Recently great effort s have been focused on designing high-performance microwave absorbers using sustainable biomass resources,but there remains a lack of green and efficient fabrication methods.Herein,inspired by na...Recently great effort s have been focused on designing high-performance microwave absorbers using sustainable biomass resources,but there remains a lack of green and efficient fabrication methods.Herein,inspired by natural porous character of biomass waste,we demonstrated a green one-step route to convert waste coffee grounds into porous C/Fe hybrids,and further explored their potential applications for broadband and high-efficiency microwave absorption.In this design,the WCG-20-750(incorporated 20 wt%Fe(C_(5)H_(7)O_(2))_(3)catalyst and carbonized at 750℃)exhibited porous microstructure with the highest char yield of 55.45 wt%.Furthermore,the as-prepared C/Fe hybrids from WCG-20-750 displayed excellent microwave absorption performances.Typically,the minimum reflection loss(RL_(min))reached to-52.86 dB and the widest effective absorption bandwidth(EAB)was 6.40 GHz at the thickness of 3.0 mm.This work provides an economically viable and environmentally friendly strategy to convert biomass wastes into value-added microwave absorbers,ultimately making contributions to the upcycling of renewable biomass resources and the fostering of sustainable environment.展开更多
In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluo...In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluorescent carbon dots (CDs). The structure and optical properties of CDs were investigated by TEM, XRD, XRF, UV-Vis, FTIR, and fluorescence spectroscopy. CDs displayed satisfactory optical pro-prieties, a high quantum yield of 23.6%, and excellent water solubility, and the particle size was 4.23-8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) between the CDs and riboflavin was achieved with CDs acting as donor and riboflavin as acceptor. A linear relationship between FRET and the riboflavin concentration from 0.10 to 3.0 μg/mL was observed, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, CDs were selective for riboflavin under optimized conditions. A paired t-test at a 95% confidence level indicated no statistically significant difference between the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and <2.6% (n = 3), respectively. CDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of CDs and determination of riboflavin.展开更多
基金supported by Taishan Scholar Constructive Engineering Foundation(No.tsqn202103079)the Talent Start-up Foundation of Qingdao University of Science and Technology(No.202203870).
文摘Recently great effort s have been focused on designing high-performance microwave absorbers using sustainable biomass resources,but there remains a lack of green and efficient fabrication methods.Herein,inspired by natural porous character of biomass waste,we demonstrated a green one-step route to convert waste coffee grounds into porous C/Fe hybrids,and further explored their potential applications for broadband and high-efficiency microwave absorption.In this design,the WCG-20-750(incorporated 20 wt%Fe(C_(5)H_(7)O_(2))_(3)catalyst and carbonized at 750℃)exhibited porous microstructure with the highest char yield of 55.45 wt%.Furthermore,the as-prepared C/Fe hybrids from WCG-20-750 displayed excellent microwave absorption performances.Typically,the minimum reflection loss(RL_(min))reached to-52.86 dB and the widest effective absorption bandwidth(EAB)was 6.40 GHz at the thickness of 3.0 mm.This work provides an economically viable and environmentally friendly strategy to convert biomass wastes into value-added microwave absorbers,ultimately making contributions to the upcycling of renewable biomass resources and the fostering of sustainable environment.
文摘In this work, lemon and onion biomasses commonly found in street markets are for the first time used to develop a facile, fast and low-cost one-step microwave-assisted carbonization method for synthesis of highly fluorescent carbon dots (CDs). The structure and optical properties of CDs were investigated by TEM, XRD, XRF, UV-Vis, FTIR, and fluorescence spectroscopy. CDs displayed satisfactory optical pro-prieties, a high quantum yield of 23.6%, and excellent water solubility, and the particle size was 4.23-8.22 nm with an average diameter of 6.15 nm. An efficient fluorescent resonance energy transfer (FRET) between the CDs and riboflavin was achieved with CDs acting as donor and riboflavin as acceptor. A linear relationship between FRET and the riboflavin concentration from 0.10 to 3.0 μg/mL was observed, allowing the development of an accurate and fast analytical method to determine this vitamin in multivitamin/mineral supplements. Despite the potential interferences in these supplements, CDs were selective for riboflavin under optimized conditions. A paired t-test at a 95% confidence level indicated no statistically significant difference between the proposed and the reference methods. Recovery test presented values ranged from 96.0% to 101.4%. The limit of detection and relative standard deviation were estimated at 1.0 ng/mL and <2.6% (n = 3), respectively. CDs were successfully synthesized in a domestic microwave oven (1450 W, 6 min), presenting satisfactory parameters when compared with results of other studies reported in the literature, suggesting that the proposed method is a potentially useful method for the synthesis of CDs and determination of riboflavin.
