Search

Greening waste presents considerable reuse potential owing to its simple organic composition. For greening waste, being simply regarded as ordinary garbage cannot adapt to the requirements of sustainable and harmless development. Resource reusing process is an inevitable trend. Utilization of urban landscape greening waste is of great significance for improving the ecological environment in urban and rural areas, building a harmonious city, increasing employment, and enhancing economic efficiency. This will be a far-reaching impact on China's economic and social sustainable development. In this work, eight typical landscape plants were selected as raw materials using the batch reactor. The concept of stepwise hydrothermal conversion and a real model with xylose, cellulose acetate (CA), and aromatic aldehyde as the target products were thereby constructed. In the third step of the stepwise conversion, the effect of reaction temperature and time in the oxidative degradation of cellulose acetate solid residues in NaOH solution to produce aromatic aldehyde was investigated. The optimum conditions were obtained as 175 ℃ and 90 min. The yield of aromatic aldehydes in all 16 branches and leaves of cellulose acetate all reached about 20% under the optimal conditions.

Xylose and cellulose acetate were prepared by hydrolysis and acetylation of hemicellulose and cellulose in landscaping biomass waste (pine) by dilute acid hydrolysis and acetylation, respectively. The obtained solid residue was rich in lignin that mainly contains three phenylpropane structural units and can be used to prepare aromatic chemicals under hydrothermal conditions. In this work, the synthesis of high value-added aromatic aldehydes (vanillin, syringaldehyde, and p-hydroxybenzaldehyde) from the solid residue (rich in lignin) by mild catalytic oxidation was studied. The oxidation degradation of the solid residue in NaOH solution to produce aromatic aldehydes was investigated by single factor experiment. The optimum reaction conditions were obtained as follows: 175 ℃, 90 min, 3.0 g solid residue, 100.0 ml NaOH solution (concentration of 2.0 mol/L), and oxygen pressure of 1.5 MPa. Under these conditions, the total yield of aromatic aldehydes from pine branch residue was 23.8 wt%.

Because of the existence of moisture in indoor air, it is still a serious challenge to capture formaldehyde indoors with the metal-organic material Fe-HHTP-MOF. To explore the relationship between the structure and performance of Fe-HHTP-MOF in dry and humid air, molecular dynamics simulation was used to study the adsorption amount of Fe-HHTP-MOF for formaldehyde and water under different temperatures and adsorption pressures, as well as the adsorption amount of Fe-HHTP-MOF for formaldehyde in the presence of both water and formaldehyde, and the differences in adsorption of formaldehyde and water by Fe-HHTP-MOF were compared and analyzed when water coexisted. The results show that under single-component isothermal adsorption, the hydrogen bond energy formed by Fe-HHTP-MOF adsorbing H 2 O molecules is much greater than the van der Waals energy formed by adsorbing HCHO molecules. In a dry state, as the temperature increases, the adsorption amount of HCHO molecules decreases. When the temperature rises to 313.15 K, even if the temperature is further increased, the effect on the adsorption amount of HCHO molecules is small. Moreover, after the adsorption pressure is greater than 7.78 MPa, the adsorption amount of HCHO molecules tends to flatten. When H 2 O molecules coexist, at the same adsorption pressure and temperature, H 2 O molecules with polar functional groups preferentially occupy the adsorption sites, and the adsorption amount of HCHO molecules in the presence of H 2 O is lower than that in the dry state. As the temperature increases, under the same adsorption pressure, the intermolecular interaction strengthens, and the molecular activity increases. The influence of water molecules on the adsorption of HCHO by Fe-HHTP-MOF weakens, and HCHO molecules reach the saturated adsorption site ahead of time. The adsorption energy of H 2 O is greater than that of HCHO, indicating that the presence of water may hinder the capture of HCHO., Competing Interests: The authors declare no competing financial interest., (© 2024 The Authors. Published by American Chemical Society.)