RESEARCH ARTICLE Green synthesis of copper nanoparticles for the efficient removal (degradation) of dye from aqueous phase Tanur Sinha 1 & M. Ahmaruzzaman 1 Received: 28 May 2015 /Accepted: 11 August 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract The present work reports the utilization of a com- mon household waste material (fish scales of Labeo rohita) for the synthesis of copper nanoparticles. The method so de- veloped was found to be green, environment-friendly, and economic. The fish scale extracts were acting as a stabilizing and reducing agents. This method avoids the use of external reducing and stabilizing agents, templates, and solvents. The compositional abundance of gelatin may be envisaged for the effective reductive as well as stabilizing potency. The mecha- nisms for the formation of nanoparticles have also been pre- sented. The synthesized copper nanoparticles formed were predominantly spherical in nature with an average size of nanoparticles in the range of 25–37 nm. The copper nanopar- ticles showed characteristic Bragg’ s reflection planes of fcc which was supported by both selected area electron diffraction and X-ray diffraction pattern and showed surface plasmon resonance at 580 nm. Moreover, the energy dispersive spec- troscopy pattern also revealed the presence of only elemental copper in the copper nanoparticles. The prepared nanoparti- cles were used for the remediation of a carcinogenic and nox- ious textile dye, Methylene blue, from aqueous solution. Approximately, 96 % degradation of Methylene blue dye was observed within 135 min using copper nanoparticles. The probable mechanism for the degradation of the dye has been presented, and the degraded intermediates have been identified using the liquid chromatography-mass spectroscopy technique. The high efficiency of nanoparticles as photocatalysts has opened a promising application for the re- moval of hazardous dye from industrial effluents contributing indirectly to environmental cleanup process. Keywords Copper nanoparticles . Gelatin . Methylene blue . Photodegradation Introduction Nowadays, fast urbanization, industrialization, and unplanned activities of human beings have increased the environmental pollution especially air and water. These are generally caused by effluents from various industries and a major part is con- stituted by the dye industries. Dyes are used in the production of various consumer prod- ucts, such as paints, textiles, printing inks, papers, plastics, etc. and exhibit significant environmental toxicity to all living or- ganisms and contribute to eutrophication (Safavi and Momeni 2012). These possess a threat to our ecosystem and water bodies. Hence, their complete dislodgement is essential for minimizing water pollution which is a very cumbersome task on account of their complicated structure and high stability. Several methodologies have been formulated in the past employing biological, chemical, and physical remediation processes, but all these methods have certain demerits (Wang et al. 2010). On the contrary, a photocatalytic approach in the presence of suitable nanocatalyst using sunlight offers a potential meth- od for the complete elimination of pollutants from the envi- ronment. In the photocatalytic pathway, sunlight activated the nanoparticles (NPs) and forms a redox atmosphere in aqueous Responsible editor: Santiago V. Luis Electronic supplementary material The online version of this article (doi:10.1007/s11356-015-5223-y) contains supplementary material, which is available to authorized users. * M. Ahmaruzzaman mda2002@gmail.com 1 Department of Chemistry, National Institute of Technology, Silchar 788010, Assam, India Environ Sci Pollut Res DOI 10.1007/s11356-015-5223-y