Recycling Of Polyvinyl Chloride Research Articles

The Carbon Footprint of Peritoneal Dialysis in Australia.

As climate change escalates with increasing health impacts, healthcare must address its carbon footprint. A critical first step is understanding the sources and extent of emissions from commonly utilised clinical care pathways. We used attributional process-based life cycle analysis to quantify CO2 equivalent emissions associated with the delivery of Baxter home automated peritoneal dialysis (APD) and continuous ambulatory peritoneal dialysis (CAPD) in Australia. Annual per patient carbon emissions attributable to the manufacture and disposal of PD fluids and consumables were 1,992 kg CO2equivalent emissions for APD and 1,245 kg CO2equivalent emissions for CAPD. Transport impacts varied depending on the distance between site of manufacture of PD fluids and consumables and the home state of the patient. As a result, the total impact of providing PD also differed by Australian state, ranging from 2,350-4,503 kg CO2 equivalent emissions for APD and from 1,455-2,716 kg CO2 equivalent emissions for CAPD. Recycling of polyvinyl chloride (PVC) could reduce emissions by up to 14 per cent for APD and 30 per cent for CAPD, depending on the distance between the site of PVC waste generation and the recycling centre. This study demonstrated higher per patient carbon emissions from APD compared to CAPD, due to both higher fluid and consumable requirements, and the consequent higher transport impacts. PVC recycling can partially mitigate PD associated carbon emissions.

Recycling PVC Waste into CO2 Adsorbents: Optimizing Pyrolysis Valorization with Neuro-Fuzzy Models

Nowadays, the environmental challenges associated with plastics are becoming increasingly prominent, making the exploitation of alternatives to landfill disposal a pressing concern. Particularly, polyvinyl chloride (PVC), characterized by its high chlorine content, poses a major environmental risk during degradation. Furthermore, PVC recycling and recovery present considerable challenges. This study aims to optimize the PVC pyrolysis valorization process to produce effective adsorbents for removing contaminants from gaseous effluents, especially CO2. For this purpose, PVC waste was pyrolyzed under varied conditions, and the resulting solid fraction was subjected to a series of chemical and physical activations by means of hydroxides (NaOH and KOH) and nitrogen. Characterization of the PVC-based activated carbons was carried out using surface morphology (SEM), N2 adsorption/desorption, elemental analysis, and FTIR, and their capacity to capture CO2 was assessed. Finally, neuro-fuzzy models were developed for the optimization of the valorization technique. The resulting activated carbons exhibited excellent CO2 adsorption capabilities, particularly those activated with KOH. Optimal activation conditions include activations at 840 °C with NaOH at a ratio of 0.66 and at 760 °C using either NaOH or KOH with ratios below 0.4. Activations under these experimental conditions resulted in a significant increase in the adsorption capacity, of up to 25%, in the resulting samples.

Revealing the long way towards lead-free plastic in China through dynamic material flow analysis of lead salt heat stabilizers in PVC products

The use of lead salt heat stabilizers (LHSs) in plastics are restricted or even prohibited owing to their high toxicity. However, little information is available on its industrial metabolism. A dynamic material flow analysis of LHSs indicates that China consumed 2952 kt LHSs between 1958 and 2020. Moreover, at present, 1020 kt of these is being used in polyvinyl chloride (PVC) products, 1007 kt is in landfills, and 681 kt is in the environment. For China to realize lead-free primary plastics by 2040, 2050, and 2060, the LHSs consumption should be reduced by at least 13 %, 10 %, and 9 % annually, respectively. Certain LHSs would gain new life with PVC recycling. Therefore, approximately 30 years would be required for LHSs to disappear completely after their use is stopped. With improvements in the plastic recycling rate, it is necessary to use chemical recycling and other methods to separate the hazardous additives such as LHSs and reduce the circulation of toxic substances.

Enhanced flotation of high density polyethylene and polyvinyl chloride mixtures based on clean corona modification

The dramatic increase in waste plastics has caused harm to both human health and the environment. Due to the variety of plastic products and their complex components, it is a technical challenge to effectively separate them. High density polyethylene (HDPE) and polyvinyl chloride (PVC) both have a high detection frequency in the common solid waste streams like automobile shredder residue (ASR), and due to the similar properties of different plastics, their mixtures lack reliable separation methods. Specifically for this kind of mixtures, this work provided a novel separation strategy with prepositive corona modification and postpositive flotation units. To obtain the optimal separation parameters, flotation performance of HDPE and PVC were investigated under different modification conditions controlled by the corona polarity, discharge power and exposure time. Besides, the modification mechanism was revealed through multi-characterization tests on surface morphology, molecular weight, contact angle, and spectrums. The results showed that corona discharge can generate non-thermal plasma to activate the surfaces of HDPE and PVC, thereby increasing their floatability difference. Under the optimal conditions of 300 W positive discharge power and 8000 ms exposure time, HDPE turned into the sinking tail while PVC still accumulated in the floating product, leading to the maximum separation recovery and purity of 96.36% and 97.01%, respectively. Amorphous low-molecular weight oxidic substances emerged on the upper layer of polymers was verified by the multi-characterization, representing in varying degrees of oxidation and chain scission (HDPE > PVC). Since the corona modification is reagent-free-addition and rapid in-line process, this work showed great advantages in the total cost of separation (only 450.03 USD/t) and potential environmental benefits, which also paves a clean way for the recycling of HDPE and PVC.

Preparation of adsorptive polyethyleneimine/polyvinyl chloride electrospun nanofiber membrane: Characterization and application

Landfilling and burning plastic waste, especially waste polyvinyl chloride (PVC), can produce highly toxic and carcinogenic by-products that threaten the ecosystem and human health. However, there is still a lack of proper methods for waste PVC recycling. Therefore, developing feasible ways for waste PVC recovery is urgently needed. The purpose of this study is to analyze the characteristics of PVC-based adsorptive nanofiber membranes and test their ability for the treatment of wastewater containing Cibacron Brilliant Yellow 3G-P, a widely used reactive dye. The polyethylenimine/polyvinyl chloride membrane (PEI/PVCM) was characterized by FTIR, FE-SEM, TGA, tensile analysis, water contact angle measurement, and zeta-potential analysis. The FTIR analysis confirmed that the PEI has successfully crosslinked with PVC. The FE-SEM images showed that the nanofibers constituting PEI/PVCM are compact with an average fiber diameter of 181 nm. The TGA results showed that the membrane was able to remain stable in wastewater below 150 °C. The average stress and strain of the PEI/PVCM were 7.64 ± 0.32 MPa and 934.14 ± 48.12%, respectively. The water contact angle and zeta potential analysis showed that after the introduction of PEI, the membrane converted from hydrophobic to hydrophilic, and the pHpzc was increased from 3.1 to 1.08. The pure water flux of the membrane was measured at 0.1 MPa and the result was 3013 ± 60 L/m2‧h. The wastewater purification capability of PEI/PVCM was measured at an initial dye concentration of 10 ppm and pH 4–9 at 0.1 MPa. The reusability of PEI/PVCM was verified through three adsorption-desorption cycles. The results demonstrated that the PEI/PVCM is a reusable membrane for efficient purification of wastewater containing reactive dyes over a wide pH range (pH 4–8).

A clean and efficient flotation towards recovery of hazardous polyvinyl chloride and polycarbonate microplastics through selective aluminum coating: Process, mechanism, and optimization

Polyvinyl chloride (PVC) and polycarbonate (PC) microplastics are major sources of hazardous chlorine and bisphenol A, threatening the ecosystem and environment. Plastic recycling can control the source of microplastics pollution, but the recycling of PVC and PC will be prevented by invalid separation. We established a novel and clean flotation method to separate PVC and PC microplastics by using aluminum coating. Trace amounts of Al(OH)3 can selectively coat the PVC microplastics surface due to its strong affinity for PVC. The contact angle of PVC decreases by 24° due to abundant hydroxyl groups of Al(OH)3 coating, whereas PC remained hydrophobic. Response surface methodology (RSM) combining Box-Behnken design (BBD) is used to optimize modification. A quadratic model is established to predict PC purity, explore the interaction between pH, aluminum chloride concentration, and ultrasonic duration. The recovery and purity of microplastics can exceed 99.65% with parameter optimization. The effects of multi-component, brand, shape, size, and mass ratio of plastics are utilized to evaluate the application potential. The suitable situations and limits of this method are disclosed. The aluminum coating offers significant benefits over other modifications in terms of reaction temperature, treatment time, and pollution prevention. Flotation based on aluminum coating provides a new insight for separating and recycling microplastics.

Flotation separation of hazardous polyvinyl chloride towards source control of microplastics based on selective hydrophilization of plasticizer-doping surfaces

As the single largest chlorine source of plastics, hazardous polyvinyl chloride (PVC) has become an increasing environmental concern with the rapid microplastics accumulation. An advanced separation method is advocated to purify waste PVC plastics, optimize physical recycling, and protect aquatic and terrestrial environment safety. In this study, we proposed a novel scheme for the flotation separation of PVC plastics with diverse plasticizer contents (PVCs) via regulating hydrophilicity based on a selective ferric deposition. Rigid PVCs were prone to loading ferric ions and generating hydrophilic shells than flexible PVCs. Plasticizers can diffuse freely through the interior and surface of PVC plastics. Abundant plasticizers thereby overlaid the surface of flexible PVC and shielded PVC matrix from ferric ions. By regulating the ferric concentration, the wettability of PVCs was adjusted to separate rigid and flexible PVCs by froth flotation. Waste PVCs could also be separated from each other through the compound process of ferric deposition and flotation, further confirming its feasibility and stability. Thus far, this study supplies distinctive insights into the wettability regulation of plasticizer-doping PVC surfaces, contributes a pioneering hydrophilization method to PVCs separation and recycling, and mitigates hazardous PVC microplastics by source control.

Comparing the effects of different metal oxides on low temperature decomposition of PVC

Polyvinyl chloride (PVC) is one of the most widely used plastics in the world. When PVC is heated, HCl will form, causing equipment corrosion, product quality decline, environmental pollution and other problems. Therefore, more attention is paid to recycling of PVC than other plastics. In this study, the reaction mechanisms of PVC with different metal oxides (MOx: CaO, ZnO, CuO, MgO, Fe2O3, Al2O3) at low temperature (310 °C) were compared, with focus on chlorine capture and dehydrochlorination product (De-Cl PVC) property. The results showed that when the radius of metal ion was smaller, the extrapolated onset temperature (Ti) of PVC-MOx pyrolysis tended to be lower, such as PVC-ZnO, PVC-CuO and PVC-Al2O3. Direct reaction of PVC and MOx was deduced for PVC-CuO and PVC-ZnO pyrolysis, based on the lower Ti and peak temperature (Tmax) than that of PVC pyrolysis. MOx that did not significantly lower Tmax was supposed to react with HCl that dissociated from PVC. The addition of ZnO significantly reduced the release of HCl (0.5%) and captured 97.6% of chlorine as inorganic chloride salts. However, the chloride salts produced from PVC-MgO pyrolysis could decompose at low temperature, thus releasing HCl again, and the C atoms in PVC-CuO system could react with copper chloride salts and H2O, to form and release HCl. The capture effects of chlorine by Fe2O3 and Al2O3 were not good. With addition of MOx, all De-Cl PVCs were rich in C=C-H and (C)3C-H structures. Fe2O3, MgO and CuO reduced the release of volatile hydrocarbons, while CaO, ZnO and Al2O3 increased the release of volatile hydrocarbons. Except for CaO and CuO, the other MOx increased the amount of residual hydrocarbon (De-Cl PVC).

Carbon footprint and embodied energy of PVC, PE, and PP piping: Perspective on environmental performance

This study is aimed at comparative data analysis of three types of polymers i.e. Polyvinylchloride (PVC), Polyethylene (PE) and Polypropylene (PP). These polymers are widely used in Piping, water sanity, and medical industries. Polypropylene is highly thermal resistant and can withstand much higher temperatures than PVC. Literature review was done to analyze Life cycle assessment and carbon footprint of these plastic production processes to find the environmental impact that contributes to global warming. However, PVC has higher energy consumption and CO2 gas emission that shows its high potential in global warming than other plastics. Moreover, the recycling of PVC has shown significant contributions in lowering the effect on climate change. This study also focuses on the industries which produces significant CO2 emissions into environment and how we can reduce these emissions in most appropriate ways.

TG-FTIR and Py-GC/MS study of the pyrolysis mechanism and composition of volatiles from flash pyrolysis of PVC

To facilitate the reuse and recycling of polyvinyl chloride (PVC) to achieve sustainable development and new industrialization, the composition and mechanism of formation of volatiles during the flash pyrolysis of PVC were studied by thermogravimetry-Fourier transform infrared (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TG and derivative thermogravimetry (DTG) analyses indicated two main degradation stages during flash pyrolysis of PVC, namely dehydrochlorination of PVC and decomposition of dechlorinated-PVC. Simultaneously, the FTIR results revealed that the main functional groups in the pyrolysis process were H–Cl, -C-Cl, C–H, CH, and aromatic groups. The relative content of main volatiles was determined by Py-GC/MS, and decreased in the following order: aromatics > alkenes > hydrogen chloride (HCl) > chlorinated hydrocarbons. Specifically, the relative content of aromatics was as high as 76.790–81.809%, while that of HCl was in the range of 3.016–3.096%. The carbon number distribution and the relative content of main products obtained from the flash pyrolysis of PVC at different final temperatures were also analysed. According to the experimental results, the mechanism of formation of the main volatiles based on free-radical reactions was deduced in detail. Therefore, this study provides further details for deepening the understanding of the PVC pyrolysis process.

Development of recycled blends based on cables and wires with plastic cabinets: An effective solution for value addition of hazardous waste plastics.

The recycling of polyvinyl chloride (PVC) recovered from the plastic insulations in wires and cables is a rising concern in the current situation due to its hazardous behaviour during recycling. Similarly, high-impact polystyrene (HIPS) and acrylonitrile butadiene styrene (ABS) used in the structural components of electrical and electronic equipment are also generated in large quantities. In the current work, three agendas were fixed: (a) to determine the effect of recycled polymeric material (HIPS and ABS) recovered from different sources on the mechanical property of the polymeric blends; (b) to formulate a high-impact strength blend; and (c) to deduce a mechanism for improved impact strength. The mechanical characterizations were conducted on the entire blends formulated. Among them, the recycled blend composed of recycled PVC (r-PVC) and recycled ABS (r-ABS) (segregated from uninterrupted power supply housing) and recycled HIPS (r-HIPS; collected from television housing) was confined for further physio-mechanical and thermal analysis. Besides, the r-PVC/r-ABS systems had shown better mechanical properties than r-PVC/r-HIPS systems in similar composition. The impact strength of blend r-PVC/r-ABS (70:30) was found to be 250 J/m, which was 200% more than the blend r-PVC/r-ABS (0:100). The compatibility and non-compatibility in PVC/ABS and PVC/HIPS blends respectively were explained with thermal, mechanical and morphological characterizations. Furthermore, a plausible cross-linking mechanism is developed between ABS and PVC, which controls the release of chlorine atoms into the environment.

Stocks and flows of polyvinyl chloride (PVC) in China: 1980-2050

Polyvinyl chloride (PVC) is a widely consumed plastic material and may lead various environmental pollutions. China produces and consumes the largest amount of PVC material in the world, owing to its rapid urbanization and economic growth. Herein, we establish a dynamic material flow analysis methodology for quantifying PVC stocks and flows in China, including material input, manufacturing and consumption distribution, and waste management stage. We examine the material flow of PVC in China from 1980 to 2015. The PVC trajectory analysis from 2016 to 2050 is based on the historical PVC material consumption data and scenario analysis. Total amount of PVC consumption in all types of products dramatically increased from 0.4 Mt (0.4 kg/capita) in 1980 to 14.5 Mt (10.7 kg/capita) in 2015, with a cumulative amount of 173.7 Mt. The rapid increase of PVC consumption in China significantly accelerated the PVC waste accumulation, reaching 66.3 Mt, accounting for 38.2% of total PVC use from 1980 to 2015. Building & construction sector has the largest PVC in-use stock, while consumer goods sector generated the largest PVC waste. In recent fifteen years, mechanical recycling, chemical recycling, incineration, and landfill of PVC waste ratios are 25.5%, 0.8%, 9.3%, and 36.0%, respectively. The PVC trajectory analysis shows that by the end of 2050, the accumulative PVC waste in China will be 508.6 Mt in the limited growth scenario and 562.0 Mt in the business as usual scenario. Based on the MFA results, policies for improving PVC recycling system were analyzed in this work.

SUN-058 Variations in Environmentally Sustainable Practice within Australian Dialysis Units: Time for a Nationwide Approach?

Climate change has been identified as one of the key threats to global health and well-being in the 21st century and will require national and global efforts to combat greenhouse gas (GHG) emissions. Health care systems are responsible for a significant proportion of overall GHG emissions and dialysis programs contribute a disproportionate amount to this. While previous studies have documented environmental practice within dialysis units in the state of Victoria, Australia, no studies have compared practice between Australian states. The Victorian Environmental Sustainability Special Interest Group questionnaire was used to assess and compare environmental practice at 4 satellite dialysis units within Australia; 2 in Brisbane, Queensland and 2 in Sydney, New South Wales. The survey asked 107 questions on energy/water use, waste management, resource consumption and procurement, transport and environmental policies and initiatives. Nurse unit managers completed the survey at each site and were encouraged to discuss with colleagues to improve the accuracy of data recorded. The median number of haemodialysis (HD) sessions performed at each satellite unit was 168/week [157.5-270]. All units reported health service support for waste recycling practices, however this was graded as ‘moderate’ by 2 units and ‘could be better’ by 2 units. 3 units reported available recycling bins for hard and soft plastics but only 1 unit reported available polyvinyl chloride (PVC) recycling bins. Only Sydney based units reported that product suppliers removed pallets after supply delivery. Cardboard was not removed by suppliers at any site, but all 4 units recycled cardboard. No unit captured reverse osmosis (RO) reject water for reuse elsewhere. Procurement of supplies occurred at least weekly across all sites, with the frequency universally determined by storage space. Only 2 units considered environmental sustainability when choosing supplies. None of the units were aware of their power supplier, whether any of their energy was derived from renewable sources or of the green star rating of their building. Movement sensitive lights were only present in 2 units. Only 2 sites offered bicycle storage facilities and 1 site an area for showering and changing. 3 units were accessible by public transport but only 1 unit provided information to patients and staff about this. The level of awareness of sustainability in health was variable, reported as low in 2 units, moderate in 1 unit and very high in the other unit. Only 1 unit reported having an environmental policy in place and 1 other an active green group within the hospital. No units had undertaken a sustainability audit. One of the units also served as a home training facility for both HD and peritoneal dialysis (PD). This service offered both cardboard and PVC recycling to patients; however only 26-50% of patients utilised this service. No patients reclaimed RO reject water, despite potential assistance in establishing a water capture system. There is no universal approach to environmental sustainability within Australian dialysis units, with inter-state and inter-unit variation in practice. This study highlights the need for nationwide data collection regarding environmentally sustainable practice as an important first step in addressing the environmental impact of dialysis.

Chemically recycled polyvinyl chloride as a bitumen modifier: synthesis, characterisation and performance evaluation

Polyvinyl chloride (PVC) is one of the most widely produced thermoplastic polymer, used in the manufacture of a variety of valuable short and long life products. Nevertheless, the increasing demand for PVC and current ineffective disposal methods have made it a potentially severe environmental hazard. The chemical recycling of PVC through hydrolytic or aminolytic routes has shown significant promise, however, their end applications have been limited as of now. This study is concerned with the chemical modification of PVC by amines into additives, and its ensuing use as a performance enhancing modifier for bitumen. In view of this, additives were firstly synthesised by the amination of PVC with two kinds of polyamines; triethylenetetramine (TETA) and ethylene diamine (ED) respectively. These were then chemically characterised by solid state Nuclear Magnetic resonance (NMR) and elemental analysis. Subsequently, the aminated PVC additives were blended with virgin asphalt binder and its effectiveness was evaluated in terms of moisture susceptibility and rheological properties. The results of the preliminary laboratory studies indicated that the binders modified with the additives showed significantly improved anti-stripping properties and overall rheological performance as compared to conventional binder. Overall, the usage of such waste PVC based additives as modifier for bituminous mixtures represents an innovative approach to deal with a relevant recycling problem while simultaneously recovering a value-added material.

Searching for Acidity or the Case of the Missing Chlorine: An Option for a Global Closed Loop Alkalinity–Acidity Cycle for Bauxite Residue Neutralization Based on HCl from PVC Recycling

The Bayer process depends on the large-scale use of caustic soda (NaOH)—produced at > 60 million tons/year from NaCl by the chlor-alkali process—and is thus one of the major consumers of the alkalinity generated by the latter. A part of this alkalinity then ultimately ends up in the bauxite residue from the Bayer process, arguably constituting one of the main chemical, technical, and environmental challenges for a valorization or long-term safe disposal and remediation of this material. By stoichiometric and chemical necessity, the complementary acidity resides in the Cl2 gas is also produced in the chlor-alkali process and is thus latent in the chlorinated compounds—notably polyvinyl chloride (PVC) and chlorinated solvents, such as dichloromethane or 1,1,1,-trichloroethane. Recapturing and recycling Cl2 from these uses in the form of hydrochloric acid (HCl) by means of a controlled thermal decomposition of the chlorinated hydrocarbons could—in principle—serve as a source of Bronsted acidity for the neutralization of bauxite residue (Red Mud) thereby transforming it into a nonhazardous material of much lower environmental concern limited to its NaCl content. This could establish a closed alkalinity–acidity cycle on a global scale while simultaneously addressing the end-of-life fate of environmentally persistent PVC that otherwise either is deposited in landfills or can end up in the oceans in form of dispersed microplastics.

Effects of Processing Methods, DOP Amount and Filler Content on the Mechanical Properties of Recycled Polyvinyl Chloride (PVC) Composites

PVC is one of the most commercialized thermoplastic materials with industrial and household applications. Plastic possesses an important percentage in waste stream and its recycling is vital. Plasticizer usage is also essential for the PVC manufacturing and recycling. It is the purpose of this study to determine the effects of processing methods, DOP concentration and wood flour amount on the mechanical properties of recycled PVC composites. 15 and 30 phr (per-hundred-resin) DOP and 0-15-30 phr wood flour was studied. Composite materials were produced using injection and compression molding methods. Tensile, flexural, impact, hardness (shore D) and density of the composites were determined. Based on these results, DOP and filler content and process had a significant effect on mechanical properties. Utilization of DOP in the PVC matrix made material softer and flexible. Resulting materials had higher elongation at break and impact strength and smaller shore D values. In an expense to these good results, it reduced the tensile and flexural strength and modulus values. Addition of wood filler in the system, increased modulus values while reducing strength values. In the case of processing methods, injection molded samples provided overall better properties than compression molded ones. It should be noted that, in the case of injection molding, samples were better mixed due to the screw in the machine. Recycling of PVC is a vital subject and more study is needed.

Alkaline hydrolysis of PVC-coated PET fibers for simultaneous recycling of PET and PVC

Polyvinyl chloride (PVC)-coated poly(ethylene terephthalate) (PET) woven fibers are one of the hardest-to-recycle polymeric materials. Herein we investigate the possibility of recycling both PVC and PET through alkaline hydrolysis of PET. The coated woven fabrics were treated with NaOH, hydrolyzing the PET fibers into water-soluble sodium terephthalate, while the PVC could be removed by filtration. The PET fibers were completely hydrolyzed between 120 and 180 °C in the presence of 1 M NaOH solution, quantitatively yielding terephthalic acid. A minimum PVC dechlorination rate of 1% was simultaneously achieved at 120 °C. Furthermore, no alkaline hydrolysis of the plasticizer contained in the PVC, di(2-ethylhexyl)phthalate, was observed. Thus, the possibility of simultaneously recycling PET and PVC from PVC-coated woven fabrics was demonstrated. Kinetic analyses of PET hydrolysis and PVC dechlorination revealed that the simultaneously occurring reaction processes did not affect the progress of each other. Thus, the absence of interactions between PET, PVC, or their degradation products enables the design of a simplified recycling process without considering the interactions between the materials derived from coated woven fabrics.

KINETIC OF ESTERIFICATION OF CITRIC ACID IN PRODUCTION OF TRIALKYL CITRATES

Polyvinyl chloride (PVC) is a body of a great many of composite materials and takes one of the leading places in thermoplastic polymers production capacity. Annual intake of PVC in the world (data of 2014 years) achieves to 35 mtpa. and has a consistent trend to further increase. PVC recycling is impossible without using of plasticizers. Nowdays scopes of use and plasticizers market used in the polymer materials production intended for contact with alimentary products, for medical equipment and children's toys production, are upon essential impact of policy statements of health, safety, security, environment. Plasticizers with citric acid – trialkyl citrates have needed properties: hazard class 4, high plasticize ability, full miscibility with polymer, high boiling and flash points, low volatility. The citric acid is available renewable raw produced from saccharified residues; world production volume is 1.6 mtpa. There are no local plasticizers production technologies with citric acid. Development of plasticizers production technologies with renewable raw material is relevant objective. Purpose of research is to create method of producing of trialkyl citrate, study of esterification regularities of citric acid with low molecular alcohol over different catalysts. In this research, the kinetic of performances of citric acid esterification by pentanol was estimated over different catalysts. Reaction orders were defined using three catalysts: sulphuric acid, orthophosphoric acid and p-toluene sulphonic acid. The rate constants and activation energies of esterification were found. Kinetic formulas were obtained. The time of esterification was defined to achieve 95 % conversion of citric acid. The time varies from 1.5 to 5 h depending on used catalyst. For citation:Sushkova S.V., Levanova S.V., Glazko I.L., Pavlova K.V. Kinetic of esterification of citric acid in production of trialkyl citrates. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N2. P. 74-78.

Optimization of surface treatment for flotation separation of polyvinyl chloride and polyethylene terephthalate waste plastics using response surface methodology

A simple process for separation of polyvinyl chloride (PVC) and polyethylene terephthalate (PET) waste plastics was investigated for sustainable development of plastic industry. Surface treatment with potassium permanganate (KMnO4) solution selectively decreases the flotation rate of PVC, promoting flotation separation of PVC and PET. Flotation rate represents the mass percentage of float particles. Oxidization action and migration of calcium carbonate on PVC surface as major mechanism of surface treatment are confirmed by scanning electron microscope and X-ray photoelectron spectroscope determinations. Single factor experiments demonstrate that the flotation rate of PVC is affected significantly by the factors of KMnO4 concentration, treatment time, temperature and stirring rate. The effects of variables, including KMnO4 concentration, treatment time and temperature, on the flotation rate of PVC are evaluated by response surface methodology with a Box–Behnken design. A modified quadratic model is achieved for predicting the flotation rate of PVC plastic. The optimum conditions are potassium permanganate concentration 4.60 mmol/L, temperature 66.5 °C, treatment time 38 min and stirring rate 200 r/min. PVC and PET mixtures with different mass ratio were separated efficiently through one-stage flotation combined with surface treatment. The purity of PET is above 97.87% and the recovery of PVC is above 97.90%. Effective separation by the proposed method enables recycling of PVC and PET waste plastics.

Pollution characteristics and health risk assessment of volatile organic compounds emitted from different plastic solid waste recycling workshops

The pollution profiles of volatile organic compounds (VOCs) emitted from different recycling workshops processing different types of plastic solid waste (PSW) and their health risks were investigated. A total of 64 VOCs including alkanes, alkenes, monoaromatics, oxygenated VOCs (OVOCs), chlorinated VOCs (ClVOCs) and acrylonitrile during the melting extrusion procedure were identified and quantified. The highest concentration of total VOCs (TVOC) occurred in the poly(acrylonitrile-butadiene styrene) (ABS) recycling workshop, followed by the polystyrene (PS), polypropylene (PP), polyamide (PA), polyvinyl chloride (PVC), polyethylene (PE) and polycarbonate (PC) workshops. Monoaromatics were found as the major component emitted from the ABS and PS recycling workshops, while alkanes were mainly emitted from the PE and PP recycling processes, and OVOCs from the PVC and PA recycling workshops. According to the occupational exposure limits' (OEL) assessment, the workers suffered acute and chronic health risks in the ABS and PS recycling workshops. Meanwhile, it was found that most VOCs in the indoor microenvironments were originated from the melting extrusion process, while the highest TVOC concentration was observed in the PS rather than in the ABS recycling workshop. Non-cancer hazard indices (HIs) of all individual VOCs were <1.0, whereas the total HI in the PS recycling workshop was 1.9, posing an adverse chronic health threat. Lifetime cancer risk assessment suggested that the residents also suffered from definite cancer risk in the PS, PA, ABS and PVC recycling workshops.