A composite based on amino-containing humic acid with the immobilization of multi-walled carbon nanotubes preliminarily tuned to a copper ion has been obtained. The synthesis of a composite pre-tuned for sorption by the local arrangement of macromolecular regions was obtained by introducing multi-walled carbon nanotubes and a molecular template into the composition of humic acid, followed by copolycondensation with acrylic acid amide and formaldehyde. The template was removed from the polymer network by acid hydrolysis. As a result of this tuning, the macromolecules of the composite “remember” conformations that are favorable for sorption, i.e., adsorption centers are formed in the polymer network of the composite, capable of repeated, highly specific interaction with the template and the highly selective extraction of target molecules from the solution. The reaction was controlled by the added amine and by the content of oxygen-containing groups. The structure and composition of the resulting composite were proven by physicochemical methods. A study of the sorption properties of the composite showed that after acid hydrolysis, the capacity increased sharply compared to a similar composite without tuning and a composite before hydrolysis. The resulting composite can be used as a selective sorbent in the process of wastewater treatment.

In this work, molecularly imprinted polymers with zinc imprints and their comparison polymers without imprints were synthesized. A comparative characterization of the physical parameters of the synthesized zinc-imprinted (ZnIP) and non-imprinted (NIP) polymers was carried out using the methods of elemental analysis, conductometry, scanning electron microscopy, and IR-Fourier spectroscopy. The ability of the resulting polymers to molecularly recognize zinc was evaluated. Based on experimental data on static adsorption, the adsorption capacity of ZnIP and NIP was determined using an atomic emission spectrometer. It was found that ZnIP is characterized by better physical parameters and a higher ability for molecular recognition of zinc compared to NIP. ZnIP with zinc imprints were found to have better sorption capacity for zinc than their reference polymers. The sorption of zinc by molecular imprinted ZnIP is mainly due to the complex formation and pores of the initial carbon product. The synthesized ZnIP have increased porosity. The presence of pores with a diameter <50 nm in ZnIP is associated with voids formed after acid hydrolysis, which is clearly visible in images recorded by scanning electron microscopy. Thus, the possibility of using ZnIP as a selective sorbent has been established.

This article examines the scientific basis for using humic acids for the chemical stabilization of mineralized water prior to reverse osmosis. The need to develop alternative approaches to water pretreatment is due to the limited effectiveness of traditional antiscale reagents at high mineralization, as well as their potential environmental risks and the likelihood of secondary contamination of water systems. The article focuses on the mechanisms of interaction between humic acids and Ca²⁺ and Mg²⁺ hardness ions, which are mediated by complexation with carboxyl and phenolic functional groups. It is demonstrated that humic stabilization differs from classical softening and demineralization in that it is aimed not at the complete removal of dissolved salts, but at reducing the activity of ions involved in the formation of carbonate deposits. The potential advantages of this approach for reducing the scale-forming potential of water, improving the stability of reverse osmosis membranes, and extending inter-flushing intervals are discussed. The technological limitations associated with residual organic load, possible membrane fouling, the need to control total organic carbon, color and stability of the filter medium, as well as a pilot test of the proposed approach are considered.

Zinc-imprinted polymer (ZnIP) and non-imprinted polymer (NIP) were synthesized by radical polymerization, and their properties were studied. The novelty of the work lies in the use of humic acids isolated from coals of the Shubarkol deposit (Karaganda, Kazakhstan) as a basis for the imprinted polymer matrix, with methacrylic acid and ethylene glycol dimethacrylate as a functional monomer and a cross-linking agent, respectively. The composition and structure of ZnIP and NIP were characterized using various physicochemical methods. The specific surface area of ZnIP determined by the BET method was 40.60 ± 0.4 m²/g, which is almost twice as high as the similar indicator for NIP (21.50 ± 0.3 m²/g). In sorption tests of solutions with bimetallic ions, ZnIP demonstrates higher adsorption: 96.15% for Zn²⁺ and 74.88% for Pb²⁺, while NIP adsorbs only 81.33% and 60.11%, respectively. Sorption on both polymers is described by a pseudo-first-order equation (r > 0.99). The distribution coefficients for ZnIP are higher than for NIP. ZnIP has a relative selectivity that exceeds NIP by 2.90 times. The research results indicate the promise of using ZnIP for the selective removal of zinc ions from solutions of multicomponent systems, including wastewater, making it a valuable material for solving environmental and technological problems.

Imprinted polymers with imprints of Zn2+ ions (ZnIP) and reference polymers without imprints (NIP) were synthesized based on humic and methacrylic acids. Comparative studies of the physical parameters of ZnIP and NIP were carried out using elemental analysis, IR spectroscopy and electron microscopy. Kinetic parameters of Zn2+ ion sorption on ZnIP and NIP were determined. It was found that the sorption kinetics on both ZnIP and NIP are approximated by a pseudo-first-order equation. The sorption rate constant for ZnIP is higher than that of NIP, indicating a higher adsorption rate of Zn2+ ions onto the surface of ZnIP. This may be due to more accessible sites on ZnIP. Adsorption of Zn2+ ions is best described by the Langmuir model, indicating monolayer adsorption on a homogeneous surface. The Langmuir model also shows that ZnIP is effective at low adsorbate concentrations. The Freundlich model describes the adsorption with less accuracy, which may indicate monolayer adsorption and less surface homogeneity. ZnIP shows better adsorption capacity and higher efficiency compared to NIP and can be proposed as a selective sorption material for Zn2+ ions.

A composite based on humic acid (HA) and reduced graphene oxide (rGO) was synthesized to evaluate the effect of rGO on the structural, functional, thermal, and preliminary phenol adsorption properties of humic acid. The incorporation of rGO increased the carbon content from 47.34 to 55.61 wt.% and decreased the oxygen content from 48.31 to 40.79 wt.%. At the same time, the total content of carboxyl and phenolic hydroxyl groups increased from 5.00 to 5.47 mmol/g, indicating improved accessibility of oxygen-containing functional sites. FTIR spectroscopy confirmed the retention of the main functional groups of the initial components after composite formation. Thermogravimetric analysis showed enhanced thermal stability, with the residual mass at 1000 °C increasing from 59.21 to 70.03%. Electron microscopy revealed the formation of a developed wrinkled surface morphology. Preliminary phenol adsorption experiments showed that the HA-rGO composite exhibited higher adsorption capacity than the initial HA and rGO. This improvement was attributed to the combined contribution of oxygen-containing functional groups and the aromatic carbon structure of rGO, which may promote hydrogen bonding and π–π interactions with phenol molecules.