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As it is impossible to define or characterize sustainability in the absolute, the pursuit of relative improvement of a properly identified system is the desirable approach for seeking sustainability. One would, however, need a set of proper indicators to measure this relative improvement. Generally, three domains of sustainability, i.e. environmental, economic, and societal are used to identify indicators. The problems of this extant approach are many as there is wide variability of the indicators that can be chosen by investigators for a system under study. Additionally, lack of orthogonality among the indicators can lead to bias, and the indicators frequently show mixed outcomes, some improving but others declining, as a result from some desired process refinement. All these difficulties have created a problem of assessing sustainability improvement and of differentiating logical versus false claims. In this perspective paper, several methods of sustainability assessments are discussed identifying these difficulties. Meanwhile, industry has been using shortcuts to claim sustainability improvements which may or may not be valid.

Professor Man Mohan Sharma was educated at Jodhpur (Rajasthan), Mumbai, and Cambridge, England. He was appointed to the rank of Professor in the Institute of Chemical Technology, Mumbai, when he was just above 27 years of age. He was the youngest ever recipient of S.S Bhatnagar prize in Engineering Sciences in 1973. Professor Sharma was elected a fellow of the Indian National Science Academy in 1976 and later became its president during 1989–1990. The crowning glory came in 1990 with his election as a fellow of the Royal Society, England as the first engineer from India to be elected to this august body. Professor Sharma was elected a foreign associate of the US National Academy of Engineering. He also was the Editor of Chemical Engineering Science, and has been a consultant to chemical industry for 50 years. (Subhas Sikdar): Professor Sharma, Thank you very much for accepting to conduct this conversation with me for this journal. I consider it a special honor to be able to converse with you on matters that span the gamut from science and chemical technologies to what we call progress and the public policy that can shape it. Your entire life has been an inimitable example of technical and pedagogic excellence, and to this day has remained a remarkable inspiration to hundreds of your students and colleagues worldwide. We will traverse those territories shortly, but first I want to engage you in a discussion on sustainability as it relates to the exploits of engineering. As the environmental stewardship dogma moved from waste minimization to pollution prevention to design for the environment eventually arriving at the concept of sustainability, you have had something important to say about all previous concepts through your ideas and research. Given that environmental pollution still is rampant in the Indian cities after all these years of development, I would like to know your ideas of relevance of sustainability to Indian condition and how the country can make significant inroads toward achieving that goal through policy measures, and particularly through the application of cleaner technologies. (M.M. Sharma): Sustainability is of great importance to India, as it is globally. We should refer to all the so-called waste streams as resource with a negative cost. We can give many valuable examples. Take the case of SO2 from smelter gas which has been valorized as H2SO4; similarly H2S from sour natural gas and from hydrodesulphurization which has been converted to S and today a major part of S is from recovered source. India does not have any sulfur mines. Active pharmaceutical ingredients (API) in pharma industry provide a fascinating example as India, along with China, has become a leading supplier for global & Subhas K. Sikdar sikdar.subhas@epa.gov

Computational process design for sustainability using various available techniques is still limited to computer-aided design featuring process optimization of energy and material flow plus minimizing greenhouse gas emission and water conservation. Sustainable process demands more, such as minimizing the impacts from other harmful emissions, discharges, waste creation, economic, and societal impacts. We have proposed an overall sustainability footprint, which in theory represents impacts of a process on all three domains of sustainability. This perspective article provides a critical analysis of attaining sustainability by minimizing this sustainability footprint using impact data as indicators. We also propose the use of the integration of the sustainability footprint in the computer-aided process design itself, rather than checking the impacts after the data have been collected on actual process options designed ahead of the analyses.

Green, clean, sustainable—these three words are frequently used casually to connote some desirable attributes. When claimed for technical systems, however, the monikers of green, clean, and sustainable must be scientifically justified. Unfortunately, this objective of introducing scientific rigor into assessing the greenness or sustainability of technical systems has not been universally accepted or practiced. For energy systems, currently the debate is conspicuously driven by the phenomenon of global warming, which more recently is described as climate change. The nonfossil modes of energy production, delivery and use of solar, wind, hydro, nuclear, or biomass, are uncritically assumed to be green and sustainable in both scientific and popular literature. This should not be the case. This chapter will look at the issues that must be considered while designing energy systems that can be described as sustainable, clean, or green.

The objective of the article is to show that indicator aggregation coupled with the use of a multivariate statistical analysis applied to the environmental sustainability indicator data of the UN Millennium Goals (MDG) can allow important inferences to be made. Goal 7 of the UN MDG aims to assess environmental sustainability by ten indicators, the dominant among them being emissions of carbon dioxide equivalent. The data is available over a period of 20 years. We used an aggregate index method to combine the various indicator values into a single index, and studied the trends of countries over the years. We have also compared among two arbitrarily chosen groups of OECD and non-OECD countries, and shown how these countries have performed among themselves and as a combined group over the time period. Using the multivariate statistical method of Partial Least Squares Variable Importance in Projection (PLS-VIP), we showed how to find the key indicators from the larger set and their relative importance over the years. Important results from our research include ranking of countries according to their overall environmental performance in a particular group. The PLS-VIP method showed that certain indicators have shifted in their importance in influencing their overall environmental performance, while others have remained relatively insignificant over the 20-year period. 2014 American Institute of Chemical Engineers Environ Prog, 2014 © 2014 American Institute of Chemical Engineers Environ Prog, 34: 198–206, 2015

Indicators are commonly used for evaluating relative sustainability for competing products and pro- cesses. When a set of indicators is chosen for a particular system of study, it is important to ensure that they vary independently of each other. Often, the number of indica- tors characterizing a chosen system may be large. It is essential to select the most important indicators from a large set so that a dependable bias-free analysis can be done using the reduced set of indicators. In this paper, we propose the use of principal component analysis (PCA) along with the partial least square-variable importance in projection (PLS-VIP) method to ensure that the explicit or tacit assumption of the independence of the chosen indi- cators is valid. We have used two case studies to demon- strate successful use of these two methods for parsimonious use of indicators for sustainability analysis of systems.

Water treatment technologies inherit the environmental, economic, and societal burdens either from polluted natural sources for potable water, or from domestic sewer water for municipal wastewater treatment plants, or from various industrial processing plants that produce highly contaminated wastewater. Application of various membrane technologies for wastewater has been growing because they enjoy relative advantage over other technologies in terms of sustainability. This advantage mainly emanates from economic benefits, ease of operation and safety. This chapter discusses what sustainability means for wastewater treatment and what specific sustainability advantages membrane processes can demonstrate. Applicable sustainability indicators are identified for various membrane technologies that can tackle a large number of wastewater problems.

Sustainability assertions are holistic in nature because they represent commentaries on the impacts of process and products on three dimensions of sustainability: environmental, economic, and societal. A large number of indicators (or metrics) may be used to observe the sustainability behavior of a process or product system. Because of the complex way these indicators interact with each other in influencing system performance, it is useful to construct a holistic measure to observe sustainability performance. The Euclidean distance, composed of the indicator values representing a system, was introduced as such a measure, and has been called the sustainability footprint. In this chapter detailed computations are shown on a test system to illustrate how the sustainability footprint is calculated and how it is used to compare among competing alternatives of a system in terms of sustainability. This method based on Euclidean distance is compared with other proposed methods for indicator aggregation, such as Vector Space Theory, Canberra distance, zCanberra distance, and Mahalanobis distance. In addition, two other objectives are achieved. First, by applying the principal component analysis, the redundant indicators are identified, and second, the rank order of the indicators in terms of their contribution to sustainability is calculated. This information will be helpful in improving sustainability performance at the redesign stage based on the relative contributions of the indicators and their controllability.

Treatment of indicator data for computing sustainability footprints of systems is shown in detail in this chapter. Three representative systems have been chosen for sustainability assessment. Sustainability footprint is the Euclidean distance of a system, De, from a reference point of the same system, where De is characterized by chosen indicators . Thus for comparing different process options of a system, this distance gives an overall sustainability performance of the contending options. These three cases show how the calculations are made for obtaining the footprints. Additionally these cases also deal with statistical analysis of the covariance data of the indicator values to arrive at two important findings: first which of the indicators are necessary and sufficient for decision making and second, of the necessary indicators what are the rank orders of the indicators in terms of importance.

International and national trades critically rest on standards provided by reputable standards organization, some of them are government laboratories, others nongovernmental. Products or process systems that can be claimed as sustainable and that change hands or cross borders must have their quality credibly supported by measurement standards. International organizations such as ISO and others have been producing documents to guide the development of such standards. The system of standards for sustainability is not mature yet, and much research needs to be conducted to provide common and acceptable standards. A conceptual framework for standards for sustainability has been proposed here. It provides ideas on the development of methods that would be useful for building standards.

Over a couple of centuries, technological innovations have produced an enormous beneficial change in man’s lifestyle and level of comfort. That outcome required the use of massive use of the earth’s natural resources. Wastes being a consequence of development, much pollution resulted in air, water and land. In the beginning the innovations were mainly about profit maximization, later they were also geared to resource use minimization. Sustainable development teaches an optimization that is supposed to provide economic benefits along with environmental protection and societal uplifting. This is the biggest challenge to innovation. Businesses and entrepreneurs are engaged and many innovations are happening especially in the product and process level. Much larger challenges remain in the bigger areas of concern such as drastic reduction of greenhouse gases, making non-fossil energy financially sound, approximating zero discharge, and solving problems of water quality and quantity.

Sustainability is related to a defined system. Sustainability assessment of a system is a determination of the sustainability performance of the system compared to a similar system with the same attributes. Indicators are representatives of the attributes that characterize the system. Since sustainability consists of three interacting dimensions: environmental, economic, and societal, a Venn diagram representation shows the classification of the intersections that can be represented by chosen indicators. For example, a three dimensional indicator will be placed at the intersection of the three dimensions. In this chapter we show how indicator dimensionality can be determined. We also recognize the types of systems—global, regional, business, and technology—to which an assessment can be applied. A general framework for implementing such an assessment of a system sustainability is presented. The same framework is applicable to a system belonging to any of the four system types. The specific indicators that adequately characterize one type of system are necessarily different from those of another type of system. Once the set of indicators is satisfactorily decided upon, data collections can begin for conducting an assessment using the framework.

Energy and water use is generally correlated with the prosperity of a nation or a community. Availability of energy and safe water are vital for development and are rightly described as the most important sustainability issues for civilized society. Energy is vastly more complicated than water because there are many different kinds of sources for power and transportation: carbon based fossil energy, non-fossil such as solar, wind, and biomass-based, and nuclear and geothermal. The global warming worries make a strong case for non-fossil but in the market-place, at the current state of development, non-fossils are not competitive, creating affordability issues for communities. Energy sustainability can be approached first by attaining energy use efficiency, and ultimately by developing inexpensive non-fossil energy-carriers. Indicators are used for both water and energy sustainability in much the same way we approach general sustainability issues for communities, ecosystems, and technologies. Water can also be affected by climate change. A strong nexus exists between energy and water, which is why in closely defined systems both should be taken together for simultaneous energy–water sustainability. Energy sustainability can belong to global, regional, business, or technology scale. Water, on the other hand has a stronger spatial meaning. Since, unlike energy, water is usually not traded across borders. It typically belongs to a regional scale, and on the business and technology scale, can be controlled by process designers. Energy–water sustainability solution for a regional scale cannot be easily exported to a different region because the scales are mismatched. In this chapter, we examine the complicated multifaceted problems that need to be solved for the future.

This chapter provides a review of the current state of the art in sustainability indicators or metrics for business and technology scales. These are the two scales at which the scientists and engineers have the most control over sustainability performance. At the business scale the purpose is to ensure investments to be secure and profitable, and for business to provide adequate support for the environment and the society. Three measurement systems are analyzed: the Global Reporting Initiative, the Dow Jones Sustainability Index, and an emerging method developed by the American Institute of Chemical engineers (AIChE), the first two being widely used. Of the technology systems, we cover the ones provided by the professional societies. The indicator system suggested by the Institution of Chemical Engineering (UK) explicitly lists the indicators under environmental, societal, and economic categories, but the AIChE system lists the most important technical indicators. Environmental Impact Assessment (EIA) and Life Cycle Assessment techniques are also presented to provide the context and tools needed for sustainability assessment at these scales.

Computer-aided simulation has been an established technique for designing and optimizing new and retrofit processes, especially in chemical process industries. Process optimization has given rise to highly useful techniques of process integration and process intensification that over the years have reduced resource use and cost. These reductions contribute to sustainable technologies no doubt but do not capture the totality of sustainability as understood in the context of simultaneous reduction of environmental, economic, and human health impacts of technologies. More and more researchers are beginning to be engaged in attempts at incorporating the remaining sustainability indicators in simulation methods. Various commercially available tools can be used as springboard for developing newer tools that would be useful to designing processes that from a holistic viewpoint are more sustainable. This chapter is a discussion on such opportunities. The field of computer-based methods of design and optimization is already very mature. This discussion is not a tutorial in that sense but an introduction to the possibilities ahead.

To date numerous environmental, economic and societal indicators have been applied to evaluate and compare the sustainability of products and processes. This study presents a set of ad hoc sustainability indicators suitable for assessing and comparing processes for the treatment of industrial waste streams and for allowing to address efficiently all aspects of sustainability. This set consists of the following indicators: energy intensity, material intensity, water consumption, land use, global warming, human toxicity and treatment cost. The application of these indicators to industrial waste treatment processes is discussed in depth. A distinction is made between direct contributions to sustainability, occurring at the process level itself, and indirect contributions related to the production of auxiliaries and the recovery of end products. The proposed sustainability assessment method is applied to treatment processes for automotive shredder residue (ASR), a complex and heterogeneous waste stream with hazardous characteristics. Although different strategies for recycling and valorization of ASR were developed, with some of them already commercialized, large quantities of ASR are still commonly landfilled. This study concludes that for ASR the most sustainable alternative to the present landfill practice, both in short and long term perspective, consists of recycling combined with energetic valorization of the residual fraction.

Sustainability analyses of systems are successful when one can ascertain unambiguous overall superiority of a state of a system compared to alternative states. These alternative states can be system conditions over time intervals, or alternative products or processes for the same function or market application. In such analyses, indicators or metrics that satisfactorily characterize the system can be used to obtain an aggregate index for easy decision making. Previously, the geometric mean of the ratios of the applied indicators was demonstrated to be useful in showing superior or inferior status of any specific state of the system compared to a chosen reference state. This multidimensional index D, in a pairwise comparison, however, does not work if any indicator can assume the value of zero, infinity, or negative numbers. The present work shows that by shifting the multidimensional reference point, this difficulty can be easily avoided. In addition, this technique of shifting the reference point also has been shown to work when the standard multidimensional Euclidean distance, i.e., the square root of the sum of the squares of the differences of the indicator values, appropriately normalized, is used to differentiate among competing alternatives for determining comparative sustainability. Two sets of data, one on fender designs for automobiles, and the other on alternate means of treating automotive shredder residues, were used to illustrate the application of the indicator integration.

Membranes containing reactive nanoparticles (Fe and Fe/Pd) immobilized in a polymer film (polyacrylic acid, PAA-coated polyvinylidene fluoride, PVDF membrane) are prepared by a new method. In the present work a biodegradable, non-toxic-“green” reducing agent, green tea extract was used for nanoparticle (NP) synthesis, instead of the well-known sodium borohydride. Green tea extract contains a number of polyphenols that can act as both chelating/reducing and capping agents for the nanoparticles. Therefore, the particles are protected from oxidation and aggregation, which increases their stability and longevity. The membrane supported NPs were successfully used for the degradation of a common and highly important pollutant, trichloroethylene (TCE). The rate of TCE degradation was found to increase linearly with the amount of Fe immobilized on the membrane, the surface normalized rate constant ( k SA ) being 0.005 L/m 2 h. The addition of a second catalytic metal, Pd, to form bimetallic Fe/Pd increased the k SA value to 0.008 L/m 2 h. For comparison purposes, Fe and Fe/Pd nanoparticles were synthesized in membranes using sodium borohydride as a reducing agent. Although the initial k SA values for this case (for Fe) are one order of magnitude higher than the tea extract synthesized NPs, the rapid oxidation reduced their reactivity to less than 20% within 4 cycles. For the green tea extract NPs, the initial reactivity in the membrane domain was preserved even after 3 months of repeated use. The reactivity of TCE was verified with “real” water system.

Developing clean and renewable energy resources ranks as one of the greatest challenges facing mankind in the medium to long term. The issues associated with developing non-fossil energy are intimately connected with economic development and prosperity, quality of life and global stability, and require smart strategies for sustainable development. This study presents a relative sustainability assessment of biodiesel, taking into account its full life cycle with the main goal of comparing alternative feedstocks, either currently used or promising for future use such as microalgae. A set of sustainability metrics relevant for biodiesel is identified using only the data available in the literature and taking into account all the three dimensions of sustainability: environmental, societal, and economic. Although this study does not attempt to identify which feedstock or process is the best, its procedural suggestions may be valuable to practitioners and policy makers seeking to identify the best alternatives. The conclusions, however, are limited by the availability and the quality of the data used in the analyses.

In this study, the influence of downstream pressure on the pervaporative removal of toluene from water was investigated. An unfilled and CBV 3002-filled PDMS membranes were compared with novel dense and porous SBS membranes. Experiments were performed by varying the downstream pressure from 1 to 40 mbar. The effect of fillers incorporation into the polymeric network of PDMS-based membranes was also studied. It was found that the performance factors of all examined membranes were dependent on downstream pressure. Both the water and toluene flux decreased with increasing downstream pressure, the former being more pronounced, resulting in increased membrane separation factors. Moreover, the partial fluxes of all examined membranes were linearly dependent on the vapor pressure difference between permeate and feed. From the analysis of the intrinsic membrane properties it was found that toluene sorption was enhanced at higher downstream pressures. This resulted in membrane swelling, and hence higher water permeability than expected; nevertheless increased the membrane selectivity. Incorporation of the CBV 3002 fillers into the PDMS network enhanced both toluene removal rate and separation performance as well as intrinsic membrane properties. For the porous SBS membrane the highest toluene flux and permeability was obtained, but the lowest separation efficiency. The dense SBS membrane showed similar separation factors as the PDMS-based membranes, although a significantly higher toluene removal rate was observed.

The processing of kiwifruit for obtaining products with a higher sensory quality, to be used in the food industry, is associated with the use of techniques which can limit the physical and chemical losses of aroma compounds. Pervaporation (PV) represents an alternative to the techniques based on distillation/evaporation or partial condensation to concentrate the aroma compounds preserving the molecule integrity (mild operational conditions used), having a high selectivity towards the organic volatile compounds, and respecting also the environment. The most representative volatile compounds of the kiwifruit aroma was chosen for evaluating the pervaporation process. SPME‐GC/ion trap mass spectrometry method was exploited to determine the amounts of these compounds. The approach was based on chemical ionization acquisition with isobutane as reagent gas and 1‐heptanol and (Z)‐3‐hexen‐yl acetate as internal standards. In these conditions, the calibration curves were satisfactory as demonstrated by the R2 values of the straight lines (0.9937–0.9999). A kiwifruit fresh juice was processed by pervaporation through the composite commercial membrane (GFT1070) and the one self‐prepared, made of styrene butadiene co‐styrene (SBS), at three different feed temperatures. Marked effects for both membranes were observed in the total and partial fluxes of aroma compounds as the temperature was increased. The studied aroma compounds were differently affected by the temperature changes during PV process, with the result of a change in concentration in the permeate of the aroma compounds recovered.

In sustainability analysis of multidimensional states of a system, it is required to establish the relative superiority of one of the states. Particularly when a finite number of quantitative metrics is used to characterize the system, the values of the metrics among the states can exhibit increasing and decreasing trends at the same time, creating difficulty in clearly preferring one to the other. Sometimes, unequal weighting factors are ascribed to metrics to show the relative importance of the metrics, further complicating the comparison. It has been deemed desirable to consolidate all the usable metrics into one aggregate metric to make this comparison easier. Such an attempt is provided here by expressing the aggregate metric as the geometric mean of the ratios of the individual metrics for pair-wise comparisons. This computation was applied to previously reported evaluations of processes with a finite number of metrics. The method also reveals the sensitivity of the aggregate metric to the individual metrics and to the weighting factors.

We have only one planet in which to live. Because of accelerating use of limited natural resources, its attendant environmental degradation, and societal inequity that has resulted among groups of people as well as that which will result between present and future generations, we generally recognize that the current development patterns are not sustainable for the long term. This realization calls for satisfying our needs by judiciously using renewable resources, recycling wastes and end-of-life products for beneficial uses, and reversing environmental degradation in some areas and minimizing environmental impacts in others. As new scientific and technological innovations are exploited to implement these goals, tools and methods are needed to ascertain that the direction of economic development for meeting increasing standard of living is protective of human life and ecology. Countries that are economically developed, and therefore wealthy, are in a better position to protect the environment than are the developing countries. This situation calls for technologies that are not only benign but also affordable for the developing world. This is the grand challenge of this century. Some ideas on the elements of this grand challenge that are relevant to the practice of chemistry and engineering are discussed here.

Various materials (particles, resins, etc.) for Hg 2+ sorption from aqueous streams have been reported in literature. Conventional sorbents are relatively inefficient because only a fraction of the immobilized ligands are accessible for metal complexation. Thus, our approach was to use open structures (0.2 m pore size alumina microfiltration membranes), immobilized with various ligands containing single or multiple thiol functional groups. Alumina has good chemical and thermal stability and abundant surface hydroxyl groups, necessary for chemical modification. Convective flow was used for all functionalization steps and Hg 2+ sorption studies. Only 3-mercaptopropyl trimethoxy silane has been immobilized by direct silylation; the other ligands (cystine, cysteine, polycysteine, polyglutamic acid) required intermediate steps. Thus, via silylation with 3-glycidoxypropyl trimethoxy silane the membrane surface was functionalized with epoxy groups, which then reacted with the terminal amine group of each of the 4 ligands mentioned previously. In the case of polyglutamic acid, the carboxylic acid groups were activated with dihexylcarbodiimide and further reacted with cysteine, making it possible to synthesize a polythiol containing 240 repeat units. Hg 2+ sorption studies on single thiol-functionalized membranes were used to analyze the interaction between Hg 2+ and various functional groups. In addition, it was determined that Hg 2+ bound to weak sites (disulfide, carboxylic acid) can be quantitatively removed by washing the membrane with water at pH = 3, making it possible to quantify the amount bound to the active sites (thiol). Polythiol-functionalized membranes showed high sorption capacities, high site accessibility, and fast sorption rates. © 2004 Elsevier B.V. All rights reserved.

The objective of the study is the development of sorbents where the sorption sites are highly accessible for the capture of mercury from aqueous and vapor streams. Only a small fraction of the equilibrium capacity is utilized for a sorbent in applications involving short residence times (e.g., vapor phase capture of mercury from coal-fired power plant flue gases). So, dynamic capacity rather than equilibrium capacity is more relevant for these kinds of situations. Rapid sorption rates and higher dynamic capacity can be achieved by increasing the accessibility of active sites and decreasing the diffusional resistance to mass transport for the adsorbing species. This requires the use of open structured sorbent materials and attachment of functional groups on the external surface area of supports. The strong interaction of sulfur containing ligands (e.g., thiol) with mercury makes them suitable candidates for immobilization on these types of materials. In this study, inorganic oxide supports like alumina and silica are functionalized with thiol moieties like mercapto silane, cysteine and poly-cysteine for capturing mercury from aqueous and vapor phase. Aqueous phase Hg (II) sorption studies with cysteine/poly-cysteine functionalized silica showed that high dynamic capacity can be achieved by attaching active sites (thiol) on the external area of supports. Vapor phase Hg capture studies with thiol-functionalized mesoporous silica (Hg0 concentration = 3.37 mg/m3 with N2 as the carrier, gas temperature = 70 °C) yielded a capacity of 143 μg Hg/g for the sorbent. Although the sulfur content for the sorbent was low (0.80 wt. %) the molar ratio of Hg captured to sulfur was comparatively high (2.86×10−3) pointing to the high accessibility of sulfur sites.

Since the publication of the report entitled, Our Common Future, under the auspices of the World Commission on Environment and Development (WCED), also known as the Brundtland Commission, it has been generally acknowledged that the increasing use of non-renewable resources to support an increasing population has created an unsustainable situation. Should this rate of use be maintained, two dire consequences will follow: first, the future generations will be unable to maintain a high standard of living, and second, developing countries will have less of an opportunity to bring their living standards to a level comparable to that of the affluent West. The practice of chemical engineering, perhaps more than any other technical discipline, involves the use of natural material and energy resources for the production of value-added articles and services of commerce, It is critically important that chemists and chemical engineers incorporate the ideas of sustainability into process and product design, manufacturing, and value chain management for the purpose of minimizing resource utilization and adverse environmental impact. This paper deals with the ideas of sustainability, and what chemists and chemical engineers can do to prevent the consequences of unsustainable resource utilization.