Silver nanoparticles for enhanced dye degradation Deepak Gola a , Anu kriti a , Neha Bhatt a , Medha Bajpai a , Astha Singh a , Arvind Arya a , Nitin Chauhan b , Sunil Kumar Srivastava b , Pankaj Kumar Tyagi a, * , Yamini Agrawal c a Department of Biotechnology Noida Institute of Engineering and Technology, Gr. Noida, U.P, India b Swami Shraddhanand College, University of Delhi, Delhi, India c Shaheed Rajguru College of Applied Sciences for Women, University of Delhi, Delhi, India ARTICLE INFO Keywords: Wastewater Synthetic dyes Silver nanoparticles TEM Catalytic activity ABSTRACT Dye wastewater discharged after improper treatment is very harmful for environment and living creatures. As per mandate, the dye wastewater should be treated well in order to prevent any negative effects after discharge. Although there are various methods which are in use, however most of these methods have some or the other associated disadvantages i.e., high cost, generation of secondary pollutants, low efficiency, complexity etc. The objective of this study is to identify the dye degradation (orange and blue dye-individually/mixture) potential of chemically synthesized silver nanoparticles (CH-AgNPs) along with NaBH 4 . Literature studies highlighted the efficacy of AgNPs for individual dye degradation, however it is very important to study the degradation potential of nanoparticles in presence of dye mixture (to mimic the natural wastewater condition). In the present study, the rapid synthesis of silver nanoparticles (CH-AgNPs) was obtained by using trisodium citrate solution. The devel- oped CH-AgNPs were examined for UV–vis Spectrophotometry (maxima-422 nm), Zeta Potential (6.70 mV), and Transmission Electron Microscopy (spherical shape with size range of 8–40 nm), highlighting the nano-size and stability of synthesized CH-AgNPs. For catalytic activity, CH-AgNPs and NaBH 4 were tested for dye degradation potential for Orange and Blue dyes individually and in mixture (orange þ blue dye). It was observed that with increase in dye concentration from 50 ppm to 200 ppm, NaBH 4 showed 28% and 25% removal for blue and orange dyes, respectively. However, when CH-AgNPs þ NaBH 4 was used, up to 100% degradation was obtained from blue dye, however the degradation of orange dye has shown 97.4% degradation. Further, as the wastewater contains multiple dyes, therefore in dye mixture studies (orange þ blue dye- 50 ppm), 100% degradation was achieved with NaBH 4 þCH-AgNPs in just 5 min, highlighting the efficient catalytic ability of NaBH 4 þAgNPs. The results clearly highlighted the potential of CH-AgNPs in enhancing the dye degradation of orange and blue dyes- individually and in mixture, therefore the present study is relevant for further research to identify the best dye degradation agents, especially in presence of dyes mixture. 1. Introduction Wastewater generated by various industries contain multiple con- taminants such as dye, heavy metals, antibiotics, pesticides, etc [1,2]. Effluent generated by the textile, plastic, paper, food, tanneries and pharmaceutical industries contains toxic chemical dyes as one of the major pollutants along with other toxic chemical components [3,4]. Azo, basic, acidic, cationic, etc are some of the major dyes that are used by industries to impart color [5]. However, these synthetic dyes are highly toxic, carcinogenic and mutagenic in nature [1,6]. Industries directly discharge dye containing wastewater to near-by water bodies such as river, lake, drain, etc [7,8]. Moreover, in some cases wastewater generated by the various industries is directly used for the irrigational purposes and such practice deteriorate the quality of crops as well as soil [9]. The presence of dye molecule in the water is toxicity and also decrease the sunlight penetration into the water bodies affecting aquatic living organism [10]. Hence, proper treatment of dye containing waste- water is very important before its discharge to near-by water bodies. Degradation of dye molecule to nontoxic component is difficult due to its chemical structure which provides high stability to the dye molecule. Metallic nanoparticles are known to possess multiple physical and chemical properties that helps researcher to exploit them in various field such as electronics, biosensors, food, textile, healthcare, environment, agriculture, etc [11–14]. Utilizing metallic nanoparticles for the * Corresponding author. E-mail address: pktgenetics@gmail.com (P.K. Tyagi). Contents lists available at ScienceDirect Current Research in Green and Sustainable Chemistry journal homepage: www.elsevier.com/journals/ current-research-in-green-and-sustainable-chemistry/2666-0865 https://doi.org/10.1016/j.crgsc.2021.100132 Received 21 April 2021; Received in revised form 17 June 2021; Accepted 25 June 2021 Available online 1 July 2021 2666-0865/© 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by- nc-nd/4.0/). Current Research in Green and Sustainable Chemistry 4 (2021) 100132