UPLC-based assay to assess the hydrophobicity of Antibody-Drug Conjugate (ADC) payloads.

Antibody-Drug Conjugates (ADCs) consist of antibodies attached to cytotoxic small molecules or biological agents (i.e., payloads) through chemical linkers which may be cleavable or non-cleavable. The development of new ADCs is challenging, particularly the process of attaching the linker-payload construct to the antibody (i.e., the conjugation process). One of the major problems associated with conjugation is high hydrophobicity of the payload which can lead to low yields of the ADC through aggregation and/or lower than desired Drug-Antibody Ratios (DARs). We report here a UPLC-based assay that can be used to study the physicochemical properties of ADC payloads at an early stage of development, and to provide information on whether the hydrophilic-hydrophobic balance is suitable for conjugation or further physicochemical optimization is required. The assay is relatively simple to establish and should be of use to those working in the ADC area.

Ferrate(VI) oxidation of pentachlorophenol in water and soil.

Although the use of ferrate (VI), an emerging green oxidant, has been widely investigated to remove organic pollutants in water, its ability to remediate contaminated soils has been scarcely evaluated. Here, we explore the use of ferrate (VI) to degrade a polychlorinated persistent compound, the pentachlorophenol (PCP), in aqueous solution and in an aged contaminated soil under batch, water-saturated and water-unsaturated flow conditions. The first results showed the prominent efficiency of ferrate (VI) over conventional oxidants (e.g. H2O2 and persulfate) in both matrices and at different oxidant doses. In aqueous solution, more than 80% of PCP was degraded by ferrate (VI) while complete removal was observed in soil under batch conditions. In column experiments, PCP removal by ferrate (VI) remained efficient but dependent on the flow rate and water saturation. Maximum PCP removal (95%) in columns was observed under water saturated conditions when ferrate (VI) (0.2 g g-1 of soil) was injected at a low flow rate (i.e. 0.025 mL min-1). This study has strong implications in the development of new sustainable processes based on ferrate (VI) for the remediation of different environmental compartments.

Effect of O2, Ni0 coatings, and iron oxide phases on pentachlorophenol dechlorination by zero-valent iron.

This study explores the zero-valent iron (ZVI) dechlorination of pentachlorophenol (PCP) and its dependence on the dissolved oxygen (O2), presence/formation of iron oxides, and presence of nickel metal on the ZVI surface. Compared to the anoxic system, PCP dechlorination was slower in the presence of O2, which is a potential competitive electron acceptor. Despite O2 presence, Ni0 deposited on the ZVI surfaces catalyzed the hydrogenation reactions and enhanced the PCP dechlorination by Ni-coated ZVI bimetal (Nic/Fe). The presence of O2 led to the formation of passivating oxides (maghemite, hematite, lepidocrocite, ferrihydrite) on the ZVI and Nic/Fe bimetallic surfaces. These passive oxides resulted in greater PCP incorporation (sorption, co-precipitation, and/or physical entrapment with the oxides) and decreased PCP dechlorination in the oxic systems compared to the anoxic systems. As received ZVI comprised of a wustite film, and in the presence of O2, only ≈ 17% PCP dechlorination observed after 25 days of exposure with tetrachlorophenol being detected as the end product. Wustite remained as the predominant oxide on as received ZVI during the 25 days of reaction with PCP under oxic and anoxic conditions. ZVI acid-pretreatment resulted in the replacement of wustite with magnetite and enhanced PCP degradation (e.g. ≈ 52% of the initial PCP dechlorinated after 25 days under oxic condition) with accumulation of mixtures of tetra-, tri-, and dichlorophenols. When the acid-washed ZVI was rinsed in NiSO4/H2SO4 solution, Ni0 deposited on the ZVI surface and all the wustite were replaced with magnetite. After 25 days of exposure to the Nic/Fe, ≈ 78% and 97% PCP dechlorination occurred under oxic and anoxic conditions, respectively, producing predominantly phenol. Wustite and magnetite are respectively electrically insulating and conducting oxides and influenced the dechlorination and H2 production. In conclusion, this study clearly demonstrates that the dissolved oxygen present in the aqueous solution decreases the PCP dechlorination and increases the PCP incorporation when using ZVI and Nic/Fe bimetallic systems. The findings provide novel insights towards deciphering and optimizing the performance of complex ZVI and bimetallic systems for PCP dechlorination in the presence of O2.

Redox properties and dechlorination capacities of landfill-derived humic-like acids.

Electron transfer capacities (ETC) of humic-like acids (HLA) and their effects on dechlorination are dependent on their redox-active properties. Aging and minerals can affect the chemical compositions and structures of HLA. However, the underlying mechanism and the impacts on the dechlorination capacities of HLA are poorly understood. We investigated how redox properties change in association with the intrinsic chemical natures and exterior minerals of the HLA extracted from landfilled solid wastes. Furthermore, the ETC of the landfill-derived HLA could be strengthened by increasing landfill age and demineralization, thereby facilitating the dechlorination of pentachlorophenol (PCP). The HLA molecules started to polymerize aromatic macromolecules during landfilling, leading to an increase in ETC and dechlorination capacities. Macromolecular HLA were dissociated to smaller molecules and exposed more aromatic and carboxyl groups when separated from minerals, which enhanced the ETC and the dechlorination abilities of the HLA. Microbial-mediated dechlorination was an effective way to degrade PCP, and almost 80% of the PCP was transformed after 40 days of demineralized HLA and Shewanella oneidensis MR-1 incubation. The demineralization and aging further facilitated the microbial-mediated PCP dechlorination. The findings provide a scientific base for improving in-situ bioremediation of chlorinated compound-contaminated soils using freshly synthesized HLA.

Ascorbic acid induced activation of persulfate for pentachlorophenol degradation.

In the present study, ascorbic acid (AA) induced persulfate activation was investigated for the further exploration of organic pollutants oxidation by persulfate. We interestingly found that AA showed a significant catalytic activity to persulfate. Under neutral pH and room temperature condition, about 71.3% of pentachlorophenol (PCP, 10 mg L-1) was decomposed in 180 min with 40 mmol L-1 persulfate and 1.0 mmol L-1 AA, while only 15.4% and 3.2% of PCP was removed by alone persulfate and AA respectively. The result of EPR spectra identified sulfate radical (SO4•-) and hydroxyl radical (OH) were generated during the reaction between persulfate and AA. Quenching experiments confirmed that both SO4- and OH contributed to the decomposition of PCP. With the addition of AA augmented from 0 to 1 mmol L-1, the PCP degradation ratio continuously increased. However, excess AA could consume the generated reactive oxygen species (ROSs) that led to the inhibition of PCP degradation. Meanwhile, the PCP degradation by persulfate-AA was strongly pH dependent. The PCP degradation rate was declined as the initial pH increased from 3.5 to 10.5. At pH above 12.5, the base activation began to predominate over AA activation of persulfate. Furthermore, it was observed that the AA inducing persulfate activation was related to the extent of AA ionization, while C6H8O6 promoted the highest persulfate activation for the PCP degradation, and C6H6O62- induced the lowest persulfate activation. This study indicates the high potential of AA induced persulfate activation for treatment of organochlorine contaminated water.

Development and characterization of a new dolomite-based catalyst: application to the photocatalytic degradation of pentachlorophenol.

The development of new catalysts from abundant raw materials, generating attractive photocatalytic activity, constitutes a real challenge in the context of sustainable development concerns. In this setting, a dolomite was treated at 800 °C (D800) and then chemically modified by Ca(NO3)2 (CaD800) using a simple procedure. The resulting materials were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy (EDS), solid state UV spectroscopy, and used as catalysts of pentachlorophenol (PCP) degradation in aqueous solutions under UV light irradiation. The treatment of dolomite at 800 °C enabled a full decarbonation of CaMg(CO3)2, with formation of CaO, Ca(OH)2, and MgO. Additional CaO was generated after chemical treatment as revealed by EDS analysis; the Ca/Mg ratio increased from 1.29 (D800) to 1.44 for CaD800. This CaO in aqueous medium hydrates by giving Ca(OH)2. CaD800 was found to be the best photocatalyst with a PCP degradation rate of 95% after only 1 h of treatment, for a CaD800/D800 degradation rate constant ratio of 1.58. In this regard, we investigated the Fourier transform infrared spectra of CaD800, PCP, and CaD800 loaded with PCP after degradation. We thus evidenced the involvement of Ca(OH)2 in the PCP degradation process. Catalytic activity was discussed through the contribution of OH radicals and electrodonation.

Polarity and Molecular Weight of Compost-Derived Humic Acids Impact Bio-dechlorination of Pentachlorophenol.

Compost-derived humic acids (HAs) as cheap soil conditioners have potential to facilitate pentachlorophenol (PCP) bio-dechlorination but lack proof and studies. To clarify this, PCP bio-dechlorination mediated by compost-derived HAs under Fe(III) reduction conditions was investigated. Reverse phase high-performance liquid chromatography and high-performance size exclusion chromatography were employed to identify the functional components within compost-derived HAs. Our results showed that compost-derived HAs facilitated the bio-dechlorination of PCP under Fe(III) reduction conditions, and four kinds of byproducts were detected during the process. The relatively hydrophilic and high molecular weight (MW) components within compost-derived HAs presented significant associations with the concentration of byproducts from bio-dechlorination of PCP in Fe2O3 reduction conditions. In contrast, the hydrophobic and low MW components were the main functional components for PCP bio-dechlorination in Fe3O4 reduction environment. These findings clarified the effects of polarity and MW of compost-derived HAs on PCP bio-dechlorination, giving clues to optimize composting technology to utilize compost products for in situ contamination remediation of paddy soil.

Pentachlorophenol-induced cytotoxicity in human erythrocytes: enhanced generation of ROS and RNS, lowered antioxidant power, inhibition of glucose metabolism, and morphological changes.

Pentachlorophenol (PCP) is a class 2B human carcinogen that is used as an insecticide, herbicide, and wood preservative. PCP is rapidly absorbed and enters the blood where it can interact with erythrocytes. We have examined the effect of PCP on human erythrocytes. Treatment of erythrocytes with PCP increased the intracellular generation of reactive oxygen and nitrogen species. It also increased lipid and protein oxidation accompanied by decrease in glutathione levels and total sulfhydryl content. The activities of all major antioxidant enzymes were altered. The antioxidant power was significantly impaired resulting in lower free radical quenching and metal reducing ability of the PCP-treated cells. PCP exposure also inhibited the activities of enzymes of glycolysis and pentose phosphate shunt, the two pathways of glucose metabolism in erythrocytes. Heme degradation was enhanced leading to the release of free iron. Incubation of erythrocytes with PCP caused significant cell lysis suggesting plasma membrane damage which was also evident from inhibition of bound enzymes. Scanning electron microscopy of erythrocytes confirmed these biochemical results and showed that PCP treatment converted the normal biconcave discoids to echinocytes and other irregularly shaped cells. Thus, PCP induces oxidative and nitrosative stress in erythrocytes, alters the enzymatic and nonenzymatic antioxidant defense systems, inhibits glucose metabolism, and causes significant modifications in cellular morphology.

Humin as an External Electron Mediator for Microbial Pentachlorophenol Dechlorination: Exploration of Redox Active Structures Influenced by Isolation Methods.

Humin (HM) has been reported to function as an external electron mediator (EEM) in various microbial reducing reactions. In this study, the effect of isolation methods on EEM functionality and the chemical/electrochemical structures of HM were examined based on the correlation between dechlorination rates in the anaerobic HM-dependent pentachlorophenol (PCP)-dechlorinating consortium and the chemical/electrochemical structures of HM. A lack of PCP dechlorination activity suggested no EEM function in the HM samples prepared as a soluble fraction in dimethyl sulfoxide and sulfuric acid (which did not contain any electric capacitance). Other HM samples exhibited EEM functionality as shown by the dechlorination activity ranging from 0.55 to 3.48 (µmol Cl-) L-1d-1. The comparison of dechlorination activity with chemical structural characteristics suggested that HM with EEM functionalities had predominantly aliphatic and carbohydrate carbons with the partial structures C=O, O=C⁻N, and O=C⁻O. EEM functionality positively correlated with the proportion of O=C⁻N and O=C⁻O, suggesting an association between peptidoglycan structure and EEM functionality. The lack of detection of a quinone structure in one HM sample with EEM functionality and a negative correlation with aromatic or C=C carbon suggested that the mechanism containing quinone structures is a minor component for the functionality of EEM.

Atypical Gasdermin D and Mixed Lineage Kinase Domain-like Protein Leakage Aggravates Tetrachlorobenzoquinone-Induced Nod-like Receptor Protein 3 Inflammasome Activation.

Our previous study showed that tetrachlorobenzoquinone (TCBQ) mediated the activation of Nod-like receptor protein 3 (NLRP3) inflammasome, which involves K+ efflux, reactive oxygen species (ROS) production, and mitochondrial DNA damage. In addition, TCBQ down-regulates NLRP3 ubiquitination and promotes the activation of NLRP3 inflammasome. However, the induction of NLRP3 inflammasome by atypical pathways has not yet been characterized. Using human umbilical vein endothelial cells (HUVEC), we discovered that TCBQ activates caspase 1/4/5 and cleaves gasdermin D (GSDMD) into N-terminal and C-terminal cleavage products. In parallel, TCBQ also activates receptor interacting protein kinase 3 (RIPK3)/mixed lineage kinase domain-like protein (MLKL) signaling pathways. The N-terminal fragments of GSDMD and MLKL translocate from cytoplasm to cell membrane and form oligomers and membrane pores on the cell membrane. The formation of membrane pores not only promotes the extracellular secretion of interleukin 1 beta (IL-1ß) but also affects cellular ion homeostasis, in particular promotes K+ outflow, which further activates NLRP3 inflammasome and aggravates cellular inflammation. These results indicated that GSDMD and MLKL play important roles in TCBQ-induced endothelial pro-inflammatory responses, which may point to potential therapeutic approaches for TCBQ-mediated toxicity.

Complete dechlorination and mineralization of pentachlorophenol (PCP) in a hydrogen-based membrane biofilm reactor (MBfR).

Complete biodegradation and mineralization of pentachlorophenol (PCP), a priority pollutant in water, is challenging for water treatment. In this study, a hydrogen (H2)-based membrane biofilm reactor (MBfR) was applied to treat PCP, along with nitrate and sulfate, which often coexist in contaminated groundwater. Throughout 120-days of continuous operation, almost 100% of up to 10 mg/L PCP was removed with minimal intermediate accumulation and in parallel with complete denitrification of 20 mg-N/L nitrate. PCP initially was reductively dechlorinated to phenol, which was then mineralized to CO2 through pathways that began with aerobic activation via monooxygenation by Xanthobacter and anaerobic activation via carboxylation by Azospira and Thauera. Sulfur cycling induced by SO42- reduction affected the microbial community: The dominant bacteria became sulfate-reducers Desulfomicrobium, sulfur-oxidizers Sulfuritalea and Flavobacterium. This study provides insights and a promising technology for bioremediation of water contaminated with PCP, nitrate, and sulfate.

Degradation pathways of pentachlorophenol and benzo(a)pyrene during heterogeneous photocatalysis.

Organic micropollutants, in particular those of anthropogenic origin, may have a toxic influence on water organisms. Photochemical oxidation processes are one of the most effective methods of decomposition of a wide range of those compounds. During the oxidation process a large number of different by-products are generated, which can still be biologically active. The development of analytical techniques, including the reduction of the detection limit to several fg/L, allows the identification of even trace concentrations of compounds. The paper presents the determination of pentachlorophenol and benzo(a)pyrene degradation pathways during the process of heterogeneous photocatalysis carried out in the presence of titanium dioxide. The gas chromatography-mass spectrometry (GC-MS) analysis of post-processing samples indicated the formation of different by-products of the parent micropollutants. Moreover, the toxicity assessment demonstrates for both tested micropollutants an increase in the toxicity within the whole time of the UV irradiation process run.

Pentachlorophenol, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans in surface soil surrounding pentachlorophenol-treated utility poles on the Kenai National Wildlife Refuge, Alaska USA.

Composite surface soil samples were collected at 0, 25, and 50 cm from the base of 12 utility poles on the Kenai National Wildlife Refuge in Alaska, to assess the extent to which pentachlorophenol, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzo furans may have leached from pentachlorophenol-treated poles. Six pairs of utility poles were included, consisting of an "old" pole manufactured in 1959 or 1963, a "new" pole manufactured within the past 20 years, and a suitable background soil sample from the same vicinity. Old poles had greater concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (TEQs) near the pole base and at 25 cm than "new" poles did. For all 12 poles combined, the mean pentachlorophenol levels in soil were 1810, 157, and 17.8 ppm dry weight (d.w.) near the pole bases, at 25 and 50 cm from the poles, respectively, while the mean total TEQ levels in soil were 15,200, 5170, and 1510 parts per trillion d.w. at those distances. Surface soil levels of pentachlorophenol and TCDD-TEQs exceeded both human health and ecological risk-based screening levels. The design and results of this study were similar to another project in Montreal, Quebec in Canada. Together the results are cause for concern, indicating that millions of similarly treated utility poles in North America may be point sources of pentachlorophenol and dioxins/furans to soil.

Effects of heavy metal species, concentrations, and speciation on pentachlorophenol sorption by river biofilms.

The sorption of trace organic pollutants at solid/liquid interfaces is one of the most important processes that influence their fate and behaviours in the aquatic environment. Sorption is affected by coexisting contaminants. The process and extent to which coexisting heavy metals affect the sorption of organochlorine pesticides (OCPs), especially acid radical anion heavy metals, are still unclear. Here, the effects of the species, concentrations, and speciation of the heavy metals Cu, Pb, and Cr, and the metalloid As on the sorption of pentachlorophenol (PCP), as a model OCP, by river biofilms were investigated through batch experiments. The results show that the presence of Cu, Pb, Cr, and As decreased the maximum sorption quantity of PCP onto the biofilms by 67.7, 9.2, 58.4, and 14.4%, respectively. The inhibitory effect of heavy metals on sorption decreased as the initial concentration ratios of heavy metals to PCP increased. In addition, the impact of heavy metals on PCP sorption was attributed to differences in heavy metal speciation. Cu and Pb commonly existed as divalent cations, but Cr and As existed as anionic acid radicals under the experimental conditions. The inhibitory effects of heavy metals on PCP sorption by biofilms were enhanced as the cation valence state increased, while the effects were weakened as the anionic acid radical valence state increased. Although all four heavy metals had inhibitory effects on PCP sorption by biofilms, there were distinct differences in the mechanisms causing these effects.

Pentachlorophenol dechlorination with zero valent iron: a Raman and GCMS study of the complex role of surficial iron oxides.

The dechlorination of chlorinated organic pollutants by zero valent iron (ZVI) is an important water treatment process with a complex dependence on many variables. This complexity means that there are reported inconsistencies in terms of dechlorination with ZVI and the effect of ZVI acid treatment, which are significant and are as yet unexplained. This study aims to decipher some of this complexity by combining Raman spectroscopy with gas chromatography-mass spectrometry (GC-MS) to investigate the influence of the mineralogy of the iron oxide phases on the surface of ZVI on the reductive dechlorination of pentachlorophenol (PCP). Two electrolytic iron samples (ZVI-T and ZVI-H) were found to have quite different PCP dechlorination reactivity in batch reactors under anoxic conditions. Raman analysis of the "as-received" ZVI-T indicated the iron was mainly covered with the ferrous oxide (FeO) wustite, which is non-conducting and led to a low rate of PCP dechlorination. In contrast, the dominant oxide on the "as-received" ZVI-H was magnetite which is conducting and, compared to ZVI-T, the ZVI-H rate of PCP dechlorination was four times faster. Treating the ZVI-H sample with 1 N H2SO4 made small change to the composition of the oxide layers and also minute change to the rate of PCP dechlorination. However, treating the ZVI-T sample with H2SO4 led to the loss of wustite so that magnetite became the dominant oxide and the rate of PCP dechlorination increased to that of the ZVI-H material. In conclusion, this study clearly shows that iron oxide mineralogy can be a contributing factor to apparent inconsistencies in the literature related to ZVI performance towards dechlorination and the effect of acid treatment on ZVI reactivity.

Sorption of pentachlorophenol (PCP) in the marine bottom sediments-batch sorption experiment at varying pressure.

Study was undertaken to determine the effect of hydrostatic pressure on the sorption of pentachlorophenol (PCP). The experiment was conducted at atmospheric pressure (1000 hPa) and at increased pressure (6000 hPa) simulating conditions at the water depth of 50 m. The sorption of PCP was examined in an artificial environment (microcosm) consisting of the marine water and the bottom sediments from a Polish harbor and the southern Baltic Sea. The first part of the experiment comprised the determination of PCP sorption parameters in the microcosms and parameters of the sediments (organic matter content, conductivity) and of the overlying water (pH, ion concentration) at 1000 hPa. The second part of the experiment was conducted at 6000 hPa inside the hyperbaric chamber. The hyperbaric exposure affected parameters of the harbor sediments and the overlying water but had little influence on the concentration of PCP in the microcosms containing the southern Baltic Sea sediments. Considering the specific characteristics of the harbor sediments, it can be assumed that the impact of hydrostatic pressure on the sorption process of PCP at 50-m depth appears to be negligible.

Effect of soil pH and organic matter on the adsorption and desorption of pentachlorophenol.

Various properties of soil affect the partition of organic contaminants within, and conversely, the properties of the organic contaminants also directly affect their partition behavior in soil. Therefore, understanding the effects of various properties of soil on the partition of organic contaminants favors subsequent assessment and provides soil remediation methods for policymakers. This study selected pentachlorophenol (PCP), a common hydrophobic ionizable organic compound in contaminated sites worldwide, as the target contaminant. The effects of pH, organic matter, and the combination of both, on PCP adsorption/desorption behavior in soil were investigated. Phosphoric acid and potassium hydroxide were used as buffer solutions to modify the soil pH by the batch and column extraction methods. A common retail organic fertilizer and fulvic acid were selected as additives to manipulate the soil organic content. Modifying the pH of the soil samples revealed that acidic soil exhibited a greater PCP adsorption rate than alkaline soil. The amount of PCP desorption increased regardless of pH of the in situ contaminated soil. The adsorption of PCP increased with increasing amount of organic additive. However, addition of fulvic acid yielded different results compared to the addition of organic fertilizer. Specifically, the organic fertilizer could not compete with the in situ contaminated soil in PCP adsorption, whereas fulvic acids increased the PCP dissolution to facilitate adsorbing contaminant adsorption. The combined effect of pH modification and organic matter addition provides additional PCP adsorption sites; therefore, adding the organic fertilizer to decrease the soil pH elevated the PCP adsorption rates of the laterite, alluvial, and in situ contaminated soil samples. The study results revealed that both pH and organic matter content are crucial to PCP adsorption/desorption in soil. Therefore, the effects of soil pH and organic matter should be considered in facilitating PCP treatment for soil remediation.

Oxidative degradation of pentachlorophenol by permanganate for ISCO application.

Potassium permanganate (KMnO4) has been an effective technology for the in situ chemical oxidation (ISCO) of many organic compounds including chlorinated alkanes and alkenes, but it has rarely been applied for oxidizing aromatic organochlorines. This study confirms the ability of permanganate to oxidize an aromatic chlorinated compound, pentachlorophenol (PCP), in an efficient manner at neutral pH. The rate of the reaction between KMnO4 and PCP was calculated and the results indicated that the reaction between PCP and permanganate is relatively fast with a second-order rate constant k″ ∼ 30 M-1 s-1. Besides the kinetic aspect, the authors identified the main reaction by-products, and proposed a possible reaction mechanism scheme. The general pathway shows the formation of chlorinated intermediates, and ultimately, the complete mineralization to chloride, water, and CO2 confirmed by total organic carbon and chloride measurement in solution. Flow-through column experiments, consisting of flushing a PCP-contaminated sandy or natural soil with oxidant, showed the good ability of permanganate to eliminate the pollutant. After 24 h of treatment, 77% and 56% of PCP abatement were obtained for sandy and natural soil, respectively. These findings show the high potential of permanganate for the in situ remediation of aromatic organochlorine contaminated soils.

Pentachlorophenol molecule design with lower bioconcentration through 3D-QSAR associated with molecule docking.

A three-dimensional quantitative structure activity relationship (3D-QSAR) model is built by using a comparative molecular similarity indices analysis (CoMSIA) technique with an experimentally determined logarithm of bioconcentration factors (logBCFs) for 36 phenols in fish. Meanwhile, with the pentachlorophenol (PCP) molecule as target molecules, contributions of the molecular fields indicate that the electrostatic fields are the main influences on the bioconcentration of the PCP molecule. Based on the analytical results of CoMSIA contour map of PCP and PCP molecular docking with SOD protease (PDB ID: 4A7T), the R6 substituent positions of PCP were modified to give seven new modified PCP molecules with low bioconcentration in this paper. The energy barrier calculation of the new modified PCP molecular reaction pathways can infer the order of the substitution reaction s as -SCl > -CH2Cl > -COCl > -CCl3 > -CH=CH2 > -NO2 > -SH. These calculations, combined with anaerobic biodegradation, ecotoxic effect, and mobility of new modified PCP molecules, enable a new environmentally friendly compound when the Cl at the R6 position of PCP was replaced with -COCl substituent with low bioconcentration (reduced by 32.89%), ecotoxic effect basically unchanged (increased by 1.37%), anaerobic biodegradation increased (increased by 24.81%), and mobility basically unchanged (reduced by 0.94%) to be designed.

Biochar based remediation of water and soil contaminated by phenanthrene and pentachlorophenol.

Phenanthrene (Phe) and pentachlorophenol (PCP) are classified as persistent organic pollutants and represent serious concern for the environment as they are toxic and ubiquitous. Biochar based remediation is an emerging technology used in water and soil contamination. In this study we used poplar (BP) and conifer (BC) biochars to remediate water and soil contaminated by Phe and PCP. BP and BC were able to remove completely either Phe or PCP from contaminated water within one to three days. When biochar was confined in a porous membrane, BC and BP maintained their sorption efficiency for several remediation cycles. However, in these conditions BC allowed faster Phe removal. In soil remediation experiments, addition of two biochar rates, i.e. 2.5 and 5 mg g-1, strongly reduced Phe extractability (up to 2.7% of the initially added Phe with the larger BC dose). This was similar to the behavior observed when compost was applied in order to verify the role of soil organic matter in the fate of both contaminants. PCP extractability was reduced only up to 75% (in average) in all samples including those with compost amendment. Only larger amount of biochar (20 and 50 mg g-1) allowed reduction of the extractable PCP and nullified phytotoxicity of the contaminant.