High Partition Coefficient Research Articles

Dry chemistry utilizing artificial luciferin for human serum albumin quantification

Dry chemistry is a popular analytical technique that allows measurements simply by dropping a sample solution, which is achieved by immobilizing analytical reagents in dry form on a strip in advance. This paper reports the first bioluminescent dry chemistry strip realized using a luciferin analog that selectively reacts with human serum albumin (HSA). The dry chemistry strip was developed by immobilizing Hulumino1, which is an artificial luciferin designed to provide HSA pseudo-luciferase activity. Dried Hulumino1 was immobilized on the strip using an organic solvent-based process, and the immobilized strip could be stored for one month. This was possible, unlike traditional bioluminescence assays, because luciferase was not included as an analytical reagent, and Hulumino1 was in a dried film state that could suppress oxidation in the air. Stable luminescence was observed from the strip for 20 minutes with a relative standard deviation of 1.1 % because the dissolution rate of Hulumino1 could be controlled due to its high partition coefficient, LogP. The stable luminescence allowed accurate measurement of luminescence intensity according to HSA concentration. The strip did not react with blood proteins other than HSA, making it possible to quantify the concentration of HSA in human serum.

Exploration of the adsorption and desorption performance of volatile organic compounds by activated carbon with different shapes based on fixed-bed experiments

Activated carbon (AC) has been widely used in volatile organic compounds (VOCs) treatment of industrial exhaust gases. Rather than modifying specific pore size distributions and surface properties, altering the shape of AC offers a more feasible approach to enhance its adsorption performance. This study investigates the adsorption-desorption performance of two different shaped ACs with highly similar properties for the removal of VOCs. The clover-shaped AC (CSAC) has a 27.46% lower internal void fraction and a 39.10% higher external void fraction compared to cylindrical AC (CAC), resulting in denser packing and longer contact time with VOCs. Adsorption experiments showed the CSAC has 40% longer adsorption breakthrough (BT) times for ethanol, ethyl acetate, and n-hexane on average, and 20% higher saturation adsorption capacity per unit volume. CSAC also has higher partition coefficients, with the highest values for ethanol, ethyl acetate, and n-hexane being 0.0187, 0.0382, and 0.0527 mol kg−1·Pa−1, respectively. The desorption process for selected VOCs is non-spontaneous and endothermic. Optimal desorption conditions were identified as an inlet space velocity of 3535 h−1, a desorption temperature of 150 °C, and a pulsed inlet method. To investigate the possibility of the application of CSAC in real-world scenarios, xylene was chosen as a representative industrial VOC. Results showed CSAC has 20% higher BT time and saturation adsorption capacity for xylene compared to CAC under different bed heights. The desorption efficiency for xylene on both ACs is below 40%. With increasing xylene inlet concentration, the mass transfer zone (MTZ) height initially increases but stabilizes beyond 1704 mg m−3. At identical bed heights, the MTZ height of CSAC is 29% shorter than CAC, indicating a higher bed utilization efficiency.

Novel Green Aqueous Two-Phase Systems (ATPSs) based on choline salts and application to the removal of pharmaceutical pollutants from water

Aqueous Two-Phase Systems (ATPSs) constitute extractive media with applicability for the removal of a wide range of solutes, such as antioxidants or pharmaceuticals, and can be designed in a non-toxic and environmentally friendly manner. Nevertheless, prior to their general use at large scale, their liquid-liquid equilibria (solubility curves and tie-line compositions) need to be thoroughly determined.In this work, 6 solubility curves were obtained for novel aqueous ternary systems containing choline salts (choline chloride, choline bicarbonate, choline (2R,3R)-bitartrate and choline di-hydrogen citrate) and either ethyl lactate (EL) or polyethylene glycol (PEG), at 298.15 K and 0.1 MPa. Moreover, 3 tie-line compositions were successfully determined for the system {ethyl lactate (1) + choline (2R,3R)-bitartrate (2) + water (3)}. Then, this novel ATPS was applied in the removal of three common pharmaceutical pollutants from aqueous media (acetaminophen, amoxicillin and salicylic acid). In these partition studies, salicylic acid and acetaminophen were effectively extracted to the top phase, with the highest partition coefficients (K=9±2) being obtained for salicylic acid in the longest tie-line (length of 0.8816). Acetaminophen achieved the most promising results (K=2.2±0.1) in the shortest tie-line (length of 0.6192).

Photochemical transformation of liquid crystal monomers in simulated environmental media: Kinetics, mechanism, toxicity variation and QSAR modeling

Liquid crystal monomers (LCMs) are a new class of emerging pollutants with high octanol-water partition coefficients; however, their transformation behavior and associated risk to environments with high organic matter content has rarely been reported. In this study, we investigated the photodegradation kinetics, mechanism, and toxicity variation of 23 LCMs on leaf wax models (e.g., organic solvents methanol and n-hexane). The order of the photolysis rates of these LCMs were biphenylethyne LCMs > phenylbenzoate LCMs > diphenyl/terphenyl LCMs under simulated sunlight, while the phenylcyclohexane LCMs were resistant to photodegradation. The phenylbenzoate and biphenylethyne LCMs mainly undergo direct photolysis, while the diphenyl/terphenyl LCMs mainly undergo self-sensitized photolysis. The main photolysis pathways are the cleavage of ester bonds for phenylbenzoate LCMs, the addition, oxidation and cleavage of alkynyl groups for biphenylethyne LCMs, and the cleavage/oxidation of chains attached to phenyls and the benzene ring opening for diphenyl/terphenyls LCMs. Most photolysis products remained toxic to aquatic organisms to some degree. Additionally, two quantitative structure-activity relationship models for predicting kobs of LCMs in methanol and n-hexane were developed, and employed to predict kobs of 93 LCMs to fill the kobs data gap in systems mimicking leaf surfaces. These results can be helpful for evaluating the fate and risk of LCMs in environments with high content of organic phase.

Mixed-crystalline-phase molybdenum disulfide-based adsorbents with high selectivity for Pb(II) capture: Crystal surface growth modulation and selectivity mechanisms

It was a challenge to prepare an adsorbent with excellent selectivity for target heavy metals, especially when treating real wastewater contaminated with various heavy metals. In the present study, MoS2 with a specific binding capacity for Pb, was selected as the substrate material. And alkaline earth metal doped SM(Sr-MoS2) adsorbent was synthesized via a simple one-step hydrothermal method. The morphology and structure of SM were characterized and the results confirmed that Sr was successfully anchored to MoS2. In addition, it indicated that Sr played a role in expanding the MoS2 spacing, increasing the ratio of 1 T phrases, and modifying the crystal growth (such as the growth direction and growth rate). Therefore, it suggested that SM had a high selectivity factor (171.26) and partition coefficient Kd (31.34 L g-1). More importantly, SM maintained good adsorption performance (∼90 % removal) after six adsorption–desorption cycles, using NaOH or Na2-EDTA as desorbent. Therefore, this work provided a new idea for the preparation of selective adsorbents based on MoS2, which was expected to be used for the remediation of Pb2+-contaminated wastewater.

Topically applied GHK as an anti-wrinkle peptide: Advantages, problems and prospective

Introduction: Peptides are promising and attractive anti-wrinkle active ingredients, amongst which glycyl-histidyl-lysine peptide (GHK) is one of the most broadly promoted peptide for topical application. This simple sequence of amino acid residues not only has the capability of tissue regeneration and the enhancement of collagen and glycosaminoglycans synthesis but also is able to increase nerve outgrowth and angiogenesis. Consequently, GHK has several properties, from wound healing to prevention/reduction wrinkles. GHK-Cu and Pal-GHK are metal complex and palmitoylated derivatives of GHK, respectively. Although GHK-Cu and Pal-GHK are widely used in anti-wrinkle products available on the cosmetic market, the published information on their skin permeability, effectiveness, physicochemical properties and so on is insufficient. Methods: This review aims to highlight whether GHK is sufficiently effective on wrinkle prevention/reduction. Apart from the effectiveness, another question that is tried to be answered is whether skin permeability of GHK allows it to act as an anti-wrinkle peptide at its site of action? Skin permeation enhancement methods employed so far are also reviewed. Results: Based on cellular studies, undoubtedly, GHK can be considered as an anti-wrinkle ingredient. Although GHK-Cu and Pal-GHK have been of interest as effective peptides to be incorporated in the anti-wrinkle products, there is a surprising absence of clinical studies using them. Metal complexation and chemical modification with a hydrophobic moiety increase permeability of this peptide. Besides, cell penetrating peptides seem promising to increase skin permeation of GHK and its derivatives. Skin pretreatment with microneedles also has the potential to be further studied for permeation enhancement of such peptides. As peptide ingredients, their formulation may encounter some challenges, mainly due to their hydrophilic (high aqueous solubility and low partition coefficient) and unstable nature. Conclusion: Although GHK-Cu and Pal-GHK are effective and relatively skin permeable, their permeability could be successfully increased using permeation enhancement methodologies.

Estimating Recovery in the Evaporation Chemical Space

Evaporation is a commonly used extract preparation technique in chemical characterization testing which can greatly impact the observed extractables. Although ideally only solvent is removed and the analytes remain, in practice the analytes evaporate as well, and these losses must be considered when addressing the appropriateness of evaporation as an extract preparation method. This issue is exacerbated when using evaporation before non-targeted analysis (NTA), where the identities of the analytes are not known prior to analysis. Herein, a means of evaluating the extent of evaporative loss in NTA is presented. To achieve this, a model for evaporative loss was adopted and verified experimentally, then applied to a relevant chemical space to determine the impact of experimental parameter selection. The model was used to predict recovery for a range of chemicals under a variety of experimental conditions (volume change, solvent, and temperature). The test solvents were selected to include a range of relevant properties, including molecular weight, density, and vapor pressure. The root-mean-square error of 70 evaporation recovery conditions was 12%. Excess losses, beyond the scope of this model, were found when samples were evaporated to dryness. Also, high recovery was demonstrated for select chemicals (with high air-solvent partition coefficients) at low concentration and with large volume changes. Overall, good agreement was found between the evaporation recovery model and experimental measurements, suggesting that the model can be used to predict the effect on a NTA.

Ivermectin-Loaded Mesoporous Silica and Polymeric Nanocapsules: Impact on Drug Loading, In Vitro Solubility Enhancement, and Release Performance.

Ivermectin (IVM), a widely used drug for parasitic infections, faces formulation and application challenges due to its poor water solubility and limited bioavailability. Pondering the impact of IVM's high partition coefficient value (log P) on its drug release performance, it is relevant to explore whether IVM nanoencapsulation in organic or inorganic nanoparticles would afford comparable enhanced aqueous solubility. To date, the use of inorganic nanoparticles remains an unexplored approach for delivering IVM. Therefore, here we loaded IVM in mesoporous silica particles (IVM-MCM), as inorganic nanomaterial, and in well-known poly(ε-caprolactone) nanocapsules (IVM-NC). IVM-MCM had a well-organized hexagonal mesoporous structure, reduced surface area, and high drug loading of 10% w/w. IVM-NC had a nanometric mean size (196 nm), high encapsulation efficiency (100%), physicochemical stability as an aqueous dispersion, and drug loading of 0.1% w/w. Despite differing characteristics, both nanoencapsulated forms enhance IVM's aqueous intrinsic solubility compared to a crystalline IVM: after 72 h, IVM-MCM and IVM-NC achieve 72% and 78% releases through a dialysis bag, whereas crystalline IVM dispersion achieves only 40% drug diffusion. These results show distinct controlled release profiles, where IVM-NC provides a deeper sustained controlled release over the whole experiment compared to the inorganic nanomaterial (IVM-MCM). Discussing differences, including drug loading and release kinetics, is crucial for optimizing IVM's therapeutic performance. The study design, combined with administration route plans and safety considerations for humans and animals, may expedite the rational optimization of IVM nanoformulations for swift clinical translation.

Effects of uptake pathways on the accumulation, translocation, and metabolism of OPEs in rice: An emphasis on foliar uptake

The often-overlooked importance of foliar absorption on the plant uptake of organic pollutants was investigated by an exposure chamber test. Rice seedlings were exposed to organophosphate esters (OPEs) through 8 scenarios arranged from 3 major uptake pathways: root uptake via solution, foliar uptake via gas, and foliar uptake via particles, to identify the contributions of these 3 uptake pathways and their influences on the translocation and metabolism of OPEs in rice. The concentration of OPEs in rice tissues showed an “additive effect” with the increase of exposure pathways. OPEs in rice shoots mainly originated from foliar uptake through particle (29.6 %–63.5 %) and gaseous (28.5 %–49.4 %) absorptions rather than root uptake (7.86 %–24.2 %) under the exposure condition. In comparison with stomal absorption, wax layer penetration was the main pathway for most OPEs to enter into leaves, especially for those compounds with high octanol-air partition coefficients. Although the subcellular distributions of OPEs in the rice tissues of the foliar exposure were slightly different from those of the root exposure, hydrophobic OPEs were mainly stored in the cell wall with hydrophilic OPEs mainly in the cytosol. The translocation of OPEs from the exposed tissue to the unexposed tissue were significantly negatively correlated with their octanol-water partition coefficients, but their basipetal translocation were limited. The result suggested that the translocation of OPEs within rice is prioritized over their degradation. This study deepens our understanding of the processes behind OPE uptake by rice and highlights the importance of foliar uptake, especially for those via particle absorption.

Dust phase and window film phase phthalates in dormitories: profile characteristics, source screening, and estimated gas-phase concentration and dermal exposure comparison.

Recently, phthalate exposure has become a major public health concern. However, gaps still remain in our understanding of phthalate profile characteristics, source screening, and gas-phase estimation. This study measured phthalate concentrations in dust and window films in 101 dormitories at 13 universities in Beijing, China, from October to December 2019. Based on the phthalate concentrations in the dust and window films, we estimated the gas-phase phthalate concentrations using steady-state and instantaneous equilibrium models, respectively, and male and female students' dermal exposure using the Monte Carlo simulation. Commonly used materials and supplies were screened for phthalate sources and evaluated using the positive matrix factorization (PMF) model. The results showed that the detection frequency of ten phthalates ranged from 79.2 to 100% in dust and from 84.2 to 100% in window films. Dicyclohexyl phthalate (DCHP), di-(2-ethylhexyl) phthalate (DEHP), and dibutyl phthalate (DBP) were the most abundant phthalates in both indoor media and were also predominant in the indoor materials and supplies. The PMF results indicated that the potential sources of phthalates in dust and window films had both similarities and differences. Indoor door seals, paint, coatings, cables, air-conditioning rubber cable ties, wallpaper, and window seals were highly probable sources of phthalates. The gas-phase phthalate concentrations estimated using the two methods differed, especially for phthalates with high octanol-air partition coefficients (Koa), varying by 1-2 orders of magnitude. Moreover, compared with related studies, the gas-phase concentrations were significantly underestimated for phthalates with high Koa values, while the estimated gas-phase concentrations of phthalates with low Koa values were closer to the measured values. The estimated dermal exposure using the two methodologies also considerably differed. Such findings suggest that more attention should be focused on the exposure risk from the dust phase and window film phase phthalates.

Sustainable production and preparative purification of thermostable alkaline α-amylase by Bacillus simplex (ON754233) employing natural deep eutectic solvent-based extractive fermentation

Using PEG-based deep eutectic solvents (PDES), the current study proposes extractive fermentation as a sustainable process integration for the production and purification of α-amylase from Bacillus simplex (ON754233). Glucose: PEG 400 outperformed five PDES in terms of tie lie length (58) and slope value (1.23) against sodium sulphatt. Apple cider pomace was used as a low-cost, sustainable carbon source to produce-amylase, with a maximum enzyme production of 2200.13 U/mL. PDES concentration (20% w/v), salt (12.75 w/v), and apple waste (2.75 g/mL) were all optimized using response surface methodology. When scaled upto 3 L benchtop bioreactor, extractive fermentation was proved to be better technology with maximum recovery of 92.4% with highest partition coefficient (3.59). The partially purified enzyme was further purified using a Sephadex G 100 followed by DEAE-Sephadex anion exchange chromatography with a purity fold of 33. The enzyme was found to be thermostable at the temperature (60 °C), remains alkaline (pH 8), and the activity was stimulated in the presence of Mg2+ ions. With SDS PAGE electrophoresis, the molecular weight was found to be around 140 kDa. Finally, the enzyme kinetics parameters were evaluated with observed Km (0.00396 mM) and Vmax (37.87 U/mL). Thus scaling up extractive fermentation entails increasing production capacity with improved extraction efficiency using green solvents.

Nanodisk–like activated carbon-branched polyamine for adsorption and degradation of gaseous formaldehyde

The adsorption potential of activated carbon (AC) is determined to a large extent by an interplay between its surface functional groups and target pollutants like volatile organic compounds (VOCs). Herein, we present a new approach to improve such property through the creation of nanodisk-like material by modifying the surface and morphology of AC with branched polyamine (BPA). The formulated AC-BPA possesses large number of surface functional moieties (e.g., amine, –COOH, –OH, and Cl−) to facilitate physical, chemical, and reactive adsorption to tackle a common air pollutant such as formaldehyde (FA). Despite its reduction in surface area (relative to AC), AC-BPA was demonstrated to have a significantly large potential for reactive adsorption and catalytic oxidation (RACO) against FA with high adsorption capacity (82.3 mg g−1) and partition coefficient (PC = of 0.64 mol kg−1 Pa−1) under dry condition. Interestingly, a noticeable enhancement in its performance is attained by the presence of moisture (e.g., 100 % RH) as evidenced by adsorption capacity of 144.3 mg g−1 (PC of 1.25 mol kg−1 Pa−1). This can be attributed to its rich heteroatom content (e.g., COO− and Cl−), possibly inducing partial ionization of water molecules and generating secondary active sites for FA adsorption. In-situ diffuse reflectance infrared Fourier-transform spectroscopy revealed that AC-BPA catalyzed the chemical transformation of FA into methylol adducts, H2O, and CO2. These findings indicate that FA adsorption is primarily influenced by surface functional groups rather than by surface area. This study is expected to pave the way for designing metal-free high-performance RACO materials against FA under ambient conditions.

A novel chitosan-glutamic acid membrane for multi-pollutant amputation: Investigational and RSM optimizations

The novel glutamic acid crosslinked chitosan membrane (CsG) was fabricated and tested for its adsorption capabilities for the removal of multiple pollutants like Cr (VI), cyanide, fluoride and diclofenac sodium from wastewater. This fabricated CsG membrane was characterized by various techniques like FT-IR, SEM, EDX and XRD, BET to assess its structural, compositional and morphological properties. The working parameters studied by batch experiments were solution pH, CsG dose, contact time, pollutant concentration and solution temperature. The CsG membrane exhibited maximum adsorption capacity of 410.7 mg/g, 310.2 mg/g, 14.3 mg/g, 132.7 mg/g for Cr (VI), cyanide, fluoride and diclofenac respectively. The validation of the operational parameters was performed by Response Surface Methodology (RSM). The experimental data fitted well with Langmuir isotherm model and followed pseudo second order kinetics for all the four targeted contaminants. The spontaneity of the process was checked by thermodynamics studies. The high partition coefficients of 7669 L/kg Cr(VI), 23,309 L/kg (CN−), 649 L/kg (F−) and 2613 L/kg (DFC) are the indicators of excellent attractive interaction between CsG membrane and target toxicants. The CsG membrane showed efficient regenerative adsorption properties up to 5 adsorption-desorption cycles. Overall, the developed novel CsG membrane promised as an effective material for the removal of multiple number of pollutants from water.

Process design, kinetics, and techno-economic assessment of an integrated liquid phase furfural hydrogenation process

The integrated liquid phase process for producing furfuryl alcohol involves three stages: i) liquid–liquid extraction for recovering furfural from the aqueous solution obtained after a conventional steam-stripping hydrolysis reactor, ii) the hydrogenation reaction, and iii) the final purification. The reaction kinetics employed in the modelling are obtained experimentally. 2-methyltetrahydrofuran is the selected green solvent, and it has a high partition coefficient and stability under hydrogenating conditions. A commercial CuZnAl catalyst is used for the first time in the liquid phase furfural hydrogenation reaction, recording very high furfuryl alcohol selectivity even at complete conversion. A dual-site Langmuir-Hinshelwood model is developed and validated. An original aspect of this model is the kinetic effect of the low water content (0–5 wt%) remaining in the solvent after extraction. Water reduces the reaction rate by competing for active sites with furfural and furfuryl alcohol, without promoting other side-reactions. The optimization of the process leads to very high yields of furfuryl alcohol (97%) and a net production of 2-methyltetrahydrofuran even after recirculation and solvent losses. The process shows preliminary economic viability, with a minimum selling price for furfuryl alcohol of around 1,300 $/t; a competitive value only 30% higher than the furfural price considered in the analysis. Moreover, in contrast to current industrial processes that use copper chromite catalysts, the one developed here has environmental benefits, as it avoids the prior need for energy-intensive furfural-water distillation, eliminates toxic catalyst waste, and co-generates a green solvent.

Carbon nanotube enhanced selective micro filtration of butanol

In this study, we present the development of a carbon nanotube (CNT), immobilized membrane (CNIM) via a phase inversion process for dewatering butanol via microfiltration. The CNTs enhanced membrane hydrophobicity and butanol permeation via adsorption on the CNTs surface leading to relatively high levels of preconcentration, which was not possible using a plain PTFE membrane. The CNIM exhibited a water contact angle of 136 ± 2°, indicating high hydrophobicity. The contact angle decreased with an increase in butanol concentration due to the strong interaction of the CNTs with the latter. The water-butanol mixtures behaved differently at different concentration zones namely water in butanol, WIB (over 80 percent butanol), butanol in water, BIW (below 30 percent butanol), and butanol-water colloidal mixtures, BWCM (30 to 70 percent butanol). At low or high concentrations of butanol, the butanol was strongly hydrogen bonded with the water, and the separation efficiency was relatively lower, between 6.50 and 15.54 % in the WIB and 1.00 to 3.05 % in the BIW regions. In the BWCM regions, water butanol formed colloidal mixtures the separation efficiency was significantly higher. At a feed butanol concentration of 40 %, the water separation reached as high as 43.40 %, with a flux of 118.08 kg/(m2h). The high separation efficiency was attributed to the influence of well-dispersed CNTs on the CNIM which provided sites for the agglomeration of nano water droplets into larger ones that could be removed more easily, as well as the high partition coefficient of the butanol on the CNIM surface.

Recovery of superbase ionic liquid using aqueous two-phase systems

Aqueous two-phase systems (ATPS) have been widely used for the purification and separation of biomolecules. However, recent studies have shown that ATPS can also be effective in the purification and recovery of other compounds, such as ionic liquids (IL). Here, we investigated the liquid-liquid phase equilibria of ATPS consisting of 5-methyl-1,5,7-triaza-bicyclo[4.3.0]non-6-enium acetate ([mTBNH][OAc]) and potassium salts (K2CO3 and K3PO4) at 293.2 K and 323.2 K. Our results indicate that both systems exhibited a high IL partition coefficient (k), exceeding 9.5, and achieved a 99.5% recovery of ionic liquid. Moreover, we found that the presence of potassium salt in the ionic liquid-rich phase had a negative impact on the IL cellulose dissolution capability. Therefore, we investigated the removal of potassium salt from the IL and successfully achieved it by using a nanoporous sodium zirconium cyclosilicate (ZS-9 or AV-13). Overall, our study suggests that ATPS can be a promising technique for the purification and recovery of ionic liquids, with potential applications in various industries.

The relative dominance of surface oxygen content over pore properties in controlling adsorption and retrograde behavior of gaseous toluene over microporous carbon

The adsorption potential of activated carbon (AC) derived from macadamia nut shells (product code of Procarb-900: namely, AC-P) has been investigated using gaseous toluene as the target pollutant. The powder AC-P with high-microporosity (96%) and oxygen content (5.62%) exhibited very high adsorption capacity (214 mg·g−1) and partition coefficient (PC: 25 mol·kg−1·Pa−1) against 100 ppm (10 Pa) toluene at 99% breakthrough levels (1 atm dry N2). The factors governing toluene adsorption were explored with respect to the key variables such as surface functional groups, pore size distribution, sorbent bed mass (50, 100, and 150 mg), and particle size (i.e., 0.212–0.6 mm (powder AC: PAC)) vs. 0.6–2.36 mm (granular AC: GAC)). Accordingly, the adsorption process was physical, mainly due to the non-polar interactions (i.e., π-π interactions) between the adsorbent and adsorbate molecules. The high affinity of AC-P at low breakthrough levels was obtained through a combination of smaller particle size (PAC) and larger adsorbent mass (i.e., 150 mg) with the appearance of a very pronounced retrograde phenomenon (e.g., at < 1% breakthrough level). As such, toluene adsorption appeared to be affected more sensitively by particle size and adsorbent mass (especially at low breakthrough levels) than by high microporosity. Most importantly, the oxygen content of AC emerges as one of the key factors governing the maximum capacity, as the changes in pore volume are not crucial to explain the observed adsorption patterns of toluene.

Physical-chemical properties of fungicides applied for protection of cereals against diseases in Belarus

Physical and chemical properties of fungicides applied for protection of cereals against diseases in Belarus and their mobility in plant tissues are analyzed. The main properties allowing to predict plant mobility of fungicides are water solubility, lipophilicity (partition coefficient – LogP), and dissociation constant (pKa). The higher partition coefficient in nonpolar molecules, the higher are their nonsystemic (contact) properties, and vice versa. For polar molecules, the lower dissociation constant, the higher their mobility in plants. Information of fungicides plant mobility allows to understand their action on pathological process. In nonsystemic (contact) molecules with high LogP have affinity to wax layer of cuticle. Therefore they have good protection (prevention) properties because of their ability to prevent spores germination. Molecules with acropetal properties have good curative action because of their mobility in xylem away from application site. Therefore they may prevent mycelium development after its penetration in plant tissues.

ENVIRONMENTAL GEOCHEMICAL INVESTIGATION OF THE GEOGENIC POLLUTION POTENTIAL OF BIDA FORMATION, NORTHERN BIDA BASIN NIGERIA

The environmental geochemistry of sandstones of Bida formation around Doko, northern Bida Basin Nigeria was studied to assess the potential for the release of toxic elements into the environment. Eight representative samples were collected and analysed to determine the total elemental concentration using X-ray fluorescence spectrometry (XRF). Four sub-samples were analysed for their near-total concentration of selected metals using atomic absorption spectrometry (AAS). The results show that many of the elements are depleted with mean enrichment ratios of less than 1. Ce, W, Nb and Pb are the exceptions with ER values of 116.4, 122.9, 25.26 and 2.22 respectively. A similar pattern was found with Igeo, where W, Ce and Nb fall within strongly to extremely polluted and extremely polluted classes. High to very high partition coefficients (KDi) for four selected PTEs show that metals are strongly held within the sandstone matrix rather than dissolving. Because the elements are not soluble, they will not be readily available for uptake by plant roots, or will not be directly toxic to soil biota. The undissolved metal pool also reflects the sandstone metal fraction that is unsusceptible to leaching and could therefore not contaminate water. We conclude that there is no significant geogenic pollution risk associated with PTE release and uptake from the formation. It is however recommended that further research should be carried out to investigate the phases hosting Ce, W, Nb and Zr in the sandstone in Doko and its environs.

Pollution characteristics and source apportionment of heavy metal(loid)s in soil and groundwater of a retired industrial park

Heavy metal(loid)s (HMs) pollution has become a common and complex problem in industrial parks due to rapid industrialization and urbanization. Here, soil and groundwater were sampled from a retired industrial park to investigate the pollution characteristics of HMs. Results show that Ni, Pb, Cr, Zn, Cd, and Cu were the typical HMs in the soil. Source analysis with the positive matrix factorization model indicates that HMs in the topsoil stemmed from industrial activities, traffic emission, and natural source, and the groundwater HMs originated from industrial activities, groundwater-soil interaction, groundwater-rock interaction, and atmosphere deposition. The sequential extraction of soil HMs reveals that As and Hg were mainly distributed in the residue fraction, while Ni, Pb, Cr, Zn, Cd, and Cu mainly existed in the mobile fraction. Most HMs either in the total concentration or in the bioavailable fraction preferred to retain in soil as indicated by their high soil-water partitioning coefficients (Kd), and the Kd values were correlated with soil pH, groundwater redox potential, and dissolved oxygen. The relative stable soil-groundwater circumstance and the low active fraction contents limited the vertical migration of soil HMs and their release to groundwater. These findings increase our knowledge about HMs pollution characteristics of traditional industrial parks and provide a protocol for HMs pollution scrutinizing in large zones.