# Synthesis and Characterization of Silica Obtained by Combined Acid–Alkali Treatment of Serpentinite

## TL;DR

This paper presents a method to recover silica from serpentinite waste using acid-alkali treatment, resulting in a high-yield, mesoporous silica suitable for adsorption and catalysis.

## Contribution

A novel combined acid-alkali treatment process for efficient silica recovery from serpentinite waste is proposed and characterized.

## Key findings

- Silica gel with a yield exceeding 60% was successfully precipitated from serpentinite waste.
- The synthesized silica is mesoporous with a specific surface area of 400 m²·g⁻¹.
- The material is suitable for adsorption and catalytic applications.

## Abstract

Serpentinite rocks and their processing waste represent a valuable source of magnesium and silicon; however, their complex composition complicates the efficient recovery of individual components. This study investigates the combined acid–alkali processing of serpentinite waste from the Zhitikara deposit (Kazakhstan). In the acid leaching stage, sulfuric acid enables magnesium extraction, while subsequent treatment with sodium hydroxide (NaOH) facilitates the selective recovery of silica gel formed during acid attack. At the final neutralization step, amorphous silica is precipitated with a yield exceeding 60% of its initial content. The obtained silica was characterized using FTIR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), inductively coupled plasma mass spectrometry (ICP-MS, Thermo iCAP-Q), and nitrogen adsorption measurements via the BET method. It was established that the synthesized silica gel, according to the IUPAC classification, belongs to mesoporous materials, possesses a well-developed specific surface area (400 m2·g−1), and is suitable for adsorption and catalytic applications.