People have long been concerned with plastic pollution in the soil environment on land but little attention has been paid to the plastic pollution in the oceans. In fact, the pollution of marine plastic garbage and their harm to the marine environment have gone far beyond our Imagine.
Marine plastic garbage pollution how serious?
Every year, 20 million tons of plastic garbage is directly discarded or transported from the land through the river, and the wind finally enters the ocean.
Large quantities of plastic particulates accumulate throughout the oceans, and the high density and widespread distribution of plastic particles has exasperated millions of seabirds, fish and other marine life and is gradually bringing toxins to human desks through the food chain.In Europe, A seafood diner may eat up to 11,000 plastic particles through the product a year.
Unlike white pollution control on land, limited by the special marine environment, it is almost impossible to collect and process these tiny plastic particles by traditional fishing methods, so the treatment of marine plastic pollution is increasingly urgent but difficult.
To develop and use plastic products that can self-degrade in the marine environment to replace hard-to-degrade plastic products such as PP, PA and PS is the most fundamental and only effective way to solve this problem.
Where is the research and development of seawater degradation materials?
At present, the international Shanghai water degradation materials related research has just started, many people blindly hope that biodegradable materials to solve the problem of plastic pollution in the oceans.
National Institute of Physical and Chemical Technology, Chinese Academy of Sciences National Engineering Research Center has long been engaged in the development of degradable plastics, industrialization and application of research, in view of the current increasingly serious problem of marine plastic pollution in the country launched the first marine degradation materials.
Ji Junhui, the director of the engineering center, said that at present, the awareness of environmental protection at home and abroad has been gradually enhanced and the ban on plastic injection has been gradually popularized around the world. PLA, PBDE and PBAT ), Polycaprolactone (PCL), and polyhydroxyalkanoates (PHAs). They have good biodegradability in soil and compost, and have replaced many non-degradable common plastics in many fields, To some extent, alleviate the white pollution on land.
However, the degradation of polyester composites is mainly due to the enzymatic hydrolysis reaction of the polymer under the action of microorganism-secreting enzymes, and the species, quantity, temperature, etc. of the environment need to meet certain requirements for rapid degradation.
Compared with the terrestrial environment, the marine environment is characterized by rich water, salt, high pressure, low temperature, mobile and dilute nutrition. In addition to the density of marine microorganisms in the offshore area slightly larger, the density of marine microorganisms in the ocean is smaller, the average is generally Few to dozens of milliliters per milliliter are almost negligible compared to hundreds of millions of milliliters per liter of soil in the composting process.Different degradation conditions and degradation conditions lead to the degradation of aliphatic polyester materials in seawater Performance and composting process have significant differences.
Obviously, the existing biodegradable materials and their research results can not be directly applied to the development of seawater degradable materials.For PLA (polylactic acid), for example, PLA spunlabs lose weight of 70% in 50 days at composting conditions; however, ℃ seawater for 1 year did not observe any significant weight loss, GPC test showed no significant change in molecular weight.
Dr. Wang Ge Xia, responsible for the development of seawater degradable materials at the engineering center, said that through the degradation experiments of typical biodegradable materials in different simulated water bodies, we have already got a preliminary understanding of the two mechanisms of seawater degradation and compost degradation. For the typical Biodegradable polyester materials in seawater and freshwater degradation cycle has been initially mastered.
The results show that the current degradation of biodegradable polyester materials in seawater and composting have great differences in seawater is difficult to have biodegradable conditions, most of the polyester material degradation cycle in seawater is very slow, or even difficult to degrade .
It is a long way to go for the study of seawater degradation materials to build a new material system based on the existing biodegradable materials.