Montmorillonite KSF Research Articles

Effect of montmorillonite activation method on formaldehyde content in urea-formaldehyde composites

In this paper, the synthesis of modified urea-formaldehyde (UF) composites with differently activated montmorillonite KSF (UF/KSF) was performed. Two types of montmorillonite (MMT) KSF were used: sample activated with sulfuric acid-KSF(H2SO4) and sample activated with acid and stirring-KSF(H2SO4+stirrer). In order to examine the effect of KSF activation mode on the thermal and hydrolytic stability of UF resins, thermogravimetric analysis (TGA) was performed, as well as A determination of the amount of liberated formaldehyde (FA) after acid hydrolysis. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis were used to characterize the samples of modified UF/KSF composites and differently activated KSF. Activation of KSF led to a decrease in its specific surface area (SSA) and to an increase in cation exchange capacity (CEC). SEM analysis showed that in the KSF(H2SO4+stirrer) sample, the layered microstructure was disrupted. Free formaldehyde was not detected in the sample of UF resin with KSF(H2SO4), and in the sample with KSF(H2SO4+stirrer) it was 0.06%. The UF/KSF(H2SO4) composite showed higher hydrolytic stability (3.9%) compared to UF/KSF(H2SO4+stirrer) (4.62%), but lower compared to the UF/KSF(inactive) (1.23%). TG analysis showed that the KSF(H2SO4) sample had better thermal stability than the KSF(H2SO4+stirrer) sample, but this did not contribute to the better thermal stability of UF/KSF(H2SO4) compared to UF/KSF(H2SO4+stirrer), both samples had a T5% value of 112 °C.

Synthesis of Chalcone Derivatives from Halogenated Vanillin and their Activity Test as Antioxidant

Synthesis of 3-chloro-4-hydroxy-5-methoxybenzaldehyde, 3-bromo-4-hydroxy-5-methoxybenzaldehyde and 2',4'-dihydroxy-3-bromo-4-hydroxy-5-methoxyhalcone and evaluation of their antioxidant activity have been carried out. 3-Chloro-4-hydroxy-5-methoxybenzaldehyde was obtained through chlorination of vanillin using Ca(ClO)2, while 3-bromo-4-hydroxy-5-methoxybenzaldehyde was obtained via bromination of vanillin using KBrO3 in glacial acetic acid solvent and 47% HBr catalyst. Then, 2',4'-dihydroxy-3-bromo-4-hydroxy-5-methoxychalcone was prepared from 3-bromo-4-hydroxy-5-methoxybenzaldehyde and 2-4-dihydroxyacetophenone through Claisen-Schmidt condensation in the presence of KOH (40%) base and KSF montmorillonite in methanol. Elucidation of the structure of these compounds was performed using FTIR, GC-MS, TLC-Scanner, MS-Direct, 1H-NMR, and 13C-NMR. The synthesized benzaldehydes and chalcone were tested for their antioxidant activities using DPPH method, where 2,6-di-tert-butyl-4-methylphenol (BHT) was used as positive control. The results showed that 3-chloro-4-hydroxy-5-methoxybenzaldehyde, 3-bromo-4-hydroxy-5-methoxybenzaldehyde and 2',4'-dihydroxy-3-bromo-4-hydroxy-5-methoxyhalcone were obtained in 53%, 97%, and 1%, respectively. The antioxidant activity assay showed that BHT, 3-chloro-4-hydroxy-5-methoxybenzaldehyde, 3-bromo-4-hydroxy-5-methoxybenzaldehyde and 2',4'-dihydroxy-3-bromo-4-hydroxy-5-methoxyhalcone displayed the IC50 of 27.94, 244.11, 269.44 and 162.10 µg/mL, respectively.

Montmorillonite KSF mediated Favorskii reaction-based eco-friendly fabrication of some 1,3-diarylpropenones using phenyl acetylene and aromatic aldehydes

Montmorillonite KSF mediated Favorskii reaction-based eco-friendly fabrication of some 1,3-diarylpropenones using phenyl acetylene and aromatic aldehydes

Trametes versicolour laccase immobilization by covalent binding and its application in Kraft E1 effluent pre-treated with ozone

Wastewater deriving from cellulose and paper manufacturing is one of the most important industrial effluents due to its large-volume production and high pollution load. Effluent deriving from the pulp bleaching stage (Kraft E1 effluent) remains one of the major issues faced by paper mills among all wastewaters generated in each stage of paper-making processes. Kraft E1 effluent was submitted to a sequential chemical (ozonization) – biological (immobilized laccase) treatment. Laccase was obtained from Trametes versicolour in liquid medium of culture using 2,5 -xylidine as inducer. Crude laccase extract was immobilized through covalent binding in Montmorillonite KSF and Eupergit®C supports based on different protocols. Eupergit®C has shown the best protein immobilization (51%), retention activity (100%), and operational stability (ten oxidative cycles) results. Enzymatic treatments using free and immobilized laccase onto Eupergit®C were applied to Kraft E1 effluent. After 18-h treatment, total phenol removal reached 20% and 40% in free and immobilized laccase, respectively. Ozone combined to enzymatic processes using reactor assembled with immobilized laccase (31 U g−1, total mass = 10.0 g) had effect on decolonization efficiency and on total phenols’ removal from Kraft effluent. Ozone treatment was capable of removing 52% of total phenols and 76% of colour from the investigated effluent. Sequential enzymatic treatment has increased total phenols’ removal to 64% within 30-minute treatment and reached 70% removal within 60 minutes. The herein observed additional phenol removal based on enzymatic treatment is an important outcome if one takes into consideration the fraction of total phenols that could not be removed by the ozone process.

Fluoride Excess Removal from Brackish Drinking Water in Senegal by Using KSF and K10 Montmorillonite Clays

Fluoride excess in drinking water is noticed in many countries around the world and particularly in Senegal where, in addition to fluoride excess, high levels of salinity are also encountered. In order to reduce fluoride excess in drinking water in the groundnut basin of Senegal, two types of clays namely montmorillonite KSF and montmorillonite K10 as well were used as adsorbent materials. The results show that the pH which was initially alkaline becomes acidic varying from 2.80 to 6.80. The pseudo first-order kinetic model fit well with the adsorption experiments for KSF montmorillonite (r2 = 0.96), while for K10 clay the same model describe the experiments with slight differences (r2 = 0.90). The KSF clay has a better fluoride adsorption capacity compared to that obtained with K10 clay due to the presence of a great level of calcium oxide in the montmorilonite KSF clay.

Utilization of Clay Materials as Support for Aspergillus japonicus Lipase: An Eco-Friendly Approach

Lipase is an important group of biocatalysts, which combines versatility and specificity, and can catalyze several reactions when applied in a high amount of industrial processes. In this study, the lipase produced by Aspergillus japonicus under submerged cultivation, was immobilized by physical adsorption, using clay supports, namely, diatomite, vermiculite, montmorillonite KSF (MKSF) and kaolinite. Besides, the immobilized and free enzyme was characterized, regarding pH, temperature and kinetic parameters. The most promising clay support was MKSF that presented 69.47% immobilization yield and hydrolytic activity higher than the other conditions studied (270.7 U g−1). The derivative produced with MKSF showed high stability at pH and temperature, keeping 100% of its activity throughout 12 h of incubation in the pH ranges between 4.0 and 9.0 and at a temperature from 30 to 50 °C. In addition, the immobilized lipase on MKSF support showed an improvement in the catalytic performance. The study shows the potential of using clays as support to immobilized lipolytic enzymes by adsorption method, which is a simple and cost-effective process.

Pyridinium Chlorochromate Supported on Montmorillonite–KSF as a Versatile Oxidant under Ball Milling Conditions

Oxidation reactions play a crucial role in organic transformations, as well as industrial and biological processes.1–3 Conventional oxidizing agents include manganese dioxide,4 hypervalent iodine,5...

Correction to: Removal of analgesics from aqueous solutions onto montmorillonite KSF

Correction to: Removal of analgesics from aqueous solutions onto montmorillonite KSF

Removal of analgesics from aqueous solutions onto montmorillonite KSF

Due to increasing consumption of analgesic drugs associated with their occurrence in wastewater, it is necessary to pay attention to find new accessible types of sorbents for effective drug removal. The objective of this work is the assessment of ability of commercial montmorillonites for the removal of drugs from aqueous solutions since these inexpensive materials exhibit both adsorption and ion exchange properties as well as environmental stability. The commercial montmorillonite KSF, primarily used as acidic catalyst, was used in both unmodified and cetyltrimethylammonium bromide (CTAB) modified form as potential sorbent for three analgesics: paracetamol (PAR), ibuprofen (IBU) and diclofenac (DC) from aqueous solutions. The samples were characterized by X-ray fluorescence (XRFS), X-ray powder diffraction (XRD), simultaneous thermogravimetry and differential thermal analysis (TG/DTA) and high-performance liquid chromatography (HPLC). XRD confirmed the intercalation of CTAB into the montmorillonite structure with the increasing of basal spacing. Thermal analysis also determined the presence of CTAB associated with increasing of the hydrophobicity accompanied by a decrease in dehydration temperature. Also, due to surfactant modification, the temperature of constitution water removal decreased. Adsorption experiments were carried out in a batch mode with different initial concentration of paracetamol, ibuprofen and diclofenac solutions. Montmorillonite samples especially in organically modified form demonstrated sufficient sorption ability of pharmaceuticals from aqueous solutions in the order diclofenac > ibuprofen > paracetamol.

English

English

High yield of glucose from cassava starch hydrolysis by poly(4‐vinylpyridine) hydrochloride

SummaryCassava is an abundant and cheap source of starch which is largely used to produce sugar and dextrin. In this work, Hydrolysis of cassava starch using some active catalysts: poly(4‐vinylpyridine) hydrochloride (PVP, HCl), green clay activated with HCl, Amberlyst 36, Montmorillonite KSF, zeolite and HCl were investigated. Temperature, reaction time, concentration of starch and catalyst amount were the parameters considered during each experience. The catalyst precursor (PVP, HCl) showed to be an efficient, selective, recyclable and gave a high yield of glucose syrup (82%) with 95% of total reducing sugar without pretreatment process. Reactions were carried out at 95 °C with various concentrations of starch, up to 600 g L−1. The consumable glucose syrup obtained with this process was similar to the commercial reference. A small quantity (2%–3%) of 5‐hydroxymethylfurfural (HMF) was the only by‐product and it could be extracted with ethyl acetate. Bio‐fermentation of the non‐treated hydrolysate gave a good yield of ethanol (93%) after only 12 h.

Regioselective Synthesis of Unsymmetrical 3-(Quinolin-3-yl)Pentane-1,5-Diones in the Aqueous Medium through Montmorillonite KSF Catalysis

In the presence of heterogeneous catalyst Montmorillonite KSF (M-KSF) 2-chloro-3-formyl quinolines, 1 were successfully converted into regioselective 3-(quinolin-3-yl)pentane-1,5-diones, 3. A one-pot sequential reaction (aldol-condensation-Michael addition) of distinct acetophenones, 2 was efficient in an aqueous medium.

Heterogeneous fenton-like reaction using Fe3-xMnxO4-MKSF composite catalyst for degradation of acid orange II dye

The selection of a good catalyst support is crucial in contributing towards the enhancement catalytic activity of a catalyst. Therefore, in this study, the influence of montmorillonite KSF (MKSF) clay loading in relation with catalytic performance of the resultant composite catalyst has been investigated. The MKSF clay loading were varied at x = 20, 40, 60 and 80 wt%, respectively. Interestingly, Fe3-0.3Mn0.3O4-MKSF(40wt%) has shown greater catalytic performance up to 98% of acid orange II (AOII) dye removal in comparison to the Fe3-0.3Mn0.3O4 and Fe3O4 catalysts. The AOII degradation kinetic using Fe3-0.3Mn0.3O4-MKSF(40wt%) was fitted well with first-order reaction kinetic and the reaction rate increased in the order of Fe3O4>Fe3-0.3Mn0.3O4>Fe3-0.3Mn0.3O4-MKSF(40wt%). It also demonstrated in the work that Fe3-0.3Mn0.3O4-MKSF(40wt%) catalyst can be reused several times without affecting its efficiency. Thus, it can be suggested that MKSF clay as catalyst support played a significant role in enhancing the overall catalytic performance of Fe3-0.3Mn0.3O4 catalyst during the heterogeneous Fenton-line reaction as well as the degradation kinetics of the AOII solutions.

Metal free montmorillonite KSF clay catalyzed practical synthesis of benzoxazoles and benzothiazoles under aerobic conditions

An efficient method for the synthesis of benzoxazoles and benzothiazoles via montmorillonite KSF clay catalyzed condensation reaction between 2-aminophenols or 2-aminothiophenols and β-diketones is reported. The efficiency of the reaction reflects from the wide substrate scope with electronic differentiation on aryls. The reaction is metal free and proceeds without the exclusion of air or moisture, and further the catalyst can be recycled up to 3–5 catalytic cycles.

Regioselective synthesis of C-prenylated flavonoids via intramolecular [1,3] or [1,5] shift reaction catalyzed by acidic clays

Prenyl side chain and dihydropyrano skeleton exists in many natural and synthetic biologically active flavonoids. A highly efficient and regioselective method for the synthesis of C-prenylated flavonoids via intramolecular [1,3] or [1,5] shift reaction of 5-O-prenylflavonoids catalyzed by Florisil or Montmorillonite clays is described. Florisil catalyzes intramolecular [1,5] shift reaction of 5-O-prenylflavonoids to obtain 8-C-prenylated flavonoids exclusively, Montmorillonite K10 exhibits the superior selectivity to promote intramolecular [1,3] shift reaction to obtain 6-C-prenylated flavonoids compared with Florisil and Montmorillonite KSF. This method provides a practical process to regioselective synthesize biologically important C-prenylated flavonoids in good yields using commercially available and inexpensive catalyst under mild conditions.

Kinetics and mechanism of the oxidation of vanillic acid using smectite clay

In this study, the oxidation of vanillic acid (VA) into protocatechuic acid (PCA) was investigated using montmorillonite KSF as inexpensive and environmentally benign solid acid, with peroxide hydrogen to afford excellent yields (more than 75%) endowed with high selectivity. To our knowledge, the aforementioned method was used for the first time in green, clean synthesis. The influence of the several operating parameters were performed using an experimental design Box–Behnken methodology. The progress of the concentrations of VA and its oxidation product PCA was accomplished using ultra-high-performance liquid chromatography coupled to quadrupole-time-of-flight mass spectrometry (RP-UHPLC-DAD-QTOF-MS) and mass spectrometry. Accordingly, PCA would be advantageous when used in food as well as cosmetic and pharmaceutical industries. Finally, a mechanistic pathway for the VA oxidation was proposed.

Brønsted and Lewis Solid Acid Catalysts in the Valorization of Citronellal

Terpenes are valuable starting materials for the synthesis of molecules that are of interest to the flavor, fragrance, and pharmaceutical industries. However, most processes involve the use of mineral acids or homogeneous Lewis acid catalysts. Here, we report results obtained in the liquid-phase reaction of citronellal with anilines under heterogeneous catalysis conditions to give tricyclic compounds with interesting pharmacological activity. The terpenic aldehyde could be converted into octahydroacridines with a 92% yield through an intramolecular imino Diels–Alder reaction of the imine initially formed in the presence of an acidic clay such as Montmorillonite KSF. Selectivity to the desired product strongly depended on the acid sites distribution, with Brønsted acids favoring selectivity to octahydroacridine and formation of the cis isomer. Pure Lewis acids such as silica–alumina with a very low amount of alumina gave excellent results with electron-rich anilines like toluidine and p-anisidine. This protocol can be applied starting directly from essential oils such as kaffir lime oil, which has a high citronellal content.

Facilitated transport of cadmium with montmorillonite KSF colloids under different pH conditions in water-saturated sand columns: Experiment and transport modeling

This study investigated the impact of pH on the migration of cadmium(II) ions (Cd2+) in relation to montmorillonite KSF colloids through a water-saturated sand column (WSSC). The sorption isotherms of Cd2+ on colloids and sand at pH values of 3, 6, and 8 were characterized by batch experiments. Cd2+ sorption by colloids and sand fit well with the Freundlich model. In the column experiments, increasing the pH increased the retardation factors and KF values of Cd2+ both with and without the presence of the colloids. The amount of Cd2+ sorbed onto the montmorillonite KSF colloids in the column effluent increased from 0.29 to 0.97 mg as the pH increased. The colloid increased Cd2+ mobility and acted as a carrier at a high solution pH. The increasing level of Cd2+ sorbed on colloids as the pH increased resulted in a long tailing of the breakthrough curve (BTC) of the total Cd, indicating that the total Cd was controlled by rate-limited reactions. These findings indicate that when the solution pH was greater than the point of zero charge (PZC) of the colloids (pH > 6), the system tended to follow a nonequilibrium two-site (TSM) model rather than an equilibrium (CDeq) model. This implies that the PZC of the colloids in the groundwater system is the main factor in predicting facilitated Cd2+ transport.

Montmorillonite-KSF mediated one step synthesis of pyranochromene derivatives

One-pot three-component reaction of substituted aromatic aldehydes, 2-cyanoacetamide and 4-hydroxycoumarin in the presence of Montmorillonite-KSF (MKSF) in ethanol results in the formation of pyrano[3,2-c]chromene-3-carboxylates (5a-m) has been described. The reaction was tested in different alcohols, afforded pyrano [3,2-c] chromene-3-carboxylates (5a-m) of the corresponding alcohols in good yield. The mechanism reveals that the alcohol (as solvent) plays a major role in the inter conversion of amide to the corresponding esters with Montmorillonite KSF (M-KSF) as a catalyst. Excellent yields, inexpensive and readily available substrates, environmentally benign reaction condition, shorter reaction time, and easy workup are the major advantageous features of this protocol.

Oxidative Degradation of Methyl Orange Solution by Fe-MKSF Catalyst: Identification of Radical Species

Iron–immobilized montmorillonite KSF (Fe-MKSF) has been recognized as promising catalyst in degrading persistence organic contaminants. However, detailed mechanistic insight during the catalysis which involving the formation and identification of radical species were remained indeterminate due to complex reaction. Inspiring by this gap, iron-immobilized clay (Fe-MKSF) was synthesized and used as heterogeneous catalyst in the oxidative degradation of methyl orange (MO) solution. Identification of radical species were determined through the inclusion of different types of radical scavenging agent during the Fenton-like reaction at optimum condition. Interestingly, dominant radical species were found to be hydroperoxyl radicals (•OOH) which subsequently followed by hydroxyl radicals (•OH) during the catalysis. Based on the percentage of MO removal, it was suggested that approximately 88% of the •OOH radicals existed at the interface of catalyst while 39% presence in bulk solution. Meanwhile, the interface •OH radicals promoted 38% of MO removal, whilst 4% by the bulk •OH radicals. Hence, these findings have conveyed novel insight on detailed radicals’ identification as well as its’ interaction during the catalysis.