Mechanical and chemical recycling of solid plastic waste.

The present rate of economic growth is unsustainable without saving of fossil energy like crude oil, natural gas or coal. Thus mankind has to rely on the alternate/renewable energy sources like biomass, hydropower, geothermal energy, wind energy, solar energy, nuclear energy, etc. On the other hand, suitable waste management strategy is another important aspect of sustainable development. The growth of welfare levels in modern society during the past decades has brought about a huge increase in the production of all kinds of commodities, which indirectly generate waste. Plastics have been one of the materials with the fastest growth because of their wide range of applications due to versatility and relatively low cost. Since the duration of life of plastic products is relatively small, there is a vast plastics waste stream that reaches each year to the final recipients creating a serious environmental problem. Again, because disposal of post consumer plastics is increasingly being constrained by legislation and escalating costs, there is considerable demand for alternatives to disposal or land filling. Advanced research in the field of green chemistry could yield biodegradable/green polymers but is too limited at this point of time to substitute the non-biodegradable plastics in different applications. Once standards are developed for degradable plastics they can be used to evaluate the specific formulations of materials which will find best application in this state as regards their performance and use characteristics. Among the alternatives available are source reduction, reuse, recycling, and recovery of the inherent energy value through waste-to-energy incineration and processed fuel applications. Production of liquid fuel would be a better alternative as the calorific value of the plastics is comparable to that of fuels, around 40 MJ/kg. Each of these options potentially reduces waste and conserves natural resources. Plastics recycling, continues to progress with a wide range of old and new technologies. Many research projects have been undertaken on chemical recycling of waste plastics to fuel and monomer. This is also reflected by a number of pilot, demonstration, and commercial plants processing various types of plastic wastes in Germany, Japan, USA, India, and elsewhere. Further investigations are required to enhance the generation of value added products (fuel) with low investments without affecting the environment. The paper reviews the available literature in this field of active research and identifies the gaps that need further attention.

Thermolysis of waste plastics to liquid fuel: A suitable method for plastic waste management and manufacture of value added products—A world prospective

Catalytic pyrolysis of plastic waste: A review

Pyrolysis of waste tyres: a review.

The continuous increase in the generation of waste plastics together with the need for developing more sustainable waste management policies have promoted a great research effort dealing with their valorization routes. In this review, the main thermochemical routes are analyzed for the valorization of waste polyolefins to produce chemicals and fuels. Amongst the different strategies, pyrolysis has received greater attention, but most studies are of preliminary character. Likewise, the studies pursuing the incorporation of waste plastics into refinery units (mainly fluid catalytic cracking and hydrocracking) have been carried out in batch laboratory-scale units. Other promising alternative to which great attention is being paid is the process based on two steps: pyrolysis and in-line intensification for olefin production by means of catalytic cracking or thermal cracking at high temperatures.

Thermochemical routes for the valorization of waste polyolefinic plastics to produce fuels and chemicals. A review

Feedstock recycling of polymers by pyrolysis in a fluidised bed

Major challenges to chimeric antigen receptor (CAR) T cell therapies include uncontrolled immune activity, off‐tumor toxicities and tumor heterogeneity. To overcome these challenges, we engineered CARs directed against small molecules. By conjugating the same small molecule to distinct tumor‐targeting antibodies, we show that small molecule specific‐CAR T cells can be redirected to different tumor antigens. Such binary switches allow control over the degree of CAR T cell activity and enables simultaneous targeting of multiple tumor‐associated antigens. We also demonstrate that ultraviolet light‐sensitive caging of small molecules blocks CAR T cell activation. Exposure to ultraviolet light, uncaged small molecules and restored CAR T cell‐mediated killing. Together, our data demonstrate that a light‐sensitive caging system enables an additional level of control over tumor cell killing, which could improve the therapeutic index of CAR T cell therapies.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/cmdc.202100722

Light‐Controllable Binary Switch Activation of CAR T Cells

The Front Cover shows light-induced activation of CAR T cells. Antibodies are coupled to small molecules protected by ultraviolet-light-sensitive cages, which can bind to proteins common to tumors and normal tissues. Only when tumors are exposed to ultraviolet light, cages dissociate from the small molecules, enabling small-molecule-specific CAR T cells to attack. In contrast, cages on small molecules prevent CAR T cell attack on normal tissues, which are not exposed to ultraviolet light. Thus, spatiotemporal control will improve the therapeutic index of CAR T cell therapies. Cover design by Rachel Davidowitz. More information can be found in the Research Article by Aya Kobayashi, Alberto Nobili, Carl D. Novina et al. 

A Sadiki

Papers

Feedstock recycling of polymers by pyrolysis in a fluidised bed

Light‐Controllable Binary Switch Activation of CAR T Cells

Front Cover: Light‐Controllable Binary Switch Activation of CAR T Cells (ChemMedChem 12/2022)