Thermophilic Bioleaching Research Articles

Green extraction of nickel and valuable metals from pyrrhotite samples with different crystallographic structures through acidophilic bioleaching.

Nowadays, due to the strategic status of nickel in the global market, utilizing its disregarded resources like low-grade nickel containing pyrrhotite is of significant importance. A comprehensive set of experiments and analyses were performed to determine the bioleaching capability and mechanism for nickel extraction from hexagonal and monoclinic pyrrhotite. Over 95% Ni extraction was achieved from the hexagonal pyrrhotite sample. Ni extraction from the monoclinic sample reached its maximum value of 67% and 90% at 3% pulp density, with mixed mesophilic and moderately thermophilic cultures, respectively. Characterization analyses indicated that jarosite and elemental sulfur formation in mixed mesophilic bioleaching reduced the samples' bio-oxidation rate and metal dissolution. The kinetics study revealed that the controlling step in thermophilic bioleaching is the chemical reaction; however, the mixed control model was best fitted on mesophilic data. Electrochemistry studies confirmed bioleaching results and indicated that monoclinic pyrrhotite's oxidation rate under the operating conditions is faster than hexagonal pyrrhotite, and the temperature positively correlates with the oxidation rate. Toxicity assessment analysis showed that the final residues of both bioleached samples could be considered environmentally safe.

Comparison of extraction methods for extracellular polymeric substances (EPS) and dynamic characterization of EPS from sessile microorganisms during pyrite bioleaching

Extracellular polymeric substances (EPS) have many beneficial functions in the bioleaching process. A mixed culture of moderate thermophilic microorganisms was used to bioleach pyrite concentrate in a stirred tank reactor at a pulp density of 6%. Three physical methods (heating, ultrasound and vibration with glass beads) and three chemical methods (NaOH, H2SO4 and formaldehyde) were assessed for the extraction of EPS from sessile microorganisms. The parameter conditions for each method were optimised to obtain the optimal settings. The EPS content of each extract varied depending on the extraction method used. Cell lysis can be minimised by optimizing the extraction conditions. Results indicated that heating method outperformed other methods with low cell lysis and yielded 355.56 ± 116.56 ug/108 cells of protein and 16.72 ± 1.45 ug/108 cells of polysaccharides. Thereafter, this method was applied to extract EPS from pyrite surface during the bioleaching process. During pyrite bioleaching, extracellular proteins were the major component of EPS extracted from sessile strains. Confocal laser scanning microscope and scanning electron microscope showed that pyrite grains were wrapped by many extracellular proteins. Therefore, this research can provide a reference for the extraction of EPS from moderate thermophilic bioleaching systems by analysing the potential impact of extraction methods.

Novel bioleaching of waste lithium ion batteries by mixed moderate thermophilic microorganisms, using iron scrap as energy source and reducing agent

Low kinetic is one of the most important disadvantages of bioleaching. The leaching rate can be increased by employing thermophilic microorganisms. In this research, the moderate thermophilic bioleaching of waste lithium ion batteries (LIBs) at 45 °C was investigated. The effects of sulfur (S0) and ferrous sulfate heptahydrate (FeSO4.7H2O) were investigated on cobalt, nickel and lithium bioleaching mechanisms. The results showed that increasing sulfur concentration improves lithium recovery; while it has no effect on cobalt and nickel dissolution. On the other hand, FeSO4.7H2O increased cobalt recovery and its leaching kinetic significantly. Fe2+ increased cobalt recovery by acting as reducing agent. Just within 2 days of bioleaching with 24.25 g/l FeSO4.7H2O, the Co, Ni and Li recoveries reached 99.9%, 99.7% and 84%. To reduce the process cost, iron sulfate heptahydrate was replaced with iron scrap. In bioleaching process, scrap was leached and produced Fe2+ which in turn acted as reducing agent and increased cobalt and nickel recoveries. The results showed that the final metals recoveries for tests with scrap and chemical FeSO4.7H2O are similar. Using iron scrap increased the bioleaching time from 2 days to 6 days. The formation of a jarosite layer on the surface of scrap particles limited the releasing ferrous ions. The microorganisms prefer to oxidize iron scrap particles before waste LIBs particles. Comparing the results of bioleaching and leaching tests shows that Li was dissolved due to acid leaching, Co was dissolved due to oxidation-reduction reactions and Ni dissolved due to direct bioleaching mechanism.

Effects of sulfur dosage and inoculum size on pilot-scale thermophilic bioleaching of heavy metals from sewage sludge

Land application of sewage sludge has received significant attention in recent years but the presence of elevated heavy metals in the sludge limits its land application. The purposes of this study were to investigate the effects of sulfur dosage and inoculum size on the thermophilic bioleaching of heavy metals from sewage sludge in a pilot-scale bioreactor. The microbial communities in this thermophilic bioleaching process were also identified using real-time polymerase chain reaction (real-time PCR). The results showed that the oxidation of sulfur and metal solubilization decreased with the increasing sulfur dosage. When the sulfur dosage was greater than 2% (w/v), the sulfur oxidation and metal solubilization rates decreased, indicating that the thermophilic bioleaching was hindered by high levels of substrate. However, it was found that the efficiency of metal solubilization and solid degradation was increased with the increase of inoculum size in the range from 5% to 20%. At the end of bioleaching, the efficiency of Mn, Zn, Ni, Cu and Cr from the sewage sludge reached 73–100%, 51–60%, 38–52%, 17–43% and 1–38%, respectively, while SS and VSS were degraded by 33–48% and 47–67%, respectively. Based on the analysis of real-time PCR, Sulfobacillus acidophilus was observed to be the predominant species (13–67% of total bacteria), whereas the populations of Sulfobacillus thermosulfidooxidans and Acidithiobacillus caldus were accounted relatively low (<1%).

Biofilm dynamics and EPS production of a thermoacidophilic bioleaching archaeon

Bioleaching of metal sulfides represents an interfacial process where biofilm formation is important in the initial steps of this process. In technical applications of bioleaching, such as reactor leaching in the temperature range of 50 up to 90 °C and also in (self-heating) heaps, thermophilic archaea play an important role and often are the leaching organisms of choice. Nevertheless, to date there is little information available on the interactions between thermoacidophilic archaea and their natural mineral substrates such as pyrite. Especially for extracellular polymeric substances (EPS) of archaea and their biofilms in bioleaching environments information is rather limited. The present work focused on investigations of biofilm dynamics and EPS production of the thermoacidophilic archaeon Acidianus sp. DSM 29099 under bioleaching conditions. The results show that biofilms are dispersed non-homogeneously on pyrite. Large parts of the pyrite surfaces remain free of cells. Cell detachment from pyrite results in microbial “footprints” which, based on lectin binding assays, consist of mannose, glucose and fucose containing compounds. A monolayer biofilm develops on pyrite after 2–4 days of incubation. In addition, the pyrite surface is covered with a layer of organic compounds. EPS analysis indicates the presence of proteins, polysaccharides and uronic acids, the composition of which varies according to substrate and lifestyle (i.e. planktonic, biofilm cells). This report provides insight into EPS and biofilm characteristics of thermophilic archaea and improves understanding of the mineral-microbial-biofilm interfacial interactions in extreme environments. Moreover, the results on interaction dynamics of archaeal microbial consortia will facilitate the understanding of thermophilic bioleaching.

Preservation of salt-tolerant acidophiles used for chalcopyrite bioleaching: Assessment of cryopreservation, liquid-drying and cold storage

Microorganisms with importance to mineral biotechnology are commonly maintained through live culture maintenance, which can be labour intensive and expensive. Live culture maintenance can also result in contamination, genetic drift and loss of traits, or whole strains, that are crucial to some biotechnological applications. This study aimed to investigate alternative preservation methods, and to determine the best method required for the preservation of mixed microbial cultures capable of bioleaching chalcopyrite under salt stress. Live culture maintenance followed by cold storage at 4°C, liquid drying and temperature-controlled cryopreservation were used to preserve mesophilic (30°C), moderately thermophilic (45°C) and thermophilic (60°C) bioleaching cultures. Recovery of cells and bioleaching activity were determined following revival. Results were compared to cultures routinely maintained by subculturing. Across all temperatures, cryopreservation with 10% (v/v) glycerol as a cryoprotectant resulted in the highest post-revival cell recovery. Further research is required to determine if the microbial diversity in each culture is impacted by the preservation method employed.

Recovery of Cobalt as Cobalt Oxalate from Cobalt Tailings Using Moderately Thermophilic Bioleaching Technology and Selective Sequential Extraction

Cobalt is a very important metal which is widely applied in various critical areas, however, it is difficult to recover cobalt from minerals since there is a lack of independent cobalt deposits in nature. This work is to provide a complete process to recover cobalt from cobalt tailings using the moderately thermophilic bioleaching technology and selective sequential extraction. It is found that 96.51% Co and 26.32% Cu were extracted after bioleaching for four days at 10% pulp density. The mean compositions of the leach solutions contain 0.98 g·L−1 of Co, 6.52 g·L−1 of Cu, and 24.57 g·L−1 of Fe (III). The copper ion was then recovered by a solvent extraction process and the ferric ions were selectively removed by applying a goethite deironization process. The technological conditions of the above purification procedures were deliberately discussed. Over 98.6% of copper and 99.9% of ferric ions were eliminated from the leaching liquor. Cobalt was finally produced as cobalt oxalate and its overall recovery during the whole process was greater than 95%. The present bioleaching process of cobalt is worth using for reference to deal with low-grade cobalt ores.

Relationship between microbial community dynamics and process performance during thermophilic sludge bioleaching.

Heavy metals can be removed from the sludge using bioleaching technologies at thermophilic condition, thereby providing an option for biotreatment of wasted sludge generated from wastewater treatment. The purposes of this study were to establish a molecular biology technique, real-time PCR, for the detection and enumeration of the sulfur-oxidizing bacteria during the thermophilic sludge bioleaching. The 16S rRNA gene for real-time PCR quantification targeted the bioleaching bacteria: Sulfobacillus thermosulfidooxidans, Sulfobacillus acidophilus, and Acidithiobacillus caldus. The specificity and stringency for thermophilic sulfur-oxidizing bacteria were tested before the experiments of monitoring the bacterial community, bacterial number during the thermophilic sludge bioleaching and the future application on testing various environmental samples. The results showed that S. acidophilus was identified as the dominant sulfur-oxidizing bacteria, while A. caldus and S. thermosulfidooxidans occurred in relatively low numbers. The total number of the sulfur-oxidizing bacteria increased during the thermophilic bioleaching process. Meanwhile, the decrease of pH, production of sulfate, degradation of SS/VSS, and solubilization of heavy metal were found to correlate well with the population of thermophilic sulfur-oxidizing bacteria during the bioleaching process. The real-time PCR used in this study is a suitable method to monitor numbers of thermophilic sulfur-oxidizing bacteria during the bioleaching process.

Chalcopyrite Bioleaching at High Sulfate Concentrations

The efficiency of chalcopyrite bioleaching in a high sulfate background was evaluated using acidophilic microorganisms adapted to sulfate. The concentration of magnesium sulfate added to mesophilic, moderately thermophilic and thermophilic bioleaching tests was equivalent to 100, 40 and 80 g L-1SO42-, respectively. Biological copper extraction was highest at 45 °C (67 %), followed by 60 °C (54 %) and 30 °C (16 %). Quantitative x-ray diffraction (QXRD) analysis of the ROM ore and bioleached residues revealed the complete disappearance of pyrrhotite and a significant reduction of pyrite at all temperatures. Significant chalcopyrite was leached at 45 and 60 °C; however, no chalcopyrite was leached at 30 °C. As the bioleach did not plateau after 31 days, it is possible that higher copper yields may have been achieved with prolonged leaching.

Chalcopyrite leaching and bioleaching: An X-ray photoelectron spectroscopic (XPS) investigation on the nature of hindered dissolution

Chalcopyrite (CuFeS2) is both the most economically important and the most difficult copper mineral to (bio)leach. The main reason for the slow rate of chalcopyrite dissolution is the formation of a layer on the surface of the mineral that hinders dissolution, termed “passivation”. The nature of this layer is still under debate. In this work, the role of bacterial activity was examined on the leaching efficiency of chalcopyrite by mimicking the redox potential conditions during moderately thermophilic bioleaching of a pure chalcopyrite concentrate in an abiotic experiment using chemical/electrochemical methods. The results showed that the copper recoveries were equal in the presence and absence of the mixed culture. It was found that the presence of bulk jarosite and elemental sulphur in the abiotic experiment did not hamper the copper dissolution compared to the bioleaching experiment. The leaching curves had no sign of passivation, rather that they indicated a hindered dissolution. XPS measurements carried out on massive chalcopyrite samples leached in the bioleaching and abiotic experiments revealed that common phases on the surface of the samples leached for different durations of time were elemental sulphur and iron-oxyhydroxides. The elemental sulphur on the surface of the samples was rigidly bound in a way that it did not sublimate in the ultra-high vacuum environment of the XPS spectrometer at room temperature. Jarosite was observed in only one sample from the abiotic experiment but no correlation between its presence and the hindered leaching behaviour could be made. In conclusion, a multi-component surface layer consisting of mainly elemental sulphur and iron-oxyhydroxides was considered to be responsible for the hindered dissolution.

Mesophilic and thermophilic bioleaching of copper from a chalcopyrite-containing molybdenite concentrate

The purpose of this study was to evaluate the bioleaching of copper from a chalcopyrite-bearing molybdenite flotation concentrate using a shake flask technique and mesophilic and thermophilic microorganisms. The premise of the study was that Cu-bearing phases may be selectively solubilized through bioleaching from the bulk molybdenite for subsequent recovery from the leach solution. The composition of mineral salts in bioleach solutions was evaluated, but it did not have significant effects on the bioleaching. The addition of pyrite or a combination of sulfur and ferrous sulfate increased the redox potential and acid formation but did not have a major effect on the bioleaching of Cu. Statistical analysis indicated no significant differences in the bioleaching of copper between eight different mineral salt formulations amended with sulfur and ferrous iron. Silver at 69mg/l (added as Ag2SO4) enhanced the dissolution of chalcopyrite. The bioleaching of the molybdenite concentrate at 3% (w/v) pulp density yielded 97% dissolution of Cu in the presence and 55% in the absence of added Ag. Bioleaching at thermophilic temperatures (70°C) yielded up to 75% Cu dissolution from the concentrate at 6% (w/v) pulp density, whereas the yields were about 27% at mesophilic temperatures. On a mass basis, molybdenum dissolution exceeded copper leaching but the relative yields were <9%. If the molybdenite concentrate is upgraded by removing Cu through bioleaching, molybdenum loss into solution may be offset by recovering it from leach solutions.

Electrochemical simulation of redox potential development in bioleaching of a pyritic chalcopyrite concentrate

The majority of the world's copper reserves are bound in the sulphide mineral chalcopyrite (CuFeS2), but supply of the copper is hindered by the recalcitrance of chalcopyrite to (bio)leaching. The main reason for the slow rate of chalcopyrite dissolution is the formation of a layer on the surface of the mineral that hinders dissolution, termed “passivation”. The nature of this layer and the role of microorganisms in chalcopyrite leaching behaviour are still under debate. Moderately thermophilic bioleaching of a pyritic chalcopyrite concentrate was mimicked in an electrochemical vessel to investigate the effect of the absence and presence of microorganisms in copper dissolution efficiency. Data from the redox potential development during bioleaching was used to program a redox potential controller in an electrochemical vessel to accurately reproduce the same leaching conditions in the absence of microorganisms. Two electrochemical experiments were carried out with slightly different methods of redox potential control. Despite massive precipitation of iron as jarosite in one of the electrochemically controlled experiments and formation of elemental sulphur in both electrochemical experiments, the efficiencies of copper dissolution were similar in the electrochemical tests as well as in the bioleaching experiment. No passivation was observed and copper recoveries exhibited a linear behaviour versus the leaching time possibly due to the galvanic effect between chalcopyrite and pyrite. The data suggest that the main role of microorganisms in bioleaching of a pyritic chalcopyrite concentrate was regeneration of ferric iron. It was also shown that the X-ray photoelectron spectroscopy measurements on the residues containing bulk precipitates cannot be employed for a successful surface characterisation.

Effect of inoculum size on the rates of whole ore colonisation of mesophilic, moderate thermophilic and thermophilic acidophiles

Bioheap leaching of low grade copper sulphides has been applied successfully at the commercial scale for the extraction of copper from secondary sulphide minerals. It is important to optimise the inoculation of heaps in order to minimise the residence time required for the heap and to maximise extraction.Thermophilic bioleaching of the primary sulphide chalcopyrite poses an additional challenge of rising temperatures inside the heap demanding microbial succession. After heap start up, rising heap core temperatures make conditions less favourable for mesophilic microbial species, and the moderately thermophilic community succeeds them in the consortium. In turn, thermophilic microorganisms succeed the moderately thermophilic microbes as the higher temperatures are reached.A detailed understanding of the microbial colonisation of whole ore is necessary to optimise microbial succession during thermophilic bioleaching, as is that of microbial growth kinetics on whole ore. Most published research is focused on microbial growth rates of bioleaching organisms in liquid cultures; little work is reported on microbial colonisation of whole ore and subsequent microbial activity. To extend the information available on the microbial diversity and succession in a bioleaching habitat, a study of bioleaching microbes colonising the ore body is required.The aim of this work was to explore aspects of colonisation of low grade chalcopyrite ore at 23°C, 50°C and 65°C by acidophilic micro-organisms. Laboratory column packed bed reactors were designed to simulate heap leach environments and to provide a systematic way of studying microbial dynamics on whole ore. The effect of inoculum size and inoculation strategies on microbial activity established and the subsequent leaching performance were investigated under conditions that support mesophilic, moderately thermophilic and thermophilic microorganisms. A relationship was shown between the inoculum size and the culture time required to achieve Eh values greater than 700mV, especially at 23 °C and 65 °C. However, the culture time required to establish an active iron- (and sulphur-) oxidising culture was also influenced by ore type, irrigation rate and inoculum adaptation. The effect on effluent Eh, pH and dissolved iron levels is also discussed.

Bioleaching of a low-grade nickel–copper sulfide by mixture of four thermophiles

This study investigated thermophilic bioleaching of a low grade nickel-copper sulfide using mixture of four acidophilic thermophiles. Effects of 0.2g/L l-cysteine on the bioleaching process were further evaluated. It aimed at offering new alternatives for enhancing metal recoveries from nickel-copper sulfide. Results showed a recovery of 80.4% nickel and 68.2% copper in 16-day bioleaching without l-cysteine; while 83.7% nickel and 81.4% copper were recovered in the presence of l-cysteine. Moreover, nickel recovery was always higher than copper recovery. l-Cysteine was found contributing to lower pH value, faster microbial growth, higher Oxidation-Reduction Potential (ORP), higher zeta potential and absorbing on the sulfide surfaces through amino, carboxyl and sulfhydryl groups. X-ray Diffraction (XRD) patterns of leached residues showed generation of S, jarosite and ammoniojarosite. Denaturing Gradient Gel Electrophoresis (DGGE) results revealed that l-cysteine could have variant impacts on different microorganisms and changed the microbial community composition dramatically during nickel-copper sulfide bioleaching.

Removal of copper from molybdenite concentrate by mesophilic and extreme thermophilic microorganisms

Mixed mesophilic and extreme thermophilic bioleaching were evaluated to remove copper from the molybdenite concentrate. Bioleaching tests were carried out in shake flasks and in a 50-L bioreactor. The shake flask tests were performed with different inoculum size, solids density, pH, and temperature in order to identify optimum conditions. The highest amount of copper elimination, 75% was obtained with extreme thermophilic microorganisms (at 12% inoculation, 10% solids, 65°C and a pH of 1.5). The highest copper elimination by mesophilic microorganisms was 55% (at 12% inoculation, 5% solids, 30°C at pH 2). The optimum conditions in shake flask tests were applied to 7days batch tests in a 50-L bioreactor. Extreme thermophilic experiment gave the best copper elimination of 60% (at 12% inoculation, 10% solids, 65°C and pH 1.5). Mesophilic test removed 50% of the copper (at 12% inoculation, 10% solids, 35°C at pH 2).

Bioleaching and Electrochemical Leaching of a Pyritic Chalcopyrite Concentrate

Moderately thermophilic bioleaching of a pyritic chalcopyrite concentrate was mimicked in an electrochemical vessel. The bioleaching was carried out for 28 days at 45°C with 2.5% (wt/vol) solid content at pH 1.5. Data from the redox potential development was used to program a redox potential controller in an electrochemical vessel to reproduce the same leaching conditions in the absence of microorganisms. Despite precipitation of iron as jarosite and formation of elemental sulphur in the electrochemical experiment, the copper recoveries were almost the same in both experiments.

The Bioleaching Characteristics of Chalcopyrite with Different Genetic Types

The copper extraction yield from thermophilic bioleaching of chalcopyrite depends on temperature, pH, and the oxidation-reduction potential (ORP), the activity of the thermophile used, as well as on the different genetic type of the chalcopyrite used. The bioleaching characteristics of chalcopyrite from marine volcanic type and porphyry type, and the influence of genetic type on microbial community were studied. The results indicated that the bioleaching of chalcopyrite is controlled by the ORP rather than by the pH. The thermophiles composition of marine volcanic type bioleaching wasMetallosphaeracuprinaandSulfobus spHB59.Metallosphaeracuprinawas the dominate bacteria during porphyry chalcopyrite bioleaching. The different leachability between marine volcanic type and porphyry type is attributed to their nature which caused by genetic type.

Feasibility study on heap bioleaching of chalcopyrite

Bioleaching of chalcopyrite often encountered the formation of passivation layer, which inhibited the leaching process and resulted in a low leaching rate. This inhibitory effect can be eliminated by thermophilic bioleaching. The industrial test of BioCOP technology based on thermophiles was successfully completed, which confirmed the feasibility of chalcopyrite bioleaching. However, industrial leaching rate of chalcopyrite heap bioleaching is lower. This paper described the development status and industrial test of chalcopyrite heap bioleaching technology. The reasons for the lower efficiency of chalcopyrite heap bioleaching were analyzed. The strategies for successful chalcopyrite heap bioleaching were proposed.

Thermophilic bioleaching of heavy metals from waste sludge using response surface methodology

The bioleaching process is considered to be more efficient and environmentally friendly than conventional technologies for removal of heavy metals from waste sludge. The objective of this study was to develop an optimal thermophilic bioleaching process for the treatment of waste sludge containing high concentrations of heavy metals. In this study, two operating parameters, sludge solid content and sulfur (substrate) concentration, were studied based on a central composite design (CCD) for their metal solubilization and solid degradation performances. The optimal bioleaching operation conditions were then determined using the response surface methodology (RSM). The results indicated that an increase in sludge solid content range from 0.5% to 5.0% resulted in a decrease in the pH reduction rate due to the increase in buffering capacity. The rate of acidification corresponded to sulfur concentration until sulfur itself became inhibitory. At sulfur concentration beyond approximately 2.75%, the lower acidification rate was caused by a lower bacteria growth rate. Similar trends were also observed in the variations of ORP and sulfate concentrations during this thermophilic bioleaching process. At the optimum conditions of a sludge solid content of 0.5% and sulfur concentration of 2.5%, the thermophilic bioleaching process achieved the maximum solubilization of 97%, 99%, 99% and 78% for Cu, Zn, Ni and Pb, respectively. At the same time, the maximum SS and VSS destruction efficiency were 69% and 63%, respectively.

Heavy metals recovery from printed circuit board industry wastewater sludge by thermophilic bioleaching process

AbstractBACKGROUNDA large quantity of heavy metal contaminated wastewater sludge is produced during the treatment of printed circuit board (PCB) manufacturing wastewater. The PCB wastewater sludge containing high concentrations of heavy metals, such as Cu and Zn, increases the potential for metal recycling. Although bioleaching is indicated as a promising technology to remove metals from electronic scrap and waste PCBs, its application for metal recovery from PCB wastewater sludge is still very limited. The purpose of this study was to develop a thermophilic bioleaching process operated in a sequencing batch reactor (SBR) to recover heavy metals from PCB wastewater sludge.RESULTSThe results show that an increase in sludge solid content from 0.5 to 5% (w/v) decreased the rate of pH reduction during the bioleaching process. It was also found that the efficiency and rate of metal solubilization decreased with increasing sludge solid content. At a sludge solid content of 0.5% (w/v), after four repeated feed/decant cycles with 10 days per cycle (40 days) of SBR operation, the maximum efficiencies of metal solubilization in the treated sludge were 65% and 100% for Cu and Zn, respectively.CONCLUSIONThe solubilization efficiency of heavy metals was lower during SBR operation with a longer 20‐day cycle time. Therefore, a shorter 10‐day cycle time for SBR operation is preferred for the thermophilic bioleaching of PCB wastewater sludge. In the treated sludge, the potential mobility and environmental risks of heavy metals were decreased significantly after the thermophilic bioleaching process. © 2013 Society of Chemical Industry