Moisture monitoring rule for plastic mixtures in plastic degradation tests

doi:10.19491/j.issn.1001-9278.2024.03.016

Abstract

Abstract:

Through comparing the measurement methods of humidity for each component of plastic mixtures， a humidity testing scheme of plastic mixtures was designed based on a drying weighing method combined with the test method of GB/T 19277.1—2011. This method does not destroy plastic mixtures to obtain relatively accurate measurement results. The results indicated that the difference between the measured mass humidity of the plastic mixture obtained from the conventional drying weighing method was 3 %~5 %. It is difficult to make rapid changes in the mass humidity when the difference reached around 9 %. There is a three⁃stage humidity change process for plastic mixtures as follows： constant rate， deceleration rate， and residue. The Boltzmann function could fit the trend of constant rate and deceleration rate better in the humidity change stage of plastic mixtures. The on⁃demand water replenishment is more advantageous to the aerobic biodegradation activity， which is in better agreement with the requirements of the national standard for the aerobic biodegradation test of plastics. According to the change curves of moisture mass dissipation of plastic mixtures at three gas⁃flow rates， the calculation method of the change curves of moisture mass dissipation at arbitrary gas flow rates was obtained.

Key words: plastics, weighing method, biodegradation, industrial composting, organic soi, data fitting, moisture content

CLC Number:

TQ321

GUO Zhihao, FENG Tao, LI Ziyi, WANG Jing, WANG Bing, WANG Yihan, CAO Bowei. Moisture monitoring rule for plastic mixtures in plastic degradation tests[J]. China Plastics, 2024, 38(3): 94-100.

Figures/Tables 11

Fig.1. Periodic variation of CO2 concentration

Fig.2. Experimental equipment and its chematic diagram for the weighing method

Fig.3. State of the plastic mixture in the reactor under controlled composting conditions

Fig.4. Stage of cumulative mass change of desiccant and accumulated change mass curves of desiccant corresponding to different flow rates

反应罐

编号

罐子内气体流量/

mL·min^-1

装入塑料混合物质量/

干燥剂累计增加质量/

初始湿度/

实验结束湿度/

修正实验结束湿度/

Tab.1. Basic data of the reaction tank

Fig.5. Comparison of carbon dioxide concentration generation in plastic degradation test with different water addition methods

Fig.6. Comparison of the water with the measured ones from plastic mixtures at various flow rate

气体流量/ mL·min^-1	Boltzmann函数拟合系数				$R 2$
气体流量/ mL·min^-1	A₁	A₂	t₀	dt	$R 2$
250	503.14	-46.748	-14 889.2	6 055.83	0.999 80
400	894.223	-117.922	-16 798.7	7 981.99	0.999 24
500	502.072	-36.095 5	-6 843.66	2 334.12	0.999 33

气体流量/ mL·min^-1	Boltzmann函数拟合系数				$R 2$
气体流量/ mL·min^-1	A₁	A₂	t₀	dt	$R 2$
250	503.14	-46.748	-14 889.2	6 055.83	0.999 80
400	894.223	-117.922	-16 798.7	7 981.99	0.999 24
500	502.072	-36.095 5	-6 843.66	2 334.12	0.999 33

Tab.2. Fitting equation of the lossable water mass of plastic mixtures at different flow rates by Boltzmann function

Fig.7. The lost water from plastic mixtures at various flow rate

变量名	含义
$L x$	已知通入的气体流量
$y L (t)$	通入 $L x$ 的塑料混合物可损失水分质量函数
$y 0$	初始塑料混合物可损失水分质量
$t 0$	初始塑料混合物湿度的残余阶段的时间
$t 30 %$	湿度为30 %塑料混合物湿度的残余阶段的时间
$t 45 %$	湿度为45 %塑料混合物湿度的残余阶段的时间
$L x$	已知通入的气体流量

变量名	含义
$L x$	已知通入的气体流量
$y L (t)$	通入 $L x$ 的塑料混合物可损失水分质量函数
$y 0$	初始塑料混合物可损失水分质量
$t 0$	初始塑料混合物湿度的残余阶段的时间
$t 30 %$	湿度为30 %塑料混合物湿度的残余阶段的时间
$t 45 %$	湿度为45 %塑料混合物湿度的残余阶段的时间
$L x$	已知通入的气体流量

Tab.3. Meaning of each variable for calculating the unknown flow function

Fig.8. Variable meaning diagram

References 14

1	国家发展改革委，生态环境部.关于印发“十四五”塑料污染治理行动方案的通知：发改环资〔2021〕1298号［EB/OL］.（2021⁃09⁃08）［2022⁃05⁃19］..
2	受控堆肥条件下材料最终需氧生物分解能力的测定采用测定释放的二氧化碳的方法第1部分：通用方法［S］.
3	Singh V P， XU C Y ．Evaluation and generalization of 13 mass⁃transferequations for determining free water evaporation［J］．HydrologicalProcesses，1997，11（3）：311－323.
4	刁晓倩，翁云宣，宋鑫宇，等. 国内外生物降解塑料产业发展现状［J］. 中国塑料， 2020， 34（5）： 123⁃135.
	DIAO X Q， WENG Y X， SONG X Y， et al. Current development situation of biodegradable plastic industry in china and abroad［J］. China Plastics， 2020， 34（5）： 123⁃135.
5	邵明安，王全九，黄明斌．土壤物理学［M］．北京：高等教育出版社，2006.
6	李旺霞，陈彦云. 土壤水分及其测量方法的研究进展［J］. 江苏农业科学， 2014， 42（10）： 335⁃339.
	LI W X， CHENG Y Y. Research progress on soil moisture and its measurement methods［J］.Jiangsu Agricultural Sciences，2014， 42（10）： 335⁃339.
7	雷志栋，胡和平，杨诗秀. 土壤水研究进展与评述［J］. 水科学进展， 1999 （3）： 311⁃318.
	LEI Z D， HU H P， YANG S X. Progress and review of soil water research ［J］.Advances in Water Science，1999（3）： 311⁃318.
8	陈全胜，李凌浩，韩兴国，等. 水分对土壤呼吸的影响及机理［J］. 生态学报， 2003 （5）： 972⁃978.
	CHEN Q S， LI L H， HAN X G，et al ．Effects of water content on soil respiration and the mechanisms［J］.Acta Ecologica Sinica，2003，23（ 5）：972⁃978．
9	马成泽. 有机质含量对土壤几项物理性质的影响［J］. 土壤通报， 1994（2）： 65⁃67.
	MA C Z. The influence of organic matter content on several physical properties of soil［J］.Chinese Journalof Soil Science，1994（2）： 65⁃67.
10	单秀枝，魏由庆，严慧峻，等. 土壤有机质含量对土壤水动力学参数的影响［J］. 土壤学报， 1998（1）： 1⁃9.
	SHANG X Z， WEI Y Q， YANG H Z，et al. The influence of soil organic matter content on soil hydrodynamic parameters［J］. Acta Pedologica Sinica， 1998（1）： 1⁃9.
11	周彩景，刘军，王益权，等. 有机物质类型与含量对土壤持水性能的影响［J］. 西北农林科技大学学报（自然科学版）， 2008， 36（12）： 115⁃120， 128.
	ZHOU C J， LIU J， WANG Y Q， et al. Effect of organic compounds content and types on soil water retention capacity［J］. Journal of Northwest A & F University（Natural Science Edition）， 2008， 36（12）： 115⁃120， 128.
12	徐士康. 土体水分蒸发过程试验与模拟［D］. 南京：南京大学， 2017.
13	欧阳斌强，唐朝生，王德银，等. 土体水分蒸发研究进展［J］. 岩土力学， 2016， 37（3）： 625⁃636， 654.
	OUYANG B Q， TANG C S， WANG D Y， et al. Advances on soil moisture evaporation［J］. Rock and Soil Mechanics， 2016， 37（3）： 625⁃636， 654.
14	罗维，陈同斌. 湿度对堆肥理化性质的影响［J］. 生态学报， 2004， 24（11）： 2 656⁃2 663.
	LUO W， CHEN T B. Effects of moisture content of compost on its physical and chemical properties［J］．Acta Ecologica Sinica，2004，24（11）：2 656⁃2 663.

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