Dr. Srećko Marač (1921-1985) : liječnik- psihijatar/psihoterapeut i pjesnik

Srećko Marač (Sušak, 1921. – Zagreb, 1990.). Nakon završetka sušačke gimnazije studira medicinu u Zagrebu i Padovi. Tijekom Drugoga svjetskog rata prekida studij i odlazi u NOR. Nakon rata završava studij u Zagrebu. Kao vojni liječnik radi u Bjelovaru i u Vojnoj bolnici u Zagrebu. Specijalizira psihijatriju i radi kao psihoterapeut u nekadašnjem Centru za mentalno zdravlje u Zagrebu.Godine 1973. objavljuje u vlastitom izdanju prvu zbirku pjesama – vlastiti izbor iz dugogodišnjeg rada – pod naslovom "Pjesme". Cilj je ovoga rada napisati cjelovitiji osvrt na tu zbirku pjesama izdanu 1973. po vlastitom izboru i nakladi. Gledalo se analizirati strukturu/kompoziciju zbirke, sadržaje, ugođaj i komunikativnost pojedinih njezinih dijelova. Kompozicijski je zbirka strukturirana u pet dijelova: Ad tyrannos, Iz partizana, Lutanja/traženja/snovi…, Satire i kušanja humora, More/brda i domovina. Umjesto zaključka valjalo bi se potruditi da ovaj liječnik-pjesnik, poeta neprijeporne književne ljepote i osoba puna ljudske dobrote, ne bude zaboravljen

Production of glycerol 1,2-carbonate from glycerol with aid of ionic liquid as catalyst

The surplus formation of glycerol (glycerine or 1,2,3-propanetriol) during biodiesel production has led to a major concern. Glycerol price has dropped and it exerts a great impact on the refined glycerol market. This has triggered an extensive research focus to find an innovative way to revalorize glycerol and transform to value-added chemicals. Yet, it is undeniably a necessary move towards achieving greener and sustainable processes. For instance, glycerol 1,2-carbonate (4-hydroxymethyl-1, 3-dioxolan-2-one) is currently one of the most celebrated glycerol derivatives that captured arising scientific and industrial attentions due to its extensive potential applicability. This cyclic ester of glycerol with carbonic acid is reasonably reactive as it has reactive electrophilic and nucleophilic sites yet having low toxicity and good biodegradability. This important product has attracted numerous applications in chemical industry such as being the novel component of gas-separation membranes, non-volatile solvent for dyes, lacquers, detergents, adhesives and cosmetics, electrolyte ingredient of lithium-based batteries, surfactants and lubricating oils. Likewise, glycerol 1,2-carbonate is beneficial not only as a polar high boiling solvent or intermediate for the synthesis of polycarbonates, polyesters, polyamides and hyper branched polyethers, it also can be used as green substitution for petro-derivatives compounds (ethylene carbonate or propylene carbonate). The reactivity of glycerol 1,2-carbonate having both electrophilic and nucleophilic sites allows for the synthesis of new polymeric materials such as glycidol which is primarily being used in the production of a number of polymers. Please click Additional Files below to see the full abstract

Selective Electrochemical Conversion of Glycerol to Glycolic Acid and Lactic Acid on a Mixed Carbon-Black Activated Carbon Electrode in a Single Compartment Electrochemical Cell

In recent years, the rapid swift increase in world biodiesel production has caused an oversupply of its by-product, glycerol. Therefore, extensive research is done worldwide to convert glycerol into numerous high added-value chemicals i.e., glyceric acid, 1,2-propanediol, acrolein, glycerol carbonate, dihydroxyacetone, etc. Hydroxyl acids, glycolic acid and lactic acid, which comprise of carboxyl and alcohol functional groups, are the focus of this study. They are chemicals that are commonly found in the cosmetic industry as an antioxidant or exfoliator and a chemical source of emulsifier in the food industry, respectively. The aim of this study is to selectively convert glycerol into these acids in a single compartment electrochemical cell. For the first time, electrochemical conversion was performed on the mixed carbon-black activated carbon composite (CBAC) with Amberlyst-15 as acid catalyst. To the best of our knowledge, conversion of glycerol to glycolic and lactic acids via electrochemical studies using this electrode has not been reported yet. Two operating parameters i.e., catalyst dosage (6.4–12.8% w/v) and reaction temperature [room temperature (300 K) to 353 K] were tested. At 353 K, the selectivity of glycolic acid can reach up to 72% (with a yield of 66%), using 9.6% w/v catalyst. Under the same temperature, lactic acid achieved its highest selectivity (20.7%) and yield (18.6%) at low catalyst dosage, 6.4% w/v

Enzymes in Biofuels Production

With the inevitable depletion of the nonrenewable resources of fossil fuels and due to their favorable environmental features, biofuels promise to be the preferred fuels of tomorrow. They can displace petroleum fuels and, in many countries, reduce the dependence on imported fuel. Biofuels, derived from biomass conversion, such as biodiesel, bioethanol, biohydrogen, and biogas, are sustainable and renewable sources of energy, which are also considered CO2 neutral. In addition, burning biofuels results in reduced levels of particulates, carbon oxides and sulfur oxides, emissions compared to fissile fuels

Production of lactic acid and glycolic acid in one-pot electrochemical cell

In recent years, due to the oversupply of glycerol globally, its price has dropped dramatically or become valueless. The aim of this study is to convert glycerol into high value-added compounds such as glycolic acid and lactic acid in one-pot electrochemical cell. The electrochemical process was carried out over platinum (as anode electrode) and activated carbon composite (as cathode electrode), with amberlyst-15 as reaction catalyst. The results obtained have proven that this simple method is applicable to produce glycolic acid and lactic acid in one step electrochemical process with a total product yield above 70 %. Finally, the overview reaction mechanism to the formation of these products was proposed. Please click Additional Files below to see the full abstract

Response surface optimization of conditions for clarification of carambola fruit juice using a commercial enzyme.

Response surface methodology (RSM) was employed for simultaneous analysis of the effects of enzymatic treatment conditions of incubation time, incubation temperature and enzyme concentration on physical characteristics such as turbidity, clarity, viscosity, and color. In this study, a two-factor central composite design was used to establish the optimum conditions for the enzymatic treatment for clarification of carambola fruit juice. Carambola fruit juice was treated with pectinase enzyme at different incubation time (20–100 min), incubation temperature (30–50 °C) and enzyme concentration (0.01–0.10 v/v%). These three variables were used as independent variables, whose effects on turbidity, clarity, viscosity and color were evaluated. Significant regression models describing the changes on turbidity, clarity, viscosity and color with respect to the independent variables were established with coefficient of determination, R2, greater than 0.70. The results indicated that the enzyme concentration was the most important factor affecting the characteristics of the carambola fruit juice as it exerted a significant influence on most of the dependent variables. The recommended enzymatic treatment condition from the study was at 0.10% enzyme concentration at 30 °C for 20 min

Atmospheric hydrodeoxygenation of bio-oil oxygenated model compounds:A review

Hydrodeoxygenation (HDO) of various bio oil oxygenated model compounds in low H2 pressure has been discussed in this study. Because of the high yield of aromatic mixtures in bio-oil, they carry great potential for fuel efficiency. Nevertheless, due to its high viscosity, abundance of acid, and heteroatom contaminants, the bio-oil ought to be upgraded and hydrotreated in order to be applied as an alternative fuel. A continuous low H2 pressure HDO of bio-oil is favored as it could be simply integrated with conventional pyrolysis systems, functioning at low pressures, as well as supporting a flexible plan for serial processing in respective bio-refineries. Additionally, such a process is cheaper and safer in comparison with the high pressure set ups. This review meticulously elaborates on the operation conditions, challenges, and opportunities for using this process in an industrial scale. The operating temperature, the H2 flow ratio, the active site, and the catalyst stability are some important factors to be considered when it is intended to reach a high conversion efficiency for the HDO in low H2 pressure

Development of Diamond Composite Electrode for Anodic Oxidation of Organic Pollutants

Abstract Nano-diamond composite electrode was prepared and used as anode for anodic oxidation process for organic chemicals. Electrochemical techniques such as impedance and cyclic voltammetry have been used to characterize the diamond composite electrode properties. The oxidation power of the electrode was 0.8 V vs. Ag/AgCl, the charge transfer rate was 12.1 Ohm, and the double layer capacitance was less than 1 μF. The anodic oxidation behavior of p-benzoquinone, 2-chlorophenol, and phenol over diamond composite electrode were investigated by cyclic voltammetry in 0.1 M H2SO4 (pH 3) solution and 0.25 M Na2SO4 (pH 6.8) solution. Results marked that the electro-oxidation of p-benzoquinone was more active than phenol and 2-chlorophenol in the both solutions. The performance of the diamond composite electrode during incineration of 200 mg/L p-benzoquinone, 2-chlorophenol, phenol were investigated in an aqueous solution of pH 3 and pH 6.8 with 0.25 M Na2SO4 as the supporting electrolyte and applied current density of 40 mA/cm2. Results showed that the degradation rate of benzoquinone was faster than 2-chlorophenol and phenol in both different pH solutions. Moreover, the benzoquinone degradation rate was enhanced at high pH solution, on the contrary of that of 2-chlorophenol and phenol were clearly favored in acid medium

A review of recent progress on electrocatalysts toward efficient glycerol electrooxidation

Glycerol electrooxidation has attracted immense attention due to the economic advantage it could add to biodiesel production. One of the significant challenges for the industrial development of glycerol electrooxidation process is the search for a suitable electrocatalyst that is sustainable, cost effective, and tolerant to carbonaceous species, results in high performance, and is capable of replacing the conventional Pt/C catalyst. We review suitable, sustainable, and inexpensive alternative electrocatalysts with enhanced activity, selectivity, and durability, ensuring the economic viability of the glycerol electrooxidation process. The alternatives discussed here include Pd-based, Au-based, Ni-based, and Ag-based catalysts, as well as the combination of two or three of these metals. Also discussed here are the prospective materials that are yet to be explored for glycerol oxidation but are reported to be bifunctional (being capable of both anodic and cathodic reaction). These include heteroatom-doped metal-free electrocatalysts, which are carbon materials doped with one or two heteroatoms (N, B, S, P, F, I, Br, Cl), and heteroatom-doped nonprecious transition metals. Rational design of these materials can produce electrocatalysts with activity comparable to that of Pt/C catalysts. The takeaway from this review is that it provides an insight into further study and engineering applications on the efficient and cost-effective conversion of glycerol to value-added chemicals

Development of a Novel Hydrophobic ZrO2–SiO2 Based Acid Catalyst for Catalytic Esterification of Glycerol with Oleic Acid

The inevitably low value of glycerol has led to extensive investigations on glycerol conversion to value-added derivatives. The esterification of glycerol with oleic acid is currently a very important industrial process. In this work, a novel heterogeneous acid catalyst featuring hydrophobic surface is developed on modified ZrO2–SiO2 support as water-tolerant solid acid catalyst is vital for biphasic esterification reactions that produce water. The novel ZrO2–SiO2–Me&Et-PhSO3H catalyst was prepared through silication and surface modification with trimethoxymethylsilane and 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane. This work showed that it is possible to control the acidity and hydrophobicity of the catalyst by tailoring the amount of surface modification agents. It was found that the hydrophobicity of the catalyst decreased as its acidity increased. Furthermore, at constant catalyst acidity, the more hydrophobic catalyst showed a better yield