A Study of The Properties of Forming Mixtures Containing Polystyrene Wastes

Expanded polystyrene is widely used as a material for packaging, in modern construction as a heat and sound insulation layer, in thermal insulation systems for buildings, as well as tanks and pipelines. It is additionally used in foundry engineering for the production of models which are gasified during the production of castings from ferrous and non-ferrous alloys under the contact with liquid metal. The use of expanded polystyrene products is associated with waste generation, both in production and in consumption. About 40–50 kg/person of polystyrene waste is generated per year. The peculiarity of polymeric wastes is their resistance to aggressive environments. They do not rot and the destruction processes in natural conditions proceed rather slowly, with the formation of harmful substances that poison the environment. Therefore, the problem of the processing of waste from polymeric materials is of great importance, not only from the standpoint of environmental protection, but also due to the fact that in conditions of a shortage of polymer raw materials, this waste becomes a powerful raw material resource. This article describes the prospects for recycling expanded polystyrene wastes in foundry engineering. In this work, the properties of molding and core sands containing a combined binder, consisting of a solution of expanded polystyrene wastes in turpentine and clay were investigated, and their main characteristics (weight during stretching and crumbling) were determined. Molding and core mixtures, which contain only a binder in the form of a solution of expanded polystyrene in turpentine, have a crude strength of not more than 0.01 MPa. The introduction of a mixture of clay in the amount of 2–3% allows a crude strength of the mixture of up to 0.05 MPa to be obtained. After drying, the investigated mixtures containing a solution of expanded polystyrene wastes and clay have a tensile strength of up to 2.1 MPa. Mixtures into which a solution of polystyrene wastes and clay was introduced have an insignificant gas capacity and satisfactory gas permeability.

NEW PATHWAYS IN CHEMISTRY

Chemistry is a science whose progress is exponential as it touches every aspect of our existence and provides all the things required for life to survive on this planet. Chemistry is rightly called the Science of Life. Chemical processes provide food, clothing, shelter medicines, and energy to sustain life. Feeding the ever-increasing population is a big challenge calling for increased production of crops, minimizing losses during their harvesting and storage and use of new, improved varieties like Genetically modified (GM) food grains and pulses. The use of fertilizers has increased manifold over the years, leading to an increase in the production of food. Clothing is made from plant fibres like cotton and silk. New and better varieties of cotton have been developed. Nylon, produced by the polymer industry is also a critical clothing material in some parts of the world. New materials like composites, fly ash bricks, and polymeric wastes are being increasingly used for construction purposes, especially for housing and roads. Research for the synthesis of new drugs to combat diseases is a continuous activity, and the pharmaceutical industry has a considerable investment, especially in our country. Indigenous medicine systems like Ayurveda, Homoeopathy and Unani are also contributing to health welfare, especially in India. Of late, nanomedicines are emerging as an essential area of medicine. Non-conventional energy sources like solar, nuclear, hydro, biodiesel and wind energy are being increasingly tapped as possible substitutes for the fast depleting coal and oil reserves. The International Solar Alliance, initiated by India, aims at forging a strong partnership between all nations to tap and use solar energy.

FEATURES OF BUSINESS OF SMALL AND MEDIUM ENTERPRISES IN THE SECONDARY POLYMERIC MATERIALS MARKET

The article is devoted to the problem of managing small and medium-sized enterprises in the secondary polymer market. The features of the secondary polymers market and the organization of a business for the production of secondary polymeric wastes are investigated. The business processes of recycling waste within the technological chain of secondary polymers production are analyzed. The problems of the activity of small and medium enterprises in the market of secondary polymers and the directions of their solution are formulated.

Adsorption of Azo Dye Methyl Orange from Aqueous Solutions Using Alkali-Activated Polypyrrole-Based Graphene Oxide

The adsorption of methyl orange (MO) from aqueous solutions onto a KOH-activated polypyrrole-based adsorbent (PACK) was investigated using batch and fixed-bed column techniques. The structural, thermal, and morphological properties of the PACK, analyzed by various methods, support its applicability as an adsorbent. An adsorption kinetic study revealed a preferably pseudo-second-order (R2 = 0.9996) and rate-limiting step controlled by both film and intra-particle diffusions. The thermodynamic adsorption tests resulted in negative ΔG°, ΔH°, and ΔS° values, which decreased as the temperature and concentration increased, indicating the spontaneous and exothermic adsorption over 25–45 °C. The adsorption isotherms fit the experimental data in the order of Langmuir ≈ Freundlich > Temkin, with evidence of adsorption operating well via the monolayer physical adsorption process, and maximum monolayer adsorption ranging from 520.8 to 497.5 mg/g. The breakthrough curve of the fixed-bed column experiment was modeled using the Thomas, Yoon–Nelson, and Hill models, resulting in an equilibrium capacity of 57.21 mg/g. A 73% MO recovery was achieved, indicating the possibility of column regeneration. Compared to other adsorbents reported, PACK had comparable or even superior capacity toward MO. For cost-effectiveness, similar nitrogen-containing polymeric wastes could be exploited to obtain such excellent materials for various applications.