch/Fe-O was synthesized and evaluated as an adsorbent for removing thorium (IV) (Th) ion from aqueous solution. The Ch/Fe-O was characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Response surface methodology (RSM) was used in the optimization of Th adsorption for parameters such as pH, the initial metal ion concentration (Th concentration) and contact time. The statistical measures (i.e. analysis of variance, R, the lack of fit test and the P value) specify that the developed model is proper. Furthermore, the adsorption kinetics was well defined by the pseudo-second-order equation, while the adsorption isotherms were better fitted by the Langmuir model. The adsorption capacity of Ch/Fe-O was 430 mg Thg composite which leads to 99% removal at 25 °C. Moreover, thermodynamic parameters which state the natural and endothermic nature of the reactions were determined. The loaded Th can be easily regenerated with HNO and the Ch/Fe-O can be used repeatedly without any significant reduction in its adsorption capacity. The desorption level of Th from the Ch/Fe-O by using 0.1 M HNO, was more than 95%.
Increasing building construction raises concerns about construction and demolition (C&D) waste management. To assess this issue the building components, the collection schemes, their recycling and disposal should be investigated. In order to manage C&D wastes, paying attention to how this kind of wastes is disposed is imperative for their correct identification. Inattention, lack of organization and proper transport and sanitary disposal of construction and demolition waste lead to problems such as accumulation of construction waste in the streets. However, more than 90 percent of the potential for recycling and re-using as raw materials is provided. Environmental Protection Agency (EPA) has classified C&D wastes into three categories: non-dangerous waste, hazardous wastes and semi-hazardous wastes. Currently in Tehran, an average of about 50,000 tons per day of construction and demolition wastes are produced from which over 30,000 tons per day are dumped in landfills. According to this research more than 57% of these wastes are placed in the first category (non-dangerous waste) and have the potential for being recycled and reused. On the other hand, items that are placed in the second category shall be managed based on the existing laws. This article provides some management solutions including proposing methods for collecting and reusing construction waste in accordance with current market needs in Iran.
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