•This article studied the synthesis of lignin-modified silica nanoparticles from black liquor.•Silicon in black liquor as industrial waste was recovered.•Lignin in black liquor can control the diameter of silica.•CO2 obtained from the waste gas can be used as a precipitating reagent.A novel and green route was developed to prepare lignin-modified silica nanoparticles from black liquor by an integrated utilization strategy of rice straw. The lignin in black liquor was used as a structure directing reagent to control the particles' size, CO2 obtained from the waste gas of pulp mills was used as a precipitating reagent and finally the lignin-modified silica nanoparticles were obtained. The effects of lignin concentration, pH and temperature on the properties of the materials have been investigated in detail, and the synthesis mechanism of the lignin-modified silica nanoparticles was proposed based on a series of experimental results.In a wet colloid, the surface of the silica particles contains silanol groups (Si-O-H). Herein, silica particles and lignin molecules are connected to form hydrogen bonds. The steric hindrance of lignin limits the aggregation of silica.

An alternative approach to the utilization of lignocellulosic biomass is reported in this paper. It was the first time that rice husk was used as carbon source to synthesize carbon coated silica particles. Rice husk was hydrolyzed and mixed with silica powder, then biochar coated silica particles were simply in situ synthesized. The coating morphology was similar to those who used pure chemicals or glucides as carbon source, while the mild reacting conditions could keep some organic functional groups on the particle surface and make the modification easier. Acid could be recycled to form a semi-closed reaction system. The composite was designed as one of the bases for the preparation of activated carbon shell. Thus, this paper may provide a low-cost and simple method to prepare functional materials.Graphical abstractHighlights► Rice husk was used as carbon source to synthesize biochar coated silica particles. ► Reaction was under mild water-bath temperature. ► Acid could be recycled. ► The composite was designed as a base to prepare activated carbon shell.

Activated carbons with high surface area were prepared by phosphoric acid as activation agent and rice husks as precursors. It was found that the characteristics of the activated carbons were influenced not only by the preparation but also by the post-processing method. The high surface area of the activated carbons was prepared under the optimum condition (50% H3PO4 with impregnation ratio of 5:1, activation temperature of 500 °C, activation time of 0.5 h, wash water temperature of 100 °C). SiO2 content could affect the surface area of activated carbons, either. The lower SiO2 content of the activated carbons, the higher pore volume the carbons had. The SiO2 content was 11.2% when used the optimum condition. The explanation was that silicon element in rice husks reacted with H3PO4 to form silicon phosphate (SiP2O7), and it could be proved further by X-ray diffraction analysis, SiP2O7 could be removed by post-process.Highlights► High surface area activated carbon can be prepared by rice husk H3PO4 without pretreatment. ► The characteristics of the activated carbon were greatly influenced by post-processing method. ► The lower SiO2 content of the activated carbons, the higher pore volume the carbons had. ► Some silica in rice husk reacted with H3PO4 to form SiP2O7 which could be removed by post-process.

Polyurethane/zinc borate (PU/ZB) nanocomposites were prepared via in situ polymerization with the main aim to increase the flame retardancy of PU. In this study, zinc borate (ZB) nanoparticles were modified with poly (propylene glycol) phosphate ester (PPG-P) and oleic acid (OA). The surface modification of ZB, the microstructure and the properties of nanocomposites were investigated by water contact angles, thermogravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and elemental analysis. It was found that the addition of a small amount of OA greatly improved the dispersion of ZB nanoparticles, meanwhile, the modified ZB with OA had very significant effects on the thermal stability of PU.Graphical abstractHighlights► Surface modification of ZB nanoparticles with PPG-P and OA. ► Well dispersion of ZB nanoparticles in PU matrix. ► Preparation of PU/ZB nanocomposites with higher performance via in situ polymeration.

Well-dispersed and long-term stable nano-CaCO3/polyol dispersions were prepared by a mechanochemical approach with the aid of poly (propylene glycol) phosphate ester (PPG-P). Polyurethane (PU)/CaCO3 nanocomposites were prepared by further in situ polymerization with 6 wt% nano-CaCO3. The microstructure and dispersion of nano-CaCO3 in the nanocomposites were investigated. It was found that well dispersion was obtained up to 6 wt% of the surface treated CaCO3 loading for PU/CaCO3 nanocomposite. The segmented structures of PU were not interfered by the presence of nano-CaCO3 in these nanocomposites as evidenced by Fourier transform infrared. Compared with the pure PU, a significant improvement in thermal stability was observed with the addition of 6 wt% of the surface treated CaCO3. The experimental results suggested that the properties of nanocomposites were correlated with the dispersion of nano-CaCO3 in PU and the interfacial interactions between nano-CaCO3 and polymer matrix.

We report here a simple approach to the synthesis of Cu2O/TiO2 core-shell nanocomposites with uniform octahedral structure in solution phase. First, fresh synthesized Cu2O octahedra were used as precursor, and butyl titanate (Ti(OBu)4) diluted by ethanol was preliminary hydrolyzed by the water adsorbed on the surface of Cu2O, so a very thin TiO2 condensed on the Cu2O surfaces. Then, when a mixture of water and ethanol was dropped into the reaction system, the Ti(OBu)4 would further hydrolyze and condense around the Cu2O to form TiO2, so octahedral Cu2O/TiO2 core-shell composites with uniform and compact TiO2 shells were obtained. This method is suitable for the formation of uniform integrated TiO2 shells and their thickness can be controlled by adjusting the ratio of water/ethanol (W/E). According to the surface photovoltage spectroscopy of the Cu2O/TiO2 composites, we think the material would have a potential application in photocatalysis and photoelectric transition.

Silica and activated carbon were simultaneously produced from rice husk ash with K2CO3. The surface area and average pore size of the activated carbon were 1713 m2/g and 4 nm. The maximum adsorption capacity of activated carbon was 210 mg/g for methylene blue and the capacitance value reached 190 F/g. The yield of silica reached 96.84% and the particle size was 40–50 nm. Potassium carbonate could be recycled. The entire synthetic procedure was simple, environmental-friendly and economical-effectively.Highlights► The raw material comes from the process that rice husk prepared into bio-oil. ► The wastewater generated in the process have been collected and reutilized. ► The high surface area of activated carbon and silica are prepared simultaneously. ► The synthetic procedure is inexpensive and environment-friendly.