Review of Microplastic Pollution in the Environment and Emerging Recycling Solutions

Microplastic pollution represents a side-effect stemming from a global plastic waste mismanagement problem and includes degraded particles or mass produced plastic particles less than 5 mm in largest dimension.The small nature of microplastics gives this area of pollution different environmental concerns than general plastic waste in the environment.The biological toxicity of particles,their internal components,and their surface level changes all present opportunities for these particles to adversely affect the environment around them.Thus,it is necessary to review the current literature surrounding this topic and identify areas where the study of microplastic can be pushed forward.Here we present current methods in studying microplastics,some of the ways by which microplastics affect the environment and attempt to shed light on how this research can continue.In addition,we review current recycling methods developing for the processing of mixed-plastic waste.These methods,including hydrothermal processing and solvent extraction,provide a unique opportunity to separate plastic waste and improve the viability of the plastics recycling industry.

Toxicity Tests of Soil Contaminated by Recycling of Scrap Plastics

The present investigation studied the toxicity of soil contaminated by untreated discharge from a factory that recycles used plastics. The nearby agricultural areas and freshwater fish ponds were polluted with high concentrations of Cu, Ni, and Mn. Water extracts from the contaminated soil retarded root growth of Brassica chinensis (Chinese white cabbage) and Cynodon dactylon (Bermuda grass) where their seeds were obtained commercially. The contaminated populations of C. dactylon, Panicum repen (panic grass), and Imperata cylindrica (wooly grass) were able to withstand higher concentrations of Cu. Ni, and Mn, especially C. dactylon, when compared with their uncontaminated counterparts. 1990 Academic Press, Inc.

Save plastic trash disaster:recycling fiber faces shuffle of the industry

In recent years,with the concept of green development and the basic national policy of conserving resources and protecting the environment,China speeds up the construction of a resource-saving and environment-friendly society,and forms a new pattern of harmonious development of man and nature.In many tasks of textile industry,it's undoubtedly a

Research on utilizing recycled plastic to make environment-friendly plywood

In our study, we replaced traditional adhesives with compounds made with recycled plastic shopping bags in order to make hot-melt plywood using various amounts of plastic film, different hot-pressing temperatures and hot-pressing times. All three variables have an effect on the intensity and water-resistance of plywood. The results show that the bonding strength of plywood does not increase with increasing amounts of plastic film. When the hot-pressing temperature is increased to 150℃, the bonding strength does not necessarily increase any further. At a hot-pressing time of 6 min, the bonding strength reaches a maximum, after which it will decrease. The optimum hot-pressing parameters are as follows： 100 g·m^-2 of recycled plastic, a hot-pressing temperature of 150℃ and a hot-pressing time of 6 min. This study puts forward a new idea of making use of plastic waste, which, ultimately, may solve the problem of formaldehyde emission without damaging the environment. It has enormous potential market applications.

Experimental Research on the Physical and Mechanical Properties of Concrete with Recycled Plastic Aggregates

In order to study the effect of recycled plastic particles on the physical and mechanical properties of concrete,recycled plastic concrete with 0,3%,5%and 7%content(by weight)was designed.The compressive strength,splitting tensile strength and the change of mass caused by water absorption during curing were measured.The results show that the strength of concrete is increased by adding recycled plastic into concrete.Among them,the compressive strength and the splitting tensile strength of concrete is the best when the plastic content is 5%.With the increase of plastic content,the development speed of early strength slows down.Silane coupling agent plays a positive role in the strength of recycled plastic concrete.The water absorption saturation of concrete has been basically completed in the early stage.The addition of silane coupling agent makes the porosity of concrete reduce and the water absorption of concrete become poor.By summing up the physical and mechanical properties of recycled plastic concrete,it could be found that the addition of recycled plastic was effective for the modification of concrete materials.Under the control of the amount of recycled plastic,the strength of concrete with recycled plastic aggregates can meet the engineering requirements.

Seepage behavior of soil mixed with randomly distributed recycled plastic materials

Seepage through embankment fill materials is crucial issue in the construction of embankments for irrigation and drainage projects.Proper ground improvement methods should be used to improve the strength and stability characteristics of soil used as fill material.Utilization of waste plastic materials to enhance the engineering properties of soil is a sustainable approach.Additionally,the use of raw products directly from plastic recycling units in the form of flakes and pellets as soil additives has the potential to further enhance the economic benefits of this method.This study randomly mixed plastic materials with soil for use in the construction of earth embankments,such as river levees,dykes,and canal diversion structures,and evaluated the effectiveness of these materials in reducing seepage failures in hydraulic structures.To achieve these goals,this study collected high-density polyethylene(HDPE)plastic from plastic recycling units and used soil mixed with HDPE plastic in the form of flakes and pellets in different contents as embankment fill materials,then evaluated how these materials affected the piping features.Laboratory experiments were conducted to determine the seepage velocity and critical hydraulic gradient of soil mixed with plastics in various contents and to compare the values with those of plain soil.The results showed that random distribution of waste plastics in the form of flakes and pellets in soil is an effective method for improving the piping resistance of soil.

Recipe Development and Mechanical Characterization of Carbon Fibre Reinforced Recycled Polypropylene 3D Printing Filament

Recycled polypropylene filaments for fused filament fabrication were investigated with and without 14 wt% short fibre carbon reinforcements. The microstructure and mechanical properties of the filaments and 3D printed specimens were characterized using scanning electron microscopy and standard tensile testing. It was observed that recycled polypropylene filaments with 14 wt% short carbon fibre reinforcement contained pores that were dispersed throughout the microstructure of the filament. A two-stage filament extrusion process was observed to improve the spatial distribution of carbon fibre reinforcement but did not reduce the pores. Recycled polypropylene filaments without reinforcement extruded at high screw speeds above 20 rpm contained a centreline cavity but no spatially distributed pores. However, this cavity is eliminated when extrusion is carried out at screw speeds below 20 rpm. For 3D printed specimens, interlayer cavities were observed larger for specimens printed from 14 wt% carbon fibre reinforced recycled polypropylene than those printed from unreinforced filaments. The values of tensile strength for the filaments were 21.82 MPa and 24.22 MPa, which reduced to 19.72 MPa and 22.70 MPa, respectively, for 3D printed samples using the filaments. Likewise, the young’s modulus of the filaments was 1208.6 MPa and 1412.7 MPa, which reduced to 961.5 MPa and 1352.3 MPa, respectively, for the 3D printed samples. The percentage elongation at failure for the recycled polypropylene filament was 9.83% but reduced to 3.84% for the samples printed with 14 wt% carbon fiber reinforced polypropylene filaments whose elongation to failure was 6.58%. The SEM observations on the fractured tensile test samples showed interlayer gaps between the printed and the adjacent raster layers. These gaps accounted for the reduction in the mechanical properties of the printed parts.

Review of recycling waste plastics in asphalt paving materials

An ever-growing demand for depleted natural resources is one of the significant challenges facing the global asphalt pavement industry in building and maintaining global asphalt pavements.Because plastics are ubiquitous in the global economy,they are the latest in a series of high-profile materials to attract attention.Their low material recovery rates and the environmental impact of current disposal methods pose a threat to plastic recycling.Recycling plastic wastes in asphalt pavement is a possible approach to reducing environmental pressure and the demand for depleted natural resources.Many studies have proposed recycling plastic waste in asphalt pavement using dry-and wet-processed technologies.This review aims to comprehensively evaluate the feasibility of various recycled plastics in asphalt pavement concerning the properties of compatibility,storage stability,microstructure,thermo-rheology,and mechanical performance and to identify hallenges and recommendations for the future.This review discusses recent developments and the feasibility of using plastic wastes as modifiers or additives to asphalt binders or asphalt mixtures in dry and wet processes,focusing on different materials from waste streams,how to produce such modified materials,and the characteristics of plastic waste modified asphalt,thus contributing to the sustainable management of resources and production of useful paving materials.

Toys, Décor, and More: Evidence of Hazardous Electronic Waste Recycled into New Consumer Products

Hazardous chemicals used in electronic and electrical consumer products can re-enter commerce when these products are recycled. The objectives of this study were to 1) identify the possible sources of unexpected chemicals and elements in consumer products, including the use of recycled E-waste plastics and 2) demonstrate bromine detection with nondestructive spectroscopy as an indicator of brominated flame retardants contaminating new products via recycled waste streams. More than 1500 consumer products of diverse types purchased in 2012-2014 were examined using X-ray fluorescence spectroscopy for correlations between bromine and other elements. New electronic products were much more likely than new non-electronics to contain greater than 1000 ppm bromine, consistent with intentionally added flame retardants, while non- electronic products were more likely to contain between 5 and 100 ppm bromine, suggesting unintentional contamination. A typical suite of elements present in E-waste was found in a majority of plastic products. Two product categories, vinyl floor tiles and beaded necklaces/garlands, were explored in more detail. Specific flame retardant chemicals in bead samples were identified by mass spectrometry and their distribution in beads was studied using scanning electron microscopy and energy dispersive spectroscopy. Five brominated chemicals typically used as flame retardants, including BDE-209, were identified in 50 of 50 Mardi Gras beads analyzed.

Towards greener polymers:Trends in the German chemical industry

Global plastics production is expected to exceed 400 million tons and reach 600 million tons by 2060.Their synthesis currently accounts for approximately 3%of global greenhouse gas emissions.Approximately 60%of all polymers are produced for single-use.Examples include shopping bags,packaging materials,mulch films,and soluble polymers for cosmetics and other purposes.Currently,only a portion of single-use plastic is recycled or disposed of in incinerators or landfills.An estimated 20%is not disposed of properly and pollutes the global environment,especially the oceans.In response to these challenges,the United Nations,European Union,and many nation-states are developing regulatory frameworks that encourage the chemical industry to produce plastics with a smaller environmental footprint and often support this through research funding.Possible solutions include:(1)the use of green energy,green hydrogen,bio-based feedstocks,or CO_(2) in synthesis;(2)the reuse or recycling of plastics through conversion or pyrolysis;and(3)the production of biodegradable polymers.The German chemical industry contributes approximately one-third of polymer production in the EU.It is embedded in the EU regulatory and research landscape and anchored in the European Green Deal,which aims for carbon neutrality by 2050.In this paper,we describe how BASF and Evonik,two leading German chemical companies with strong but different polymer portfolios,respond to the call for greener polymers and how technologies are being developed to make polyurethanes,a particularly important and difficult-to-recycle family of elastomers and duromers,renewable and circular.Reducing the environmental footprint of plastics requires not only innovative materials but also proper governance,regulatory and collection systems,and public willingness to cooperate.In an international comparison of these competencies,expressed by the"polymer management index"(PMI),Germany achieved a top position.

Appropriate solid waste management system in Quelimane (Mozambique):study and design of a small-scale center for plastic sorting with wastewater treatment

Appropriate solid waste management(SWM)strategies are necessary to avoid severe environmental and sanitary impacts,especially in low-income countries.Such strategies are most likely to succeed whether implementing actors are supported by scientific research.In this paper,the results of a collaboration between local authorities and researchers are presented and discussed that are the assessment of waste generation in the city of Quelimane(Mozambique),integrating existing and field-collected data and the design of a small-scale center for plastic sorting to complement the SWM system of the city.The center is expected to receive about 0.3-0.4 t/day of plastic waste(5%-7%of the overall amount of plastic waste daily produced in Quelimane).As long-term sustainability represents a typical issue,simplicity of operation was a leading principle in the design of the center;moreover,the design included a treatment plant(WWTP)for generated wastewater,whose management is usually neglected in such interventions.Among others,natural wastewater treatment(constructed wetlands)has been chosen for its affordability.Noteworthy,the so-conceived WWTP appears as a novelty in the scientific literature associated with small-scale plastic sorting plants.The system is designed to treat an average flow of 6 m3/day and consisted of a septic tank followed by a subsurface flow constructed wetland.Overall,the COD(chemical oxygen demand)and TSS(total suspended solids)removal higher than 80%and 90%were estimated,respectively.Based on this work,both the center and the WWTP were successfully realized,which are waiting to become operational.In the authors’opinion,the implemented procedure could become a reference for broader investigations and surveys.

Flammability Properties of Composites of Wood Fiber and Recycled Plastic

Flammability properties of composites of wood fiber and recycled plastic were evaluated by the cone calorimeter and oxygen index chamber. Results were shown as follows: 1) Wood-PVC composite showed worse thermal stability on time to ignition (TTI) and mean heat release rate (MHRR), but better performance on heat release rate (HRR) and mean efficient heat of combustion (MEHC); wood-PP composite had better thermal stability properties, but was worse on other fire performance; 2) Compared with wood-PVC composite, wood-PP composite showed excellent thermal stability, but behaved dangerous as a whole; 3) Coupling agent PAPI changed fire performance of wood-PP composite and showed a longer TTI, lower EHC but higher HRR. It can be concluded that flame resistance treatment should be considered if wood-plastic composites are used as decorated materials.

Microwave Catalytic Depolymerization of Polyethylene Terephthalate Plastic to the Monomers

Plastic waste management has emerged as a critical environmental issue due to the exponential increase in plastic consumption worldwide.Polyethylene terephthalate(PET)is extensively used in the production of water bottles,which constitutes a significant fraction of the plastic waste.PET recycling is a challenging task due to the lack of efficient and cost-effective depolymerization methods.In this study,we developed a microwave(MW)catalytic depolymerization method for PET recycling using modified zinc oxide loaded with manganese oxide as a cocatalyst.The modified Mn_(3)O_(4)/ZnO catalyst presents high efficiency in depolymerizing PET into its monomers with only 0.4 wt% ratio of the catalyst to PET at 175℃ for 5 min,resulting in 100% conversion of PET and 88% selectivity toward bis-hydroxyethyl terephthalate monomers.It is believed that Mn_(3)O_(4)provides additional Lewis acid sites,promoting the dissociation of glycol from PET,and the MW irradiation plays a crucial role in rapidly heating the ethylene glycol and the catalyst,thereby accelerating the PET depolymerization process.In addition,the heterogeneous nature of the catalyst facilitates its easy separation from the reaction mixture for reuse,simplifying the catalyst recovery process and enabling costeffective and sustainable PET recycling.Thus,this study provides an innovative and sustainable solution for PET recycling,contributing toward the circular economy and mitigating the environmental impact of plastic waste.

Evolution of the global polyethylene waste trade system

Introduction:China’s import bans on solid wastes starting from 2017 have challenged the global trade system of plastic wastes,which remains poorly characterized.This study chooses polyethylene(PE)as a case and aims to map out the global trade networks of PE waste(GPETN)from 1976 to 2017.Outcomes:We find that the size and complexity of the GPETN had been growing until 2016.After the mid-1990s,PE waste basically flowed from developed economies,mainly the EU and the US,to developing economies such as China.Since 2001 when admitted into the WTO,China’s PE waste import surged until 2014 when it absorbed over 60%of global export.Regulations on solid waste import following the Green Fence campaign in 2013 resulted in substantial reductions in China’s import as well as the global export of PE waste after 2014.Several other developing economies,such as Malaysia,Turkey,and Vietnam,had transitioned to net importers,but their imports were insufficient to replace China as new recycling bases for PE waste.Conclusion:The results highlight the urgent need of a joint effort for developed and developing countries to build a stronger global circular economy system with sufficient capacity to treat PE waste locally.