RESEARCH PAPER Green Synthesis of SnO 2 Nanoparticles for Catalytic Degradation of Rhodamine B Prashanna Suvaitha Sundara Selvam 1 • Dhinagaran Ganesan 1 • Vinodh Rajangam 2 • Atchudan Raji 3 • Venkatachalam Kandan 1 Received: 6 November 2019 / Accepted: 30 April 2020 Ó Shiraz University 2020 Abstract A novel method was utilized for the synthesis of Tin (IV) oxide nanoparticles using the leaf extract of Carica papaya, Murraya Koenigii, Moringa Oleifera, and Acalypha Indica. The leaf extract acts as an excellent stabilizing, reducing and capping agent for nanoparticles. From XRD analysis, we found that the average crystallite size of SnO 2 nanoparticles was equal to 5 nm (SnO 2 –CP), 19 nm (SnO 2 –MK), 38 nm (SnO 2 –MO), 11 nm (SnO 2 –AI). The band gap of the prepared SnO 2 nanoparticles was in the range 2.8–3.1 eV. Further, the green synthesized SnO 2 nanoparticles were tested for degradation of organic pollutant dye namely Rhodamine B in the presence of solar light. The effect of several parameters such as dye concentration, catalyst loading and pH level was studied. The results of optimization showed a maximum removal of color efficiency 86% at pH 8 for 1 9 10 –5 M dye concentration and 100 mg catalysts. The pseudo-first-order kinetics was employed for all the catalysts. Keywords Carica Papaya  Murraya Koenigii  Moringa Oleifera  Acalypha Indica  SnO 2  Rhodamine B 1 Introduction Environmental pollution refers to an undesirable change which is happening in the chemical, biological and physi- cal composition of the environment consisting of water, air, and soil. The presence of harmful pollutants makes the environment unhealthy to live. A pollutant can cause damage when it interferes with the biochemical process of an organism either directly or indirectly. Water is one of the essential enablers of life on the earth. Nearly 3.2 million people die worldwide per year because of the contaminated drinking water and poor sanitation. Thus, the quality of water affects the living standard of human beings and animals directly. So, the removal of water pollutants from our earth is essential. Water pollutants may exist in different toxic wastes like pharmaceuticals, pesticides, herbicides, textile dyes, resins and phenolic compounds. Out of these the textile dye pollutants are more toxic than the other pollutants because they are extensively used for various purposes in industries such as paper industry, plastic industry, tanning industry, textile industry, leather industry, etc. Water pollution is the main issue when it comes to textile industry because of the processes of dye- ing and finishing. In order to remove these dyes from the polluted water, there are many methods based on chemical, physical and biological strategies. Among these methods, the photocatalytic degradation of dyes is regarded as an efficient one because of its economic feasibility and sim- plicity (Saravanan et al. 2017). Metal oxide semiconductor-based photocatalytic meth- ods maintained a constant research interest among the researchers because of the breakdown of organic dyes. Among various metal oxide nanoparticles, tin dioxide (SnO 2 ) has emerged as an effective photocatalyst because Electronic supplementary material The online version of this article (https://doi.org/10.1007/s40995-020-00885-5) con- tains supplementary material, which is available to autho- rized users. & Venkatachalam Kandan venkatachalam@unom.ac.in 1 Department of Analytical Chemistry, University of Madras, Guindy Campus, Chennai, Tamilnadu 600025, India 2 Department of Electrical and Computer Engineering, Pusan National University, Busan, South Korea 3 School of Chemical Engineering, Yeungnam University, Room No. 313, 280 Daehak-ro, Gyeongsan, Gyeongbuk-do 38541, Republic of Korea 123 Iran J Sci Technol Trans Sci https://doi.org/10.1007/s40995-020-00885-5