Evaluation of the Effect of Polyethylenimine on Boron Adsorption by Soil Minerals.

The removal of hazardous ions from water is crucial for safeguarding both the environment and human health. Soil minerals, integral components of soil, play a vital role as adsorbents for various contaminants, including heavy metal ions, organic dyes, and detergents. This study investigates the interaction between boron ions and soil minerals (gibbsite, kaolinite, and montmorillonite) in the presence of polyethylenimine (PEI). The minerals underwent characterization based on specific surface area, particle size distribution, zeta potential, and the presence of functional groups. The influence of PEI addition on the stability of the soil mineral suspension was evaluated by turbidimetry. Mineral-boron and mineral-boron-PEI interactions were explored under varying conditions, including pH, initial boron concentration, and mineral quantity, with all adsorption experiments conducted over 24 hours. Using the Langmuir isotherm, the maximum adsorption capacity of the studied minerals was determined for boron both without and in the presence of PEI. For gibbsite, kaolinite and montmorillonite, it was 30.63, 24.55 and 26.62 mg g-1, respectively, while in the presence of PEI, it increased to 33.11, 26.61 and 45.47 mg g-1, respectively. The addition of PEI enhanced boron adsorption from aqueous solutions, increasing the removal efficiency from 65 % to about 80 %.

Adsorption Capacity of Carbon-Silica Composites Towards Diclofenac in Poly(acrylic acid) Containing Systems: A Crucial Study on Common Wastewater Contaminants.

Diclofenac is one of the most popular over-the-counter non-steroidal anti-inflammatory drug and poly(acrylic acid) is a frequently used as thickener, filler or stabilizer. For these reasons, they are common organic contaminants in raw wastewater. The purpose of the presented studies was to compare the adsorption capacity of three carbon-silica composites - metal-free C/SiO2, iron-enriched C/Fe/SiO2 and manganese-enriched C/Mn/SiO2 towards diclofenac. The studies were carried out in single, and mixed systems in the presence of poly(acrylic acid) polymer. Adsorption, desorption and kinetics of the adsorption process were investigated. The concentration of diclofenac in the supernatants was determined using high-performance liquid chromatography. The solids were also characterized with an ASAP apparatus using low-temperature nitrogen desorption adsorption isotherms at liquid nitrogen temperature. In addition, potentiometric titrations and electrophoretic mobility measurements, as well as stability tests of the studied suspensions were carried out. The most efficient composite among investigated ones proved to be C/Fe/SiO2 removing diclofenac at the level of 46.68 mg/g for its initial concentration of 90 ppm. The results obtained clearly demonstrated that the carbon-silica composites are effective in separation of drugs from aqueous solutions and can be successfully used in the future for the removal of organic pollutants from water environment.

The influence of sodium alginate on the structural and adsorption properties of resorcinol-formaldehyde resins and their porous carbon derivatives.

A series of carbon composites were synthesised by carbonisation of resorcinol-formaldehyde resin mixtures with the addition of different amounts of sodium alginate (SA) and compared with a composite prepared using Na2 CO3 as a catalyst for the polymerisation reaction. The effect of operating parameters such as SA concentration and polycondensation time on the structural and morphological properties of resorcinol-formaldehyde resins (RFR) and carbon-derived composites was investigated for further use as adsorbents. The synthesised composites were characterised by FTIR, SEM, Raman spectroscopy and N2 adsorption/desorption techniques. It was found that the morphology, specific surface area (SBET ~347-559 m2 /g), volume and particle size distribution (~0.5-4 µm) and porosity (Vpor =0.178-0.348 cm3 /g) of the composites were influenced by the concentration of SA and the synthesis technique and determined the adsorption properties of the materials. It was found that the surface of the filled chars was found to have an affinity for heavy metals and has the ability to form chemical bonds with cadmium ions. The maximum sorption capacities for Cd(II), i. e. 13.28 mg/g, were observed for the sample synthesised with the highest SA content. This confirms the statement that as-synthesised materials are promising adsorbents for environmental applications.

Comparison of Structural, Water-Retaining and Sorption Properties of Acrylamide-Based Hydrogels Cross-Linked by Physical and Chemical Methods.

Two series of hydrogels based on acrylamide and its copolymers with acrylonitrile and acrylic acid were synthesized by two cross-linking methods - chemical (using N,N'-methylene bis-acrylamide) and physical (using montmorillonite (MMT)) ones. The structure of the gels was characterized by Fourier Transform Infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The swelling and sorption properties were analyzed as a function of both the monomer composition and the cross-linking method. The shift of the band corresponding to Si-O (995-1030 cm-1 ) confirmed the formation of intercalation structures for MMT-cross-linked gels. Moreover, physically cross-linked gels demonstrated a non-monotonic dependence of the swelling degree on the MMT concentration, and acrylamide-acrylic acid copolymer MMT-cross-linked gels showed pH sensitivity and the highest swelling degree of 150 g/g. The highest sorption capacity towards cadmium(II) ions was demonstrated by acrylamide-acrylic acid copolymer gels, both covalently cross-linked (30 mg/g) and MMT-cross-linked (8.9 mg/g).

Comparison of Monovalent and Divalent Ions Removal from Aqueous Solutions Using Agricultural Waste Biochars Prepared at Different Temperatures-Experimental and Model Study.

Copper (Cu) and silver (Ag) occur naturally in the environment but have toxic effects on organisms at elevated concentrations. This paper discussed the removal of Cu and Ag from aqueous solutions using biochars obtained at different pyrolysis temperatures. Three biomass sources-sunflower husks (SH), a mixture of sunflower husks and rapeseed pomace (SR) and wood waste (WW)-were pyrolyzed at 300, 400 and 500 °C. Biochars produced at 500 °C exhibited a higher specific surface area, lower variable surface charge and lower contents of surface functional groups than those obtained at 400 or 300 °C. The pseudo-second-order model and intra-particle diffusion (IPD) model well-described the Cu and Ag adsorption kinetics. The Cu adsorption was about 1.48 times slower than the Ag adsorption on the biochars obtained at 500 °C. The model of Langmuir-Freundlich well-described the equilibrium adsorption. Agricultural biochars obtained at >500 °C had a surface with a higher affinity to attract Ag than Cu and were able to remove a larger amount of heavy metals from aqueous media than those prepared at lower pyrolysis temperatures.

Purification of Aqueous Media by Biochars: Feedstock Type Effect on Silver Nanoparticles Removal.

Due to the harmful effects of nanoparticles in the environment, their effective removal from aqueous media is of great importance. This paper described the research on the silver nanoparticles (Ag-NPs) sorption on biochars obtained from different feedstock types. The sorbents were produced through pyrolysis (double-barrel method) of the vineyard (BV), paulownia tree (BP), and tobacco (BT). BV exhibited the highest specific surface area, porosity, value of variable surface charge, and content of surface acidic functional groups among the used biochars. The pseudo-second order model best described the obtained adsorption kinetics, whereas the Freundlich model accounted for the registered adsorption data. The Ag-NPs removal was highly efficient in the case of BV, especially in the nanoparticle concentration range 50-500 mg/L. Thus, this biochar can be considered as an ecofriendly, effective, low-cost organic adsorbent, potentially used in the aqueous media purification.

Insight into the interaction mechanism of iron ions with soil humic acids. The effect of the pH and chemical properties of humic acids.

The main aim of this work was to study the mechanisms of interaction between iron(II) ions and humic acids as a function of pH, iron concentration and various humic acids chemical properties, including the degree of humification, elemental composition, aromaticity and content of acidic functional groups. The results indicated that iron was bound by humic acids at pH 7 in amounts ∼2 times higher than at pH 5 (averaged capacities: 117 and 57 cmol/kg, respectively). Iron binding at pH 7 increased with increasing the total carboxylic and phenolic groups content and the degree of humification of humic acids (R-coefficients: 0.99 and 0.95, respectively). The stability of humic acid-iron complexes at pH 7 were only slightly lower than at pH 5 due to iron hydroxides formed at pH > 5 (averaged stability constants: 5.18 and 5.26, respectively). Iron coordination mode varied depending on pH: at pH 5, the bidentate (chelate) mode dominated, whereas at pH 7 the bridging mode appeared prevalent. The total amount of bound iron was much smaller than the content of the carboxylic and phenolic groups in humic acids, on average by ∼80 (pH 7) and ∼90.1% (pH 5) indicating the occurrence of steric effects in humic acid structure i.e. the reduction of the complexation capacity of free functional groups by adjacent groups occupied by iron and/or the formation of intramolecular aggregates with iron hindering the access of further metal ions. At pH 5 the complexes were soluble in the iron concentration range positively correlated to carboxylic and phenolic groups content, showing the protective nature of negatively charged functional groups on the stability of the solution. At this pH, the destabilization of the system was governed by the neutralization of humic acid charged structures by metal cations and the compression of the double electric layer. At pH 7 the stability of the humic acid-iron solution was largely determined by the form of iron, mainly by the precipitation of metal hydroxides acting as a flocculant destabilizing the solution by co-precipitation of humic acid-iron complexes.

Lysozyme as a flocculant-inducing agent improving the silica removal from aqueous solutions - A turbidimetric study.

In this paper, the lysozyme (LSZ) adsorption impact on the silica suspension stability was established. In other words, the stabilization/destabilization mechanism of the SiO2/LSZ system was explained based on the adsorption, electrokinetic and stability measurement results. Lysozyme adsorbs on the silica surface in the whole pH range. This process contributes to the changes in silica surface charge and zeta potential values. The lysozyme addition influences the system stability too. At pH 7.6 and 9, a large decrease in the silica suspension stability was found. It is connected with the neutralization of solid negative charge by the positively charged macromolecules. As a result, large aggregates can be formed, which is highly desirable in the silica removal procedure.

Separation of plant protection products from complex aqueous bodies using carbon-mineral composites incorporated with double metals (Ni/Mn or Ni/Fe).

Due to the extensive application of pesticides and their hazardous effects on organisms, there is an urgent need to remove them effectively from wastewater. Metal-incorporated carbon-mineral composites (Ni/Mn-CMC and Ni/Fe-CMC) described in this paper can certainly be applied for this purpose. They were synthesized by combining mechanochemical and pyrolytic processes and their physicochemical properties were investigated using numerous methods (SEM-EDS, N2 adsorption/desorption, XRD, surface charge, FTIR). Adsorption capacity towards diuron and carboxin with and without impurities commonly detected in natural ecosystems, cadmium ions or arsenite, was measured. The obtained results indicated that Ni/Fe-CMC is more efficient adsorbent of pesticides due to its well-developed surface. It was able to bind 158.34 mg g-1 of diuron and 133.58 mg g-1 of carboxin in the solutions, where only one pesticide was present. In turn, these values for the Ni/Mn-CMC sample were 126.49 mg g-1 and 102.08 mg g-1, respectively. It should be noted that the composites maintained their high adsorption capacity in the multicomponent solutions, i.e., containing both pesticide and metal ions. Then, the maximum reduction in pesticide adsorption was only 8.36. Ni/Mn-CMC and Ni/Fe-CMC were successfully regenerated with ethanol without changing their structure and adsorption capacity. Also, the extracts from investigated materials did not have negative impact on plant growth. This confirmed suitability of carbon-mineral composites for repeated multiple use without toxic effects to organisms.

Ammonia hydroxide and citric acid modified wheat straw-biochars: Preparation, characterization, and environmental applications.

This study presents an assessment of inorganic and organic modification of biochar on physicochemical properties, dissolved organic carbon (DOC) release, sorption efficiency towards enrofloxacin (E) and silver nanoparticles (Ag-NPs), as well as an evaluation of addition of prepared materials on hydro-physical properties and adsorption capacity of montmorillonite (M). The biochar was derived from wheat straw at 650 °C. An inorganic modification was performed using ammonia hydroxide, whereas an organic modification, using citric acid. The ammonia hydroxide and citric acid changed the biochar nature and surface chemistry by introducing amino and ester groups. The lowest DOC release was from ammonia-biochar (BCN) and the highest, from citric acid-biochar (BCC). The adsorption data were better described by pseudo-II order equation and Marczewski-Jaroniec isotherm. Results showed that BCN exhibited the highest efficiency in adsorption of E and Ag-NPs. It also improved the adsorptive abilities and saturated hydraulic conductivity of M. This provides the chemically modified biochars have an excellent potential to improve pollution removal from aqueous media and hydro-physical/sorption properties of soil sorption complex. They can be used with advantageous in environmental applications.

Green Synthesis and Efficient Adsorption: Na-X Zeolite vs. C/Mn/SiO2 Composite for Heavy Metals Removal.

The studies aimed to test the adsorption capacity of two silica-enriched porous materials, synthetic Na-X zeolite and Mn-containing carbon composite, towards Pb(II) and Zn(II) ions in single and mixed systems and in the presence of diclofenac (DCF) and (or) poly(acrylic acid) (PAA). The synthetic zeolite was characterized by a well-developed surface area of 728 m2/g and a pore diameter of 1.73 nm, while the carbon composite exhibited 268 m2/g and 7.37 nm, respectively. Na-X was found to be more efficient than the carbon composite (75-212 mg/g) in adsorbing heavy metal ions in both single and bimetallic systems (322-333 mg/g). In turn, the C/Mn/SiO2 composite was more effective in removing Pb(II) ions from the systems that simultaneously contained DCF or PAA (480 and 476 mg/g, respectively). The Na-X zeolite demonstrated the greatest stability in all the systems studied. The highest stability was observed in the DCF + Pb(II) mixture, in contrast to the carbon composites where the stability was much lower. To evaluate the possibility of regeneration of the solids, HCl proved to be the best desorbent for heavy metal ions (efficiency of 99%). In general, both adsorbents offer promising potential for solving environmental problems.

Management of hazardous fly-ash energy waste in the adsorptive removal of diclofenac by the use of synthetic zeolitic materials.

Zeolite-carbon composites (Na-P1(C), Na-X(C)) and pure zeolites (Na-P1, Na-X) were synthesized from hazardous high-carbon fly ash waste (HC FA) via hydrothermal reaction with sodium hydroxide (NaOH). These solids were applied in the removal of diclofenac (DCF) from aqueous solution, with and without poly(acrylic acid) (PAA). The experiments included adsorption-desorption measurements, as well as electrokinetic and stability analyses. The obtained results showed that HC FA and Na-P1(C) had the greatest adsorption capacity towards DCF, i.e., 26.51 and 21.19 mg/g, respectively. PAA caused considerable decrease in the DCF adsorption due to the competition of both adsorbates of anionic character for active sites. For example, the adsorbed amount of DCF on Na-P1 without PAA was 14.11 mg/g, whereas the one measured with PAA was 5.08 mg/g. Most of prepared solids were effectively regenerated by the use of NaOH. Desorption degree reached even 73.65% in the single systems (with one adsorbate) and 97.24% in the mixed ones (with two adsorbates). Zeolitic materials formed suspensions of rather low stability, which underwent further deterioration in the organic molecules presence. All the results obtained in this study indicated that HC FA can be successfully managed in the removal of organic substances.

Assessment of agricultural waste biochars for remediation of degraded water-soil environment: Dissolved organic carbon release and immobilization of impurities in one- or two-adsorbate systems.

This paper presents a method of agricultural waste management - the production of two biochars (BC) from potato and raspberry stems. It defines the potential of these materials for remediation of degraded water and soil environments. The performed study included analyses of BC physicochemistry, dissolved organic carbon (DOC) release and ability to immobilize copper (Cu), tetracycline (TC) and carboxin (CB) in one- and two-adsorbate systems. The BCs were obtained with pyrolysis at 600 °C for 30 min in a nitrogen atmosphere. Their DOC was predominantly constituted of substances with large molecular weights and high aromaticity, meaning that both BCs can be safely applied as soil additives. Potato-biochar (P-BC) had a more developed surface than raspberry-biochar (R-BC). The specific surface area (SBET) of P-BC was 122 m2/g, whilst of R-BC was 87 m2/g. As a result, the efficiency of impurity adsorption in the one-adsorbate systems was higher for P-BC (61.75% for Cu, 73.84% for TC, and 54.43% for CB). In the two-adsorbate systems, organic impurities improved the immobilization of heavy metal ions on BCs. The efficiency of Cu adsorption on P-BC when TC was present was 88.29%. Desorption of Cu from BC was highest using HCl, whilst that of TC and CB was highest using NaOH. Maximum desorption was observed in a two-adsorbate system with TC + CB (up to 63.6% for TC). These results confirmed that potato and raspberry stems can be used to produce highly effective BCs with large application potential, especially for remediation of degraded soils and polluted waters.

Chemical modification of biochars as a method to improve its surface properties and efficiency in removing xenobiotics from aqueous media.

Biochar (BC) is a carbonaceous material produced by pyrolysis of biomass, applied in various areas such as water purification, fuel production, soil amendment, etc. Many types of BC are characterized by insufficient textural parameters or poor surface chemistry, and hence by low adsorption capacity. This makes innovative chemical methods increasing BC ability to remove xenobiotics from aquatic environments highly needed. Many of them have already been described in the literature. This review presents them in detail and evaluates their effectiveness in improving textural parameters, surface chemistry, and adsorption capacity of BC.

Novel carbon-based composites enriched with Fe and Mn as effective and eco-friendly adsorbents of heavy metals in multicomponent solutions.

With increasing demand for adsorbents highly effective in pollutant removal, carbon-based porous materials are becoming more and more popular. In this work, a new approach to the synthesis of such solids using an environmentally friendly, two-step preparation method is presented. A series of hybrid porous silica-containing carbon composites was synthesized, namely: metal free (C/SiO2), enriched with manganese (C/Mn/SiO2), as well as iron (C/Fe/SiO2). The effect of additives on the structure and morphology of the composites was evaluated using X-ray photoelectron spectroscopy (XPS), nitrogen adsorption/desorption and scanning electron microscope (SEM). The as-synthesized carbons were used as effective adsorbents for the simultaneous removal of heavy metals, including lead (Pb(II)) and zinc (Zn(II)) ions. In particular, it was determined that C/Mn/SiO2 sample demonstrated the highest adsorption capacity towards Pb(II) and Zn(II) ions. It was equal to 211.60 mg/g for Pb(II) and 74.95 mg/g for Zn(II). Zeta potential and surface charge density of the solids, with and without metals, were investigated to determine electrical double layer structure, whereas stability studies and aggregate size measurements were performed to estimate solid aggregation under selected conditions. It was established that solids with adsorbed metals formed suspensions with lower stability than those without ions. This, in turn, facilitates their separation from aqueous solutions.

Scavenging of copper(II) ions, phosphate(V) ions, and diuron from aqueous media by goethite modified with chitosan or poly(acrylic acid).

Goethite was modified by chitosan (CS) or poly(acrylic acid) (PAA) to improve its adsorptive abilities toward components of agrochemicals, i.e., copper ions (Cu), phosphate ions (P), and diuron. The pristine goethite effectively bound Cu (7.68 mg/g, 63.71%) and P (6.31 mg/g, 50.46%) only in their mixed systems. In the one adsorbate solutions, the adsorption levels accounted for 3.82 mg/g (30.57%) for Cu, 3.22 mg/g (25.74%) for P, and 0.15 mg/g (12.15%) for diuron. Goethite modification with CS or PAA did not yield spectacular results in adsorption. The maximum increase in adsorbed amount was noted for Cu ions (8.28%) after PAA modification as well as for P (6.02%) and diuron (24.04%) after CS modification. Both goethite modifications contributed to clear reduction in desorption of pollutants (even by 20.26% for Cu after PAA coating), which was mainly dictated by electrostatic attractive forces and hydrogen bonds formation occurring between macromolecules and impurities. The only exception in this phenomenon was Cu desorption from CS-modified solid-the polymer made it higher (to 95.00%). The Cu adsorption on PAA-modified goethite enhanced solid aggregation and thus facilitated metal cation separation from aqueous media. Consequently, the goethite modification with PAA was considered more promising for environmental remediation.

Polyacrylamide Hydrogel Enriched with Amber for In Vitro Plant Rooting.

In this work, a new material for in vitro plant rooting based on highly dispersed polyacrylamide hydrogel (PAAG) enriched with amber powder was synthesized and investigated. PAAG was synthesized by homophase radical polymerization with ground amber addition. Fourier transform infrared spectroscopy (FTIR) and rheological studies were used to characterize the materials. They showed that the synthesized hydrogels have physicochemical and rheological parameters similar to those of the standard agar media. The acute toxicity of PAAG-amber was estimated based on the influence of washing water on the viability of plant seeds (pea and chickpea) and Daphnia magna. It proved its biosafety after four washes. The impact on plant rooting was studied using the propagation of Cannabis sativa on synthesized PAAG-amber and compared with agar. The developed substrate stimulated the rooting of the plants to more than 98% in comparison to standard agar medium (95%). Additionally, the use of PAAG-amber hydrogel markedly enhanced metric indicators of seedlings: root length increased by 28%, stem length-by 26.7%, root weight-by 167%, stem weight-by 67%, root and stem length-by 27%, root and stem weight-by 50%. This means that the developed hydrogel significantly accelerates reproduction and allows obtaining a larger amount of plant material within a shorter period of time than the standard agar substrate.

Effect of Biochar Modification by Vitamin C, Hydrogen Peroxide or Silver Nanoparticles on Its Physicochemistry and Tetracycline Removal.

Chemical modification of biochars can improve their adsorption capacity relative to antibiotics, posing a serious threat to the environment. Therefore, this research is aimed at the treatment of sunflower husk biochar (BC) by vitamin C, hydrogen peroxide or silver nanoparticles and the impact of this procedure on the biochar porosity, surface chemistry, and ability to remove tetracycline (TC). During the study, BC was produced by pyrolysis of sunflower husks at 650 °C. All solids were characterized using potentiometric titration, nitrogen adsorption/desorption, Fourier transform infrared spectroscopy, etc. The experimental adsorption data was described by kinetics equations: pseudo-first order, pseudo-second order, and particle internal diffusion (IPD) models as well as by isotherms of Langmuir, Langmuir-Freundlich, and Redlich-Peterson. The obtained results indicated that the biochar upgraded by vitamin C (BCV) had the highest ability to attract antibiotic molecules and, as a result, the TC adsorption on its surface was the largest. Furthermore, the TC desorption from this material was minimal. The measured TC adsorbed amounts for the modified BCs were as follows: 47.75% (7.47 mg/g) for BCV, 37.35% (8.41 mg/g)-for biochar treated by hydrogen peroxide (BCH), and 42.04% (9.55 mg/g) for biochar modified by silver nanoparticles (BCA). The lowest adsorption level was noted for non-modified biochar, i.e., 34.17% (6.83 mg/g). Based on the presented results it can be stated that the upgraded biochars had a good potential to improve the tetracycline removal from aqueous media, e.g., groundwater.

Immobilization mechanism of Cd2+/HCrO4-/CrO42- ions and carboxin on montmorillonite modified with Rhizobium leguminosarum bv. trifolii exopolysaccharide.

The modification of clay minerals by exopolysaccharides (EPSs) may significantly increase their adsorption capacity. Therefore, this study focused on the impact of the EPS synthesised by the soil bacterium Rhizobium leguminosarum bv. trifolii on the adsorptive features of montmorillonite relative to two heavy metal ions (cadmium/Cd(II) and chromium/Cr(VI)) and a pesticide (carboxin). The characterization of montmorillonite was carried out using various methods: X-ray diffraction, X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy. The adsorption/desorption data were modelled using theoretical equations (Langmuir-Freundlich, Redlich-Peterson, etc.). The obtained results showed that EPS promoted the accumulation of heavy metals on the clay mineral and, simultaneously, contributed to a lower degree of their desorption. This resulted from complexation between the biopolymer and the Cd(II)/Cr(VI) ions. After montmorillonite modification with 100 mg/L EPS, the maximum noted growth in Cd(II) adsorption was 26.10%, whereas it was 20.30% for Cr(VI). The adsorbed amounts of Cd(II) and Cr(VI) were then 24.24 and 14.45 mg/g, respectively. In the case of carboxin, the EPS effect on its adsorption/desorption rates was opposite - its adsorption level decreasing by 10.80%, was 0.27 mg/g. Thus, the presence of EPS-producing bacteria could reduce the bioavailability of the heavy metals, but not of the selected pesticide.

Carboxin and Diuron Adsorption Mechanism on Sunflower Husks Biochar and Goethite in the Single/Mixed Pesticide Solutions.

The study focused on the adsorption mechanism of two selected pesticides: carboxin and diuron, on goethite and biochar, which were treated as potential compounds of mixed adsorbent. The authors also prepared a simple mixture of goethite and biochar and performed adsorption measurements on this material. The adsorbents were characterized by several methods, inter alia, nitrogen adsorption/desorption, Boehm titration, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The adsorption study included kinetics and equilibrium measurements, in the solution containing one or two pesticides simultaneously. The adsorption data were fitted to selected theoretical models (e.g., Langmuir, Freudlich, Redlich-Peterson, pseudo first-order and pseudo second-order equations). Based on the obtained results, it was stated that, among all tested adsorbents, biochar had the highest adsorption capacity relative to both carboxin and diuron. It equaled 0.64 and 0.52 mg/g, respectively. Experimental data were best fitted to the pseudo second-order and Redlich-Peterson models. In the mixed systems, the adsorption levels observed on biochar, goethite and their mixture were higher for diuron and lower for carboxin, compared to those noted in the single solutions. The presented results may enable the development of new mixed adsorbent for remediation of soils polluted with pesticides.