One more paper of our work is accepted for publication in Advanced Powder Technology (Impact factor: 1.510) published by Elsevier; a journal on various areas of powder and particles that include: Production of powder and particulate materials in gases and liquids (nanoparticles, fine ceramics, pharmaceuticals, novel functional materials, etc.); Aerosol and colloidal processing; Powder and particle characterization; Dynamics and phenomena; Calculation and simulation (CFD, DEM, Monte Carlo method, population balance, etc.); Measurement and control of powder processes; Particle modification; Comminution; Powder handling and operations (storage, transport, granulation, separation, fluidization, etc.).
A facile method for the production of high-surface-area mesoporous silica gels from geothermal sludge
Srie Muljani, Heru Setyawan,Gede Wibawa, Ali Altway
- High-surface area mesoporous silicas were succesfully prepared by a facile chemical method.
- Two-step aging increases the surface area of silica gels and can reach 600 m2 g-1.
- The silica gel properties can be tailored by changing the operating conditions.
- The silica gels can be used for adsorbent, catalyst host and ultrafilters.
Mesoporous silica gels were successfully produced from geothermal sludge by alkali extraction followed by acidification. The silica in the geothermal sludge was dissolved by NaOH solution to produce a sodium silicate solution, which was then reacted with HCl or tartaric acid to produce silica gels. The effects of silica concentration and pH on the silica gel properties were investigated. In addition, an improved method was proposed by incorporating two-step aging. The first aging step, which was conducted at pH 10, was used to induce Ostwald ripening to increase the size of the primary particles, and the second step was used to strengthen the gel network. Decreasing the silica concentration by diluting the as-prepared sodium silicate solution tended to increase the surface area and pore volume of the prepared silica gels. The silica gels produced by tartaric acid possessed higher surface area and pore volume than those by HCl.The surface area and pore volume reached approximately 450 m2 g−1 and 0.8 cm3 g−1, respectively. When the gelation pH was decreased to 6, the surface area exceeded 600 m2 g−1. The first aging process increased the size and uniformity of the primary particles, which in turn increased the surface area of the particles. The pore diameter for all cases was greater than 5 nm, indicating that the silica gels were mesoporous.