Safety culture has to be painstakingly built and assiduously nurtured. The recent spate of accidents in the chemical industry probably points to a breakdown in the safety culture. Complacence and overconfidence are arch enemies of safety. Digital tools of Industry 4.0 can be leveraged to enhance safety in multiple ways.

After a significant downtrend in the number of accidents and fatalities in the chemical industry in the years leading up to the pandemic, 2020 and 2021 have witnessed an unfortunate reversal. A major explosion in a chemical plant in Leverkusen, Germany, that killed seven people in July 2021, was eerily reminiscent of the notorious Seveso incident of 1976 due to the possible release of dioxin. A chemical leak in a Texas plant in July 2021 that killed two and injured thirty, is being regarded as the worst chemical accident since 2019. India witnessed a sudden spurt in accidents following the resumption of industrial activities after the lockdown restrictions were eased in mid-2020. 118 fatalities were reported in 64 accidents between May and December 2020. This unfortunate turn of events has extended into 2021 with 117 fatalities and 142 injuries reported from 52 industrial accidents between January and June. Even as this article was being drafted, a major fire broke out in Indian Oil refinery, killing three and injured more than 40. Poor safety awareness, lax implementation of safety protocols, inadequate risk assessment, large number of poorly trained contract workers and breakdown of emergency response systems are responsible for this setback.

Seveso Directive
On 10th July 1976, Dioxin, an extremely toxic chemical was released into the atmosphere from a reactor in a chemical plant on the Italian town of Seveso. Over the next few weeks, several people took ill and a large swathe of area around the plant to the extent of 17 square km was declared contaminated. Following this incident, the European Commission developed a legislation that is now famously known as the Seveso Directive. Formally adopted in 1982, the Seveso Directive soon became the gold standard for policy and legislation on industrial accidents in many countries across the world. In the aftermath of the Bhopal tragedy, the directive was amended in 1987 and 1988 to expand its ambit to include storage of hazardous substances. In 1996, Seveso II Directive came into existence and it laid down the requirements of a Safety Management System and planning for emergency. The Seveso III Directive, which was adopted in 2012, made the provisions more robust by strengthening the standards of inspection and recognising the community’s Right to Know. In September this year, the European Commission published its first report on the effectiveness of the Seveso Directive, which covers some 12,000 establishments across Europe. The report has come out with the very encouraging conclusion that the number of major accidents has continuously decreased between 2000 and 2018 to reach less than 25 per year.

Leverkusen Explosion
Ironically, just a couple of months before the release of this report, there was a major explosion in a plant in Leverkusen, Germany. Seven people died in the explosion that could be heard over a radius of 40 km. The accident occurred in a waste disposal plant and is being attributed to the negligence in handling and storing the waste. The accident raised the spectre of transboundary consequences should the toxic substances contaminate the nearly Rhine river. The accident prompted France to review and test its readiness in notifying the neighbouring countries in the event of a transboundary incident. The Leverkusen accident is yet another timely reminder of the challenges faced by the chemical industry as villages and towns expand and encroach into the sterile zone around hazardous chemical plants.

Illinois Incident
In September this year, the US Chemical Safety and Hazard Investigation Board (CSB) released its final report on the May 2019 accident at a specialty chemicals plant in Illinois, USA. The accident which killed 4 employees occurred during a batch operation that involved manually adding and mixing chemicals in a tank, a scenario that happens day in and day out in hundreds of MSMEs across our country. In the Illinois incident, the operator added a wrong chemical, which was incompatible with another chemical already present in the tank. The mistake happened because the two substances were stored in identical drums with poorly differentiated markings. The two incompatible chemicals resulted in a chemical reaction that released hydrogen which ignited causing an explosion and fire. CSB has attributed the incident to deficiencies in the company’s policies and practices including a weakness in process safety culture and lack of a safety management system.

Lessons from Illinois
In its recommendations, that ought to resonate through the Indian specialty chemicals sector, CSB suggests to put in place a system to manage chemical reactivity hazards covering the elements recommended by Centre for Chemical Process Safety (CCPS) of American Institute of Chemical Engineers. These include collecting reactivity hazard information, identifying chemical reactivity hazards and assessing their risks and testing for chemical reactivity. CSB wants companies to document chemical reactivity risks and use it for communication and training. Further, CSB has advocated the development of a gas detection and alarm programme for all hazardous gases that could be released in the work area. The programme should address proper installation, calibration, inspection, maintenance and training to ensure that the hazardous gas detection and alarm systems are functional at all times.

Digital Tools
Digital tools of Industry 4.0 are now being leveraged by big chemical companies in multiple ways to enhance safety. Internet Of Things (IOT) coupled with predictive analytics is significantly improving the Mean Time Between Failures (MTBF) of safety-related hardware. It is possible to use Artificial Intelligence for gleaning valuable insights from incident databases and unstructured near-miss reports. Digital Twins – virtual replicas of the physical plant – have been used for improved decision making and thus enhance process safety. Virtual Reality and Augmented Reality (VR/AR) platforms are now making it possible for plant operators to be trained in a safe, controlled and realistic environment and learn to respond to emergencies. Operators are plunged into simulatedenvironments that are otherwise too dangerous and expensive to recreate in real life. The trainer can also join the simulation and provide feedback in real time.

Afterword
Creating and nurturing a robust safety culture is a complex multi-layered and multidimensional endeavour. Safety management systems need to be regularly reviewed, audited and updated. Safety related hardware need to be regularly inspected, tested and maintained. Operators need to be continuously trained and retrained. Disaster management plans should be regularly reviewed and tested for preparedness to handle emergencies. Long incident-free periods can lull us into complacence and overconfidence.

Readers’ responses may be sent to:
k.sahasranaman@gmail.com or
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Decarbonising of the cement industry is a challenging but pressing problem as the demand for concrete is expected to grow unabated. Release of carbon dioxide is intrinsic to the process of cement manufacture, yet concrete with its ability to absorb carbon dioxide can become a global carbon sink. This month’s column examines the many dimensions of the cement-concrete conundrum.

If the cement industry were a country, it would be the third largest emitter of carbon dioxide in the world after China and USA and above India. The cement industry’s contribution to global warming is 8 percent. But unlike many other sectors, the emission from the cement industry is intrinsic to the manufacturing process. 60 percent of the carbon dioxide emitted in cement industry is released during the calcination process; the remaining 40 percent is contributed by the use of fuel and electricity. Thus decarbonisation of cement industry is extremely difficult as it cannot be achieved through change of fuel or higher energy efficiency.

Cement is the primary constituent of concrete, the second most consumed material in the world next only to water. The per capita consumption of concrete is threetons per annum. Twice as much concrete is used in construction than all the other materials combined. With infrastructure in much of the developed world rapidly approaching the limit of their useful life and an insatiable appetite in the developing world, the demand for concrete and cement is likely to grow unabated in the foreseeable future.

Carbon dioxide is released in the cement industry during the production of clinker by calcination of limestone. Substitution of clinker partially or even eliminating it completely is emerging as the main strategy for decarbonisation of the cement manufacturing process. Carbon dioxide capture and storage is another alternative. Also important are recycling and reuse of concrete and reducing the usage of concrete through design.

Clinker Substitution
The key ingredient of cement is clinker. Clinker is produced by calcination of limestone, a process that releases large quantities of carbon dioxide. Clinker production is also the most energy-intensive part of the cement manufacturing process. Typically, the cement specification lays down a range for clinker concentration and most cement producers have traditionally been erring on the side of caution and including more clinker than necessary to meet the specification. Closer a cement plant can get to the lower end of the clinker concentration range, lower would be its operating costs and carbon footprint. The average global clinker to cement ratio is currently 0.81. The balance is made up of gypsum and Supplementary Cementitious Materials (SCM). Among the SCM widely used today are blast furnace slag, fly ash from coal-fired boilers, calcined clay and natural pozzolans. It is estimated that the average clinker to cement ratio will fall below 0.60 by 2030.

Concrete without Cement
Carbicrete, a Montreal-based company has developed a technology to make concrete without using cement. Instead of cement, the company uses waste slag from the steel industry plus carbon dioxide captured from other industrial plants. The technology can thus stake claim for negative emission. During the curing of traditional concrete with water, the calcium oxide in cement reacts with carbon dioxide in atmosphere to form strengthened calcium carbonate. In Carbicrete’s technology, carbon dioxide captured from other industrial processes is injected to react with the calcium oxide present in the waste slag from steel industry. Though having exactly the same chemical composition, Carbicrete claims that concrete made this way has 30 percen higher compressive strength than the traditional concrete. However, Carbicrete’s technology can only be used in the controlled environment of a factory to produce precast concrete panels that can be delivered to a construction site. It cannot be used for production of ready-mix for on-site curing of foundations at the construction sites. Also the process depends on a steady supply of steel slag, which is not enough to meet the global demand of concrete.

Carbon Capture
Concrete has the potential to become a global carbon sink. This will happen when carbon capture utilisation and storage (CCUS) technologies mature to a level, where more carbon dioxide is captured and stored in concrete than is generated during its production. Carbon dioxide from a cement kiln or even from other external sources can be captured and injected into fresh concrete, where it becomes permanently embedded through a process of mineralisation and actually helps in improving the strength of concrete. Among the handful of companies that are working on this solution is the Canada-based CarbonCure, which has won the Carbon XPrize for the successful demonstration of a fully integrated CCUS solution, where the carbon dioxide from a cement kiln was used for the production of ready mix concrete.

Circular Economy
Concrete structures are now being recycled after demolition instead of being dumped in landfills. Recycled concrete is made up of several constituents, among them hardened cement paste together with fines from sand and aggregates. The hardened cement paste has hydrates rich in calcium that are able to react with carbon dioxide and form calcite, the main component of limestone originally used for cement production. Theoretically all the carbon dioxide released from limestone during calcination can be bound back by the hardened cement paste. But since the rate of carbonation is low, only half of the carbon dioxide gets bound, thereby creating an opportunity for perpetual recycling in a circular economy.

Embodied Carbon
Embodied carbon of an infrastructure project is the carbon dioxide emitted during its entire lifecycle. It includes carbon dioxide released during different phases of the project lifecycle – manufacture of building materials, transport of materials to the manufacturer, the manufacturing process, transport of manufactured products to the job site, the construction process, maintenance of the asset and finally demolition and recycling of waste. It is estimated that embodied carbon will account for 50% of the carbon footprint of all new construction from now and 2050. Cement is the biggest contributor to embodied carbon in the built environment. Several leading organisations including World Green Building Council have embarked on a mission to reduce embodied carbon in buildings. One of the easiest ways of achieving this is to alter the specification of concrete. At the recent COP26 in Glasgow, 5 countries – India, UK, Germany, Canada and UAE pledged to achieve net-zero in major public construction of steel and concrete by 2050.

Sustainable Specification
Concrete is a unique material in that the specifier has the ability to directly influence the constituents to ensure that the performance criteria are met while also satisfying the precepts of circular economy. Guidelines encompassing many considerations are available for designers to specify a concrete that is more sustainable.

Afterword
Energy consumption levels for clinker production are almost at the theoretical value. Nearly all the available SCMs have already been exploited for cement and concrete production. Also the energy transition will see a decrease in the availability of fly ash and blast furnace slag, which will become inadequate to meet the growing appetite for concrete. CCUS based solutions are currently the best approach for decarbonising the cement industry. Reducing concrete in construction, extending the service life of concrete and recycling and reuse of concrete at the end of their useful life are also extremely important ways of reducing the Embodied Carbon in our built environment.

Readers’ responses may be sent to:
k.sahasranaman@gmail.com or
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Electrochemical processes are energy efficient, safer and have a high atom economy. Coupled with the use of renewable electricity, electrochemical processes are a greener and more sustainable alternative for the production of chemicals. Electrochemistry also opens up hitherto uncharted pathways for synthesis of specific molecules of interest for agrochemical and pharmaceutical industries.

Michael Faraday laid down the laws of electrolysis in 1834 and Hermann Kolbe carried out the first organic electrosynthesis in 1848. While electrolysis is used for the large scale manufacture of caustic soda/chlorine and aluminium, electrochemistry has been received with lukewarm enthusiasm in the production of organic chemicals on an industrial scale. The largest commercial scale organic electrosynthesis process in vogue today is for the manufacture of adiponitrile, a precursor for Nylon 6,6. Commercialised in 1965 by Monsanto, the process involves electrohydrodimerisation of acrylonitrile to adiponitrile. With more and more electricity being generated from renewable resources at lower and lower costs, electrochemistry is experiencing a renaissance. Not only has electrosynthesis emerged as a potential tool in the sustainable manufacture of chemicals, it has also opened up novel mechanistic pathways for innovative chemical transformations. Electrosynthesis has many advantages over conventional methods of synthesising chemicals. It is energy efficient, inherently safe and eliminates waste. However, there are several barriers for the adoption of electrosynthesis in the mainstream chemical industry.

Greener Process
Redox reactions are an important technique for synthesising organic compounds and have been traditionally accomplished by the use of oxidising and reducing chemicals. This conventional approach inevitably leads to generation of waste, which often pose environmental concerns during disposal. Electrosynthesis achieves the redox transformation by replacing chemical reagents with electric current. Redox transformation through anodic oxidation and cathodic reduction does away with the use of oxidising and reducing chemicals and is thus a greener alternative. Another important advantage of electrochemical reactions is that they occur under milder conditions compared to traditional methods which require elevated temperatures and pressures. Electrosynthesis thus saves energy.

Safety
Electrochemistry also confers other advantages that are singularly lacking in conventional chemical processes. Electrochemical reactions are faster and thus require lesser residence time and smaller inventories. The reaction can be controlled with greater precision by manipulating the current or voltage. The reaction can also be stopped instantly by switching off the power. The improved control features coupled with the milder conditions make electrosynthesis safer than conventional processes.

Novel Platform
Besides offering a more sustainable and safer alternative, electrosynthesis provides a uniquely powerful platform to synthesise targeted molecules. Electrochemistry offers redox potentials that are incapable of being achieved by chemical oxidants and reductants. This allows creation of new reactive intermediates and currently unimaginable strategies to synthesise molecules with novel properties. Electrosynthesis enables enantioselective reactions and thus offers great value to agrochemical and pharmaceutical industries.

Energy Economy
Every electrochemical reaction consists of two half-reactions – the oxidation at anode and the reduction at cathode. The two half-reactions are linked to one another through electron transfer from cathode to anode through the electrolyte. But typically, only the anodic oxidation is utilised for synthesis and the cathodic reduction is frittered away. This reduces the energy economy of the overall electrochemical redox reaction. The energy economy can be improved if the reduction reaction at cathode can be gainfully utilised to create another product. This has led to the concept of “paired electrolysis”, in which both the half-reactions are used to produce desirable products at the anode and cathode. One way of achieving this is to carry out the electrolysis in a divided cell, in which the anode and cathode are separated by a semi-permeable membrane. For example, the oxidation of an alcohol at the anode can be matched with the reduction of unsaturated C-C bonds by the hydrogen released at the cathode. The same outcome can be realised by piping away the hydrogen liberated at cathode and carrying out the hydrogenation reaction in a separate reactor.

Flow Reactors
Electrosynthesis is best carried out in Flow Reactors (See Chemingineering – Small is Beautiful, June 2019). Electrochemical reactions are regarded as heterogeneous as they take place at the surface of electrodes. The two key requirements for an electrochemical reactor are a small interelectrode gap so as to minimise the ohmic drop in the electrolyte and having a sufficiently high flow velocity to avoid gas hold-up at the electrode. Flow Reactors will also facilitate easy scale-up from lab to commercial production.

Electrodes
Electrodes are at the core of electrosynthesis. Material of electrodes and their morphology are both important in determining the outcome of the electrochemical reaction. A wide range of materials have been studied by researchers. These include both non-metallic electrodes such as graphitic carbon as well as metallic electrodes. Transition metals such as copper and nickel and noble metals like platinum, palladium and ruthenium have been examined. The electrodes usually provide the oxidising or reducing equivalent of the chemical reagent, but sometimes play a catalytic role. In some situations, active transition metal catalysts are generated electrochemically at the electrodes to drive challenging reactions like C-C coupling and C-H activation. Chemoselectivity, the preference for one functional group over other competing groups, can be induced into redox transformations through the use of appropriately modified electrodes. For example, while carbonyl compounds were produced at a platinum anode, carbon-based anode yielded tetrahydrofuranes. Using different materials for electrodes coupled with appropriate surface modifications, innovative strategies can be developed for molecular synthesis.

CO2 Capture
Electrochemical reduction of carbon dioxide to carbon monoxide and subsequently to valuable feedstocks and fuels is emerging as a promising technology in the battle against global warming. Since the electrochemical reaction can be powered by renewable energy, the technology simultaneously provides an elegant solution to the problem of energy storage. The reduction occurs in the presence of a catalyst and a variety of catalysts have been examined. Catalysts are primarily of two types – transition metals and nanostructures. Copper has emerged as the most effective transition metal catalyst. However, it is plagued by poor efficiency and low stability. Nanostructures of copper supported on graphene have shown encouraging efficiencies in the electrochemical conversion of carbon dioxide to ethanol. Lack of a stable, efficient and inexpensive catalyst continues to be a major impediment in the commercialisation of this technology.

Afterword
A multinational consortium in EU called PERFORM has been set up with the objective of developing electrochemical processes for the production of chemicals from bio-feedstocks. Under this initiative, two demonstration projects are under development – one for electrochemical production of maleic acid from furfural paired with production of valeric acid from levulinic acid and the other to produce adipic acid from glucose.

Readers’ responses may be sent to:
k.sahasranaman@gmail.com or
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