A novel hydrophobic ZRO2-SIO2 based heterogeneous acid catalyst for the esterification of glycerol with oleic acid

The low market value of glycerol has led to extensive investigations on glycerol conversion to value-added derivatives. This work focuses on industrially important catalytic esterification of glycerol with oleic acid due to the high commercial value of the resulting products. In this work, a novel heterogeneous acid catalyst featuring hydrophobic surface was developed on ZrO2-SiO2 support as water tolerant solid acid catalyst is vital for biphasic esterification reactions producing water. The synthesized catalyst (ZrO2-SiO2-Me&Et-PhSO3H) was prepared through silication and surface modification using trimethoxymethylsilane (TMMS) and 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane. The surface morphology, physiochemical and textural properties, acidity and hydrophobicity were characterized. The mechanism of the catalyst surface modification is thereof proposed according to comprehensive characterization results. A novel technique to control acidity and hydrophobicity level of the designed catalyst is disclosed in this work. The acidity and hydrophobicity of the catalyst were tuned by controlling the amount of surface modification agents. It was found that the hydrophobicity of the catalyst decreased as its acidity increased. ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst with 70 mol% of TMMS and 0.62 mmol/g acidity is the optimal catalyst for glycerol esterification with oleic acid. Furthermore, the role of hydrophobicity in catalytic reaction was investigated herein. It was found that at constant catalyst acidity, the more hydrophobic catalyst showed better yield. The conversion using the designed catalyst (ZrO2-SiO2-Me&EtPhSO3H_70) is 88.2% with 53.5% glycerol monooleate selectivity and 40.0% glycerol dioleate selectivity (combined 94% selectivity of glycerol monooleate and dioleate) at equimolar oleic acid-to-glycerol ratio, 160 oC, reaction temperature, 5 wt% catalyst concentration with respect to weight of oleic acid, solvent-less reaction conditions and 8 h reaction time. This work reveals that the hydrophobicity and the pore volume of the designed catalyst significantly affect the product selectivity. In addition, the performance of the hydrophobic designed ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was used to benchmark with catalytic activity of sulfated zirconia (SO42-/ZrO2) and commercial catalysts (Amberlyst 15 and Aquivion). The correlation results showed that the average pore volume (pore size) influenced the product selectivity when ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was compared to three SO42-/ZrO2 catalysts that were developed from different zirconium precursors. Whereby, the higher pore volume catalyst is favourable to glycerol dioleate production at identical reaction conditions. It can be concluded that pore volume and size can be used to control the product selectivity. In addition, this study also revealed that hydrophobicity characteristic facilitated initial reaction rate effectively

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

Structure–selectivity relationship of a zirconia-based heterogeneous acid catalyst in the production of green mono- and dioleate product

A novel catalytic technique is vital to produce mono- and dioleate (GMO and GDO) from bioglycerol: a renewable resource and by-product of biodiesel. The advantage of this invention is the direct production of GMO and GDO through catalytic approach compared to the conventional method that requires transesterification and distillation processes. In this paper, glycerol esterification with oleic acid using a catalyst was experimented. The process was carried out over a hydrophobic mesoporous zirconia–silica heterogeneous acid catalyst (ZrO2–SiO2–Me&Et–PhSO3H) with three types of sulphated zirconia catalysts (SO42−/ZrO2) to produce high-selectivity GMO and GDO products. The catalytic performance of the hydrophobic ZrO2–SiO2–Me&Et–PhSO3H catalyst was benchmarked with that of SO42−/ZrO2 which was developed from three zirconium precursors. Results showed that the pore volume and hydrophobicity of the designed catalyst greatly could influence the product selectivity, thus enabling smaller substrates GMO and GDO to be dominated in the synthesis. This finding was supported by characterisation data obtained through N2 adsorption–desorption, X-ray diffraction and scanning electron microscopy. In addition, a good correlation was found between pore volume (pore size) and product selectivity. High pore volume catalyst favoured GDO production under identical reaction conditions. Pore volume and size can be used to control product sensitivity. The hydrophobicity of the catalyst was found to improve the initial reaction rate effectively

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

Catalytic role of solid acid catalysts in glycerol acetylation for the production of bio-additives: a review

Bio-additives obtained from the acetylation of biodiesel-derived glycerol have been extensively synthesized because of their nature as value-added products and their contribution to environmental sustainability. Glycerol acetylation with acetic acid produces commercially important fuel additives. Considering that the recovery of individual monoacetin, diacetin (DA), and triacetin (TA) is complicated, many endeavours have enhanced the selectivity and total conversion of glycerol using acetic acid during catalytic acetylation. In this work, we extensively review the catalytic activity of different heterogeneous acid catalysts and their important roles in glycerol acetylation and product selectivity. In addition, the most influential operating conditions to attain high yields of combined DA and TA are achieved by closely examining the process. This review also highlights the prospective market, research gaps, and future direction of catalytic glycerol acetylation

May Measurement Month 2017 blood pressure screening: findings from Malaysia—South-East Asia and Australasia

Elevated blood pressure (BP) is a growing burden worldwide, leading to over 10 million deaths each year. However there are still many individuals, particularly in many countries in Asia, who have poor BP control. In Malaysia, less than two-fifths have achieved BP control. We participated in BP screening in Malaysia in conjunc- tion with the May Measurement Month 2017 (MMM17), a global initiative by the International Society of Hypertension (ISH) aimed at screening more individuals for earlier detection of hypertension. A nationwide screening of adults aged 18 was carried out through health campaigns at clinics, hospitals, during family day events, and charity runs from 1 April 2017 to 31 May 2017 in 42 centres. We used the detailed protocol provided by ISH for data collection. A total of 4116 individuals were screened during MMM17. After multiple imputation, 32.4% (n1⁄41317/4059) had hypertension. Out of this, 63.9% (842/1317) of those with hypertension were on treatment. Of individuals receiving antihypertensive medication with an imputed BP, 59.5% (n1⁄4496/834) of them had controlled BP. MMM17 was the largest organized BP screening campaign undertaken by health profes- sionals in Malaysia. This study identified that 32.4% of screened individuals had hypertension and 59.5% individu- als with treated hypertension had achieved BP control

Développement de nouveaux catalyseurs hydrophobes pour l'estérification du glycérol par l'acide oléïque et étude du procédé

Le faible coût du glycérol sur le marché a conduit à des études approfondies sur la conversion du glycérol en dérivés à valeur ajoutée. Ce travail se concentre sur l'estérification catalytique du glycérol, avec l'acide oléique, réaction d’intérêt industriel en raison de la grande valeur commerciale des produits obtenus. Dans ce travail, un nouveau catalyseur acide hétérogène présentant une surface hydrophobe a été développé sur le support ZrO2-SiO2 car un catalyseur acide solide tolérant à l'eau est essentiel pour les réactions d'estérification en milieu biphasique produisant de l'eau. Le catalyseur synthétisé (ZrO2-SiO2-Me&Et-PhSO3H) a été préparé par silication et modification de surface en utilisant du triméthoxyméthylsilane (TMMS) et du 2-(4- chlorosulfonylphényl) éthyltriméthoxysilane. La morphologie de surface, les propriétés physicochimiques et texturales, l'acidité et l'hydrophobicité ont été caractérisées. Le mécanisme de modification de la surface du catalyseur est proposé en fonction des résultats de caractérisation complets. Une nouvelle technique pour contrôler le niveau d'acidité et d'hydrophobicité du catalyseur conçu est décrite dans ce travail. L'acidité et l'hydrophobicité du catalyseur ont été réglées en contrôlant la quantité d'agents de modification de surface. Il a pu être montré que l'hydrophobicité du catalyseur était diminuée à mesure que son acidité augmentait. Le catalyseur ZrO2-SiO2-Me & Et-PhSO3H_70 avec 70% molaire de TMMS et 0,62 mmol/g d'acidité est le catalyseur optimal pour l'estérification du glycérol avec l'acide oléique. Enoutre, le rôle de l'hydrophobicité dans la réaction catalytique a été étudié ici. Ce travail a montré qu'à acidité constante du catalyseur, le catalyseur le plus hydrophobe présentait un meilleur rendement. La conversion en utilisant le catalyseur préparé (ZrO2-SiO2-Me et EtPhSO3H_70) est de 88,2% avec une sélectivité en monooléate de glycérol de 53,5% et une sélectivité en dioléate de glycérol de 40,0% (sélectivité combinée de 94% en monooléate et dioléate de glycérol) pour un rapport équimolaire d'acide oléique/glycérol, une température de réaction de 160°C, une concentration massique du catalyseur de 5% par rapport à la masse d’acide oléique introduit, en conditions de réaction sans solvant et avec un temps de réaction de 8 h. Ce travail révèle que l'hydrophobicité et le volume des pores du catalyseur conçu affectent significativement la sélectivité en produit. De plus, les performances du catalyseur hydrophobe ZrO2-SiO2-Me&Et- PhSO3H_70, ont été comparées à celles de la zircone sulfatée (SO42-/ZrO2) et des catalyseurs commerciaux (Amberlyst 15 et Aquivion). Les résultats de corrélation ont montré que le volume moyen des pores (taille des pores) influençait la sélectivité du produit lorsque le catalyseur ZrO2- SiO2-Me&Et-PhSO3H_70 était comparé à trois catalyseurs SO42-/ZrO2 développés à partir de différents précurseurs de zirconium. Ainsi, le catalyseur à volume de pores le plus élevé est favorable à la production de dioléate de glycérol dans des conditions réactionnelles identiques. On peut conclure que le volume et la taille des pores peuvent être utilisés pour contrôler la sélectivité en produit. En outre, cette étude a également révélé que la propriété d'hydrophobicité améliorait la vitesse de réaction initiale.The low market value of glycerol has led to extensive investigations on glycerol conversion to value-added derivatives. This work focuses on industrially important catalytic esterification of glycerol with oleic acid due to the high commercial value of the resulting products. In this work, a novel heterogeneous acid catalyst featuring hydrophobic surface was developed on ZrO2-SiO2 support as water tolerant solid acid catalyst is vital for biphasic esterification reactions producing water. The synthesized catalyst (ZrO2-SiO2-Me&Et-PhSO3H) was prepared through silication and surface modification using trimethoxymethylsilane (TMMS) and 2-(4-chlorosulfonylphenyl) ethyltrimethoxysilane. The surface morphology, physiochemical and textural properties, acidity and hydrophobicity were characterized. The mechanism of the catalyst surface modification is thereof proposed according to comprehensive characterization results. A novel technique to control acidity and hydrophobicity level of the designed catalyst is disclosed in this work. The acidity and hydrophobicity of the catalyst were tuned by controlling the amount of surface modification agents. It was found that the hydrophobicity of the catalyst decreased as its acidity increased. ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst with 70 mol% of TMMS and 0.62 mmol/g acidity is the optimal catalyst for glycerol esterification with oleic acid. Furthermore, the role of hydrophobicity in catalytic reaction was investigated herein. It was found that at constant catalyst acidity, the more hydrophobic catalyst showed better yield. The conversion using the designed catalyst (ZrO2-SiO2-Me&EtPhSO3H_70) is 88.2% with 53.5% glycerol monooleate selectivity and 40.0% glycerol dioleate selectivity (combined 94% selectivity of glycerol monooleate and dioleate) at equimolar oleic acid-to-glycerol ratio, 160 oC, reaction temperature, 5 wt% catalyst concentration with respect to weight of oleic acid, solvent-less reaction conditions and 8 h reaction time. This work reveals that the hydrophobicity and the pore volume of the designed catalyst significantly affect the product selectivity. In addition, the performance of the hydrophobic designed ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was used to benchmark with catalytic activity of sulfated zirconia (SO42-/ZrO2) and commercial catalysts (Amberlyst 15 and Aquivion). The correlation results showed that the average pore volume (pore size) influenced the product selectivity when ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was compared to three SO42-/ZrO2 catalysts that were developed from different zirconium precursors. Whereby, the higher pore volume catalyst is favourable to glycerol dioleate production at identical reaction conditions. It can be concluded that pore volume and size can be used to control the product selectivity. In addition, this study also revealed that hydrophobicity characteristic facilitated initial reaction rate effectively

A novel hydrophobic ZrO2-SiO2 based heterogeneous acid catalyst for the esterification of glycerol with oleic acid / Kong Pei San

The inevitably low value of glycerol has led to extensive investigations on glycerol conversion to value-added derivatives. This work focuses on industrially important catalytic esterification of glycerol with oleic acid due to its high commercial value. In this work, a novel heterogeneous acid catalyst featuring hydrophobic surface was developed on ZrO2-SiO2 support as water tolerant solid acid catalyst is vital for two phase esterification reactions producing water. The synthesized catalyst (ZrO2-SiO2-Me&Et-PhSO3H) was prepared through silication and surface modification using trimethoxymethylsilane (TMMS) and 2-(4-chlorosulfonylphenyl)ethyltrimethoxysilane. The surface morphology, physiochemical and textural properties, acidity and hydrophobicity were characterized. The mechanism of the catalyst surface modification is thereof proposed according to comprehensive characterization results. A novel technique to control acidity and hydrophobicity level of the designed catalyst is disclosed in this work. The acidity and hydrophobicity of the catalyst were tuned by controlling the amount of surface modification agents. It was found that the hydrophobicity of the catalyst is decreased as its acidity increased. ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst with 70 mol% of TMMS and 0.62 mmol/g acidity is the optimal catalyst for glycerol esterification with oleic acid. Furthermore, the role of hydrophobicity in catalytic reaction was investigated herein. It was found that at constant catalyst acidity, the more hydrophobic catalyst showed better yield. The conversion obtained with the designed catalyst (ZrO2-SiO2-Me&EtPhSO3H_70) is 88.2% with 53.5% glycerol monooleate selectivity and 40.0% glycerol dioleate selectivity (combined 94% selectivity of glycerol monooleate and dioleate) at equimolar oleic acid-to-glycerol ratio, 160 oC, reaction temperature, 5 wt% catalyst concentration with respect to weight of oleic acid, solvent-less reaction conditions and 8 h reaction time. This work reveals hydrophobicity and pore volume of the designed catalyst affect the selectivity of product significantly. In addition, the performance of the hydrophobic designed ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was used to benchmark with catalytic activity of sulfated zirconia (SO42-/ZrO2) and commercial catalysts (Amberlyst 15 and Aquivion). The correlation results showed that pore volume (pore size) influenced the product selectivity when ZrO2-SiO2-Me&Et-PhSO3H_70 catalyst was compared to three SO42-/ZrO2 catalysts that were developed from different zirconium precursors. Whereby, the higher pore volume catalyst is favourable to glycerol dioleate production at identical reaction conditions. It can be concluded pore volume and size can be used to control the selectivity of the products. In addition, this study also revealed hydrophobicity characteristic facilitated initial reaction rate effectively

Methods for Endoscopic Removal of Over-the-Scope Clip: A Systematic Review

Aims. The over-the-scope clip (OTSC) has recently emerged as a new endoscopic device for treating gastrointestinal bleeding, perforations, fistulas, and leaks. A modified OTSC device (full-thickness resection device, FTRD) has been widely used for endoscopic full-thickness resection. However, there is less experience regarding the indications and methods for OTSC removal. We aimed to summarize the existing methods and indications for OTSC removal. Methods. We searched PubMed, Cochrane Library, and ClinicalTrials.gov to identify relevant publications on OTSC removal. The details of OTSC removal, including the methods, indications, success rates, adverse events, and failure causes, were extracted and summarized. A meta-analysis of pooled success rates was conducted using STATA 15.0. Results. Eighteen articles were included. The reported methods for OTSC removal included (1) grasping forceps, (2) the Nd : YAG laser, (3) argon plasma coagulation, (4) the remOVE system, (5) endoscopic mucosal resection/endoscopic submucosal dissection, and (6) ice-cold saline solution. Indications for OTSC removal were (1) poor healing, (2) OTSC misplacement, (3) repeat biopsy/therapy or further treatment, (4) adverse events after OTSC implantation, (5) removal after recovery, and (6) patient wishes. The pooled success rate of OTSC removal was 89% in patients treated with the remOVE system. Minor bleeding, superficial thermal damage, and superficial mucosal tears were common adverse events. Mucosal overgrowth was the main cause of OTSC removal failure. Conclusions. The remOVE system is the best investigated method, with sufficient efficacy and safety for OTSC removal. This is the first systematic review of OTSC removal and provides significant guidance for clinical practice