An improved method for the production of biogenic silica from cornhusk using sol–gel polymeric route

Abstract

Porous silica was synthesized from cornhusk using the sol–gel polymeric route and compared with ash obtained from the direct combustion process under laboratory conditions. The unmodified ash from the direct combustion process was dissolved in NaOH for 1 h to form sodium silicate, which was subsequently hydrolyzed with citric acid to yield a silica xerogel. The obtained xerogel was characterized using inductively coupled plasma–optical emission spectrometry (ICP-OES), Fourier transforms infrared (FTIR) spectroscopy, X-ray diffraction (XRD), simultaneous thermal analysis (STA), gas sorption techniques to determine their elemental constituents, functional groups, crystalline phases, thermal stability, and porosity, respectively. The results showed that the synthesized silica xerogel exhibited porous network structures with a high-specific surface area and mesopore volume of 384 m2/g and 0.35 cm3/g, respectively. The pore size distribution revealed a complete transformation of the pore network structures of the unmodified ash from a monomodal to a bimodal pore system, with micro- and mesopore peaks centered around 1.5 and 3.8 nm, respectively. The ICP-OES results showed that the silica content significantly increased from 52.93 to 91.96 wt.% db after the sol–gel treatment. XRD diffraction confirmed the amorphicity of the silica particles obtained from the sol–gel extraction method. In addition, the STA data showed that the silica xerogel has high thermal stability compared to the unmodified ash, as the latter exhibited poor thermal stability and low textural properties. The high surface area and narrow pore cavity size distribution of the porous silica xerogel make it an ideal substrate for catalysts and an excellent template for growing other nanoparticles within the pores.

Comparative Study of Commercial Silica and Sol-Gel-Derived Porous Silica from Cornhusk for Low-Temperature Catalytic Methane Combustion

“…The catalyst prepared from cornhusk support showed better resistance to water vapor than the commercial catalyst. For example, the methane conversion over the prepared catalyst was still above 70%, while the commercial catalyst showed a methane conversion of approximately below 50% in wet conditions at 600 • C. This observation may be due to the hydrophobic nature of the sol-gel support [42], the high dispersion of the active metal particles, and the strong metal-support interactions in the Pd/CeO 2 /CHSiO 2 catalyst, which helped to prevent the sintering of the metal particles and maintained the stability of the catalyst under the water vapor atmosphere. Similar adverse effects of water inhibition on catalytic performance have been reported in the literature [32,33].…”

“…Cornhusk, as an agricultural residue, is therefore ideal for use in a holistic manner, not only thermally but also materially for the production of porous biogenic silica [41]. As a result, Prempeh et al [42] synthesized high-quality biogenic silica nanoparticles using the sol-gel polymeric route with high potential in catalysis operations. Sol-gel products benefit from favorable properties such as high surface area with a bimodal pore size distribution, allowing for adequate surface for the active species immobilization and unimpeded mass transfer of gaseous species (reactants and products) [43].…”

Optimization of purity and yield of amorphous bio‐silica nanoparticles synthesized from bamboo leaves

“…[5,6] On the other hand, several crops can naturally convert mono-silicic acid from the soil to silica by the oxolation process. [7,8] Crops with rich silica content include bamboo (leaves), [9][10][11][12] rice and corn (husks), [13][14][15] and sugarcane (stems as bagasse). [16][17][18] Bamboo crops (Phyllostachys pubescens) are widely found in tropical countries.…”

“…[30] Many studies explain silica extraction from biomass ash by sol-gel method. [14,[31][32][33] Chemical pretreatment through acid washing is widely used to remove alkaline mineral impurities in the ash. [11,[34][35][36][37] The washed ash is initially extracted using NaOH or KOH as alkaline solvent.…”