The use of mesoporous silica in the removal of Cu(I) from the cyanidation process Ma. Mercedes Salazar-Herna ´ndez • Carmen Salazar-Herna ´ndez • Enrique Elorza-Rodrı ´guez • Higinio Jua ´rez Rı ´os Received: 18 July 2014 / Accepted: 12 September 2014 / Published online: 23 September 2014 Ó Springer Science+Business Media New York 2014 Abstract This research proposed the use of a mesoporous silica material (SiO 2 ) as a Cu(I) adsorbent in a pre-treat- ment of cyanide effluents employed in gold and silver extraction. Two copper sources were employed: a [Cu(CN) X ] -(X?1) standard solution, and a cyanide solution obtained from an ore of Pen ˜a de Bernal, Chihuahua, Me ´xico, which was named Cu(I)–CN–PB. Mesoporous silica removes around 90 % of the Cu(I)–CN at 30 min in Cu(I)–CN solutions with 50 ppm of the metals; while, in a solution with a high concentration of copper (311 ppm), around 52 % was removed. The adsorption dates were adjusted following the Langmuir model; obtained a maxi- mum adsorption capacity (Q 0 ) of 8.01 mg g -1 and a sep- aration factor (R L ) lower than one, which indicates a favorable thermodynamic adsorption process of Cu(I)–CN by SiO 2 . However, a similar copper removal capability and low selectivity was observed when Cu(I)–CN–PB was employed as the copper source. Therefore, a modification on the silica’s surface with phenyl groups was performed, in order to enhance the metallic ion selectivity. IR spec- troscopy and TGA/DTA analysis confirmed the coupling of organic groups; on the other hand, nitrogen adsorption indicated a decrease on the BET surface area of the silica at 76 %, a modification of the silica structure was observed with the formation of two pore diameter (3.6 and 5.37 nm); 13 C CP-MAS NMR indicated two different chemical shifts that corresponded to the phenyl groups on the two different pores observed. Phenyl groups enhance the selectivity for copper in the cyanide effluent, increasing the removal to 99 %. Introduction In the last years, the ordered mesoporous silica (OMS) has caught the attention of specialists in the scientific and technological fields. This is due to its highly chemical, mechanical, and thermal stability, therefore, rendering usefulness as catalytic support, column chromatography, adsorbent materials, bio-reservoir of drugs, and immobi- lizer of enzymes or proteins, among other applications [1– 11]. Mesoporous silica presents a high surface area (400–900 m 2 g -1 ) and an organized porous structure. These properties allow the OMS to be used as an adsorbent in environmental applications [7–14], where the inorganic solid can trap different organic molecules and metallic particles within its pores. However, several authors have proposed the modification of the silica through the immo- bilization of functional groups on the surface material, improving the interaction between the analyte (molecule to be removed) and the silica [9]. A special application for this chemically modified silica is the removal of heavy metals [2, 7–15]. Kim et al. have reported the synthesis of sol–gel silica chemically bonded with Cyanex 272 for the removal of Cu(II), Ni(II), and Zn(II) [8]. Additionally, Sahoo et al. modified the silica’s surface with alamine 336S increasing the adsorption of heavy metals under acidic conditions [14]. Ma. M. Salazar-Herna ´ndez (&)  E. Elorza-Rodrı ´guez Departamento de Ingenierı ´a en Minas, Metalurgia y Geologı ´a, Universidad de Guanajuato, Ex-Hacienda San Matı ´as S/N, 36000 Guanajuato, Mexico e-mail: merce@ugto.mx C. Salazar-Herna ´ndez (&)  H. Jua ´rez Rı ´os Unidad Profesional Interdisciplinaria de Ingenierı ´as Campus Guanajuato, Instituto Polite ´cnico Nacional, 36275 Silao de la Victoria Gto, Mexico e-mail: msalazarh@ipn.mx 123 J Mater Sci (2015) 50:439–446 DOI 10.1007/s10853-014-8603-7