Nanoscale Res Lett (2010) 5:1408–1417 DOI 10.1007/s11671-010-9654-6 N A N O E X P R E S S Novel Crystalline SiO2 Nanoparticles via Annelids Bioprocessing of Agro-Industrial Wastes A. Esp´ındola-Gonzalez • A. L. Mart´ınez-Herna´ ndez • C. Angeles-Cha´ vez • V. M. Castan˜ o • C. Velasco-Santos Received: 20 April 2009 / Accepted: 17 May 2010 / Published online: 15 June 2010 The Author(s) 2010. This article is published with open access at Springerlink.com Abstract The synthesis of nanoparticles silica oxide from rice husk, sugar cane bagasse and coffee husk, by employing vermicompost with annelids (Eisenia foetida) is reported. The product (humus) is calcinated and extracted to recover the crystalline nanoparticles. X-ray diffraction (XRD), transmission electron microscopy (TEM), high- resolution transmission electron microscopy (HRTEM) and dynamic light scattering (DLS) show that the biotransfor- mation allows creating speciﬁc crystalline phases, since equivalent particles synthesized without biotransformation are bigger and with different crystalline structure. Keywords Silica nanoparticles Agricultural waste Bioprocessing Worms A. Esp´ındola-Gonzalez V. M. Castan˜o (&) Centro de F´ısica Aplicada y Tecnolog´ıa Avanzada Universidad Nacional Auto´noma de Me´xico, Campus Juriquilla, Quere´taro, Me´xico e-mail: castano@fata.unam.mx A. Esp´ındola-Gonzalez Facultad de Ingenier´ıa, Universidad Nacional Auto´noma de Me´xico, Ediﬁcio Bernardo Quintana. Cd. Universitaria, Quere´taro 04510, Me´xico A. L. Mart´ınez-Herna´ndez C. Velasco-Santos (&) Instituto Tecnolo´gico de Quere´taro, Av. Tecnolo´gico S/N Esq. Gral. Mariano Escobedo, Col, Centro Histo´rico 76000, Me´xico e-mail: carlosv@fata.unam.mx C. Angeles-Cha´vez Instituto Mexicano del Petro´leo, Eje Central La´zaro Ca´rdenas Norte 152, San Bartolo Atepehuacan, Gustavo A. Madero 07730, Me´xico 123 Introduction Agro-industrial wastes have recently attracted a great deal of attention as potential sources of novel green alternatives such as biotransformation for fuels and other materials. Many of these wastes contain amorphous silica that can be transformed into crystalline nanoparticles of industrial interest. Silicon is the most common element of the Earth’s surface after oxygen; this element is released into the soil by chemical and biological processes [1]. Industrially speaking, silicon is the basis of semiconductors, glasses, ceramics, plastics, elastomers, resins, mesoporous molec- ular sieves and catalysts, optical ﬁbers and coatings, insu- lators, moisture shields, photoluminescent polymers, ﬁllers, cosmetics and biomedical devices [2, 3], among many other applications. The manufacture of these materials typically requires high temperatures, high pressure and/or the use of caustic chemicals [4]. In contrast, in nature, silica architectures with delicate morphologies are gener- ated under ambient conditions [5]. Unicellular organisms, such as diatoms, use structuring and templating biomole- cules to produce silica shells that not only contain hierar- chically ordered porous structures, with dimensions ranging from the nanometer to the micrometer domain, but also possess remarkable mechanical and structural prop- erties [6–8]. Other approach involves the use Fosuarium oxysporum, a plant pathogenic fungus for the biotransfor- mation of naturally occurring amorphous plant bio-silica into quasi-spherical crystalline silica nanoparticles and its extracellular leaching in the aqueous environment at room temperature [9]. An analysis suggested that extreme ther- mophilic bacteria within the genera thermus and hydroge- nobacter are predominant components among the indigenous microbial community in siliceous deposits.