Analysis of sorption capacity of natural sorbents in relation to aqueous solutions of heavy metal compounds

The main preconditions emergence of an environmental crisis in the country due to surface water pollution include irrational use of water resources in violation of the environmental requirements, discharge of untreated and insufficiently treated industrial and municipal wastewater into water bodies and inflow of polluting substances from agricultural lands as a result of surface water drainage. The whole set of considered factors leads to depletion and pollution of surface water of Ukraine, reduction of their self-cleaning capacity, degradation, impoverishment and collapse of aquatic ecosystems. Excessive content of heavy metal ions in surface water has a negative impact on the environment, causing acute and chronic diseases. Ingress of such pollutants into surface water is almost entirely due to anthropogenic economic activity. Wastewater from chemical, ferrous and nonferrous metallurgy brings a great amount of such pollutants. Among various methods used for removing heavy metal ions from aqueous media, sorption methods remain one of the most effective and popular, mainly due to the fact that they ensure a high degree of purification at relatively low costs. Along with the adsorbents traditionally involved in these processes, a number of studies and practical implementations with use of natural dispersed minerals as adsorbents were conducted lately. The research aims at studying the sorption capacity and efficiency of natural and modified sorbent such as bentonite clay for purification of aqueous solutions containing heavy metal ions in the form of dissolved compounds and justifying its potential application. It studies the efficiency of wastewater treatment aimed at removing heavy metal ions by the natural clay sorbent of bentonite clays of the Cherkaskyi Deposit (Dashukovskyi deposit). The paper presents a technique for modification of bentonite clay in order to increase its adsorption capacity for heavy metal ions using the following three methods: physical (thermal), chemical (processing with application of Iron(III) chloride solution) and combined (thermal processing of the original sorbent followed by processing with application of Iron(III) chloride solution). It has been experimentally proved that a natural sorbent modified via thermal and chemical processing is characterized by a high absorption capacity to heavy metal ions contained in water solutions, in particular to chromium(VI) ions, copper(II) ions and aluminum(III) ions with the purification degree ranging from 5% to 83%. The highest adsorption rate, 83%, is demonstrated by the combined method of bentonite clay modification, therefore proving the effectiveness of application of environmentally friendly natural sorbents for wastewater treatment processes aimed at removing heavy metal ions. The paper indicates the advantages of wastewater treatment sorption methods allowing removal of pollutants of different origin and any concentration.

Utilization of Cellulose to Its Full Potential: A Review on Cellulose Dissolution, Regeneration, and Applications

As the most abundant natural polymer, cellulose is a prime candidate for the preparation of both sustainable and economically viable polymeric products hitherto predominantly produced from oil-based synthetic polymers. However, the utilization of cellulose to its full potential is constrained by its recalcitrance to chemical processing. Both fundamental and applied aspects of cellulose dissolution remain active areas of research and include mechanistic studies on solvent–cellulose interactions, the development of novel solvents and/or solvent systems, the optimization of dissolution conditions, and the preparation of various cellulose-based materials. In this review, we build on existing knowledge on cellulose dissolution, including the structural characteristics of the polymer that are important for dissolution (molecular weight, crystallinity, and effect of hydrophobic interactions), and evaluate widely used non-derivatizing solvents (sodium hydroxide (NaOH)-based systems, N,N-dimethylacetamide (DMAc)/lithium chloride (LiCl), N-methylmorpholine-N-oxide (NMMO), and ionic liquids). We also cover the subsequent regeneration of cellulose solutions from these solvents into various architectures (fibers, films, membranes, beads, aerogels, and hydrogels) and review uses of these materials in specific applications, such as biomedical, sorption, and energy uses.

VDM NICKEL 200

VDM Nickel 200 is an unalloyed nickel grade that contains at least 99.2% nickel. It has characteristics that are useful in several fields, notably chemical processing and electronics. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Ni-778. Producer or source: VDM Metals GmbH (a subsidiary of Acerinox, S.A.).