Scientific Symposium Today on Green Chemistry and the Environment

EMBARGOED FOR RELEASE: Monday, Sept. 9, 2013, 9 a.m. Eastern Time Note to journalists: Please report that this research was presented at a meeting of the American Chemical Society. A press conference on this topic is tentatively scheduled for Sunday, Sept. 8, at 2:30 p.m. in the ACS Press Center, Room 211, in the Indiana Convention Center. Reporters can attend in person or access live audio and video of the event and ask questions at www.ustream.tv/channel/acslive.

Newswise — INDIANAPOLIS, Sept. 9, 2013 — Chemical processes are involved in production of almost 96 percent of all manufactured goods, and some of the latest advances in efforts to redesign those processes from the ground up are on the agenda here today at the 246^th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society.

Those efforts — called "green chemistry" or "sustainable chemistry" — involve the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. Green chemistry involves a range of efforts such as using renewable raw materials, switching to production processes that work at room temperature and use less energy, and minimizing or eliminating toxic waste from the outset, rather than clean up afterwards.

ACS is holding a symposium, "Green Chemistry and the Environment," during the meeting, which continues through Thursday in the Indiana Convention Center and downtown hotels. It is being held here today at the 246^th National Meeting & Exposition of the ACS. Thousands of scientists and others are expected for the event, which features almost 7,000 reports on new discoveries in science and other topics.

Among the topics:

• Using banana-peel powder to remove lead and other potentially toxic metals from water.
• Sustainable production of nanoparticles used in energy harvesting.
• Green processes for producing nanomaterials.
• Using mechanical force, rather than solvents and catalysts, to synthesize medicines.

Abstracts in the symposium appear below.

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Abstracts

Reuse of waste coffee grounds to produce biodiesel and purification material 

Biodiesel, as one of the renewable energy, is increasing in production in recent years. Biodiesel reduces the emission of carbon monoxide, hydrocarbons and total particular matters as compared with petroleum diesel. In this study, waste coffee ground (WCG) was reused to produce biodiesel. In the US, the average coffee consumption was 24.2 gallons per person in 2008. Since WCG is disposed as waste at this point, to obtain WCG as biodiesel feedstock comes at negligible cost for the biodiesel producers. There were two goals to be investigated during this study. The first goal was to extract oil from WCG. The transesterification process would convert triglycerides (oil) and alcohol to glycerin and biodiesel. During the experiment, variables included extraction time, types of solvent, and types of catalysts were examined. The WCG after extraction would be recovered and dried for purification purpose. The second goal was to examine the purification ability of the WCG. GC-MS was used to determine the composition of the biodiesel and the effectiveness of after-extraction WCG as the polishing material was examined by testing the fuel quality with respect to the ASTM D6751 standard for biodiesel. In addition, physical and chemical characteristics of the after-extraction WCG were examined. For example, BET test was used to examine the surface area of the after-extraction WCG. The preliminary results showed that the oil extracted from WCG was between 8.37-19.63% and the efficiency of using the after-extraction WCG as purification material to remove methanol, glycerin, Na+K, and Ca+Mg was around 50%.

Degradation of thermal properties of surface treated woven flax fibers 

Natural fibers offer an excellent choice to replace glass and carbon. The current research objectives are to find the optimal uses of the natural fiber and to address known challenges, such as high degree of moisture absorption and poor thermal stability. Surface modification by means of chemical treatment was carried out to remove components of natural fibers such as lignin, pectin and hemicellulose that contribute to the known challenges of natural fibers. In this research study, chemical treatments were used on a commercially obtained woven flax fiber. Alkali treatment were chosen for this project at various times and concentrations. The treatment analysis was divided into two phases: 1) Alkali treatment using potassium hydroxide varying the concentration between 1 and 5% for 30 minutes and 1 hour thus 1, 3, and 5% for 2, 4, and 8 hours, and 2) Analyze effects of the surface modification on the thermal properties. The Thermogravimetric analysis (TGA) data in the first and second stages of treatment show very little change in the degradation temperature, when compared to the neat at 353.29° C. The samples treated for 1 hour & 30 minutes showed a temperature increase from 362.51° C & 356.29° C respectively. A common pattern was noticed for all of the treatment times, where the 2 – 3 % batches decrease in temperature like the neat system, but still showed an increase. There was a 3 – 4% reduction in the amount of residue compared the neat samples at 18.17%. These results indicate that the treatment causes the amount of moisture to reduce, which leaves less char. Scanning electron microscope (SEM) was used to study specific treatment time and concentration where the fibers began to degrade the cell walls. From the SEM results, 3% KOH for 4 hours showed the best results.

Role of surface chemistry in the photocatalytic properties of carbon-doped TiO₂ 

Carbon-doped TiO₂ has been well studied as an efficient visible light photocatalyst. It can be prepared using nontoxic precursors under mild conditions. Various carbon precursors including glucose have been used to prepare Carbon-doped TiO₂. This work investigates the surface chemistry of the Carbon-doped TiO₂ in relation to its photocatalytic activity for visible light degradation of 2,4-diclorophenol (2,4-DCP) in water. Photocatalysts prepared from sucrose, glucose and fructose are observed by XPS and ToF-SIMS to deposit different surface carbon fragments and moieties following heat treatment. Catalysts with comparable bandgap energies were observed to display very different photocatalytic activity and product distribution. It was also observed that certain surface moieties such as carboxylic and carbonyl groups affect the adsorption of 2,4-DCP, and participate in the reaction.

Ultrasound as a basic and auxiliary process for dye remediation 

Ultrasonic treatment of recalcitrant contaminants has been of utmost interest recently due to the advantages of the cavitation phenomenon, which enhances the efficiency of Advanced Oxidation Processes (AOPs). The current review summarizes the use of ultrasound with biochemical, electro-chemical, ozonation, photolysis, photocatalysis and Fenton processes for the degradation of mostly textile dyes and dyebath. There are a few studies about ultrasonic degradation of textile effluents or wastewater due to highly variable contents. It was found that the most common use of ultrasonic irradiation for dye degradation is combined with the heterogeneous catalysts/adsorbents. The reaction mechanism of the ultrasonic irradiation in heterogeneous media was well investigated and understood. However, there is still lack of information about the reaction mechanism of ultrasonic irradiation in the homogeneous solutions, especially containing ferrous ions. Fenton reaction is already fast itself and gives effective degradation during the oxidation. Therefore, addition of ultrasonic irradiation to Fenton oxidation was less effective compared to other auxiliary processes. It should also be noted that ultrasonic irradiation had a negative effect on dye degradation during combined with electro-oxidation process.

Revealing the intermediates and pathways of microcystin-LR degradation under visible light TiO₂ photocatalysis 

Cyanotoxins are a concerning class of emerging contaminants. Recent anthropogenic activities are suspected to be responsible for increasing frequencies of the bacteria that produce these toxins, cyanobacteria. As their prevalence grows, cyanobacteria increasingly threaten drinking water sources around the world. Unfortunately, Microcystin-LR (MC-LR)—the most common cyanotoxin and also one of the most potent cyanotoxins—is inefficiently treated by conventional methods. Concurrently, a worldwide push for sustainable methods guides the search potential technologies for treatment of MC-LR. Photocatalysis using nitrogen- and fluorine-doped titanium dioxide (NF-TiO₂) shows great potential in this field. Without the nonmetal dopants, TiO₂ requires ultraviolet light to induce catalysis. Incorporating the dopants allows activation of the material by visible light. However, the underlying chemical reactions may change as well. This being the case, although the intermediate degradations products of conventional TiO₂ have been identified, it is very timely to consider an investigation of the corresponding intermediates for NF-TiO₂. This research explores the degradation intermediates of visible light-activated photocatalysis of MC-LR and results on reaction intermediates and pathways will be presented.

Understanding microbial biodegradability of green chemicals 

Green chemistry is a field that is inevitably interdisciplinary. Some goals of green chemistry, (low volatility, flammability), may be achieved by chemical design alone. However toxicity and biodegradability of green chemicals requires collaboration with toxicologists, microbiologists and ecologists. Our studies focus on ionic liquids (ILs) , a class of green chemicals with a variety of potential industrial uses. While ILs have low toxicity to aquatic organisms, they are often not biodegradable and may persist in the environment. ILs fulfill the majority of the Principles of Green Chemistry, but may require extra input to meet them all. The Pollution Prevention Act states that pollution should be prevented "at its source". Our group is working to develop a means of biodegrading ILs on-site, before release to a wastewater facility. By providing a green chemical and a biodegradation strategy, chemists and biologists can provide innovative solutions for sustainable chemical design.

Sustainable preparation of size-dependent metal nanoparticles and their applications in energy harvesting applications 

Quantized metal nanoparticles have gained increased attention due to their unique electronic, optical and chemical properties relative to their bulk materials. We have developed sustainable methods for the preparation of quantized metallic nanoparticles and studied their electron-storage properties. For example, by varying the nanoparticle size we found a dependence on the particle ability to store electrons and energy. These systems are ideal as they mimic natural photosynthetic systems in their ability to convert solar energy to chemical energy. The purpose of the study was to fabricate the nanoparticles in aqueous solution and to understand their size-dependent properties. The particles were found to store electrons that in turn could be used to remediate various organic pollutants.

Green synthetic pathways toward shape-controlled nanomaterials and their stability under various environmental conditions 

We report a facile, one pot, green synthetic process for developing size- and shape-controlled metallic and bimetallic nanomaterials, as well as studies to understand their interactions under various environmental conditions. Monodisperse metallic and bimetallic nanoparticles were fabricated at room temperature using environmentally friendly reaction conditions. These nanostructures were produced with controlled size, shape, composition, crystallinity, and structure (i.e. hollow vs. solid). Controlling the morphology of metal nanoparticles is essential toward understanding their structure-function properties especially under varying temperature, pH and ionic strength conditions. Shape control of metal nanomaterials is important because it allows one to tune their optical, magnetic, and catalytic properties. The synthesis of well-defined anisotropic nanoparticles under green reaction conditions is important toward advances in nanoscale synthesis. Characterization of the nanoparticles was carried out using high resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD), small angle electron diffraction (SAED) and energy dispersive spectroscopy (EDS).

On the properties of CO₂ and flue gas at the piperazinium-based ionic liquids interface 

CO₂ capture using ionic liquids is among the most promising alternatives for flue gases treatment, in particular, piperazine-based fluids have attracted great attention both in industry and academia. The reported results obtained in this work using molecular dynamics simulations allow to analyze the behaviour of CO₂ and a model flue gas at the interface of N-alkylpiperazinium-based ionic liquids. Density profiles across the boundary show changes in the orientation and ordering of involved ions at the interface, and thus, leading to changes in surface tension. Likewise, CO₂ / ionic liquids systems show strong accumulation of CO₂ molecules at the interface in short times, whereas crossing the interface and diffusing to the bulk ionic liquids is a slower process. For flue gas / ionic liquids systems CO₂molecules also accumulate at the interface, water molecules also tend to form a layer out of the interface, whereas the effect of the remaining flue gas components is not remarkable. The behaviour of the studied systems show the prevailing role of interfacial behaviour on the dynamic of CO₂ absorption processes for the studied ionic liquids.

Sonochemical production of biofuels using solid Lewis acid catalysis 

It is important that developing countries have a sufficient energy supply to promote growth in their economies. As a society, we encourage growth to reduce the problems associated with underdeveloped countries: poverty, mortality rate, social unrest, etc. Equally as important are the effects that the production and consumption of energy have on the environment. Biodiesel is a viable alternative to petroleum-based products. It is a renewable energy source that causes less pollution than traditional petroleum-based products. It is produced from biomass, which could be from plant sources or animal sources. Biodiesel is produced by combining methanol or ethanol with the fatty acids found in vegetable oil or the fat in animals in the presence of a catalyst. Traditionally, NaOH or KOH is used as the catalyst for making biodiesel. Using solid Lewis acid catalysts is a good alternative because they are recoverable. In the past, acid-based catalysts were considered to be inferior because they required high temperatures and longer times to produce biodiesel. Using ultrasound, this problem has been ameliorated. In this study, we have examined the use of high-intensity ultrasound to produce biodiesel fuel using six different oxide- and chloride-based Lewis acids as catalysts. The best performing catalysts, FeCl₃, CrCl₃, and SnCl₂ are all either soluble in water or in methanol. High yields of biofuels are produced in 1/10 of the time of traditional thermal reactions. In addition, unlike in the case of the classic base-catalyzed esterification reaction, the catalysts are recyclable and reusable. This technology thus results in a greener approach to the production of biofuels.

Utilization of treated abbatoir sludge as soil conditioner 

Abattoir sludge was collected, characterized and then treated using aerobic biological method. The treated sludge was mixed with organic fertilizers at varying proportions and then used for planting of maize seedlings. The growth of the plant was monitored for 30 days consecutively. From the results, the values for nitogen, phosphorus, potassium, iron and zinc were observed to be (16.34, 3.72, 161.91, 3.08 and 4.29) mg/kg respectively before treatment and the following values (18.6, 4.52, 199.2, 5.02 and 7.22) mg/kg respectively were obtained after aerobic treament.

Preparation and characterization of modified lignin for energy storage applications

Lignin, one of the most abundant and cheap natural biopolymers, can be efficiently converted to low cost porous carbon fibers. Although the mechanical properties of these lignin based materials limit their use in structural applications, these materials have great potential for use in the energy storage applications. In this work, Alcell lignin is chemically modified to generate porous carbon fibers suitable for use as battery anode materials. Lignin and modified lignin samples are characterized by NMR (¹³C and HMQC) which clearly show chemical changes in modified lignin samples. Thermo-gravimetric analysis (TGA) and differential scanning calorimetry (DSC) of modified lignin samples show higher thermal stability than that of the unmodified lignin.

Spectrophotometric determination of trace nitrite with a novel self-coupling diazotizing reagent J acid

Self-coupling diazotizing reagent was explored to replace the toxic reagents for clean chemistry. In the presence of potassium bromide at 25℃, nitrite reacted with J acid in hydrochloric acid producing diazonium salt and then coupled with excess J acid in the sodium carbonate solution yielding red colored derivatives. At wavelength of 500 nm, Beer's law was obeyed over the concentration range of 0.02∼0.60 μg·mL^-1. The molar absorptivity was 3.92×10⁴ L·mol^-1 cm^-1.

Hydrothermal liquefaction of Chlamydomonas reinhardtii: Influence of varying cell composition on liquid fuel yield and quality 

There is growing interest in microalgae-derived biofuel as a sustainable replacement for fossil fuels due to the advantages of microalgae as a feedstock, such as rapid growth rates, high biomass yields, and minimal nutrient requirements. Hydrothermal liquefaction (HTL) is a novel process that uses water as the reaction medium to convert biomass into biocrude oil under high temperatures and autogenous pressures (250-350^oC, 5-20 MPa). While there is extensive literature on the separate processes of microalgae cultivation and HTL conversion, little consideration has been given to synergistically optimizing cultivation and HTL processing in order to maximize both biocrude production (yield, quality, and net energy balance) and nutrient recovery. This study examines the influence of varying microalgae cell composition (lipid, protein, carbohydrate fractions) on HTL biocrude yield and chemical composition.Chlamydomonas reinhardtii, a model green alga, was cultivated under variable growth conditions (e.g., N-available vs. N-starved) to obtain biomass with variable cell composition, and harvested biomass was converted under typical HTL conditions (80 wt% moisture, 300^oC, 10-12 MPa, 30 min reaction time). Conversion products (biocrude, water, solid, and gas) were characterized to evaluate energy yield as biocrude and nutrient (N, P) recovery in aqueous and solid phase products. Results show that biocrude yield from cells grown under lipid-accumulating conditions was significantly higher than those grown under non-accumulating conditions, yet both products have similar elemental composition and higher heating values (31.8-32.2 MJ/kg). Results from this study will contribute towards understanding the interconnection between upstream cultivation and downstream conversion processes to establish a more complete biomass to biofuels model.

Establishing the role of carbon dioxide for extractions and processing in an integrated biorefinery 

This work explores the use of carbon dioxide (CO₂) in the context of a biorefinery for both the extraction and conversion of lipids into biodiesel and the potential applications and implications of using CO₂ for further chemical isolation. Supercritical carbon dioxide (scCO₂) has been shown to effectively and selectively extract triglycerides from microalgae. Further, a mixed pressurized carbon dioxide and methanol system with the use a heterogeneous catalyst has been shown to successfully transesterify triolein into methyl oleate, a fatty acid methyl ester (FAME) useful as biodiesel. Cloud point curves of the ternary system are reported to describe the complex phase behavior of this reaction. An experimental design was developed to explore the effects of system pressure, temperature, and methanol loading, all of which influence the system phase behavior. It was found that certain conditions were favorable for the successful conversion of triolein to methyl oleate and can be achieved at temperatures below 100˚C. Energy calculations suggest that this lower reaction temperature, as compared to previous work reported on supercritical methanol alone, may significantly decrease the required energy inputs of extraction and conversion steps of biodiesel production. Further the use of CO₂ in this system allows for selectivity of the FAME product. Differences in the reactivity of TG feedstocks allows for enrichment of certain FAME fractions and thus facilitates separations. These results when combined with previous results of scCO₂ extraction of lipid from wet biomass feedstocks advance the development of a one-pot extraction and conversion of biomass to biodiesel. This work fits within the context of a biorefinery where CO₂may be utilized for its selectivity for the extraction, conversion, and separation of fuel and value-added products.

Assessment of the catalytic activity of metallic and bimetallic nanoparticles in glass capillary microreactors 

We have developed a reliable protocol for in situ immobilization of PVP-stabilized palladium (Pd), ruthenium (Ru) and Pd-Ru alloyed nanocatalysts in glass capillary microreactors. The immobilization procedure is reproducible and robust, and promotes catalyst recovery and reuse with improved stability compared to the PDMS microfluidic reactors we used in our earlier work. The system can be used to efficiently and reliably evaluate intrinsic catalytic activity for selective hydrogenation of α, ß-unsaturated aldehydes under a variety of reaction conditions, and to assess kinetic parameters such as turnover frequencies and apparent activation energies. This continuous microreactor has enabled stable and more selective production of target intermediate products compared to batch reactors, as we have demonstrated in the hydrogenation of trans-cinnamaldehyde.

Sequester of toxic metal by banana peel powder

Banana can be considered as a heavily consumed fruit in the world. Their peels are in general disposed in the trash, and they possibly create a major agro-waste problem. Studies reported that they contain high amount of dietary fibers such as hemicelluloses and pectin polysaccharides that can act as adsorbents, and a variety of metal ions, primarily potassium, that can replace toxic metal ions from air, or water through ion-exchange, or physico-chemical adsorption. In this study, we will demonstrate the sequester capability of banana peel powder (BPP) for toxic metal ions, such as barium, silver, cadmium, lead, and nickel, from aqueous solutions. The effects of pH, retention time, and initial metal concentration on the removal capability of BPP were also studied. SEM/EDS, and FTIR studies have been also carried out as supporting data. We will also present our preliminary results for removal of air pollutants, such as aromatic hydrocarbons, using BPP.

Solid-state chemistry and mechanochemistry for clean, rapid, and efficient synthesis of porous and pharmaceutical metal-organic materials 

Reactions initiated and/or sustained by mechanical force (mechanochemical reactions) have evolved from a laboratory curiosity into a powerful alternative to conventional synthesis. [Friščić Chem. Soc. Rev. 2012 , 41, 3493.] The presentation will focus on catalytic, solvent-free synthesis of porous metal-organic frameworks (MOFs) and metallodrugs (e.g., Pepto-Bismol®) from the simplest precursors. Despite MOFs being one of the "hottest" areas of materials chemistry, factors controlling their stability and design remain unknown. This presentation will show how mechanochemistry and solid-state chemistry can be used to achieve the low-solvent and energy-efficient synthesis of MOFs, as well as to study factors controlling their stability and structure. The results of the first methodology [Friščić et al. Nature Chem. 2013 , 5, 66.] for in situ X-ray diffraction monitoring of reactions during mechanical milling will be presented, demonstrating how real time mechanistic studies lead to a higher understanding of mechanochemistry and improve the ability to design mechanochemical processes. Finally, a new, bioinspired technique of "accelerated aging" will be presented. Accelerated aging mimics the processes of biological mineralization (mineral neogenesis) to achieve a mild, solvent-free and low-energy route to metal-organic materials, specifically porous MOFs, directy from metal oxide or sulfide precursors.[Friščić et al. Nature Chem. 2013 , 5, 66.]