Cellulose is the most abundant natural biopolymer material, which has been widely used in film making and food packaging in recent years. However, lignin, a natural bioaromatic material, is always applied as a waste resource due to its low utilization efficiency. In this study, a ZnCl2/CaCl2/cellulose mixed system was used to prepare film materials via a regeneration method. The chemical structure and corresponding properties were characterized. The thermal decomposition process of film materials showed that with an increase of the heating rate, the maximum weight loss temperature gradually shifted to the higher-temperature region. Additionally, the combination of lignin with cellulose as composite films can effectively improve thermal stability. Furthermore, kinetics methods such as Kissing–Akahira–Sunose (KAS), Flynn–Wall–Ozawa (FWO), and Friedman were used to calculate the average activation energy (E). This study proposed a facile method for preparing biobased multifunctional composite films using two kinds of naturally renewable materials.
Wenmei Tao,Wenyan Duan,Chunbo Liu,Dongdong Zhu,Xiaoxi Si,Ruizhi Zhu,Patryk Oleszczuk,Bo Pan
The presence of persistent free radicals (PFR) in biochars may greatly broaden the application of biochars in pollution control , but may also cause negative impacts to the environment. Understanding the structural basis and the formation mechanisms of PFR is essential for a targeted biochar production and application. This study used rice straw (RS), a ubiquitous agricultural waste , to investigate the generation processes of PFR in relation to RS pyrolysis kinetics. Based on a detailed thermogravimetric (TG) and derivative thermogravimetric (DTG) analysis, the activation energy was calculated by Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods. This work combined pyrolysis kinetics analysis and solid particle characterization. Our results showed that lignin started to pyrolyze at a lower temperature than cellulose and hemicellulose. Lignin was the main factor for PFR generation. Chemical bond breaking contributed only slightly to PFR formation. The reconfiguration of the carbonaceous structures may be a more important contributor to PFR formation, while the cross-linking between different compositions and the interactions between the chemical compositions and inorganic minerals may play a significant role for PFR generation and stabilization in RS. This study provides useful theoretical basis to understand the thermal pyrolysis process of RS and the manipulation of biochar properties.
Xiaoao Shi,Jinping Li,Lingna Shang,Sijia Wang,Si Chen,Jingxin Liu,Meng Mei,Yongjie Xue,Teng Wang
Microplastics (MPs), as emerging contaminant detected in dyeing sludge (DS), inevitably affected the subsequent treatment and disposal of DS. However, the effect of MPs on the predominant disposal path (incineration) of DS remains far from explicit. This study used thermogravimetry-mass spectrometry (TG-MS) method to explore the effect of representative MPs, polyethylene terephthalate (PET) and polyvinyl chloride (PVC), on combustion characteristics, gas evolution and kinetics on DS combustion. Results showed that PET inhibited the whole combustion of DS by physical barrier. Relatively, PVC delayed the combustion of light volatile but promoted heavy volatile and char reaction due to HCl catalyst. Generally, MPs deteriorated the combustibility , burnout performance and combustion stability of DS. MPs aggravated HCl and gaseous N emissions. Noticeably, the interactions between DS and PVC accelerated the emissions of gaseous pollutants , especially under high dose condition. DAEM and FWO models could well describe the combustion kinetic of DS containing MPs. MPs led to an increase in activation energy of DS, namely, it deteriorated the combustion efficiency of DS. The combustion mechanisms could be divided into two stages: (1) diffusion (D 3 ) stage: melted MPs blocked the gas channels, (2) chemical reaction (F 3 ): the residual chars were thermally stable.
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