The plasticizer market: an assessment of traditional plasticizers and research trends to meet new challenges

In the area of water purification, nanotechnology offers the possibility of an efficient removal of pollutants and germs. Today nanoparticles, nanomembrane and nanopowder used for detection and removal of chemical and biological substances include metals (e.g. Cadmium, copper, lead, mercury, nickel, zinc), nutrients (e.g. Phosphate, ammonia, nitrate and nitrite), cyanide, organics, algae (e.g. cyanobacterial toxins) viruses, bacteria, parasites and antibiotics. Basically four classes of nanoscale materials that are being evaluated as functional materials for water purification e.g. metal-containing nanoparticles, carbonaceous nanomaterials, zeolites and dendrimers. Carbon nanotubes and nanofibers also show some positive result. Nanomaterials reveal good result than other techniques used in water treatment because of its high surface area (surface/volume ratio). It is suggested that these may be used in future at large scale water purification. It is also found that the coliform bacteria treated with ultrasonic irradiation for short time period before Ag- nanoparticle treatment at low concentration, enhanced antibacterial effect. In future, combination of both may be the best option for treatment of waste water.

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Application of Nanoparticles in Waste Water Treatment

https://arpi.unipi.it/bitstream/11568/214337/1/ChielliniF_REVISED.pdf

Perspectives on alternatives to phthalate plasticized poly(vinyl chloride) in medical devices applications

The current scenario of water resources shows the dominance of pollution caused by the draining of industrial effluents. The polluted waters have resulted in severe health and environmental hazards urging for a suitable alternative to resolve the implications. Various physical and chemical treatment steps currently in use for dye effluent treatment are more time consuming, cost-intensive, and less effective. Alternatively, nanoparticles due to their excellent surface properties and chemical reactivity have emerged as a better solution for dye removal and degradation. In this regard, the potential of silver nanoparticles in dye effluent treatment was greatly explored. Efforts were taken to unravel the kinetics and statistical optimization of the treatment conditions for the efficient removal of dyes. In addition, the role of silver nanocomposites has also experimented with colossal success. On the contrary, studies have also recognized the mechanisms of silver nanoparticle-mediated toxicity even at deficient concentrations and their deleterious biological effects when present in treated water. Hence, the fate of the silver nanoparticles released into the treated water and sludge, contaminating the soil, aquatic environment, and underground water is of significant concern. This review summarizes the current state of knowledge regarding the use of silver nanoparticles and silver-based nanocomposites in effluent treatment and comprehends the recent research on mitigation of silver nanoparticle-induced toxicity.

Silver nanoparticles in dye effluent treatment: A review on synthesis, treatment methods, mechanisms, photocatalytic degradation, toxic effects and mitigation of toxicity.

The internal plasticization of PVC by displacement of chlorine with phthalate-based thiol additives, that is, the covalent attachment of the plasticizer to the PVC chain, is described for the first time. Using this methodology, a good plasticization efficiency is achieved although flexibility is reduced compared with that of commercial PVC−phthalate systems. However, the migration is completely suppressed. This approach may open new ways to the preparation of flexible PVC with permanent plasticizer effect and zero migration.

Phthalate Plasticizers Covalently Bound to PVC: Plasticization with Suppressed Migration

A plasticized poly(vinyl chloride) surface was modified by azidation using sodium azide in the presence of a phase transfer catalyst in aqueous media. Subsequent to azidation, the surface was crosslinked using ultraviolet radiation. Contact angle measurements showed that the surface became hydrophilic on azidation whereas photoirradiation did not have any further effect on the hydrophilicity of the azidated surface. Control, azidated, and photocrosslinked surfaces were exposed to two strains of bacteria commonly implicated in device infection such as Staphylococcus aureus and Escherichia coli. Whereas the control and photocrosslinked surfaces showed no significant difference in bacterial adhesion, the azidated surface showed significantly reduced adhesion to both strains. Data obtained indicate that the presence of an intact azide function on the polymer surface is responsible for the reduced bacterial adherence and the surface hydrophobicity/hydrophilicity did not exert any effect in the present case. Although azides are known to be effective only against Gram-negative species, surprising was the observation that the azidated polymer surface was equally effective against a Gram-positive species such as S. aureus. Because sodium azide is routinely used as a preservative to prevent bacterial and fungal growth in many microbiology reagents and diagnostic kits, covalent binding of the azide onto a polymer surface or synthesizing azide containing polymers may be an interesting method to investigate in tackling the problem of bacterial adhesion and colonization of medical devices.

Bacterial adhesion onto azidated poly(vinyl chloride) surfaces.

Plasticized poly(vinyl chloride) (PVC) is one of the most widely used polymeric materials in medical and related applications, and usually contains up to 40 per cent di-(2-ethylhexyl)phthalate (DEHP), which acts as the ‘plasticizer’ to impart flexibility to an otherwise rigid PVC1. The plasticizer can migrate from PVC-based devices and storage bags into physiological fluids, however, and has been detected in storage media such as blood, plasma, serum, drug solutions and fatty foods2,3,4, as well as in the bodies of patients undergoing haemodialysis and transfusion5. This is a concern because DEHP is a lipid-removing liver carcinogen6, and causes hepatic7 and reproductive toxicity8 in rodents, although opinion is divided on its toxicity in humans9.

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Immobile plasticizer in flexible PVC

Synthesis, surface properties and performance of thiosulphate-substituted plasticized poly(vinyl chloride).

To describe the diagnostic test properties of Cardiac Troponin-T (cTnT) in predicting myocardial dysfunction in asphyxiated term neonates by taking echocardiography as the gold standard and to establish the optimum cut-off values of cTnT for myocardial dysfunction, shock, severe hypoxic ischemic encephalopathy (HIE) and mortality by receiver operator characteristic (ROC) curve analysis. This was a prospective study based on diagnostic test evaluation. The study included 120 term asphyxiated neonates in a tertiary care neonatal intensive care unit (NICU) in Southern India from June 2011 through June 2015. All the neonates were clinically evaluated. Venous blood was taken at 4 h of life for cTnT estimation. Echocardiography was done within 24 h of birth. The mean cTnT level of asphyxiated term neonates was 0.207±0.289 ng/ml (mean ± SD). Asphyxiated neonates with myocardial dysfunction had higher cTnT levels (0.277±0.231) as compared to those without myocardial dysfunction (0.061±0.036, p = 0.0001). Using ROC curve, the cut-off cTnT values for myocardial dysfunction was 0.1145 ng/ml with sensitivity 92.4% and specificity 94.1%. Cardiac Troponin-T levels were significantly higher among asphyxiated neonates with shock (0.378±0.348, p = 0.0001) and the levels also correlated positively with increasing grades of HIE. The cut-off cTnT value for mortality was 0.2505 ng/ml with sensitivity 83.9% and specificity 96.6%. In asphyxiated term neonates, early cTnT elevation is a marker for predicting myocardial dysfunction and elevated cTnT levels had high sensitivity and specificity. There was significant relation with increasing cTnT values and increasing grades of HIE.

S. Lakshmi

Papers

Bacterial adhesion onto azidated poly(vinyl chloride) surfaces.

Immobile plasticizer in flexible PVC

Synthesis, surface properties and performance of thiosulphate-substituted plasticized poly(vinyl chloride).

Cardiac Troponin-T as a Marker of Myocardial Dysfunction in Term Neonates with Perinatal Asphyxia