Abstract
Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan–magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV–visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15–30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan–magnetite nanocomposite strip from aqueous solution was evaluated using UV–visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan–magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.
Highlights
Removal of chromium was carried out using chitosan–magnetite nanocomposite strip
Amount of chromium adsorbed by chitosan strip and chitosan–magnetite nanocomposite strip from
Heavy metals like Hg (II), Pb (II), Cd (II) and Cu (II) are harmful because they are non-biodegradable in nature, long half-life, and get accumulated in different parts resulting in environmental pollution, of which, chromium is one of the most lethal heavy metal
Summary
Heavy metals like Hg (II), Pb (II), Cd (II) and Cu (II) are harmful because they are non-biodegradable in nature, long half-life, and get accumulated in different parts resulting in environmental pollution, of which, chromium is one of the most lethal heavy metal. Chromium exists in two forms namely the trivalent (III) and hexavalent (VI) form. The industrial sources of Cr(VI) primarily include alloy and steel manufacturing, metal finishing, electroplating, leather tanning, pigments and dyeing industries. The effluents from these industries contain Cr(III) and Cr(VI) at concentrations ranging from tenths to hundreds of ppm (Mcbain et al 2008). Hexavalent chromium usually exists in water as oxyanions such as chromate (CrO42) and dichromate (Cr2O72-) and does not precipitate using the conventional methods (Campo et al 2005)
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