School of Earth and Environment
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Juan Diego Rodriguez Blanco Dr Juan Diego Rodriguez Blanco

Research Fellow

Telephone number: +44(0) 113 34 35225
Email address: J.D.RodriguezBlanco@leeds.ac.uk
Room: 9.128

Amase 2009 blog from Svalbard

Goldschmidt 2009 Conference Blog

Research Interests

I am a postdoctoral research fellow at the University of Leeds. I come from the University of Oviedo (NW Spain) where I graduated in Geology and did my Ph.D. about As(V)aq-gypsum interaction.

Present work: "The kinetics and mechanisms of calcium carbonates nucleation and growth from solution."

Funding: Mineral Nucleation and Growth Kinetics (MIN-GRO) Research and Training Network funded by the European Union under the Sixth Framework Marie Curie Actions.

This project will combine synchrotron-based methods (including SAXS and XAS), with wet chemical, dynamic light scattering and HR-TEM techniques and aims to quantify the rates and mechanisms of calcium carbonate nucleation and growth in real time and on an atomic/nano scale. This data will be linked with first principle geochemical modelling and will provide base information for the development of the database for carbonate mineral growth rate laws that is the major output of the whole Min-Gro network.

International consortium with Leeds PI: Liane G. Benning

Co-Pi's Sam Shaw; Rik Brydson

More information about past research:

1.- Interaction of As(V) with gypsum at different pH ranges.

This study is focused on the As(V)-gypsum interactions in aqueous solutions within different ranges of pH and concentration. All this research corresponds to my Ph.D. Thesis, which was supervised by Prof. M. Prieto and Dr. A. Jiminez (both from the Crystallography and Mineralogy Area of the Geology Department, University of Oviedo, Spain).

The main goals of this study were:

  1. to evaluate the capacity of gypsum to remove arsenic from aqueous solutions;
  2. to understand the nature of the processes by which the removal takes place and,
  3. to characterize the solid phases derived from these interactions.

Although the mobility and toxicity of arsenic in the environment has been abundantly studied, the crystal-chemistry and thermodynamic properties of arsenates continues to be poorly known. Moreover, the determination of thermodynamic solubility products of arsenates has received little attention, perhaps as a consequence of the complicated crystallization behavior of these compounds in aqueous environments, which involves formation of an enormous diversity of hydrates, double salts, acidic arsenates, etc. This lack of data is an important handicap because an in-depth study of arsenate mobility in natural systems requires a precise knowledge of the solid phases that may or may not precipitate, as well as their crystal-chemistry, and their solubility. The study was carried out at different pH ranges using batch experiments. The aqueous solutions were characterized by atomic absorption spectrometry, ionic chromatography, and ICP-AES. The solids were characterized using SEM-EDS, powder, grazing incidence, and single-crystal X-ray diffraction.

The results show that at high pH (>10.5) there is a virtually complete removal of As(V) due to the surface precipitation of amorphous Ca4(OH)2(AsO4)2•4H2O and crystalline NaCaAsO4•7.5H2O.

In contrast, the effectiveness of the uptake process is very low at lower pHs, as it involves the surface precipitation of different calcium arsenates (guerinite, sainfeldite, pharmacolite, ferrarisite...).

The study included determination of solubility products, growth morphologies, and epitaxial relationships.

In addition, structural characterization by single crystal X-ray diffraction has been accomplished for NaCa2H(AsO4)2•6H2O and NaCaAsO4•7.5H2O.

2.- Removal of cadmium from wastewaters by aragonite shells and the influence of another divalent cations.

I have participated in this research about the study of uptake of divalent metals by biogenic aragonite, in collaboration with Dr. S. Kuhler (Graz University of Technology), Prof. M. Prieto (University of Oviedo), Dr. P. Cubillas (The University of Manchester) and Prof. E. H. Oelkers (LMTG, Toulouse).

The effect of dissolved Zn, Co, Pb, Mg, and Ca on the uptake of cadmium by biogenic aragonite was investigated. Experiments were performed in batch-reactors using metal cadmium-bearing solutions and shell fragments with diameters in different ranges, the solid/liquid ratio being 10 grams per litre.

Different initial concentrations of cadmium and metals (1.0-0.005 mM) were used. Uptake takes place via heterogeneous nucleation of metal-bearing crystallites onto the shell surfaces. Cadmium removal occurs by surface precipitation of otavite. Under the conditions used here, Co and Ca as well as Pb e 0.3 mM and Zn e 0.3 mM do not have a significant effect on the removal of cadmium. At higher concentrations, Pb and Zn outcompete Cd for the dissolving carbonate ions and thus decrease significantly the Cd removal rates. In contrast, Mg has a slight enhancing effect. Pb and Zn are removed faster than Cd, precipitating as PbCO3, Pb3(CO3)2(OH)2, and Zn5(CO3)2(OH)6. Within 24-72 h the concentrations of lead, cadmium, and zinc decrease until ~0.5 μM, and the presence of aragonite buffers the solution to a pH above 8 avoiding redissolution. The study demonstrates the high effectiveness of biogenic aragonite in removing Cd and other metals from polluted waters.

3.- Interaction of gypsum with Pb bearing aqueous solutions

I am participating in this research concerning with the study of uptake of Pb by gypsum in collaboration with Dr. J. M. Astilleros (Complutense University, Madrid), Dr. Godelitsas (University of Athens), Prof. L. Fernandez-Diaz (Complutense University, Madrid) and Prof. M. Prieto (University of Oviedo).

The aim of this research is investigating the effectiveness of gypsum (CaSO4•2H2O) as a Pb-sequester.

Our experimental results show that the concentration of Pb2+ in the aqueous solution rapidly decreases during the first minutes of the interaction.

 

 

Publications

  • Roncal-Herrero, T; Rodriguez-Blanco, JD; Oelkers, EH; Benning, LG (2011) The direct precipitation of rhabdophane (REEPO4 center dot nH(2)O) nano-rods from acidic aqueous solutions at 5-100 A degrees C, J NANOPART RES, 13, pp.4049-4062. doi:10.1007/s11051-011-0347-6
  • Rodriguez-Blanco, JD; Shaw, S; Benning, LG (2011) The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite., Nanoscale, 3, pp.265-271. doi:10.1039/c0nr00589d
  • Astilleros, JM; Godelitsas, A; Rodriguez-Blanco, JD; Fernandez-Diaz, L; Prieto, M; Lagoyannis, A; Harissopulos, S (2010) Interaction of gypsum with lead in aqueous solutions, APPL GEOCHEM, 25, pp.1008-1016. doi:10.1016/j.apgeochem.2010.04.007
  • Rodriguez-Blanco, JD; Bots, P; Terrill, NJ; Shaw, S; Benning, LG (2010) The mechanism of ACC nanoparticle transformation to vaterite, GEOCHIMICA ET COSMOCHIMICA ACTA, 74, pp.A876-A876.
  • Roncal-Herrero, T; Rodriguez-Blanco, JD; Benning, LG; Oelkers, EH (2009) Precipitation of Iron and Aluminum Phosphates Directly from Aqueous Solution as a Function of Temperature from 50 to 200 degrees C, CRYST GROWTH DES, 9, pp.5197-5205. doi:10.1021/cg900654m
  • Rodriguez-Blanco, JD; Jimenez, A; Prieto, M; Torre, L; García-Granda, S (2008) Interaction of gypsum with As(V)-bearing aqueous solutions: Surface precipitation of guerinite, sainfeldite, and Ca2NaH(AsO4)2·6H2O, a synthetic arsenate , American Mineralogist, 93, pp.928-939. doi:10.2138/am.2008.2750
  • Rodriguez-Blanco, JD; Shaw, S; Benning, LG (2008) How to make 'stable' ACC: protocol and preliminary structural characterization, MINERALOGICAL MAGAZINE, 72, pp.283-286. doi:10.1180/minmag.2008.072.1.283
  • Rodriguez-Blanco, JD; Jimenez, A; Prieto, M (2007) Oriented overgrowth of pharmacolite (CaHAsO4·2H2O) on gypsum (CaSO4·2H2O) , None, 7, pp.2756-2763. doi:10.1021/cg070222+
  • Kohler, SJ; Cubillas, P; Rodriguez-Blanco, JD; Bauer, C; Prieto, M (2007) Removal of cadmium from wastewaters by aragonite shells and the influence of other divalent cations, ENVIRON SCI TECHNOL, 41, pp.112-118. doi:10.1021/es060756j
  • Jimenez, A; Rodriguez-Blanco, JD; Torre-Fernández, L; Prieto, M; García-Granda, S (2006) Crystal structure of dicalcium sodium monohydrogen diarsenate hexahydrate, Ca2Na[HAsO4][AsO4]·6H2O, Zeitschrift für Kristallographie, 221, pp.241-242. doi:10.1524/ncrs.2006.0055