Carlos J. Durán-Valle

Universidad de Extremadura | UNEX · Department of Organic and Inorganic Chemistry

A new adsorbent material was prepared by coating an activated carbon with hydrothermal carbon obtained from sucrose. The material obtained has different properties from the sum of the properties of the activated carbon and the hydrothermal carbon, which shows that a new material was obtained. It has a high specific surface area (1051.9 m2 g−1) and...

Carbonaceous materials are a highly appealing class of adsorbents, owing to their exceptional properties, such as high surface area and thermal and chemical stability. These materials have found successful applications in water purification. Sweet chestnut (Castanea sativa) cupules are disposed of as waste. Valorization of these residues is a step...

Even though protection-free protocols represent a key principle of green chemistry, both protection and deprotection routes are indispensable strategies in synthetic pursuits, especially towards highly functionalized pharmaceuticals and agrochemicals, often decorated by promiscuous OH or NH groups, among others. Herein a sustainable carbon-based ca...

This study analyzed the fabrication and characterization of polybenzoxazine/polydopamine/ceria as tertiary nanocomposites. To this end, a new benzoxazine monomer (MBZ) was fabricated based on the well-known Mannich reaction of naphthalene-1-amine, 2-tert-butylbenzene-1,4-diol and formaldehyde under ultrasonic-assisted process. Polydopamine (PDA) wa...

The development of new chemical synthetic methodologies that transform industrial chemical processes into more sustainable ones, constitutes one of the challenges and objectives of chemical research both in academia and in industry. The use of activated carbons as heterogeneous catalysts represents one of the most beneficial options for process eff...

In this research, a new generation of ternary nanocomposites based on poly(ethylene terephthalate) (PET), phosphorylated chitosan and surface modified alumina nanoparticles were fabricated in four steps. The phosphorylation process was targeted for the insertion of phosphorus moieties as a flame retardant agent in the final PET nanocomposite. Likew...

Development of imaging probes for identification of tumors in the early stages of growth can significantly reduce the tumor-related health hazards and improve our capacity for treatment of cancer. In this work, three different furan and imidazole fluorescent derivatives abbreviated as Cyclo X, SAC and SNO are introduced for in vivo and in vitro ima...

Titania graphene hybrid nanocomposites (TiO2-FLG) synthesized from graphite and TiO2 precursors, in a simple and sustainable approach via a three-step method, including the mechanochemical treatment of pre-synthesized FLG and TiO2 NPs are efficient has led to the preparation of titania graphene hybrid nanocomposites (TiO2-FLG) as efficient nano-cat...

In this research, a new generation of ternary nanocomposites based on poly(ethylene terephthalate) (PET), phosphorylated chitosan and surface modified alumina nanoparticles were fabricated in four steps. The phosphorylation process was targeted for the insertion of elemental phosphorus as a flame retardant agent in the final PET nanocomposite. Like...

A commercial activated carbon was modified with acid and basic reagents -an acidic one via treatment with sulphuric acid and a basic via treatment with pentaethylenehexamine- to yield adsorbents with different surface acid/base character. These modified adsorbents were characterised by elemental and immediate analysis, N2 adsorption, XPS and point...

Cross-coupling reactions leading to carbon–heteroatom bonds yield compounds that attract substantial interest due to their role as structural units in many synthetic protocols for bioactive and natural products. Therefore, many research works aim at the improvement of heterogeneous catalytic protocols. We have studied the use of magnetite nanoparti...

Solvatochromism is a property of many different compounds in which color change is a consequence of solvent polarity. Strong blue fluorescent aminofuran was synthesized from the three-component reaction. It was found that the product is highly fluorescent and shows solvatochromic shift between 280 and 380 nm in solvents ranging from water to hexane...

New titania-reduced graphene oxide (TiO2-rGO) nanocomposites have been studied to assess their application in the solar assisted photodegradation of a complex mixing of pesticides (pyrimethanil, isoproturon, alachlor and methomyl) at solar pilot plant, opening the opportunity to extend the use of these hybrid photocatalysts to complex wastewater ef...

Two commercial activated carbon were functionalized with nitric acid, sulfuric acid, and ethylenediamine to induce the modification of their surface functional groups and facilitate the stability of corresponding AC-supported iron catalysts (Fe/AC-f). Synthetized Fe/AC-f catalysts were characterized to determine bulk and surface composition (elemen...

Porous carbon materials are considered extremely versatile and environmental friendly. These materials have found application in many and distinct fields such as energy generation and storage, water treatment including adsorption of emergent pollutants, NOx removal, biomedical engineering, and catalysis, among other research fields. Porous carbon i...

This paper provides a detailed analysis of the recycling of Tetra Pak waste via pyrolysis to recover the most valuable solid products within its composition, char and aluminum, and the subsequent application of the char in the adsorption of mercury in aqueous solutions. The impact of the Tetra Pak pyrolysis conditions on the char and aluminum yield...

Global warming coupled with declining fossil fuel reserves has attracted a great deal of attention for sustainable processes using renewable resources. Among them, obtaining fuels from biomass stands out. There are two main routes for obtaining biofuels from biomass: biological and thermochemical. Thermochemical processes for the transformation of...

Adsorption studies were carried out to determine the behaviour of three carbonaceous adsorbents with different magnetic orderings (ferromagnetic, paramagnetic and diamagnetic) and the effect of an external magnetic field on the adsorption of a cation (Pb2+) and an anion (F-). Two different static magnetic field intensities were used to analyse the...

Nanostructured calcium oxides supported onto biochar obtained by pyrolysis of avocado seeds were prepared, characterized and successfully used as catalysts to produce biodiesel from waste oils. The effect of increasing calcium load (5, 10 and 20 wt%) was investigated. Elemental analysis, FTIR, XRD, SEM, BET, acid and basic sites were used to charac...

The preparation of an alternative material for the adsorption of arsenic from aqueous solution was studied. This adsorbent was obtained from the pyrolysis and ZnCl2 activation of Opuntia ficus indica biomass (widely known as nopal), which is a typical plant of the Mexican landscape. Preparation conditions of this adsorbent were improved to increase...

This study has focused on the recovery of grape bagasse biomass to prepare new adsorbents for the removal of mercury from aqueous solutions.

Eco-sustainable and recyclable porous carbons are reported as metal-free catalysts for the synthesis of benzodiazepines for the first time. The porous carbons were able to efficiently catalyse the synthesis of benzodiazepine 1 from o-phenylendiamine 2 and acetone 3 under mild conditions. Both acidic functions and the porosity of the catalysts were...

This manuscript reports the study of lanthanum- and cerium-based surface functionalization of activated carbons and chars, prepared from a lignocellulosic-based precursor, for facing the geogenic water pollution caused by fluoride and arsenic (V) ions. The incorporation of these rare elements on the adsorbents increased the adsorption capacities up...

The junction of graphene oxide with TiO2 particles can help develop more efficient photocatalysts capable to harvest radiation in a wider range of the electromagnetic spectrum for real photocatalytic applications. The synthesis procedure of TiO2 P25-rGO composites was optimized to photodegrade a selected mixture of pesticides classified by EU as pr...

The catalytic activity of six different carbons was tested in the solvent-free acetylation reaction of alcohols, phenols, and monosaccharides with acetic anhydride. Three commercial carbons—a basic activated carbon M (Merck KGaA), a moderately basic carbon gel X (Xerolutions S.L.), and an activated carbon N (Norit Netherland B.V.)—were studied. Fro...

This work reports for the first time a new series of promising porous catalytic carbon materials, functionalized with Lewis and Brönsted acid sites useful in the green synthesis of 2,3‐dihydro‐1H‐1,5‐benzodiazepine ‐ nitrogen heterocyclic compounds. Benzodiazepines and derivatives are fine chemicals exhibiting interesting therapeutic properties. Ca...

In the pyrolysis process carried out to obtain charcoal from plants, a concentration of the radionuclides found in trace amounts in the raw material is produced. This fact would influence its possible uses. Radioactive characterization of a wide set of charcoal samples from different provenances was analysed. Activity concentrations of the radionuc...

This paper reports the synthesis of novel adsorbents for fluoride removal from water using avocado kernel seeds and pyrolysis with and without physical activation. Avocado-based adsorbents were synthetized at different carbonization conditions where CO2 activation was studied to determine its impact on fluoride adsorption properties. Fluoride adsor...

This article reports the modification of 17 different kinds of carbons with H2 SO4, HNO3, H2 O2, KCl, and NaCl for the removal of anionic dyes, reactive red 2 (RR2) and reactive black 5 (RB5), and cationic dyes, basic blue 9 (BB9) and basic brilliant green (BBG), in single and binary solutions with Cd²⁺ and CrO4 2–. The results show that the better...

The hydrothermal carbonisation process has attracted great interest in recent years, as it is an eco-friendly method for obtaining carbonaceous materials. This method consists of heating an organic material in the presence of water in a closed vessel at temperatures above 100 °C. The pressure generated by the water vapour next to a heat supply give...

Different homemade iron-activated carbon catalysts (Fe/AC) have been studied in the CWPO of phenol at mild conditions (atmospheric pressure and 50 °C). Both iron content and the way to introduce iron active phase in Fe/AC catalysts were analyzed to select the most stable and efficient activated carbon-supported iron catalyst. The major differences...

The photocatalytic activity of a home-made titanium dioxide (TiO2) and its corresponding composite based on graphene oxide (GO), the GO-TiO2 catalyst, has been investigated under UV–vis in the photodegradation of a mixture of four pesticides classified by the European Union as priority pollutants: diuron, alachlor, isoproturon and atrazine. The inf...

This article reports the antagonistic and synergistic adsorption involved in the multicomponent removal of acid blue 25 dye (AB25) and heavy metal ions (Zn2+, Ni2+, Cd2+) from ternary systems using an activated carbon modified with wastes of egg shell. Adsorption experiments were performed in ternary mixtures: Zn2+Ni2+ AB25, Ni2+Cd2+ AB25 and Z...

We describe the first examples of Friedländer reactions efficiently catalyzed by carbon materials. We report herein a series of acidic activated carbon materials, which can be considered as an environmentally friendly, cheaper alternative to the traditional acidic mesoporous silicates or even zeolites for the synthesis of quinolines/quinolones. Tex...

The ring opening reaction of epoxides by alcohols and amines using mesoporous activated carbon as efficient and environmentally friendly heterogeneous catalyst is reported. Carbon xerogels were synthesized by polymerization of resorcinol and formaldehyde. The surface of the activated carbon was oxidized in liquid phase with HNO 3 and then functiona...

We report the simultaneous adsorption of acid blue 25 dye (AB25) and heavy metals (Zn(2+), Ni(2+) and Cd(2+)) on a low-cost activated carbon, whose adsorption properties have been improved via a surface chemistry modification using a calcium solution extracted from egg shell wastes. Specifically, we have studied the removal performance of this adso...

The ring opening reaction of epoxides by alcohols and amines using mesoporous activated carbon as efficient and environmentally friendly heterogeneous catalyst is reported. Carbon xerogels were synthesized by polymerization of resorcinol and formaldehyde. The surface of the activated carbon was oxidized in liquid phase with HNO3 and then functional...

An activated carbon Norit RX3 has been treated with acids (sulphuric, nitric and sulphonitric mixture). The modified activated carbons have been characterized by elemental analysis, point of zero charge, N2 adsorption, XPS and FTIR. The solids obtained have been used as acidic heterogeneous catalyst in the reaction between imidazole and haloalkanes...

This review is devoted to the application and knowledge developed in the past 10 years in the area of chemical processes catalyzed by activated carbon supported catalysts. Activated carbons are well known for their catalytic properties and for being used as support in heterogeneous catalysis. The supported catalysts have been successfully used in t...

N-Alkylimidazoles have been synthesized by sonochemical irradiation of imidazole and 1-bromobutane using alkaline-promoted carbons. The catalysts were characterized by X-ray photoelectron spectroscopy, thermal analysis and nitrogen adsorption isotherms. Under the experimental conditions, N-alkylimidazoles can be prepared with a high activity and se...

The epoxides (styrene oxide and 1,2-epoxyhexane) reaction with ethanol was carried out, catalysed with acidic activated carbons. The reactions were carried out under microwave irradiation. In the 1,2-epoxyhexane reaction, high yields were attained in some of the reaction conditions tested, although the regioselectivity was not high. For the styrene...

Coal and charcoal present similar physical and chemical characteristics. There is no standardized procedure to distinguish them. However, their differences in age and origin result in several differences in their natural radionuclide content. Moreover, charcoal can be contaminated with fallout. In this work, activity concentrations of (228)Th, (226...

The adsorption of HgCl2, [HgCl4](2-) and Hg2+ onto a series of activated carbon fibres was studied. These included the as-received commercial activated carbon fibre (K), that obtained after modification via by sulphuric acid oxidation (K-AC) and that obtained after modification by reaction with pentaethylenehexamine (K-BAS). The effects of concentr...

Two activated carbons treated with mineral acids (HNO3 and sulfonitric mixture) have been tested as acid catalysts in the epoxides (1,2-epoxyhexane and styrene oxide) ring-opening reaction with 1-butanol under microwave (MW) irradiation. The mayor obtained product is that resulting of the alcohol addition to the most substituted carbon in the epoxi...

Cherry stones (CS) are carbonised at 400–1000°C for 0–4h in N2 and the charcoals obtained are characterised to gain information about their chemical composition and porous texture, with a view to their use in the preparation of activated carbon. Depending on the heating conditions, the products obtained may possess a low ash content and a high fixe...

N-Alkyl-imidazole has been synthesized by sonochemical irradiation of imidazole and 1-bromobutane using alkaline-promoted carbons (exchanged with the binary combinations of Na, K and Cs). The catalysts were characterized by X-ray photoelectron spectroscopy, thermal analysis and N2 adsorption isotherms. Under the experimental conditions, N-alkyl-imi...

Chalcones have been synthesized under sonochemical irradiation by Claisen–Schmidt condensation between benzaldehyde and acetophenone. Two basic activated carbons (Na and Cs-Norit) have been used as catalysts. The effect of the ultrasound activation has been studied. A substantial enhancing effect in the yield was observed when the carbon catalyst w...

The condensation of benzaldehyde and different substituted benzaldehydes, such as 2-nitrobenzaldehyde, 3-nitrobenzaldehyde, and 2,4-dichlorobenzaldehyde, with ethyl cyanoacetate was carried out using two alkaline carbons (Na-Norit and Cs-Norit) as catalysts in the absence of solvent. The reaction products are precursors in the production of 1,4-dih...

Thermal treatment of carbonaceous materials shows two related phenomena: the graphene molecule (or carbon layer) increases in size and its carbon content also increases. In this work, a simple relationship between both effects was deducted, based on the structure geometry of carbonaceous materials. This relationship provides an approach to the mean...

The synthesis of chalcones via Claisen-Schmidt condensation between benzaldehyde and acetophenone by sonochemical and thermally-activated reactions over a new type of zeolite as catalyst is reported. The catalysts were prepared by grafting amino groups on sodium and cesium exchanged X zeolite. In this green, solvent free procedure, chalcones are se...

The Claisen–Schmidt condensation between benzaldehyde and acetophenone has been carried out for the preparation of chalcones. Two basic activated carbons (Na- and Cs-Norit) have been used as catalysts. The order of activity is Na-Norit < Cs-Norit. Chalcones have been synthesized by sonochemical irradiation. The effect of the ultrasound activation h...

Cherry stones (CS) have been characterised in terms of chemical composition, texture, and thermal behaviour with a view to be used as a raw material in the preparation of activated carbon. Ashes obtained from CS have also been studied. CS have been heated in various atmospheres (i.e., in the atmosphere of the products released during the pyrolysis...

The synthesis of N-propargyl imidazoles via alkylation of imidazole with propargyl bromide by sonochemical and thermally activated reactions over two alkaline promoted carbons (Na and Cs-Norit) as catalysts is reported. In this green, solvent free procedure, we produce exclusively N-propargyl imidazoles in very high yields (>80%) when the Cs+-Norit...

N-Alkyl imidazoles have been prepared by sonochemical irradiation of imidazole and 1-bromobutane using alkaline promoted carbons. Under the experimental conditions, N-alkyl imidazoles can be prepared with a high activity and selectivity. It is observed that imidazole conversion increases in parallel with increasing basicity of the catalyst. For com...

The influence of the activation temperature on the pore structure of granular activated carbons prepared from rockrose (Cistus ladaniferus L.), extracted previously into petroleum ether, is comparatively studied. The preparation was carried out by pyrolysis of a char in nitrogen and its subsequent activation by carbon dioxide and steam (flow of wat...

This paper discusses the pore structure of chars and activated carbons prepared at different temperatures from rockrose (Cistus ladaniferus L.), extracted previously into petroleum ether. The isothermal temperature of carbonization in nitrogen ranged from 600 to 1000°C. The starting char for activated carbons was prepared by treating a larger amoun...

Using cherry stones (CS) as starting material and commonly air as activating agent, formation of oxygen structures in activated carbon is investigated. In the preparation of samples, CS was first heated at temperatures between 450 and 900°C in N2 atmosphere. Then, in a successive activation stage, the product carbonized at 600°C was maintained in c...

This paper discusses the chemical composition and chemical structure of rockrose (Cistus ladaniferus L.) extracted into petroleum ether and resulting chars as well as activated carbons. The isothermal temperature of carbonization of extracted rockrose (Jex) in N2 ranged between 600 and 1000°C. The char (CJex-600) employed in the preparation of acti...

Chars were prepared by heating rockrose (Cistus ladaniferus L) under dynamic and isothermal conditions between 200 and 1000°C in nitrogen. Several techniques including chemical analysis, Fourier transform infrared (FTIR) spectroscopy, molecular simulation, density measurements, mercury porosimetry and adsorption were used to study the chemical stru...

Reactions of thioamides with metal carboxylates in organic solvents are described. These processes enable the selective preparation of nitriles, imides or amides depending on the substitution pattern of the starting material. Mechanistic hypotheses supported by experimental evidences, including the unequivocal synthesis of bis(thioacetanilide)mercu...

The surface chemistry and the porous texture of activated carbons prepared from a charred product (Cjex-600), which was obtained from rockrose (Cistus ladaniferus, L.) extracted previously into petroleum ether, were studied. Activated carbons were prepared by heating Cjex-600 between 350 and 850 °C in air to 40% burnoff. Methods of chemical analysi...

The configuration and conformation of glycoamidines in solution have been studied by a combination of NMR data (proton and carbon chemical shifts, coupling constants, NOEs, and variable temperature experiments), and MNDO-PM3 semiempirical calculations.

Fourier transform-infrared spectroscopy was used in the study of rockrose (Cistus ladaniferus, L.) and of rockrose chars and activated carbons. Chars were prepared by heating the starting material between 200 and 1000 °C in nitrogen. Also, a sample was obtained at 600 °C in the atmosphere of the products of the thermal decomposition of rockrose. Th...

Glycoamidines are readily prepared by a mercury-promoted reaction of the corresponding thioamides with amines. The reaction appears to involve the participation of bidentate mercury complexes with N-monosubstituted thioamides, whereas N,N-disubstituted derivatives form presumably monocoordinated species. In the light of these assumptions, two diffe...

Syntheses of nitriles, imides, and amides by reaction of silver carboxylates with unsubstituted, N-substituted, and N,N-disubstituted thioamides in aprotic media are described.

The oxidation of 7 sugar enamines such as (I) with KMnO4/NaIO4 is described.

The oxidation of sugar enamines with KMnO4–NaIO4 has been studied. The products depend on the extent of substitution of the enaminic double bond. For 2′-monosubstituted enamines, N-formyl or N-acyl amino sugars are obtained, whereas the 2,2′-disubstituted substrates afforded α-hydroxy amides, together with those products of double-bond cleavage. Z–...