Search

Laccase immobilization is an effective way to realize the industrial application of laccase, but the loss of immobilized laccase activity is serious, which is an urgent problem to be solved. In this study, a novel laccase immobilization material was prepared by mixing waste Mn–Cu-loaded activated carbon with cellulose solution and regenerated in hydrochloric acid solution, which significantly improved the immobilized laccase activity. The optimum immobilization conditions (T, pH and initial laccase concentration) of Mn–Cu-AC/cellulose beads (Mn–Cu-ACC) for laccase were studied by the response surface method. Under the optimum conditions (T = 43 °C, pH = 4.0 and c = 6.8 g L−1), immobilized laccase (Laccase@Mn–Cu-ACC) showed excellent performance in terms of pH stability, thermostability and storage stability. And the enzyme activity of the laccase immobilized on the Mn–Cu-ACC carrier remarkably increased by 29.6% compared to that of the ACC. At last, the Laccase@Mn–Cu-ACC was used for the degradation of bisphenol A (BPA). Under the optimum conditions (t = 5.5 h, T = 45 °C, pH = 4.0 and initial cBPA = 70 mg L−1), the removal rate of BPA reached 72.3% in the first cycle, and after 5 cycles of reusing the immobilized laccase, the relative removal rate of BPA was retained at 53.2% of the initial removal rate. This study developed a new type of immobilized laccase carrier and provided a new path for the application of waste heavy metal loaded activated carbon. [ABSTRACT FROM AUTHOR]

Corn stalk and diatomite were cross-linked by N,N'-Methylenebisacrylamide (MBA) to obtain gel porous materials for methylene blue adsorption, which improved the multi-element pores effect. The process solved the difficult recovery problem of powder adsorbents as well. Results showed that the optimal preparation conditions of corn stalk/diatomite gel porous materials were: 1 mL of glutaraldehyde, 6 g of acrylic acid, 150 mg of MBA and 100 mg of potassium persulfate. The adsorption process conditions were optimized: At the pH = 8, 8 mg of gel porous material was adsorbed for 1 hour. Under the optimal conditions, the removal percentage was 93.65% and the adsorption capacity reached 288.43 mg/g. The characterization results indicated that the corn stalk was successfully combined with diatomite. Corn stalk/diatomite gel porous materials had a three-dimensional network structure with more active sites. The adsorption isotherms fit the Langmuir model. Furthermore, the adsorption kinetics fit the pseudo-second-order model. The adsorbent surface is uniform and the adsorption process is mostly monolayer adsorption. The adsorption process includes chemical and physical adsorption. The maximum saturated adsorption capacity was 657.89 mg/g. Corn stalk/diatomite gel porous materials maintained good adsorption performance after cyclic adsorption. The adsorbent prepared in this study has a good regeneration cycle and methylene blue removal capacity. [ABSTRACT FROM AUTHOR]

Transparent bamboo (TB) is an attractive biomass‐derived material. However, the interrelation between process parameter and product performance is not clear yet. In this paper, the process parameter during preparation is optimized by orthogonal experiment and finally TB with excellent optical and mechanical properties is successfully prepared. Among the investigated runs, TB‐12 exhibited the best performance with high transmittance (89.2%), good color difference property (L: 76.8, A: 5.4, B: 5.9), and excellent tensile strength (119.3 MPa). As the final aim of this work, deeper insight into the interrelation between process parameters and product performance is also investigated by response surface methodology (RSM) and linear analysis method. Based on the analysis result, it can be concluded that i) X2‐ temperature is the most influential factor to the lignin content (p‐value = 0.0532) during delignification process; ii) during resin impregnation process, lignin content has strong correlation with optical property: for example, transmittance (R2 = 0.90423) and A value (R2 = 0.92073), but has no significant correlation with mechanical property (tensile strength: R2 = 0.04186). Moreover, it is found that the correlation between lignin content and transmittance can be preliminarily predicted before the experimental start. This hypothesis has been validated by importing experimental data of previous references into the model. This work demonstrates a deep analysis of TB preparation process and may provide the referenced gist for parameter selection. [ABSTRACT FROM AUTHOR]

Aldol condensation of cyclopentanone is an attractive reaction for bio‐jet fuel production. KOH is an efficient homogeneous catalyst for aldol condensation but suffering the problem of separation. In this paper, a heterogeneous catalyst, diatomite stabilized KOH (KOH/diatomite) was prepared in a simple way (dry‐mixed impregnation process), and exhibited good activity (overall yield: 85.0 %) and reusability. To clarify the support effect of diatomite, KOH/SiO2 catalyst was also prepared. According to characterizations of these two catalysts, we suggest that the excellent catalytic activity of KOH/diatomite can be attributed to the formation of K−O−Si bond. In addition, the impurity elements existed in diatomite (e. g. CaO, Na2O, Al2O3) and higher BET surface areas may also benefit to this reaction. This study provides a new possibility for converting homogeneous catalyst (KOH) to heterogeneous catalyst (KOH/diatomite). In this way, KOH/diatomite performed excellent catalytic activity and exhibited stable reusability, which can avoid the problem of separation and pollution. [ABSTRACT FROM AUTHOR]