How to efficiently utilize most abundant biomass of cellulose, lignin and their derivatives has become an emerging challenge as the anticipative oil depletion. In this paper, the ternary anionic copolymer of carboxymethyl cellulose-acrylamide-lignosulfonate (CAL) was successfully prepared by hydrothermal polymerization. Based on the flocculation characteristics of cationic methylene blue, the optimal polymerization process was confirmed as the raw material ratio of 1:1:1, initiator dosage of 0.9 wt %, the reaction time was 5 h and the reaction temperature was 55 °C. The results showed that the decolorization ratio was 87.5% at the CAL dosage of 600 mg/L for the 500 mg/L methylene blue simulated wastewater. The CAL achieved fast flocculation kinetics and super color removal ratios in the wide ranges of environmental pH, temperature and salt concentration. The flocculation mechanism is single charge neutralization. Moreover, the estimated treatment cost of CAL is 68.3% lower than that of commercial anionic PAM. The prepared anionic CAL flocculant has the characteristics of environmental safety, excellent flocculation performance and cost-effectiveness, which shows great potential in the field of dye wastewater treatment, and also provides a feasible way for the effective utilization of biomass resources.
A new nematic liquid crystalline polymer as a highly active β-nucleator (LCP-N) of isotactic polypropylene (iPP) was synthesized and characterized. The effect of LCP-N on thermal behavior of the iPP was investigated with differential scanning calorimetry. LCP-N showed a melting transition at 85.0°C and a nematic to isotropic phase transition at 278.0°C. The incorporation of LCP-N could lead to substantial changes in the thermal behavior of the iPP. The nucleating activity of LCP-N mainly depended on its content, mesogenic molecular structure, and thermal history of processing. A high content of β-form could be obtained by the combined effect of the optimum LCP-N concentration and crystallization temperature and time. The Φβ reached 77% when the LCP-N content, crystallization temperature, and crystallization time were 0.4 wt.%, 125°C, and 1 h, respectively. 相似文献
The activation of C?H bonds in alkanes is currently a hot research topic in chemistry. The atomic oxygen radical anion (O?.) is an important species in C?H activation. The mechanistic details of C?H activation by O?. radicals can be well understood by studying the reactions between O?. containing transition metal oxide clusters and alkanes. Here the reactivity of scandium oxide cluster anions toward n‐butane was studied by using a high‐resolution time‐of‐flight mass spectrometer coupled with a fast flow reactor. Hydrogen atom abstraction (HAA) from n‐butane by (Sc2O3)NO? (N=1–18) clusters was observed. The reactivity of (Sc2O3)NO? (N=1–18) clusters is significantly sizedependent and the highest reactivity was observed for N=4 (Sc8O13?) and 12 (Sc24O37?). Larger (Sc2O3)NO? clusters generally have higher reactivity than the smaller ones. Density functional theory calculations were performed to interpret the reactivity of (Sc2O3)NO? (N=1–5) clusters, which were found to contain the O?. radicals as the active sites. The local charge environment around the O?. radicals was demonstrated to control the experimentally observed size‐dependent reactivity. This work is among the first to report HAA reactivity of cluster anions with dimensions up to nanosize toward alkane molecules. The anionic O?. containing scandium oxide clusters are found to be more reactive than the corresponding cationic ones in the C?H bond activation. 相似文献
A silver‐catalyzed decarboxylative trifluoromethylthiolation of secondary and tertiary carboxylic acids under mild conditions tolerates a wide range of functional groups. The reaction was dramatically accelerated by its performance in an aqueous emulsion, which was formed by the addition of sodium dodecyl sulfate to water. It was proposed that the radical, which was generated from the silver‐catalyzed decarboxylation in the “oil‐in‐water” droplets, could easily react with the trifluoromethylthiolating reagent to form the product. 相似文献
A hollow-fiber liquid-phase microextraction (HF-LPME) method has been developed for the purification and preconcentration of biogenic polyamines and their precursor amino acids in human saliva. Putrescine (Put), cadaverine (Cad), spermidine (Spe), ornithine (Orn), lysine (Lys), and arginine (Arg) were determined by the CE-LIF detection after microextraction. Several factors that affect extraction efficiency, separation, and detection were investigated. Under the optimum conditions, six analytes could achieve baseline separation within 30 min, exhibiting a linear calibration at three orders of magnitude (r2 〉 0.998); the obtained enrichment factors of HF-LPME were between 19 (for Orn) and 2] 8 (for Cad), and the LODs were in the range of 0.0072-0.26 nmol/L. The proposed HF-LPME/CE-LIF method has been successfully applied for the sensitive analyses of the real-world saliva samples collected from healthy volunteers and different patients with oral diseases, providing a potential method for primary non-invasive diagnosis of some oral diseases. 相似文献