Air

The chemical properties of the volatile elements in groups 15 to 18 are outlined, showing how the the periodicicty of the properties of the elements shapes their chemistry. The manufacture of hydrogen and chlorine is described, showing how mercury-free methods have been developed for the latter. The effect of the formation of atmospheric CO2 on atmospheric oxygen content is explained in terms of dissolution in the oceans. Remediation of the exhaust gases from internal combustion engines by catalysts to remove CO2, NOx and carbonaceous particulates is explained. Options for carbon capture and storage by physical and chemical processes are evaluated, and examples provided of these processes in operation. Exploitation of the atmosphere for energy capture using wind turbines has been aided by the development of high performance magnets. The basis of these magnets and the role of rare earth elements is explained.

Study Guide

8.1 Overview 294 8.2 Chapter 1: Planet Earth 295 8.3 Chapter 2: The Palette of Elements 303 8.4 Chapter 3: Earth 309 8.5 Chapter 4: Air 313 8.6 Chapter 5: Fire 318 8.7 Chapter 6: Water 325 8.8 Chapter 7: Prospects 331 This book emanated from a course given within Chemistry degrees of the University of Southampton entitled ‘Sustainable Chemistry’. This was an optional course and could be taken by BSc students in their third year, MChem students variously in third or fourth years, and also by postgraduate students (MSc or MPhil). Mine was the first half of the course, its more general section. The course had a high uptake. The majority of the assessment was through a two-hour examination, but a significant component was by two short literature projects. Within each half of the course a small group (about four students) were given a topic about which they would provide a joint report (a three-page report as a pdf file) and five-minute presentation to the class using PowerPoint or pdf files. The assessment was based on criteria for the report, the presentation, and by peer assessment of their colleagues’ contributions. For this section of the course the topic was a particular element. For the allocated element the supply, production, application, long-term hazards, and possible alternatives were to be addressed. The reason for this is that it is a topic that needed to be owned by personal investigation....

Prospects for Planet Earth

Here the elemental spheres are considered against the context of plant Earth in 2019. There is good evidence that the global population might reach 11.2 billion by 2100 and stabilise later. The greenhouse emissions per person may have stabilised but the overall direction for anthropogenic emissions is upward. The protections to achieve a limit of 1.5 oC by 2100 envisaged a sharp drop in emissions in the 2020s, and that is not yet projected. Polar ice loss is increasing and annual sea level rise is ca. 3.4 mm. Energy consumption in 2018 was dominated by fossil fuel sources. However, the annual growth rate in renewable energy provision was ca. 15% in that year; the annual growth in solar power generation was ca. 30%. Wind and solar power are evidently the technologies available to effect reductions in emissions in the coming decade.

Planet Earth

The pressure on planetary resources is substantially driven by increases in energy demands that have been mostly met by the combustion of fossil fuels. The basis of the warming in the troposphere is explained starting from the molecular structure of atmospheric components and their resulting rotational and vibrational spectra. From the absorptions in the infrared, the radiative efficiencies of atmospheric gases can be established. The residence times of gases in the atmosphere is explained on the basis of their atmospheric chemistry. Taking these factors together with atmospheric concentrations, the Global-Warming and -Temperature Potentials can be derived. The overall energy balance in the atmosphere is shown and the resulting net radiative forcing. The principle of the sustainability triangle is explained showing that reduction in radiative forcing may be achievable by a summation of contributions.

Earth: Minerals to Materials

The periodicity shown by selected elements in the s-, p-, d- and f-blocks in the Periodic Table is considered. The particular elements chosen include those with significant levels of use that can affect greenhouse gas emissions - either up or down. These include lithium, aluminium, silicon, iron, cobalt, platinum, neodymium and uranium. The means of extraction, formation and purification of the solid elements are discussed. The structural chemistry and energetics involved are elaborated, and estimations of the embodied energy of the elements presented. In terms of properties, the basis of magnetic materials is introduced; in terms of process, the concept of exergy is introduced. The large scale structural materials cement and glass are also discussed.

Water

The physical properties of water provide a framework for many day-to-day experiences: including the energy intrinsic to the melting and boiling of water, and in the increase in vapour density with temperature. The availability of freshwater is sequestered mainly in ice caps and groundwater and most readily acquired water emanates from the rainwater that falls on land. The demands of water for processing (Virtual water) are substantial. Extension fo water supply by desalination of seawater by reverse osmosis is explained. Options for extraction of minerals from seawater are also developed. The challenges posed by heavy elements, pharmaceuticals and plastics on wastewater treatment and drinking water supplies are elaborated

Fire

Approaches towards substituting fossil fuel sources of their products, energy and petrochemicals are elaborated. Synthesis gas (CO/H2) provides an intermediate for reconverting waste (from plastics and biomass) as well as carbon fuels into petrochemicals from methanol to petrol to waxes. Energy sources such as nuclear power and photovoltaic cells are explained. Modes of forming hydrogen and avoiding the release of greenhouse gases to afford a green fuel are explained. Electrochemical methods provide secondary energy sources are alternatives are compared: e.g. by powering transport using fuel cells or batteries. The demands of these technologies on the supplies of key elements like lithium and cobalt are discussed to understand whether developments may or may not be sustainable.

The Palette of Elements

The supply of the known 118 elements is considered in terms of their abundance in the universe and in the Earth?’s crust, the availability of minerals and their formation of elements from natural and induced transmutation. The blocks of the elements of the Periodic Table are analysed to consider whether their availability is such that can allow them to participate in solutions of the pressure on resources on the Earth. The roles of the elementary properties, radii, ionisation energies and electronegativities in affording the characteristics of the elements, including conductivity properties, are explained. The factors influencing the properties of compounds that affect their modes of extraction, such as their energetics, solubility and oxidation state stability are also discussed.