German Perez-Sanchez

German Perez-Sanchez
University of Aveiro | UA · CICECO - Centre for Research in Ceramics and Composite Materials

PhD Physics

About

39
Publications
3,946
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509
Citations
Additional affiliations
July 2015 - present
University of Aveiro
Position
  • PostDoc Position
Description
  • A)Coarse-grain model for triblock copolymers (Pluronics) in aqueous solutions and mixtures with ionic liquids. This work is focused in the purification/extraction processes of biomolecules by computer simulations. B)Coarse-Grain model for silica/surfactant materials in water to shed light into the synthesis of complex system such as the (Mobil Composition of Matter Materials) MCM family. C)Layered double hydroxide materials atomistic model for MD simulations and Monte Carlo simulations of MOF
April 2013 - present
University of Porto
Position
  • Computer Modelling of Heterogeneous Catalysis
Description
  • Design of smart catalytic materials using advanced computational modelling tools.
March 2013 - June 2015
University of Porto
Position
  • PostDoc Position
Education
September 2000 - September 2005
University of Vigo
Field of study
  • Physics

Publications

Publications (39)
Article
Full-text available
We report a molecular modeling paradigm to describe silica polymerization reactions in aqueous solutions at conditions that are representative of realistic experimental processes like biosilicification or porous silica synthesis – i.e. at close to ambient temperatures and over a wide range of pH. The key point is to describe the Si-O-Si chemical bo...
Article
In this work, the challenging solvent extraction (SX) separation of Pt(iv) from Pd(ii) is investigated using non-ionic hydrophobic type V deep eutectic solvents (DES) incorporating trioctylphosphine oxide (TOPO) as a constituent. Type V DES are highly structured solvents characterised by the existence of an intermolecular hydrogen bonded network, t...
Article
Poly(oxyethylene) alkyl ethers, usually denoted by CiEj surfactants, exhibit a rich phase behavior in water, self-assembling to form a variety of 3-D structures with a controllable morphology that find multiple applications across different industrial segments. Hence, being able to describe and understand the effect of molecular structure on the ph...
Article
This study is aimed to enhance the understanding of the interaction between ionic liquids (ILs) and non-ionic Pluronic triblock copolymers in aqueous two-phase micellar systems (ATPMS) used for selective separation/purification of hydrophobic biomolecules. The ILs allow a precise control of the cloud point phase separation temperatures (CPT), parti...
Article
Porous robust materials are typically the primary selection of several industrial processes. Many of these compounds are, however, not robust enough to be used as multifunctional materials. This is typically the case of Metal-Organic Frameworks (MOFs) which rarely combine several different excellent functionalities into the same material. In this r...
Article
The structure and composition of a zinc‑aluminum layered double hydroxide (Zn2Al LDH) with the intercalated 2-mercaptobenzothiazole corrosion inhibitor (a.k.a. benzo[d]thiazole-2-thiol) are interpreted by means of atomistic molecular dynamics (MD) simulations. The results concerning the proportion of intercalated 2-mercaptobenzothiazole and water s...
Article
Full-text available
Solubilizing agents are widely used to extract poorly soluble compounds from biological matrices. Aqueous solutions of surfactants and hydrotropes are commonly used as solubilizers, however, the underlying mechanism that determines their action is still roughly understood. Among these, ionic liquids (IL) are often used not only for solubilization o...
Article
Full-text available
The tuneable properties of surface-active ionic liquids (SAIL) and Pluronics are dramatically magnified by combining them in aqueous solutions. The thermo-controlled character of both, essential in the extraction of valuable compounds, can be fine-tuned by properly selecting the Pluronic and SAIL nature. However, further understanding of the nanosc...
Article
A coarse-grained (CG) model is developed to reproduce the early stages of the templated synthesis of periodic mesoporous organosilicas (PMO), focusing on benzene as the organic linker. Molecular dynamics simulations of hexadecyltrimethylammonium bromide (CTAB) surfactant in aqueous organosilicate solutions were performed to analyze the micelle form...
Article
Hypothesis: Imidazolium-based ionic liquids (ILs) in water exhibit a surfactant-like behavior that is only partially characterized by experimental techniques with molecular dynamic (MD) simulations emerging as a complimentary tool to study their phase behavior. However, while atomistic models suffer of time and size scale limitations, higher-level...
Article
The specific interactions of ions with biomolecules in aqueous solutions play a very important role in the life sciences and biotechnology. This work aims to study the effect of NaCl, KCl, NH4Cl, CaCl2 or MgCl2 on the solubility of two glycine derivatives, glycylglycine (a.k.a. diglycine) and N-acetylglycine, and to understand the nature of the int...
Article
In comparison to the well-described ionic eutectic mixtures, hydrophobic eutectic solvents (HES) composed of two non-ionic compounds represent a relatively new class of eutectic. In this work, a number of non-ionic HES liquid at room temperature were identified from a large initial screening of potential mixtures. Three new HES based on Thymol+TOPO...
Article
Full-text available
In this paper, we develop a new coarse-grained model, under the MARTINI framework, for Pluronic block copolymers that is able to describe the self-assembly mechanism and reproduce experimental micelle sizes and shapes. Previous MARTINI-type Pluronic models were unable to produce realistic micelles in aqueous solution, and thus our model represents...
Article
A series of zirconium-dicarboxylate based metal-organic frameworks (Zr MOFs) of the UiO-66 (tetrahedral and octahedral cages) or MIL-140 (triangular channels) structure type was investigated for the separation of ethane/ethylene mixtures. The adsorption, investigated both experimentally and computationally, revealed that the size and the type of po...
Article
The temperature responsive solubility of ionic liquids with ‘bulky’ polar regions, such as tributyltetradecyl phosphonium chloride [P44414]Cl, in acidic aqueous solutions, is elucidated through a combined experimental and computational approach. The temperature effect in the acidic aqueous biphasic system HCl/[P44414]Cl/H2O was characterised in the...
Article
Full-text available
It is presented a straightforward procedure based on the CLAYFF force field to perform molecular dynamics (MD) computer simulations with the GROMACS open source package of layered double hydroxide (LDH) materials with different intercalated anions. This procedure enables running very long simulations of systems where all atomic positions are allowe...
Article
Ionic liquid-based acidic aqueous biphasic systems (AcABS) represent a promising alternative to solvent extraction process for the recovery of critical metals in which the substitution of the inorganic salt by an acid allows for the ‘one pot’ approach to the leaching and separation of metals. However, a more fundamental understanding of AcABS forma...
Article
Periodic Mesoporous Silicas (PMS) are one of the prime examples of templated porous materials – there is a clear connection between the porous network structure and the supramolecular assemblies formed by surfactant templates. This opens the door for a high degree of control over the material properties by tuning the synthesis conditions, and has l...
Article
Molecular dynamics simulations of a coarse-grained model are used to study the formation mechanism of periodic mesoporous silica over a wide range of cationic surfactant concentrations. This follows up on an earlier study of systems with low surfactant concentrations. We started by studying the phase diagram of the surfactant-water system and found...
Article
A detailed theoretical understanding of the synthesis mechanism of periodic mesoporous silica has not yet been achieved. We present results of a multi-scale simulation strategy that, for the first time, describes the molecular-level processes behind the formation of silica/surfactant mesophases in the synthesis of templated MCM-41 materials. The pa...
Article
Glucose is an important carbohydrate, relevant both for its biological functions and as a raw material for industrial processes. As a monomer of cellulose, the most abundant biopolymer, it is an alternative feedstock for fuels and chemicals in the biorefinery framework. Since glucose is often used and processed in aqueous solutions, it is important...
Conference Paper
Mesoporous materials have been extensively studied because of their potential applications in catalysis and separations of molecules that are too large to fit into micropores. Additionally, ordered mesoporous materials have also been applied in biotechnology as bioadsorbents and biocatalysts, and as drug delivery vehicles. These materials differ fr...
Article
Full-text available
In this work the solid-fluid equilibrium for carbon dioxide (CO2) has been evaluated using Monte Carlo simulations. In particular the melting curve of the solid phase denoted as I, or dry ice, was computed for pressures up to 1000 MPa. Four different models, widely used in computer simulations of CO2 were considered in the calculations. All of them...
Article
A novel coarse-grained (CG) model to study the self-assembly of silica/surfactant mesostructures during the synthesis of periodic mesoporous silica is reported. Molecular dynamics simulations of hexadecyl trimethylammonium bromide (also called cetyltrimethylammonium bromide, or CTAB) surfactants in water and in aqueous silicate solutions have been...
Article
Isobaric heat capacity per unit volume, C(p), and excess molar enthalpy, h(E), were determined in the vicinity of the critical point for a set of binary systems formed by an ionic liquid and a molecular solvent. Moreover, and, since critical composition had to be accurately determined, liquid-liquid equilibrium curves were also obtained using a cal...
Article
Full-text available
We present experimental data of the isobaric heat capacity per unit volume C(p,x)V(-1) for mixtures containing nitrobenzene and an alkane (C(N)H(2N+2), with N ranging from 6 to 15) upon approaching their liquid-liquid critical points along a path of constant composition. Values for the critical amplitude A(+) have been determined. They have been co...
Article
The thermodynamics of asymmetric liquid-liquid criticality is updated by incorporating pressure effects into the complete-scaling formulation earlier developed for incompressible liquid mixtures [C. A. Cerdeirina et al., Chem. Phys. Lett. 424, 414 (2006); J. T. Wang et al., Phys. Rev. E 77, 031127 (2008)]. Specifically, we show that pressure mixing...
Article
The behavior of the isochoric heat capacity of pure fluids and the isobaric heat capacity at constant composition of binary mixtures along isothermal paths of approach to liquid-gas and liquid-liquid critical points is studied. From the complete scaling formulation of fluid-fluid criticality, explicit expressions for the critical amplitudes of the...
Article
Full-text available
The behavior of the dielectric constant epsilon of pure fluids and binary mixtures near liquid-gas and liquid-liquid critical points is studied within the concept of complete scaling of asymmetric fluid-fluid criticality. While mixing of the electric field into the scaling fields plays a role, pressure mixing is crucial as the asymptotic behavior o...
Article
Full-text available
The thermodynamic consistency of the isobaric heat capacity per unit volume at constant composition C(p,x) and the density rho near the liquid-liquid critical point is studied in detail. To this end, C(p,x)(T), rho(T), and the slope of the critical line (dT/dp)(c) for five binary mixtures composed by 1-nitropropane and an alkane were analyzed. Both...
Article
We present a phenomenological approximation to the study of various non-universal features of liquid–liquid phase transitions in the framework of an approximate equation that relates the excess volume, the excess enthalpy, and the slope of the critical line. The mixtures under study are those containing 1-nitropropane (NP) or nitrobenzene (NB) and...
Article
Measurements of the refractive index n as a function of the temperature T provide an effective method for investigating the shape of coexistence curves in liquid-liquid phase transitions. To gain useful information from such measurements, experimental T-n data need to be converted into T-x and T-ρx data (where x and ρx stand for the mole fraction a...

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Project (1)
Project
SILVIA aims to put in place a computational strategy to guide experiments in the discovery and design of new nanoporous materials, using periodic mesoporous silica as a prototype system. It is built upon previous groundbreaking research by the team members, where a hierarchy of models ranging from the quantum-mechanical level, to the classical atomistic level, to the mesoscale level, were proven to be able to reach all the relevant length and time scales of the process. The goal of SILVIA is to develop a more complete model, with optimal balance between accuracy and computational tractability that is able to simultaneously describe the co-operative self-assembly of silica/surfactant mesostructures and their phase separation, explicitly accounting for silica condensation during the PMS synthesis, i.e. a model that goes from reactants to the final material. Such a model would enable us to replicate an experimental surfactant template synthesis on the computer for the first time.