Preparation of mesoporous silica (MCM41) and its use as an adsorbent for heavy metals for acid mine drainage

Abstract

Potassium silicate solutions obtained were used as a source for MCM41. The preparation of MCM41 was affected by the gelation pH. A pH of 7 produced the purest MCM41 with an external surface area of 98,000 m . The MCM41 could be used as an adsorbent for heavy metals in AMD. A 4% m/v solid loading of MCM41 could remove 95.5, 97.3 and 99.6% of Ni, Cu and Fe respectively. The adsorption process was found to fit the Langmuir isotherm and pseudo second order kinetics. The Gibbs free energy of adsorption for all metals was below -20 kJ/mol for all metals. The enthalpy for Fe, Cu and Ni removal were 19.97, 21.40 and 16.44 kJ/mol respectively and thus endothermic. The entropy for the removal of Fe, Cu and Ni were found to75.6, 76.2 and 56.5 J/mol respectively showing the strong affinity of MCM41 for the metals. The process was also thermodynamically spontaneous with the spontaneity increasing with an increase in temperature.

Synthesis, Characterizations, and Recent Applications of the Silica-based Mobil Composition of Mesoporous Material: A Review

“…[74]. XRF is used to determine the oxide content in materials, revealing that SiO2 is the main compound in members of the M41S family, as well as trace amounts of Al2O3, P2O5, and K2O3 [75][76]. The FESEM images provide information on the morphology of the silica-based mesoporous arrays [30].…”