The dissipation of energy in the form of heat causes a huge energy loss across the globe. Thermal insulation materials which reduce heat loss can alleviate the energy crisis. Among many thermal insulation materials, silica aerogels (SAs) have attracted extensive attention due to their high surface area, low density and low thermal conductivity. However, the applications of SAs are restricted by their mechanical fragility. In this paper, a series of different ratios of silica–chitosan composite aerogels (SCAs) were prepared by mixing sodium silicate aqueous solution and chitosan solution followed by freeze drying. The surface morphology of SAs, CAs and SCAs was studied by scanning electron microscopy (SEM). The specific surface area, pore volume and pore size of the composite aerogels were studied by N₂ adsorption–desorption isotherms. The thermal conductivities, chemical structures, thermal stabilities and hydrophobicities of SAs, CAs and SCAs were tested and analyzed. In addition, the adsorption properties of SCAs were measured using different organic solvents. The results reveal that when the proportion of sodium silicate aqueous solution and chitosan solution is 1:1, the obtained SCA−1/1 has the best performance, with a low thermal conductivity of 0.0369 W/m·K, a large specific surface area of 374.7 m²/g, and good thermal stability. In addition, the prepared SCAs also have good hydrophobicity and absorption properties, with adsorption capacities of 6.7–9.4 g/g, which show great application potential in the fields of insulation and adsorption.

Porous carbon nanofibers are commonly used for adsorption processes owing to their high specific surface area and rich pore structure. However, the poor mechanical properties of polyacrylonitrile (PAN)-based porous carbon nanofibers have limited their applications. Herein, we introduced solid waste-derived oxidized coal liquefaction residue (OCLR) into PAN-based nanofibers to obtain activated reinforced porous carbon nanofibers (ARCNF) with enhanced mechanical properties and regeneration for efficient adsorption of organic dyes in wastewater. This study examined the effects of contact time, concentration, temperature, pH, and salinity on the adsorption capacity. The adsorption processes of the dyes in ARCNF are appropriately described by the pseudo-second-order kinetic model. The maximum adsorption capacity for malachite green (MG) on ARCNF is 2712.84 mg g⁻¹ according to the fitted parameters of the Langmuir model. Adsorption thermodynamics indicated that the adsorptions of the five dyes are spontaneous and endothermic processes. In addition, ARCNF have good regenerative performance, and the adsorption capacity of MG is still higher than 76% after 5 adsorption-desorption cycles. Our prepared ARCNF can efficiently adsorb organic dyes in wastewater, reducing the pollution to the environment and providing a new idea for solid waste recycling and water treatment.

The adsorption separation and extraction of low-concentration boron from salt-lake brine have great significance. Magnetic separation avoids the problem of adsorbent granulation and improves the usage efficiency. The silicon-based adsorbents have attracted interest due to their superior acid and alkali resistance, in which polyhydroxy graphene enhances the adsorption of boron ions. Herein different boron adsorbents, derived by magnetic separation, were developed and characterized by SEM, TEM, XPS, VSM, FT-IR, and XRD analysis. The adsorption-desorption performance of boron adsorbents with different compositions was evaluated. The isotherms and kinetics parameters of the boron extraction were evaluated based on adsorption-desorption tests. The graphene-based magnetic adsorbent (Go-Fe₃O₄@SiO₂@mSiO₂-Glu) registered a high boron adsorption capacity of 23.90 mg/g at pH = 9 in the boron solution and 24.84 mg/g for East Taigener salt-lake brine. The Na⁺, Mg²⁺, Ca²⁺, and Cl⁻ ions have little interference with the boron adsorption. The adsorbents exhibit magnetic separation performance and good cycle life. The results showed that acid-alkali desorption solution has little effect on the adsorbents, and the composite of graphene enhances the adsorption of boron ions. The adsorbents developed in this study are promising to recover boron from low-concentration boron-containing salt-lake brines.