Rice straw is a common agricultural waste. In order to increase the added value of rice straw and improve the performance of rice straw biochar. MgO-modified biochar (MRBC) was prepared from rice straw at different temperatures, pyrolysis time and MgCl₂ concentrations. The microstructure, chemical and crystal structure were studied using X-ray diffraction (XRD), a Scanning Electron Microscope (SEM), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption desorption isotherms and Elementary Analysis (EA). The results showed that the pyrolysis temperature had significant influence on the structure and physicochemical property of MRBCs. MRBC-2 h has the richest microporous structure while MRBC-2 m has the richest mesoporous structure. The specific surface area (from 9.663 to 250.66 m²/g) and pore volume (from 0.042 to 0.158 cm³/g) of MRBCs increased as temperature rose from 300 to 600 °C. However, it was observed MgCl₂ concentrations and pyrolysis time had no significant influence on pore structure of MRBCs. As pyrolysis temperature increased, pH increased and more oxygen-containing functional groups and mineral salts were formed, while MgO-modified yield, volatile matter, total content of hydrogen, oxygen, nitrogen, porosity and average pore diameter decreased. In addition, MRBCs formed at high temperature showed high C content with a low O/C and H/C ratios.

Activated carbon fiber was prepared from liquefied wood by chemical activation with ZnCl₂ (Z-LWACF) at different impregnation ratios, with a particular focus on its adsorption property, kinetic and isotherm. The characterization and properties of Z-LWACFs were investigated by nitrogen adsorption/desorption, X-ray photoelectron spectroscopy (XPS), methylene blue (MB) and iodine adsorption. Two activation process methods were employed to prepare Z-LWACF and contrasted with others fibers. The results showed that the Z-LWACF obtained by one-step ZnCl₂ activation present higher yields and specific surface area than others fibers. Besides, the change of MB adsorption value at different impregnation ratios was consistent with pore structure distribution above 1.5 nm pore size, indicating that larger micropores (1.5 to 2 nm) and mesopores played a major role in the MB adsorption by Z-LWACF. The kinetics of MB adsorption process was found to follow the pseudo-second-order kinetic model and the adsorption rate was controlled by chemisorption. It was also found that MB adsroption by Z-LWACF belonged to monolayer adsorption and Z-LWACF was easy to adsorb MB.

Biochar is important for soil improvement, fertilizer innovation, and greenhouse gas reduction. In this paper, Mg-modified biochar was prepared from rice and corn straw and mixed with soil at a 1% (w/w) addition in an indoor soil simulation experiment to study the effect of Mg-modified biochar on the chemical properties of acidic soil. The results showed that the addition of Mg-modified biochar reduced soil acidity and improved soil fertility. Compared with the control group, the Mg-modified biochar treatment significantly increased the concentrations of available potassium, available phosphorus, total phosphorus, organic carbon and exchangeable calcium and magnesium in the soil, and effectively increased the concentration of total nitrogen. Rice straw Mg-modified biochar treatment was more effective in increasing the soil-available potassium, available phosphorus, total phosphorus and exchangeable magnesium concentration, while corn straw Mg-modified biochar was more effective in increasing the soil organic carbon and exchangeable calcium concentration. In addition, the high pyrolysis temperature of Mg-modified biochar was more effective in promoting the soil-available potassium, available phosphorus and total nitrogen concentration, while the low pyrolysis temperature of Mg-modified biochar was more effective in promoting soil alkaline nitrogen, exchangeable calcium and magnesium.

A Fe³⁺-doped SiO₂/TiO₂ composite film (Fe³⁺-doped STCF) was prepared on a wood surface via a sol–gel method to improve its photocatalytic activity and hydrophobicity. The structure of the composite film was analyzed by Fourier Transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity toward degradation of methyl orange and its hydrophobic nature were investigated. The results showed that the composite film was anatase TiO₂ crystal form, and the addition of Fe³⁺ ions and SiO₂ enhanced the diffraction peaks for the anatase crystal form. The photocatalytic activity of the wood coated with the composite film was enhanced. The highest degradation percentage was at 1 wt % Fe³⁺ (40.37%), and the degradation ability of the wood towards methyl orange solution was further improved under acidic conditions. In addition, the composite film was hydrophobic, and the hydrophobic property was enhanced as the immersion time in the sol increased. The wood surface coated with Fe³⁺-doped STCF exhibited strong hydrophobicity and photocatalytic activity, which could effectively prevent moisture from adhering to the surface and degrade organic pollutants; thus, the modified wood surface had good self-cleaning function.

A sol-gel method was employed to improve wood surface properties by generating SiO2 with tetraethoxysilane and methyl triethoxysilane as co-precursors. The effect of SiO2 on the wood surface properties was studied by the analysis of size stability, ultraviolet radiation aging resistance, and contact angle of the modified wood. The improvement mechanism was explored using scanning electron microscopy (SEM), energy dispersive X-ray (EDAX), and Fourier transform infrared spectroscopy (FT-IR). The results showed that the water absorption and the hygroscopic expansion rate of the modified wood were less than those of the control samples. The discoloration resistant properties were improved 1.5 times more than that of the control samples. The thickness of SiO2 on the wood surface was approximately 60 μm, and the silicon content increased as the dipping time increased. The contact angle of modified wood showed that it was more hydrophobic than that of the control sample, and this increased as the dipping time increased. The variation in contact angle of the modified wood was less than that of the control sample before and after aging. The anti-aging performance of the modified wood surface was also improved.

To analyze the chemical composition and evaluate the potential commercial value of Dalbergia odorifera leaves, the chemical component and content of the essential oils (EOs), fatty acids (FAs), polyphenols and flavonoids in the leaves of D. odorifera were studied. The composition of the EOs obtained by simultaneous distillation extraction (SDE) (at the yield of 0.092%) and hydro-distillation (HD) (at the yield of 0.050%) from D. odorifera leaves was analyzed by gas chromatography-mass spectrometry (GC-MS). Seventy-six compounds were identified and the major compounds were phytol (22.5–24.3%), 4-vinylguaiacol (8.7–12.7%), dihydroedulan II (7.4–11.2%), γ-elemene (5.1–6.2%), cedrol (2.8–6.1%), coumaran (0.9–3.1%) and hexahydrofarnesyl acetone (2.5–2.7%). The FA yield extracted by ultrasound was 1.145% (w/w), and the most abundant FA components were palmitic acid (C16:0), oleic acid (C18:1) and linoleic acid (C18:2) in leaves. The results of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoli-ne-6-sulfonic acid (ABTS⁺) radical scavenging experiments demonstrated that the EOs and FAs possess strong antioxidant activity. The ethanol extract of the leaves had a high polyphenol content [16.00 mg gallic acid equivalent (GAE) g⁻¹ dry weight (DW)] and flavonoid content [8.92 mg rutin equivalent (RE) g⁻¹ DW]. This research has determined qualitatively and quantitatively the isoflavonoids (biochanin A, isoliquiritigenin, tectorigenin and genistein) by ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS/MS). The phytochemical analysis (EOs, FAs and flavonoids) of the extract showed that the D. odorifera leaf is a rich source of high bioactive compounds and might have the potential to be recommended for further cosmetics, food and pharmaceutical applications.