Identification and analysis of green supplier development indicators in the petrochemical industry

Introduction
Participation in environmental protection activities and pro-environmental behaviors are related to consumers' willingness to pay for products that harm the environment less. In order to know the status of the supplier in terms of green development, appropriate indicators should be defined. In past studies, including the study of Bai and Sarkis (2010), factors have been introduced for GSD, but not all of them can be considered as indicators. Rather, they need to be fundamentally revised, and for localization, the opinions of industry experts should be gathered. After the study of Bai and Sarkis (2010), new dimensions and factors have been introduced for GSD, which further confirms the necessity of this research. In the studies of Olfat et al. (2019 and 2020), indicators and activities have been introduced for the environmental dimension of SD, but they are very limited and localized for the automotive industry. Therefore, at present, the introduction of GSD indicators seems to be a necessity. According to our knowledge, no study on GSD indicators has been comprehensively introduced in domestic research. Bai and Sarkis (2010) were the first to propose GSD. They evaluated supplier performance based on environmental dimensions and introduced indicators for GSD in this regard. After Bai and Sarkis (2010), researchers such as Fu et al. (2012), Dou et al. (2013), Blume et al. (2014) raised and investigated the issue of GSD. Petrochemical industries are one of the industries that pollute the environment and introduce various types of pollutants, which are sometimes very dangerous, into the air, water, and soil. According to the above, it can be said that conducting such research in the petrochemical industry can become important. This research deals with green development in the aspect of raw material supply. Since many processes in the supply chain are carried out by suppliers today, and also manufacturers have turned to outsourcing many of their own activities, the green development of suppliers in industries such as the petrochemical industry that have different pollutions can be useful.
 
Materials and Methods
First, by reviewing the literature, the GSD indicators are identified and localized by a survey of university and petrochemical industry experts, which reduces the number of indicators from 12 to 10 and changes and consolidates the indicators. In the next step, the DEMATEL questionnaire will be prepared and the necessary data will be collected by distributing it among academic and petrochemical industry experts. After analyzing the data using the DEMATEL method, the relationships between the indicators are displayed as a network.
 
Findings
The results show that based on the net impact, indicators of responsibility, knowledge, and capabilities of the supplier in environmental measures, the existence of the environmental performance evaluation system in the supplier and the managerial and organizational practices of the supplier in connection with green development are definitely effective and the indicators of sharing environmental information, programs and Supplier activities for green development, green technology, compliance with environmental standards and certifications by the supplier, and reverse logistics activities by the supplier are definitely affected. Based on the results of this research, practical proposals for the petrochemical industry and research proposals for researchers are presented.
 
Discussion and Conclusion
In this research, GSD indicators were identified and localized in the petroleum industry. Considering that sub-indices were also defined for each of the indicators, it is suggested that future research use confirmatory factor analysis to investigate the classification of indicators and sub-indices. It is also possible to use appropriate multi-criteria decision-making methods to rank indicators and sub-indices. Considering that the indicators were localized for the petrochemical industry, they can be revised and localized in other industries such as the automobile industry, tile industry, etc., which cause a lot of environmental pollution.