Lu Shaoyuan and Yang Zhichun research team of Hong Kong University of Technology: application of lignin porphyrin nano environmental protection polymer in enhanced photoluminescence and heavy metal detection

Introduction lignin is a common by-product in the pulping industry, and lignin polymer contains a variety of functional groups and three-dimensional composite structure, which makes lignin become a cheap, high-quality and environmentally friendly alternative to carbon based materials Unfortunately, a lot of lignin is discarded as waste every year As we all know, porphyrin family has a wide range of applications in many fields, especially in the medical application of photoluminescent imaging developer, with great potential However, in the antisolvent environment, the strong π - π electron interaction between porphyrins tends to form aggregates, which leads to fluorescence quenching, that is, aggregation leads to fluorescence quenching (ACQ) Recently, the research team of Lu Shaoyuan and Yang Zhichun from Hong Kong University of technology developed the lignin porphyrin nano environmental protection polymer based on waste lignin It combines the excellent functions of these two chemicals, enhances the effect of photoluminescence and has the function of heavy metal detection in high water environment Relevant research results were published in green chem (DOI: 10.1039 / c8gc02904k) under the title of "development of a waste derived lignin porphyrin bio polymer with enhanced photoluminescence at high water fraction with wide pH range and heavy metal sensitivity investigations" Profile of Assistant Professor Lv Shaoyuan, assistant professor, Hong Kong Polytechnic University In 2009, he received his Ph.D from the Department of civil and environmental engineering, UCLA In 2013, he finished his postdoctoral research in the forest products laboratory of the United States Department of agriculture, Madison, Wisconsin, USA, and joined Hong Kong Polytechnic University after returning home In 2018, the first bioenergy research laboratory was established at Hong Kong University of technology At present, it is mainly engaged in the research of wood chemistry, water chemistry and biomass conversion fuel Brief introduction of researcher Yang Zhichun, researcher of Hong Kong University of technology In 2015, he received his doctorate from the University of Hong Kong During his doctorate, his research focuses on the properties of various organic compounds in photophysics and photochemistry, and he has published several articles in major SCI journals (including greenchem And chem EUR J) In 2018, he joined Hong Kong University of technology At present, he is mainly engaged in the research of advanced materials, water chemistry, photophysics and photochemistry of various organic compounds Cutting edge scientific research achievements: the application of lignin porphyrin nano environmental protection polymer in enhanced photoluminescence and heavy metal detection First, the author screened the remaining lignin in the pulping industry, including the investigation of discard amount, functional group content, molecular weight and the analysis of the stability of preparing nano particles (Figure 1) In the end, the basic lignin with a large amount of waste and considerable amount of molecular weight and functional groups was selected as the matrix for modification and further study Figure 1 Analysis of the stability of the preparation of nanoparticles (source: Green chem.) later, the author investigated the synthesis method by using the hydroxyl group on lignin as the ester bond binding point It was found that under the mild photoextension reaction conditions, the one pot synthesis method was used to combine lignin with porphyrin to obtain the lignin porphyrin nano environmental protection polymer (Figure 2 ) It is worth noting that porphyrins generally have multiple reaction substitution sites The author deliberately retains the reaction substitution sites on three phenyl groups in the porphyrins of this polymer to facilitate further modification Fig 2 Synthesis of lignin porphyrin nano environmental protection polymer (source: Green chem.) after the synthesis of nano environmental protection polymer, the author conducted a series of photoluminescence control experiments to explore the possibility of enhancing photoluminescence of the polymer in the environment of high water content and different pH (Fig 3) Compared with porphyrin monomers or lignin itself, lignin porphyrin nanocomposites have significant photoluminescence enhancement effect under different water content and pH value When pH = 7 and water content reaches 95%, the luminous intensity between 600 and 780 nm increases by 30 times It is concluded that the main reason for the enhancement of photoluminescence may be that the natural three-dimensional complex structure of lignin itself and the branching of macromolecular groups produce huge steric hindrance, separating the porphyrin modules connected to lignin by stable ester bond In the high water and acid environment, because porphyrins can no longer perform aggregation fluorescence quenching with effective π - π electron interaction, even if there is aggregation between molecules, aggregation fluorescence quenching is greatly slowed down In the study of luminescent kinetics, the measurement of luminescent decay time and the comparison of differences prove that in the environment of high moisture and acid, the lignin porphyrin nano environmental protection polymer has different polymerization forms and longer luminescent decay time Figure 3 Photoluminescence control experiment (source: Green chem.) finally, the author studied the detection effect of lignin porphyrin nano environmental protection polymer on different types of heavy metal ions in water by UV-Vis absorption spectroscopy (including: Ni 2 +, CO 2 +, Mn 2 +, Zn 2 + and Cu 2 +) The range of detection concentration is from 10 to 500 ppm (Figure 4) The results show that the lignin porphyrin Nanopolymer can be used for the detection of heavy metal ions with high selectivity and sensitivity This fully demonstrates the functional diversity of lignin porphyrin nano environmental protection polymer and its wide application in water environment Figure 4 The detection effect of lignin porphyrin nano environmental protection polymer on different types of heavy metal ions in water (source: Green chem.) related results were recently published online in green chem (DOI: 10.1039 / c8gc02904k) Dr Xie Haoxian, Ph.D., and Dr Zheng Xinxiang, research assistant, are the co first authors of the paper, Assistant Professor Lv Shaoyuan is the corresponding author, and researcher Yang Zhichun is the co first author and co corresponding author Nowadays, people and scientific research have been paid more and more attention in the economic life China has ushered in the "node of science and technology explosion" Behind the progress of science and technology is the work of countless scientists In the field of chemistry, in the context of the pursuit of innovation driven, international cooperation has been strengthened, the influence of Returned Scholars in the field of R & D has become increasingly prominent, and many excellent research groups have emerged in China For this reason, CBG information adopts the 1 + X reporting mechanism CBG information, chembeangoapp, chembeango official microblog, CBG wechat subscription number and other platforms jointly launch the column of "people and scientific research", approach the domestic representative research group, pay attention to their research, listen to their stories, record their demeanor, and explore their scientific research spirit.