Peigao Duan,Caicai Zhang,Feng Wang,Jie Fu,Xiuyang Lü,Yuping Xu,Xianlei Shi
This study examined a two-stage (noncatalytic pretreatment followed by catalytic upgrading) hydrothermal processing of crude bio-oil produced from the hydrothermal liquefaction of duckweed. The activities of six activated carbons (ACs)-pine wood AC, coconut shell AC, bamboo stem AC, apricot pit AC, peach pit AC, and coal AC-toward the deoxygenation and denitrogenation of the pretreated duckweed bio-oil were determined in supercritical water at 400 °C for 1 h with the addition of 6 MPa of H 2 and 10 wt% AC. All of the ACs exhibited activity similar to Ru/C toward the denitrogenation and deoxygenation of the pretreated duckweed bio-oil. Of the ACs tested, bamboo stem AC produced an upgraded bio-oil with the highest yield (76.3 wt%), the highest fraction (90.13%) of material boiling below 350 °C, and the highest energy density (44.1 MJ/kg). Decreased ash and acidic groups in the pre-treated AC disfavored the production of upgraded bio-oil but aided denitrogenation and desulfurization. The ACs are suspected to leach ions and weak acids into the reaction solution, which would catalyze denitrogenation and desulfurization. The gases mainly consisted of unreacted H 2 , CO 2 and CH 4 together with small amounts of C x H y ( x ≤ 5, y ≤ 12) hydrocarbon gases produced from the cracking of the upgraded bio-oil.
As one of the most widely used nanomaterials, CeO2nanoparticles (NPs) might be released into the aquatic environment. In this paper, the interaction of CeO2NPs and Ce3+ions (0~10 mg/L) with duckweed (Lemna minorL.) was investigated. CeO2NPs significantly inhibited the root elongation of duckweed at concentrations higher than 0.1 mg/L, while the inhibition threshold of Ce3+ions was 0.02 mg/L. At high doses, both reduced photosynthetic pigment contents led to cell death and induced stomatal deformation, but the toxicity of Ce3+ions was greater than that of CeO2NPs at the same concentration. According to the in situ distribution of Ce in plant tissues byμ-XRF, the intensity of Ce signal was in the order of root > old frond > new frond, suggesting that roots play a major role in the uptake of Ce. The result of XANES showed that 27.6% of Ce(IV) was reduced to Ce(III) in duckweed treated with CeO2NPs. We speculated that the toxicity of CeO2NPs to duckweed was mainly due to its high sensitivity to the released Ce3+ions. To our knowledge, this is the first study on the toxicity of CeO2NPs to an aquatic higher plant.
Mengge Xiao,Andrew Yuk Keung Leung,Zhonghao Zhu,Liang Zhu,Kaijun Xiao
In this paper, response surface methodology (RSM) was used to optimize the extraction process of proteins from duckweed and the protein extraction rate was increased to 24.11 ± 0.04 %. The duckweed protein extract (DP) was mixed with sodium carboxymethyl cellulose (CMC) and glycerol to prepare DP/CMC antioxidant membranes with different additions (0.5 % ∼ 2.5 %), and 2.0 % DP/CMC antioxidant membranes were used in blueberry preservation experiments. The results showed that the moisture permeability of DP/CMC antioxidant membrane was significantly reduced, the thermal stability was significantly improved, and the antioxidant property was significantly higher than that of CMC membrane ( p < 0.05). The lowest oxygen content in the 2.0 % DP/CMC membrane package compared to PE and CMC membranes may be due to the synergistic effect of aerobic respiration of blueberries and oxidation of antioxidants in the membrane, under which the loss of antioxidants in the blueberries was lowest and the quality of blueberries was effectively maintained. In this study, for the first time, antioxidant membranes with significant freshness preservation effects were prepared using duckweed protein extract (DP), demonstrating its great potential as an active packaging material for food preservation, and opening up a new development direction for the application of DP.
危险品化学品经营许可证（带存储）