LIQUID-PHASE CATALYST FREE AEROBIC-PEROXIDE OXIDATION OF DECALIN AND ADAMANTANE@DECALIN (1:10) SOLUTION

Hormones occur naturally in humans, animals, and plants, but estrogens in contraceptives and hormone replacement therapy, those given to agricultural animals, and industrial chemicals that mimic estrogen add to the enormous volume of biologically active compounds in the environment. These compounds are among the PPCP (pharmaceutical and personal care product) category of contaminants that, when excreted, make their way into surface and ground-water, wastewater treatment plants, and, eventually, back into drinking water supplies. Now scientists are looking to catalysts called Fe-TAML® (iron plus tetra-amido macrocyclic ligand) activators as a promising way to remove these contaminants from wastewater.

The main objective of this study was to evaluate the potential of sodium percarbonate and sodium perborate utilization during repulping of old news and magazine paper mixture. A series of experiments were performed to determine the effects of bleaching agents on ISO brightness and ink removal efficiency of pulp after flotation deinking. Conventionally, with other parameters are constant, the ISO brightness of pulp was increased from 45.24% to 54.10% and ink elimination ratio at 950 nm of pulp was increased to 69.12% with 1% sodium hydroxide and 1% (as active oxygen content) hydrogen peroxide usage. However, when sodium percarbonate was utilized instead of hydrogen peroxide (as 1% active oxygen content) without alkaline addition, the ISO brightness of the pulp was increased to 55.00%. Also, unlike the other bleaching agents, a favorable effect of sodium percarbonate on ink detachment was observed. The ink elimination ratio of floated pulp was increased to 74.31% with 1% (active oxygen) sodium percarbonate addition without alkaline usage. There were no additive effects of sodium perborate usage on brightness, and ERIC value of pulp could be determined. In this respect, sodium percarbonate utilization without sodium hydroxide addition was proposed for effective repulping, deinking, and prebleaching of waste papers, in a similar manner to the use of hydrogen peroxide.

Recent years have seen a disheartening string of revelations in which everyday items once considered safe—food packaging, toys, clothes, furniture, electronic components, and many more products—are found to contain carcinogens, endocrine disruptors, and other harmful chemicals.1 Growing demand for healthier alternatives, already seen in food production and housing construction,2 is also happening at the building-block level of manufacturing, where so-called green chemistry represents a revolutionary change in preventing pollution and health problems starting at the chemical design stage. Many industry and government entities are beginning to espouse the principles of green chemistry on their websites and in public statements. Now comes the task of crafting policy to put those principles into action. The U.S. Environmental Protection Agency (EPA) defines green chemistry as “the design of chemical products and processes that reduce or eliminate the use or generation of hazardous substances. Green chemistry applies across the life cycle of a chemical product, including its design, manufacture, and use.”3 Green chemistry also aims to mitigate the type of uncertainty Alan Gold-berg, a professor of toxicology at the Johns Hopkins Bloomberg School of Public Health, recently described to The New York Times: “I can get [toxicity] information on only 20 percent of chemicals we interact with on a daily basis.”4 Of that 20%, he now says, he may be able to find information on overt toxicity for about half, but for details on specific effects such as developmental neurotoxicity, the figure shrinks toward zero. So what does green chemistry look like? Consider the example of pregabalin, the active ingredient in the neuropathic pain drug Lyrica®. Pfizer developed an alternative green-chemistry process that converted several steps of pregabalin synthesis from use of organic solvents to water. That reduced both health hazards and production heating requirements. With the new synthesis, waste from the process dropped from 86 kg of waste per kg product to 17 kg, and energy use dropped by 82%.5 Proponents say that’s how the field can offer a win–win–win solution: good performance, lower cost, and less environmental impact—what Richard Engler, program manager of the EPA Green Chemistry Program, calls the “triple bottom line.” For many, a standard is a logical next step. “At some point you have to go beyond a definition and principles,” says Engler. “I think that’s something the standard will enable.”

Nowadays, it is clear that the target of creating a sustainable future for the next generations requires to re-think the industrial application of chemistry. It is also evident that more sustainable chemical processes may be economically convenient, in comparison with the conventional ones, because fewer by-products means lower costs for raw materials, for separation and for disposal treatments; but also it implies an increase of productivity and, as a consequence, smaller reactors can be used. In addition, an indirect gain could derive from the better public image of the company, marketing sustainable products or processes. In this context, oxidation reactions play a major role, being the tool for the production of huge quantities of chemical intermediates and specialties. Potentially, the impact of these productions on the environment could have been much worse than it is, if a continuous efforts hadn’t been spent to improve the technologies employed. Substantial technological innovations have driven the development of new catalytic systems, the improvement of reactions and process technologies, contributing to move the chemical industry in the direction of a more sustainable and ecological approach. The roadmap for the application of these concepts includes new synthetic strategies, alternative reactants, catalysts heterogenisation and innovative reactor configurations and process design. Actually, in order to implement all these ideas into real projects, the development of more efficient reactions is one primary target. Yield, selectivity and space-time yield are the right metrics for evaluating the reaction efficiency. In the case of catalytic selective oxidation, the control of selectivity has always been the principal issue, because the formation of total oxidation products (carbon oxides) is thermodynamically more favoured than the formation of the desired, partially oxidized compound. As a matter of fact, only in few oxidation reactions a total, or close to total, conversion is achieved, and usually the selectivity is limited by the formation of by-products or co-products, that often implies unfavourable process economics; moreover, sometimes the cost of the oxidant further penalizes the process. During my PhD work, I have investigated four reactions that are emblematic of the new approaches used in the chemical industry. In the Part A of my thesis, a new process aimed at a more sustainable production of menadione (vitamin K3) is described. The “greener” approach includes the use of hydrogen peroxide in place of chromate (from a stoichiometric oxidation to a catalytic oxidation), also avoiding the production of dangerous waste. Moreover, I have studied the possibility of using an heterogeneous catalytic system, able to efficiently activate hydrogen peroxide. Indeed, the overall process would be carried out in two different steps: the first is the methylation of 1-naphthol with methanol to yield 2-methyl-1-naphthol, the second one is the oxidation of the latter compound to menadione. The catalyst for this latter step, the reaction object of my investigation, consists of Nb2O5-SiO2 prepared with the sol-gel technique. The catalytic tests were first carried out under conditions that simulate the in-situ generation of hydrogen peroxide, that means using a low concentration of the oxidant. Then, experiments were carried out using higher hydrogen peroxide concentration. The study of the reaction mechanism was fundamental to get indications about the best operative conditions, and improve the selectivity to menadione. In the Part B, I explored the direct oxidation of benzene to phenol with hydrogen peroxide. The industrial process for phenol is the oxidation of cumene with oxygen, that also co-produces acetone. This can be considered a case of how economics could drive the sustainability issue; in fact, the new process allowing to obtain directly phenol, besides avoiding the co-production of acetone (a burden for phenol, because the market requirements for the two products are quite different), might be economically convenient with respect to the conventional process, if a high selectivity to phenol were obtained. Titanium silicalite-1 (TS-1) is the catalyst chosen for this reaction. Comparing the reactivity results obtained with some TS-1 samples having different chemical-physical properties, and analyzing in detail the effect of the more important reaction parameters, we could formulate some hypothesis concerning the reaction network and mechanism. Part C of my thesis deals with the hydroxylation of phenol to hydroquinone and catechol. This reaction is already industrially applied but, for economical reason, an improvement of the selectivity to the para di-hydroxilated compound and a decrease of the selectivity to the ortho isomer would be desirable. Also in this case, the catalyst used was the TS-1. The aim of my research was to find out a method to control the selectivity ratio between the two isomers, and finally to make the industrial process more flexible, in order to adapt the process performance in function of fluctuations of the market requirements. The reaction was carried out in both a batch stirred reactor and in a re-circulating fixed-bed reactor. In the first system, the effect of various reaction parameters on catalytic behaviour was investigated: type of solvent or co-solvent, and particle size. With the second reactor type, I investigated the possibility to use a continuous system, and the catalyst shaped in extrudates (instead of powder), in order to avoid the catalyst filtration step. Finally, part D deals with the study of a new process for the valorisation of glycerol, by means of transformation into valuable chemicals. This molecule is nowadays produced in big amount, being a co-product in biodiesel synthesis; therefore, it is considered a raw material from renewable resources (a bio-platform molecule). Initially, we tested the oxidation of glycerol in the liquid-phase, with hydrogen peroxide and TS-1. However, results achieved were not satisfactory. Then we investigated the gas-phase transformation of glycerol into acrylic acid, with the intermediate formation of acrolein; the latter can be obtained by dehydration of glycerol, and then can be oxidized into acrylic acid. Actually, the oxidation step from acrolein to acrylic acid is already optimized at an industrial level; therefore, we decided to investigate in depth the first step of the process. I studied the reactivity of heterogeneous acid catalysts based on sulphated zirconia. Tests were carried out both in aerobic and anaerobic conditions, in order to investigate the effect of oxygen on the catalyst deactivation rate (one main problem usually met in glycerol dehydration). Finally, I studied the reactivity of bifunctional systems, made of Keggin-type polyoxometalates, either alone or supported over sulphated zirconia, in this way combining the acid functionality (necessary for the dehydrative step) with the redox one (necessary for the oxidative step). In conclusion, during my PhD work I investigated reactions that apply the “green chemistry” rules and strategies; in particular, I studied new greener approaches for the synthesis of chemicals (Part A and Part B), the optimisation of reaction parameters to make the oxidation process more flexible (Part C), and the use of a bioplatform molecule for the synthesis of a chemical intermediate (Part D).

Hydrogen peroxide and applications in green hydrocarbon nitridation and oxidation

هدف از این مطالعه بررسی اثر روش استخراج به کمک مایکروویو بر بازدهی استخراج و بعضی از خصوصیات شیمیایی روغن جوانه گندم در مقایسه با روش متداول سوکسله بود. همچنین، روغن جوانه‌ گندم به‌عنوان یک آنتی‌اکسیدان طبیعی برای بهبود پایداری اکسایشی روغن ماهی کیلکا مورد بررسی قرار گرفت. ابتدا نمونه‌‌های جوانه گندم تحت پیش تیمار مایکروویو قرار گرفته و سپس عملیات استخراج با روش سوکسله انجام گردید. بازدهی استخراج، عدد صابونی، عدد اسیدی، عدد یدی و پروفایل اسیدهای چرب روغن جوانه‌ گندم استخراج شده با مایکروویو با روش متداول سوکسله مقایسه شدند. روغن جوانه‌ گندم در غلظت ppm 1000 به روغن ماهی کیلکا افزوده شد. روغن ماهی کیلکای فاقد آنتی‌اکسیدان نیز به‌عنوان نمونه‌ی کنترل در نظر گرفته شد. عدد پراکسید و آنیزیدین نمونه‌های روغن ماهی کیلکا طی 15 روز نگهداری در دمای 60 درجه سلسیوس اندازه‌گیری شدند. روش استخراج به کمک مایکروویو بازدهی استخراج روغن جوانه‌ گندم را 27-15% افزایش داد. ترکیب اسید چرب روغن جوانه‌ گندم استخراج شده به کمک مایکروویو مشابه با روغن استخراج شده با روش متداول سوکسله بود. عدد اسیدی و صابونی نمونه استخراج شده با مایکروویو به‌ترتیب 07/2% و 65/9% بیشتر از نمونه استخراج شده با سوکسله بود. عدد یدی در روش‌های استخراج با مایکروویو و سوکسله و به‌ترتیب برابر با 75/124 و 90/132 ‌گرم ید/100 گرم روغن بود. روغن جوانه گندم به شکل قابل توجهی عدد پراکسید، آنیزیدین و توتوکس روغن ماهی کیلکا را کاهش داد. زمان القاء و فاکتور حفاظت نمونه روغن ماهی کیلکا حاوی جوانه گندم (به‌ترتیب 20/120 ساعت و 42/1) به‌طور قابل توجهی بیشتر از نمونه‌ کنترل (به‌ترتیب 40/84 ساعت و 00/1) بود. به شکل کلی، روغن جوانه‌ گندم استخراج شده با مایکروویو می‌تواند به‌عنوان یک آنتی‌اکسیدان طبیعی جهت افزایش پایداری اکسایشی روغن ماهی کیلکا پیشنهاد شود.

Consumption of food containing cholesterol and saturated fatty acids such as butter can increase serum cholesterol and cause cardiovascular diseases. Therefore many efforts have been done for decreasing these constituents in foods. In this study, hazelnut and walnut powders were added to butter samples in amounts of 0 (not enriched sample), 10, 20 and 30% for evaluation of chemical characteristics (acid value, peroxide value and oxidative stability). Samples were then packed in 2 forms; vacuum and common packed and stored for 90 days at 5°C in refrigerator and were analyzed every 30 days. Adding hazelnut and walnut to butter samples caused significant increase in acid value of samples. Also rising trend of acid value in nut enriched samples was higher during storage. Control samples (without nut) showed higher peroxide value than nut enriched samples. During storage both control and nut enriched samples showed significant increase in peroxide value . Although all of nut enriched samples’ peroxide value were lower than standard limit during storage. Vacuum packed samples also showed lower acid and peroxide value than common packed samples. Adding nuts to butter samples also caused a decrease in oxidative stability of butter samples. This study shows that butter enriched in hazelnut and walnut can be introduced as a new and functional dairy product to consumers, because of its essential fatty acids content. Keywords: Butter, Walnut, Hazelnut, Oxidative Stability, Acid Value, Peroxide Value

Storage chemistry of palm oil and groundnut oil samples were studied for their quality over the course of storage time and their impact on quality and health. Palm oil and groundnut oil samples were subjected to different moisture contents (water concentration) for some time. The acid values (AVs), free fatty acid (FFA) values, peroxide (P.O) vales, and iodine values (IVs) were determined using standard methods of the American Society of Oil Chemistry monitored during this period. Results indicate that AVs, FFA, and IVs increase with moisture content. Secondly, the AVs, FFA, and IVs of palm oil are higher than those of groundnut oil. Thirdly, the AVs, FFA, and IVs are directly dependent on the moisture content of the oils and increase correspondingly with an increase in water content. Generally, palm oil was found to be more susceptible to spoilage during storage and more affected by lipid oxidation. It is recommended that a threshold limit aw of ? 0.21 for moisture content be the standard for stored edible oils. Consumers should avoid storing and eating palm oil stored for a long period.

Hydrocarbon and lipid oxidation in micro heterogeneous systems formed by surfactants or nanodispersed Al 2O 3, SiO 2 and TiO 2

Green chemistry and catalysis

Silk sericin microcapsules loaded with horseradish peroxidase (HRP) are prepared through protein self-assembly in a green environment containing enzymes to protect liver cells from alcohol damage. Load content and release dynamics of HRP in sericin microcapsules are investigated. The role of HRP-loaded microcapsules in hydrogen peroxide (H2 O2 ) degradation is demonstrated using electrochemical method. Furthermore, the effect of the HRP-loaded microcapsules on cells and intracellular reactive oxygen species (ROS) level is evaluated using an alcohol damage model in vitro. Results show that HRP can be loaded effectively in the sericin microcapsules and can be released ROS-responsively from microcapsules. Cell survival rate increases after suffering from alcohol damage due to the presence of HRP-loaded microcapsule, and the active oxygen content in cells is maintained at a stable level even when it remained in an environment with high alcohol concentration. We believe that the internalized sericin microcapsules maintain HRP activity intracellularly, allow controlled HRP release within a host cell, and show excellent ability in antioxidative stress injury.

Individual orthophosphates of copper (II) and nickel (II) were synthesized and a new method of synthesis was developed, and a new complex catalytic system based on them of the type xCu3(PO4)2×yNi3(PO4)2 - 50%Cu3(PO4)2∙50%Ni3(PO4)2 was obtained, which has the predicted optimal acidic surface properties and the corresponding active centers. The acidic properties of the surface of the obtained individual copper (II) and nickel (II) phosphates and complex copper-nickel phosphate catalytic systems and the distribution of active centers on them were investigated. The peculiarities of the influence of synthesis conditions and temperature on the composition, structure and acidic properties of the surface of the obtained catalysts, as well as the nature and character of the formation of active centers of different strengths, were studied. It is established that calcination of the new synthesized copper-nickel phosphate catalytic system in the studied temperature range (120-700оС) allows not only to carry out complete dehydration of the obtained crystalline hydrate, but also contributes to a gradual change in the value of surface acidity. This leads to the formation on the surface of the synthesized complex copper-nickel phosphate catalytic system 50%Cu3(PO4)2∙50%Ni3(PO4)2 acidic active centers of appropriate strength. The promoting role of nickel ions Nі2+ in the structure of the copper-phosphate catalyst was confirmed and the presence of a synergistic effect of both these phosphates on the value of acidity in the structure of the synthesized complex catalytic system was established. A new active and cheap acidic complex catalyst – 50%Cu3(PO4)2∙50%Ni3(PO4)2, which has the necessary structure, optimal acidic surface properties, and appropriate active centers, has been obtained; therefore, it can be used for research in the chemical industry as an active and efficient catalyst for the partial oxidation of hydrocarbons into valuable products. Keywords: catalysts; heterogeneous catalysis; phosphates; complex oxides; oxidation; n-alkanes; hydrocarbons; ethane; ethylene.

Mechanism of the effect of boric acid on liquid-phase oxidation of paraffin hydrocarbons

هدف از این پژوهش، مطالعه و بررسی ترکیبات شیمیایی و تغذیه ای پوسته و مغز هسته میوه پسته وحشی گونه خینجوک (Khinjuk) بود. برای این منظور، از پوسته و مغز هسته میوه به روش سرد با هگزان روغن گیری شد و پروفایل اسیدهای چرب با روش کروماتوگرافی گازی بررسی گردید. همچنین از روغن های استخراجی نگهداری شده به مدت 3 ماه در دمای اتاق، هر 30 روز آزمون های عدد پراکسید، عدد اسیدی و مقدار کلروفیل اندازه‌گیری شدند. از پوسته و مغز هسته خشک شده میوه به روش پرکولاسیون با اتانول عصاره گیری شد و میزان ترکیبات فنلی و قدرت مهار رادیکال‌های آزاد DPPH عصاره ها مورد ارزیابی قرار گرفت. همچنین عصاره ها در درصدهای 1، 2 و 3 درصد به روغن کلزا اضافه شدند و پایداری اکسیداتیو آن ها با دستگاه رنسیمت بررسی گردید. نتایج نشان داد نوع و درصد اسیدهای چرب غالب در پوسته و مغز هسته میوه به ترتیب اولئیک اسید 33 و 2/41، لینولئیک اسید 6/10 و 5/21، آلفالینولنیک اسید 6 و 1/3، پالمیتیک اسید 2/17 و 11، پالمیتولئیک اسید 1/13 و 1/3 بودند. میزان ترکیبات فنلی در پوسته و مغز هسته به ترتیب 6/25 و 3/6 میلی گرم اسید گالیک درگرم نمونه خشک بدست آمد. عدد پراکسید و عدد اسیدی در طول 4 ماه نگهداری به طور معنی داری افزایش پیدا کرداما مقدار کلروفیل در طول زمان به طور معنی داری کاهش پیدا کرد (01/0≥p ). بیشترین پایداری اکسیداتیو روغن کلزا مربوط به تیمار 3 درصد عصاره پوسته بود (05/0≥p ). عصاره پوسته تاثیر بیشتری بر مهار رادیکال های آزاد (88 درصد) نسبت به مغز هسته (75درصد) داشت که این دو می توانند ناشی از مقادیر بالاتر ترکیبات فنولیک پوسته باشد.

‡ To whose memory this paper is dedicated. Joe Breen was a leading pioneer of green chemistry. Following his retirement from EPA, Office of Pollution Prevention and Toxics, where he worked on asbestos, dioxins, and pollution prevention, Joe became Executive Director of the Green Chemistry Institute, a not-for-profit organization promoting environmentally benign syntheses and processing. His premature death on 19 July 1999 created a void in the Working Party team, but encouraged all of us to continue our mission, having in mind his passion for this work and his exquisite friendship.