Research on the development of green chemistry technology assessment techniques: a material reutilization case
Article information
Abstract
Objectives
This study presents a methodology that enables a quantitative assessment of green chemistry technologies.
Methods
The study carries out a quantitative evaluation of a particular case of material reutilization by calculating the level of “greenness” i.e., the level of compliance with the principles of green chemistry that was achieved by implementing a green chemistry technology.
Results
The results indicate that the greenness level was enhanced by 42% compared to the pre-improvement level, thus demonstrating the economic feasibility of green chemistry.
Conclusions
The assessment technique established in this study will serve as a useful reference for setting the direction of industry-level and government-level technological R&D and for evaluating newly developed technologies, which can greatly contribute toward gaining a competitive advantage in the global market.
Introduction
Rapid advancements in the chemical industry have helped in maintaining the high quality of life of the modern society. Unfortunately, the excessive abuse and misuse of harmful chemical materials, such as nylon, plastic, and phthalate, under the pretext of “modern society’s convenience” has given rise to various human health and environmental problems. To address such problems, leading countries/regions that dominate the chemical sector, such as the US and the European Union (EU), have been advocating green chemistry through collaborative efforts between their governments and the industry; this approach has been labeled “sustainable development.” The general idea behind green chemistry is promoting the design and use of zeroor low-toxic chemical materials and minimizing the production and emission of hazardous chemical substances by means of ecofriendly production process management.
In 1998, Anastas and Warner [1] defined “green chemistry” as the totality of activities that reduce or eliminate the generation and use of substances harmful to human health and environment in the design and production process, and application of chemical products. They presented 12 principles of green chemistry [1]: minimizing waste generation, maximizing synthetic production efficacy, using less hazardous chemical synthesis methods, using low-toxicity chemical product design, minimizing the use of auxiliary substances such as solvents, minimizing energy consumption, maximizing the use of renewable raw material, minimizing the use of derivatives, using catalysts with high selectivity, designing products degradable into innocuous materials at the end of their function, preventing the formation of hazardous substances through real-time monitoring, and selecting materials with low risk for accidents.
In response to international regulations associated with chemical products along with increasingly stringent safety requirements, South Korea (hereafter Korea) has also been striving to apply green chemistry principles and develop green chemistry technologies. However, the evaluation of the level of compliance with the principles of green chemistry (hereafter greenness) has been carried out only at a qualitative level, exposing the limitations in quantifying the greenness compared to the state prior to the implementation of green chemistry technologies.
Against this backdrop, this study was conducted to develop an evaluation technique that enables a quantitative assessment of the greenness of green chemistry technologies. The study also tests the validity of the assessment technique by quantitatively assessing the greenness achieved in a case of material reutilization through the application of green chemistry.
Materials and Methods
We performed a preliminary analysis of various foreign cases for quantitative assessment of green chemistry and presented supplementary features by evaluating the suitability of indices and their respective proxy variables in an additional expert panel. The selected indices are 1) environment: ecological footprint, thereby classifying the substances generated during production and use of chemical products into greenhouse gases (GHGs) as an international issue and hazardous substances affecting residents’ health and living environment as a domestic issue; 2) safety: industrial chemical accidents such as explosion and fire; 3) resource: energy consumption as a social factor, and 4) economy: economic feasibility of green chemistry technologies [2]. Table S1 presents the proxy variables of each index. Each of these four indices is extracted as a value, allowing a quantitative assessment of greenness using equation (1) (Figure 1).
Scope of assessment of the green chemistry technology applied in this study.
where α, β, γ, and δ are the results of analytic hierarchy process (AHP) analysis derived via an expert questionnaire survey and denote weights for respective weights.
Environment
Environment is defined as the sum of GHGs and hazardous substances reflecting the international and local factors, respectively, and expressed by equation (2).
Greenhouse gases
GHGs are defined as the total amount of GHG reduction, and their sum total is calculated in equation (3) in compliance with the Intergovernmental Panel on Climate Change method.
- Energy consumption and GHGs are calculated after converting them into toe and tCO2, respectively.
- GHG emissions during the production process are calculated after converting them into tCO2.
Hazardous Substances
Hazardous substances are defined as the sum total of the health hazard factors (HHFs) and environmental hazard factors (EHFs) for assessing the harmful effects on humans and environment; their sum total is calculated in equation (4).
Hazardous substances include the impact of raw materials, products/by-products, and emissions of each substance. Figure S1 presents these impact factors in a mimetic diagram.
The raw material in Figure S1 comprises the main ingredients, adjuncts, and catalysts. Products mean the final products of the production process, and by-products are concurrently generated secondary products usable without further process. If a by-product can be used for the production process, it is classified as resource, and if it is discharged to the living environment, it is classified as emission, such as the substances released to the environment after waste treatment, including the waste itself.
Health Hazard Factor
The HHF, i.e., the impact of a hazardous substance on the human body, is calculated with equation (5). To implement a quantitative assessment of the HHF, carcinogenicity expressed as Integrated Risk Information System (IRIS) categories, permissible exposure limit (PEL), and risk phrase (R-Phrase) for all hazardous components involved in the production process (raw material, products/by-products, and emissions) should be determined and quantified with respect to a reference scale.
∙ IRIS categories: evaluation and quantification of carcinogenicity of chemicals, the IRIS categories offered by the US Environmental Protection Agency (EPA) are used (Table S2).
∙ PEL: for airborne chemicals, we referred to the Occupational Safety and Health Act (OSHA) as legal standard reference values. Equation (6) represents the reference scale of PEL:
∙ R-Phrase: the risk phrase of each hazard component is determined according to the classification of and standard for dangerous substances as set out in the EU Directive 67/548/EEC.
Environmental Hazard Factor
EHF, i.e., the impact of a hazardous substance on environment, is calculated with equation (7). To implement a quantitative assessment of the EHF, the median effective concentration (EC50) and R-Phrase for all hazardous components involved in the production process (raw material, products/by-products, and emissions) should be determined and quantified with respect to the reference scale.
∙ EC50: the reference scale for the median or half maximal effective concentration is set out using the classification labeling of GHS after measuring the acute toxicity to arthropods (Table S3).
∙ R-Phrase: The risk phrase of a hazard component is determined according to the hazardous substance classification and standard, as set out in EU Directive 67/548/EEC.
Safety
Safety can be quantified by checking the R-Phrase of each chemical substance involved in the production process (raw material, products/by-products, and emissions) against the reference scale using equation (8).
Resource
Improvement of resource consumption means efficacious production of chemical products by minimizing the depleting resources, i.e., reduction in waste generation. To calculate the improvement in resource consumption, we selected raw materials with a high resource value and materials that reflect well the characteristics of the raw materials as a reference scale. For example, the consumption improvement rates for organic chemical compounds and precious or rare metals are calculated in terms of carbon efficiency and content, respectively, and expressed by equation (9).
Economy
Although not included in the 12 principles of green chemistry, it is considered essential to include the economic aspect in the green chemistry technology assessment technique in order to make green economy more attractive to the industry. Additionally, the market share of the technology concerned can serve as a reliable yardstick for gauging its impact on the market , and expressed by equation (10).
Summary of Greenness Calculation
Table S4 gives an overview of the greenness calculation methods by index as described above in order to perform a quantitative assessment of green chemistry technologies.
Results
Equipment Improvement Case
The example presented in this study is a case of reutilization of waste acid from the pickling process of electronic parts. By installing cooling equipment to address the problem posed by excessive use of nitrogen chemicals and ensuing increase in costs for purchasing chemicals and treating waste, the acid solution could be used three times instead of discarding it after the first use, thus achieving reduction in the use of chemicals and waste treatment volume [3]. Figure 2 illustrates the simplified production process of the example case and “pre and post” comparison of economic and ecological impacts.
Production process design of the reutilization of waste acid from the acid pickling process. (A) Improvement compare before and after of process. By installing cooling equipment to address the problem posed by excessive use of nitrogen chemicals and ensuing increase in costs for purchasing chemicals and treating waste, the acid solution could be used three times instead of discarding it after the first use. (B) The whole process and scope of assessment. (C) Economic improvement. Data from Korea Institute of Industrial Technology. Regional eco-innovation program success casebook. Cheonan: Korea Institute of Industrial Technology; 2011 [3]. KRW, Korean won.
Green Chemistry Technology Assessment
Based on the above-described procedure, we could quantify the hazard factors, safety factors, resource consumption, and economic feasibility of nitrogen used as input substance for the pickling process (Table 1), and nickel nitrate emitted as output substance from the pickling process (Table 2). Table 3 and Figure 3 show the results of quantitative assessments of the green chemistry technology applied to the specimen equipment.
Green chemistry technology assessment results
Green chemistry technology assessment results. The values of greenness and improvement factor indicated in the table reflect the guarantee period of 5 years for the cooling equipment.
Raw information on nitrogen and nickel nitrate was sourced from the IRIS categories provided by the US EPA and their respective material safety data sheets (R-Phase: EU Directive 67/548/EEC; PEL: OSHA; EC50: EPA). The costs for pollutant treatment and expenditure for a 5-year period were taken from the regional eco-innovation program success casebook.
The application of the green chemistry assessment technique developed in this study revealed a 48% improvement in greenness compared to the state before the improvement. Breaking down 48% into individual indices, safety was found to occupy the highest portion with 17.9%, followed by economic feasibility (17.9%), environment (9.9%), and resource (8.6%). The weights used for the calculation were derived from the AHP analysis performed through an expert questionnaire survey.
Discussion
We proposed a novel technique for quantitative assessment of green chemistry technologies and calculated the improvement in an example case of material reutilization by quantifying the level of greenness that was achieved by implementing a green chemistry technology. The calculation results revealed an enhancement of the greenness level by 42% compared to the level before the improvement, including economic benefits. This study will serve as a basis for establishing a useful tool for evaluating the greenness of technologies from a strategic perspective for businesses to use it for setting the directions of their R&D plans and for the governments to perform objective evaluations of technologies. In particular, it is expected to greatly aid businesses in gaining competitive advantage in the global markets.
Acknowledgements
This subject is supported by Korea Ministry of Environment (MOE) as “MOE’s R&D Program on environmental technology development” (no. 412-111-007), and by Korea Environment Institute (KEI, 2014-025).
Notes
The authors have no conflicts of interest with material presented in this paper.
Supplementary Material
Weight of each indicator
Integrated Risk Information System (IRIS) carcinogen classification criteria
Classification table of the median effective concentration (EC50)
Green chemistry technology assessment index/proxy variable with related data