Optimized production of single-use plastic-Eucalyptus wood char composite for application in soil Kumar Raja Vanapalli a , Jayanta Bhattacharya a, b, d, * , Biswajit Samal a , Subhash Chandra a , Isha Medha b , Brajesh K. Dubey a, c a School of Environmental Science and Engineering, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India b Department of Mining Engineering, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India c Department of Civil Engineering, Indian Institute of Technology, Kharagpur, West Bengal, 721302, India d Zelence Industries Private Limited, Kharagpur, India article info Article history: Received 9 January 2020 Received in revised form 22 August 2020 Accepted 26 August 2020 Available online 28 August 2020 Handling editor. Bin Chen Keywords: Co-pyrolysis Single-use plastic Biomass Char composite Characterization Optimization abstract Co-pyrolysis of Eucalyptus wood (EW) and Single-use plastic (SUP) can be a sustainable and green technological option ensuring optimum resource recovery and plastic waste management in a circular economy. This study aims to optimize the variables of pyrolysis [temperature (300, 400, 500, 600  C), residence time (90, 120, 150 min), and proportion of plastic (w/w - 0.25, 0.33)] for application of SUP - EW char composite in soil. Statistical analysis showed that all three process variables had significant influence on properties of the char. With temperature and residence time, the char became dense, carbonaceous, ash-rich, aromatic, and alkaline for both the proportions of SUP in the feed. Further characterization also revealed that the highest plant extractable concentrations of major nutrients, cation exchange capacity, and electrical conductivity of char composite were recorded with temperatures of 400 e500  C, residence time of 120 min, and 33% (w/w) of SUP. The surface morphology analysis revealed the char to have a porous structure with a coating of plastic at lower temperatures of 300  C and an increase in microporosity at higher temperatures of 500, 600  C. Significant positive correlations between radicle root growth and prominent plant growth parameters observed through seed germination test indicate the char’s potential applicability in soil. The optimized process parameters of char obtained through regression modeling for application in soil were 415.2  C, 125.2 min, and 0.325 (w/w) proportion of SUP. The highest mean seed length of z17.5 cm observed at 400  C, 120 min, and 0.33 (w/w) proportion of SUP was consistent with these optimized parameters. Soil incubation test further showed that amend- ment with optimized char composite significantly improved its properties with a 3.7-fold increase in soil fertility index at 5% rate of application. So, the application of optimized SUP - EW char composite could significantly improve the properties of soil while promoting greener sustainable development through ideal utilization of the so far mismanaged waste resources. © 2020 Elsevier Ltd. All rights reserved. 1. Introduction With the rise in the global population, innovation in packaging and utility sectors, and changes in people’s lifestyles, there is a tremendous increase in the consumption of plastics over the last couple of decades. The global production of plastics has increased from 200 to 348 million tons from 2002 to 2017 (Association of Plastics manufacturers, 2018). With almost 36% of its use in single-use packaging, this sector has been a significant contributor to the rise in the generation of waste as well (Geyer et al., 2017). While the high-income countries were able to reduce and recycle a large percentage of this waste, middle and low-income countries owing to their technological and financial constraints, end up mismanaging most of it (Jambeck et al., 2015). Although mechanical recycling is considered high up in the pyramid of plastic waste management, some of its technical and economic feasibilities have not been encouraging to recyclers (Vanapalli et al., 2020). For example, considering polystyrene as a potential human carcinogen if mismanaged, it has been of recyclers’ * Corresponding author. School of Environmental Science and Engineering, In- dian Institute of Technology, Kharagpur, West Bengal, 721302, India. E-mail addresses: jayantab@mining.iitkgp.ac.in, jayantaism@gmail.com (J. Bhattacharya). Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2020.123968 0959-6526/© 2020 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 278 (2021) 123968