Viral removal has long been a key part of FDA-approved processes. Anion-exchange chromatography is commonly used to bind negatively charged viruses and separate them from therapeutic products. Each individual process must confirm that virus has been removed. This empirical determination of virus removal is now being pushed toward a more mechanistic understanding of virus removal. There are two key parts of a virus removal operation with charged media: the physicochemical attributes of the virus and proteins in solution, and the chromatography media. With new biophysical and computational tools, improvements are being made to provide a scientific basis for deviations in virus binding. New formats of ion-exchange media are also improving the scale-up and reliability of virus removal mechanisms. Virus removal is becoming more of a science and less of an empirical art that will greatly improve the safety of biotherapeutics in the future.

A dynamic model of the transfer and molecular sorption processes inside a sorption column is considered, based on the acid retardation of a gel anion exchanger. A three-layer model of a space filled with a solution is used to describe the process of keeping solution components inside nanosized pores in a multicomponent system. Allowance is made for the heterogeneity of the concentrations of molecules in the pores of the sorbent, caused by the forces acting on polar molecules from the sorption centers. The model allows calculation of changes in the concentrations of components over time inside the sorption column and, based on output concentration curves obtained experimentally, to determine characteristics of the process of holding molecules inside nanosized pores. Results from modeling are compared to experimental data on the purification of industrial extractive phosphoric acid.

The development of nanomaterials designed for enhanced and controlled delivery of metallodrugs is a challenging task and requires using reliable analytical tools. In this bioanalytical study, we employed high-resolution inductively coupled plasma-mass spectrometry to assess a novel type of nanocarrier based on cation-exchanger nanoparticles (CENs). By recording the signals of Pt and S isotopes, it was shown that direct interaction between CENs and activated cisplatin drug results in a fast and high drug loading (up to 0.12 g Pt per gram) and in human serum environment the loaded CENs are rapidly converted into the protein-bound form but do not discharge the payload. To gain an insight into the composition of the protein corona, the relative abundances of proteins attached to the surfaces of parent and cisplatin-loaded CENs were determined using LC-MS/MS. The potential of CENs as a nanocarrier for smart drug delivery has been further confirmed by a sizeable release of cisplatin under conditions relevant to cancer cytosol (but negligible in normal cytosol setting). It is believed that binding to the CENs would provide the cisplatin treatment more targeted action, higher (when necessary) dosages, and possibly reduced side effects.

The potential to organize steady-state self-sustaining processes of the softening–desalination of brackish water was studied in a numerical experiment on the example of multicomponent model solutions containing sodium and calcium chlorides and sulfates. In the steady-state, self-sustaining processes of softening, water is subjected to desalination by means of a cation-exchange resin, and the formed brine is used to regenerate this cation-exchange resin in repeated sorption–desorption cycles without the addition of any surplus reagents. The interest in self-sustaining processes is associated with new technological opportunities in the creation of a new generation of water-treatment systems, e.g., mobile, stand-alone setups or systems with a high degree of freshwater recovery. The calculations of ion-exchange dynamics have been carried out for dozens of consecutive softening–desalination cycles via changes in the varied parameters, in particular, the ratio of components in the initial solution and the composition of desalted water. The conditions under which no steady-state regimes are formed or attained are shown. Based on the results of numerical experiments, a criterial relationship for the preliminary estimation of the feasibility of self-sustaining processes is proposed.

In this paper, we propose a new, effective, and easy-to-implement technology for hydrothermal synthesis of an adsorption material based on carboxymethylcellulose (CMC) and graphene oxide (GO) decorated with iron nanoparticles (FeNPs) for water purification from heavy metals. The purpose was to study the effect of the iron content in the materials on their physicochemical and adsorption properties. The synthesized materials were examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Complex adsorption studies were performed using the example of lead ion removal from contaminated aqueous media. The influence of pH and contact time on the process efficiency was studied. The mechanism of adsorption was analyzed using pseudo first -order and pseudo second-order, intraparticle diffusion, and Elovich kinetics models. The results showed an optimal pH of 6 and contact time of 30 min. The process is best described by a pseudo second-order model. The material with a mass content of iron nanoparticles of 18% (CMC/GO + Fe 18 wt%) showed the largest adsorption capacity for Pb ions (1850 mg g-1). Adsorption isotherms of lead ions from aqueous media by the synthesized composite materials were studied using Dubinin-Radushkevich and BET models. The adsorption process is based on the chemical interaction of extracted ions with the surface of an adsorbent. Desorption studies showed the possibility of using the GO/CMC/FeNPs in real processes for purification of aqueous media. The obtained maximum value of adsorption capacity for the CMC/GO + Fe 18 wt% material was 1850 mg g-1, which is one of the highest in the literature for composite materials based on GO and vegetable raw material processing products.

The decrease in the availability of high-quality bauxites makes the processing of high-silica raw materials inevitable, and in this regard, it is necessary to develop acid–salt methods suitable for these ores. The purpose of the work was to study various stages of the hydrosulfate method for processing alumina-containing raw materials on the example of nepheline concentrate in order to investigate the possibilities of their improvement. A. The distribution of various macro- and meso-components of leaching between phases at the stage of isolation of ammonium alum depending on sulfate concentration were experimentally and theoretically studied. It was shown that, with an increase in the total concentration of sulfate in the equilibrium mother liquor, the concentration of main impurity components, including iron, in a solid phase decreases significantly. To obtain relatively pure alum, it was recommended to use ammonium hydrosulfate with a concentration of at least 4 mol/L. B. Different embodiments for further purification of alum were explored. It was found that the use of the recrystallization process in the presence of small additions of sodium thiosulfate reduces the content of iron impurities in alum by almost an order of magnitude. C. A method for isolating purer final product was demonstrated. Isolation of ammonium aluminum carbonate hydroxide (ASACH), as a precursor of high-purity alumina, using ammonium bicarbonate is currently the most promising method in the hydrosulfate technology. In combination with the process of recrystallization, the preparation of AACH makes it possible to eliminate the need for expensive methods of selective sorption or extraction for deep purification of aqueous solutions of alum.

Current economic and ecological analyses of the various processes available for recovery of minerals from seawater favor ion exchange and sorption technology. The steam power stations in some countries which border the sea use seawater for cooling the turbine stream. Traditional methods for producing magnesium by processing hydromineral sources fail to satisfy the newer ecological standards. Potassium is the fourth most abundant macroelement in the sea. It is produced on a small scale from seawater by evaporation and crystallization methods. The ion-exchange capacity of clinoptilolite in extracting potassium from seawater reaches a value of 30 mg/g, which far exceeds the capacity values quoted for the much more costly zirconium phosphate. The air-stripping production of bromine from seawater is effective only under relatively high seawater temperatures and sufficient bromine concentration.

An electrochemical cell was created and experimentally tested and the process of intense capacitive deionization (CDI) of aqueous solutions in a cyclic mode was studied. The paper presents a developed mathematical model for CDI process on electrodes with complex structure of pore space. This allows to describe the process and obtain results that are in good agreement with the experimental ones. Model parameters are easily determined at one stage of the deionization process.

Magnesium oxide is a necessary binding agent for the synthesis of a magnesium potassium phosphate (MPP) matrix based on MgKPO4 × 6H2O, which is promising for the solidification of radioactive waste (RW) on an industrial scale. The performed research is devoted to finding a cost-effective approach to the synthesis of MPP matrix by using MgO with an optimal ratio of the quality of the binding agent and the cost of its production. A method for obtaining MgO from the widely available natural mineral serpentinite was proposed. The phase composition, particle morphology, and granulometric composition of MgO were studied. It was found that the obtained MgO sample, in addition to the target periclase phase, also contains impurities of brucite and hydromagnesite; however, after calcining at 1300 °C for 3 h, MgO transforms into a monophase state with a periclase structure with an average crystallite size of 62 nm. The aggregate size of the calcined MgO powder in an aqueous medium was about 55 μm (about 30 μm after ultrasonic dispersion), and the specific surface area was 5.4 m2/g. This powder was used to prepare samples of the MPP matrix, the compressive strength of which was about 6 MPa. The high hydrolytic stability of the MPP matrix was shown: the differential leaching rate of magnesium, potassium, and phosphorus from the sample on the 91st day of its contact with water does not exceed 1.6 × 10−5, 4.7 × 10−4 и 8.9 × 10−5 g/(cm2·day), respectively. Thus, it was confirmed that the obtained MPP matrix possesses the necessary quality indicators for RW immobilization.

New techniques were developed for the synthesis of monolithic highly porous composite aerogels (hydrogels) from reduced graphene oxide and carbon nanotubes, as well as graphene-containing composites based on mesoporous activated carbon. Simple operations for hydrophilization of synthesized samples were proposed. New electrode materials for electrosorption and deionization of water were fabricated. The resulting materials were investigated and tested in electrochemical cells for membrane capacitive deionization (MCDI).

In determining thiocyanates by photometry as complexes with iron in chloride-containing solutions, it is necessary to take into account the complex dependence of the absorbance of solutions on their composition because of the formation of iron chloride complexes, as well as ternary colored iron thiocyanate and chloride complexes. A mathematical model relating the equilibrium concentrations of components in solutions with the total concentrations of all forms of these components is developed, and the molar absorption coefficients of the [Fe(SCN)]2+ and [Fe(SCN)Cl]+ complexes are determined on its basis. An example of a technological process for the purification of a thiocyanate-containing solution by a two-temperature sorption method is considered, the analytical support of which by the known methods leads to incorrect results, but becomes possible using the developed model.

Acid methods for processing of bauxites and aluminosilicates with high silicon content become attractive in connection with the exhaustion of natural alumina-containing resources suitable for processing by standard procedures based on using alkalis. The main problems in using acid procedures are associated with organization of closed-loop processes with low consumption of chemicals and power. The acid–salt technologies suggested by now are based on using ammonium hydrosulfate in the whole cycle and are economically inferior to the classical Bayer alkaline procedure. This study demonstrates on the laboratory level good prospects for developing a new efficient technology for alumina production from low-grade raw materials in a closed-loop process with recuperation of the consumed salt reagent in each cycle. The process takes advantage of the relationships of the aluminum and iron distribution in the solid phases and equilibrium solutions, revealed by the authors. Another feature is the use of a special method of acid retardation in nanoporous media for separating the residual amounts of the acid and salt, which are returned to the head of the process, with substantial saving of the power and chemicals.

Using the method of numerical experiment, the possibility of arranging steady-state self-sustaining processes for softening and desalinating salty water has been studied with use of two-component model solutions containing calcium and sodium ions as an example. In such processes, water softened by ion exchange is subjected to desalination, and the brine formed in this process—without any additional chemicals—is used to regenerate the cation-exchange resin in repeated sorption–desorption cycles. Interest in self-sustaining processes is associated with new technological capabilities for creating a new generation of water-treatment systems, for example, mobile independent units or systems with high degrees of freshwater extraction and brine concentration. The basic foundations of self-sustaining processes are discussed. The ion-exchange dynamics is calculated for many dozens of successive softening–desalination cycles under conditions of varying parameters, such as the ratio of components in the initial solution, the degree of mineralization of such solutions, the degree of concentration of brines, and the composition of desalinated water. The conditions under which the steady-state regimes are formed or not achieved are found.

The problem of substantiating a pseudo-second order equation in the kinetics of sorption processes is considered. A simple way is presented of transforming the Langmuir kinetic equation written for a process within a limited volume into a polynomial relation in the form of the sum of difference terms of first- and second-order kinetic equations. It is shown that such a relation is reduced to a good approximation of a pseudo-second order equation over a much wider range of conditions determined by the equilibrium and kinetic characteristics of the sorbent and the experimental parameters than was predicted earlier. It is established that the errors of such a theoretical approximation are either negligible or do not exceed the corresponding errors at the initial stage of kinetic experiments within a confined space. It is concluded that the applicability of the pseudo-second order model is independent of the mechanisms determining the rate of sorption and does not require concepts of chemisorption or special equations of kinetics controlled via chemical reactions or diffusion.