Abstract
Modifications of rice straws surfaces by sodium hydroxide (NaOH) were carried out in order to study the effects of this on the surface functional groups properties. Comparison was made between untreated and alkali-treated rice straws on the removal of Fe(III) from aqueous solution. In this study, four characterizations of raw rice straw have been conducted. The morphological characteristics by Scanning Electron Microscope (SEM), Energy Dispersive X-ray Analysis (EDXA)the functional group present in the rice straw by Fourier Transform Infrared (FTIR) spectroscopy and the X-ray Diffraction (XRD). The result of Scanning Electron Microscopy (SEM) also shows that rice straw is a porous material. Rice straw contains on –OH functional group that can bind with metal ions. To be able to enhance the sorption capacity of rice straw in metals, removing from waste water, alkali treatment should be done. This shows that rice straw can be used as adsorbent for ferric ions removing from wastewater.The effect of pH, sorption kinetics and isotherms were studied in batch experiments. The good correlation coefficient was obtained from pseudo second-order kinetic model, which agreed with conception as the rate-limiting mechanism. Sorption isotherm test showed that equilibrium sorption data were better represented by Temkin model. The highly efficient, low cost and the rapid uptake of Fe(III) by untreated (RS) in comparison with alkali-treated (MRS) rice straws, indicated that it could be an excellent alternative for the removal of ferric ions by sorption process.
Highlights
Water pollution due to toxic heavy metals has been a major cause of concern
Recently,[1,2] reviewed the technical feasibility of various low-cost adsorbents for heavy metal removal and concluded that the use of low-cost adsorbents may contribute to the sustainability of the surrounding environment and offer promising benefits for commercial purpose in the future
The changes in the surface and adsorption properties of rice straw modified by NaOH were monitored by scanning electron microscopy (SEM) and attenuated total reflection (ATR) Fourier Transform Infrared (FTIR) spectroscopy
Summary
Water pollution due to toxic heavy metals has been a major cause of concern. The main techniques, which have been utilized to reduce the heavy metal ion content of effluents, include lime precipitation, ion exchange, adsorption into activated carbon, membrane process, and electrolytic methods. The use of rice straw would provide a less costly sorbent to activated carbon or synthetic ion-exchanger as it is cheap and available, but will save the environment from the above-mentioned pollution. NaOH removes natural fats and waxes from the cellulose fiber surfaces revealing chemically reactive functional groups like –OH. The changes in the surface and adsorption properties of rice straw modified by NaOH were monitored by scanning electron microscopy (SEM) and attenuated total reflection (ATR) FTIR spectroscopy
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