Pascal Habimana,Yanjun Jiang,Jing Gao,Jean Bernard Ndayambaje,Osama M. Darwesh,Jean Pierre Mwizerwa,Xiaobing Zheng,Li Ma
The continuous use of chemical dyes in various industries, and their discharge into industrial effluents, results in severe problems to human life and water pollution. Laccases have the ability to decolorize dyes and toxic chemicals in industrial effluents as green biocatalysts. Their possible industrial applications have been limited by poor reusability, low stability, and loss of free laccase action. In this research, laccase was immobilized on zeolitic imidazolate framework coated multi-walled carbon nanotubes (Laccase@ZIF-8@MWCNTs) via metal affinity adsorption to develop an easy separable and stable enzyme. The optimum reaction conditions for immobilized laccase are at a pH of 3.0 and a temperature of 60 °C. The immobilized laccase was enhanced in storage and thermal stability. The results indicated that Laccase@ZIF-8@MWCNTs still maintained 68% of its original activity after 10 times of repeated use. Most importantly, the biocatalytic system was applied for decolorization of different dyes (20 mg·L −1 ) without a mediator, and up to 97.4% for Eriochrome black T and 95.6% Acid red 88 was achieved in 25 min. Biocatalysts with these properties may be used in a variety of environmental and industrial applications.
Peiqing Zhang,Sihang Li,Fan Xiao,Yongfang Xiao,Yi Zhang,Zhongguo Shan,Zhenyu Li,Haihua Wang
Membrane distillation (MD) represents a promising advance in wastewater purification, contributing to the mitigation of water scarcity. Hydrophobic poly(vinylidene fluoride) (PVDF) microporous membrane is susceptible to wetting by low surface tension substances, leading to fouling. To address this, PVDF membrane was superhydrophobically modified using modified ZIF-8 to obtain two composite membranes, AZ/PVDF and Z@C/PVDF. AZ/PVDF and Z@C/PVDF composite membranes were prepared by coating more dispersible APTES-ZIF-8 and ZIF-8@MWCNT, respectively, onto the surface of PVDF membrane. The hydrophobicity of the composite membranes was regulated by silane types, fluorination methods, and fluorination time, resulting in reduced surface roughness and increased surface energy. The contact angles of AZ/PVDF and Z@C/PVDF were 154.2 ± 3.4° and 156.8 ± 4.2°, respectively. Both AZ/PVDF and Z@C/PVDF membranes demonstrated outstanding mechanical, thermal, and chemical stability. AZ/PVDF and Z@C/PVDF membranes outperformed PVDF membrane, extending operation times by 2 h and 3 h, respectively, without obvious NaCl crystals. Furthermore, Z@C/PVDF membrane exhibited superior resistance to wetting by SDS than AZ/PVDF and PVDF membranes, treating pickle brine via the direct contact MD (DCMD) process with a recovery rate of 30.2 % within 10 h. Overall, this research offers a promising approach to fabricating superhydrophobic composite membranes for high-salt brine treatment via DCMD.
危险品化学品经营许可证（带存储）