Role of Nb2O5 Crystal Phases on the Photocatalytic Conversion of Lignin Model Molecules and Selectivity for Value-Added Products.

The photocatalytic conversion in aqueous media of phenol and guaiacol as a lignin model compound using Nb2O5 with different crystal phases was studied. Nb2O5 particles were synthesized using hydrothermal methods, where it was observed that changes in the solvent control their morphology and crystal phase. Different photocatalytic behavior of Nb2O5 was observed with the selected model compounds, indicating that its selection directly impacts the resulting conversion and selectivity rates as well as the reaction pathway, highlighting the relevance of model molecule selection. Photocatalytic conversion of phenol showed conversion rate (C%) up to 25 % after 2 h irradiation and high selectivity (S%) to pyrogallol (up to 50 %). Orthorhombic Nb2O5 spheres favored conversion through free hydroxyl radicals while monoclinic rods did not convert phenol. Guaiacol photocatalytic oxidation showed high conversion rate but lower selectivity. Orthorhombic and monoclinic Nb2O5 favored the formation of resorcinol with S % ~0.43 % (C % ~33 %) and ~13 % (C % ~27 %) respectively. The mixture of both phases enhanced the guaiacol conversion rate to ~55 % with ~17 % of selectivity to salicylaldehyde. The use of radical scavengers provided information to elucidate the reaction pathway for these model compounds, showing that different reaction pathways may be obtained for the same photocatalyst if the model compound is changed.

Effect of particle size of nanoscale zero-valent copper on inorganic phosphorus adsorption-desorption in a volcanic ash soil.

Zero-valent copper engineered nanoparticles (Cu-ENPs) released through unintentional or intentional actions into the agricultural soils can alter the availability of inorganic phosphorus (IP) to plants. In this study, we used adsorption-desorption experiments to evaluate the effect of particle size of 1% Cu-ENPs (25 nm and 40-60 nm) on IP availability in Santa Barbara (SB) volcanic ash soil. X-Ray Diffraction results showed that Cu-ENPs were formed by a mixture of Cu metallic and Cu oxides (Cu2O or/and CuO) species, while specific surface area values showed that Cu-ENPs/25 nm could form larger aggregate particles compared to Cu-ENPs/40-60 nm. The kinetic IP adsorption of SB soil without and with 1% Cu-ENPs (25 nm and 40-60 nm) followed the mechanism described by the pseudo-second-order (k2 = 0.45-1.13 x 10-3 kg mmol-1 min-1; r2 ≥ 0.999, and RSS ≤ 0.091) and Elovich (α = 14621.10-3136.20 mmol kg-1 min-1; r2 ≥ 0.984, and RSS ≤ 69) models. Thus, the rate-limiting step for IP adsorption in the studied systems was chemisorption on a heterogeneous surface. Adsorption equilibrium isotherms without Cu-ENPs were fitted well to the Freundlich model, while with 1% Cu-ENPs (25 nm and 40-60 nm), isotherms were described best by the Freundlich and/or Langmuir model. The IP relative adsorption capacity (KF) was higher with 1% Cu-ENPs/40-60 nm (KF = 110.41) than for 1% Cu-ENPs/25 nm (KF = 74.40) and for SB soil (KF = 48.17). This study showed that plausible IP retention mechanisms in the presence of 1% Cu-ENPs in SB soil were: i) ligand exchange, ii) electrostatic attraction, and iii) co-precipitate formation. The desorption study demonstrated that 1% Cu-ENPs/40-60 nm increased the affinity of IP in SB soil with a greater effect than 1% Cu-ENPs/25 nm. Thus, both the studied size ranges of Cu-ENPs could favor an accumulation of IP in volcanic ash soils.

nZVI-Based Nanomaterials Used for Phosphate Removal from Aquatic Systems.

In the last decade, the application of nanoscale zero-valent iron (nZVI) has garnered great attention as an adsorbent due to its low cost, non-toxicity, high porosity, and BET-specific surface area. In particular, the immobilization of nZVI particles onto inorganic and organic substrates (nanocomposites) decreased its agglomeration, allowing them to be effective and achieve greater adsorption of pollutants than pristine nanoparticles (NPs). Although nZVI began to be used around 2004 to remove pollutants, there are no comprehensive review studies about phosphate removal from aquatic systems to date. For this reason, this study will show different types of nZVI, pristine nZVI, and its nanocomposites, that exist on the market, how factors such as pH solution, oxygen, temperature, doses of adsorbent, initial phosphate concentration, and interferents affect phosphate adsorption capacity, and mechanisms involved in phosphate removal. We determined that nanocomposites did not always have higher phosphate adsorption than pristine nZVI particles. Moreover, phosphate can be removed by nZVI-based nanoadsorbents through electrostatic attraction, ion exchange, chemisorption, reduction, complexation, hydrogen bonding, and precipitation mechanisms. Using the partition coefficient (PC) values, we found that sepiolite-nZVI is the most effective nanoadsorbent that exists to remove phosphate from aqueous systems. We suggest future studies need to quantify the PC values for nZVI-based nanoadsorbents as well as ought to investigate their phosphate removal efficiency under natural environmental conditions.

Impact on Some Soil Physical and Chemical Properties Caused by Metal and Metallic Oxide Engineered Nanoparticles: A Review.

In recent years, the release of metal and metallic oxide engineered nanoparticles (ENPs) into the environment has generated an increase in their accumulation in agricultural soils, which is a serious risk to the ecosystem and soil health. Here, we show the impact of ENPs on the physical and chemical properties of soils. A literature search was performed in the Scopus database using the keywords ENPs, plus soil physical properties or soil chemical properties, and elements availability. In general, we found that the presence of metal and metallic oxide ENPs in soils can increase hydraulic conductivity and soil porosity and reduce the distance between soil particles, as well as causing a variation in pH, cation exchange capacity (CEC), electrical conductivity (EC), redox potential (Eh), and soil organic matter (SOM) content. Furthermore, ENPs or the metal cations released from them in soils can interact with nutrients like phosphorus (P) forming complexes or precipitates, decreasing their bioavailability in the soil solution. The results depend on the soil properties and the doses, exposure duration, concentrations, and type of ENPs. Therefore, we suggest that particular attention should be paid to every kind of metal and metallic oxide ENPs deposited into the soil.

Adsorption kinetics studies of ciprofloxacin in soils derived from volcanic materials by electrochemical approaches and assessment of socio-economic impact on human health.

The use of antibiotics in the livestock sector has resulted in the entry of these drugs into the soil matrix through the disposal of manure as an organic amendment. To define the fate of these drugs, it is necessary to evaluate kinetic aspects regarding transport in the soil-solution. The aim of this paper is to evaluate the adsorption kinetic parameters of Ciprofloxacin (CIPRO) in Ultisol and Andisol soil which allows obtaining main kinetic parameters (pseudo-first and pseudo-second order models) and to establish the solute transport mechanism by applying kinetic models such as the Elovich equation, Intraparticle diffusion (IPD) and, the Two-site non-equilibrium models (TSNE). The adsorption kinetics of this fluoroquinolone (FQ), on both soils derived from volcanic ashes, is developed using electrochemical techniques for their determination. The experimental amount of CIPRO adsorbed over time (Qt) data best fit with the pseudo-second order kinetic models; R2 = 0.9855, Ɛ = 10.17% and R2 = 0.9959, Ɛ = 10.77% for Ultisol and Andisol, respectively; and where CIPRO adsorption was considered time dependent for both soils but the lower adsorption capacity in Ultisol; with 17.6 ± 2.8 µmol g-1; which could mean a greater risk in environmental. Subsequently, applying models to describe solute transport mechanisms showed differences in the CIPRO adsorption extent for the fast and slow phases. Adsorption isotherms were evaluated, where Ultisol occurs on heterogenous sites as multilayers and Andisol by monolayer with similar Qmax. Finally, the socio-economic impact of antibiotic usage is presented, giving the importance of antibiotics in the livestock sector and their effects on human health.

Connecting the evidence about organic pollutant sorption on soils with environmental regulation and decision-making: A scoping review.

There exists an increase of review articles of pollutant sorption on soils due to the relevance of this process in environmental fate. However, this information is not used to make environmental decisions. We conduct a scoping review to identify and categorize the state-of-the-art of pesticide sorption (organic pollutant model) and decision-making studies in 2015-2020 using databases (Web of Science, Scopus and ScieLo) to detect potential gaps and create a framework that guide the connection between scientific evidence and its institutionalization. We detect research gaps (inside sorption or decision-making studies) and evidence gaps (between sorption and decision-making) from literature based on five categories to describe sorption (sorbate-sorbent system, system variables to study the sorption process, objectives pursued by authors, experimental approaches to study the sorption process, and quantification of sorption) and four topics for regulatory contexts (sponsor contextualization, descriptive information, environmentally relevant issues and Sustainable Development Goals (SDGs)). The gaps included (i) unrelated study designs, (ii) unreliable causal mechanisms, (iii) unrelated SDGs, (iv) lack of collaboration, (v) lack of representativeness, (vi) lack of knowledge, (vii) lack of relevant studies, and (vii) unknown causal extrapolation. Our framework connected the gaps with relevant environmental issues and common research topics on sorption studies, including suggested solutions and inclusion of lacking SDG in literature. The framework can assist the science-policy interaction, promoting cooperation for different study designs, pollutant-soil systems, and socio-environmental applications, such as environmental fate and management, risk assessment, monitoring, remediation, and local regulations.

Insect Epigenetic Mechanisms Facing Anthropogenic-Derived Contamination, an Overview.

Currently, the human species has been recognized as the primary species responsible for Earth's biodiversity decline. Contamination by different chemical compounds, such as pesticides, is among the main causes of population decreases and species extinction. Insects are key for ecosystem maintenance; unfortunately, their populations are being drastically affected by human-derived disturbances. Pesticides, applied in agricultural and urban environments, are capable of polluting soil and water sources, reaching non-target organisms (native and introduced). Pesticides alter insect's development, physiology, and inheritance. Recently, a link between pesticide effects on insects and their epigenetic molecular mechanisms (EMMs) has been demonstrated. EMMs are capable of regulating gene expression without modifying genetic sequences, resulting in the expression of different stress responses as well as compensatory mechanisms. In this work, we review the main anthropogenic contaminants capable of affecting insect biology and of triggering EMMs. EMMs are involved in the development of several diseases in native insects affected by pesticides (e.g., anomalous teratogenic reactions). Additionally, EMMs also may allow for the survival of some species (mainly pests) under contamination-derived habitats; this may lead to biodiversity decline and further biotic homogenization. We illustrate these patterns by reviewing the effect of neonicotinoid insecticides, insect EMMs, and their ecological consequences.

Study of Sorption Kinetics and Sorption-Desorption Models to Assess the Transport Mechanisms of 2,4-Dichlorophenoxyacetic Acid on Volcanic Soils.

The sorption behavior of 2,4-dichlorophenoxyacetic acid (2,4-D) in the abundant agricultural volcanic ash-derived soils (VADS) is not well understood despite being widely used throughout the world, causing effects to the environment and human health. The environmental behavior and risk assessment of groundwater pollution by pesticides can be evaluated through kinetic models. This study evaluated the sorption kinetics and 2,4-D sorption-desorption in ten VADS through batch sorption experiments. Differences in the sorption extent for the fast and slow phases was observed through the IPD model where 2,4-D sorption kinetics was controlled by external mass transfer and intra organic matter diffusion in Andisols (C1 ≠ 0). We confirmed from the spectroscopic analysis that the carboxylate group directly drives the interaction of 2,4-D on Andisol soil. The MLR model showed that IEP, FeDCB, and pH×Silt are important soil descriptors in the 2,4-D sorption in VADS. The Freundlich model accurately represented sorption equilibrium data in all cases (Kf values between 1.1 and 24.1 µg1-1/n mL1/ng-1) with comparatively higher sorption capacity on Andisols, where the highest hysteresis was observed in soils that presented the highest and lowest OC content (H close to 0).

Nicosulfuron sorption kinetics and sorption/desorption on volcanic ash-derived soils: Proposal of sorption and transport mechanisms.

Nicosulfuron sorption/desorption kinetics were studied through batch sorption studies in ten volcanic ash-derived Andisol and Ultisol soils with acidic pH and variable surface charge. Two different kinetic models were used to fit the experimental data: i) Models to establish kinetic parameters (Pseudo-First and Pseudo-Second-Order), and ii) Models to describe solute transport mechanisms of organic compounds on sorbents (Intraparticle Diffusion, Dimensionless Intraparticle, Boyd, and Two-Site Nonequilibrium). Sorption kinetic data best fit the pseudo-second-order model. Application of these models to describe solute transport suggests that underlying mechanisms are complex in all soils due to: i) surface sorption, with mass transfers controlling sorption kinetics across the boundary layer; and ii) pore diffusion (i.e. intraparticle diffusion into macropores and micropores). The Freundlich model explained equilibrium sorption data in all cases (R2 > 0.9979) with Kf values higher than those reported for different class of soils (6.85-16.08 µg1-1/n mL1/n  g-1). The hysteresis was significant in all studied soils. The lower sorption rate on Ultisols must be considered in regards to Nicosulfuron leaching potential.

Electrochemical method to study the environmental behavior of Glyphosate on volcanic soils: Proposal of adsorption-desorption and transport mechanisms.

Glyphosate is used extensively worldwide, but current evidence suggests detrimental effects on the environment, pollinators, and human health. Glyphosate adsorption kinetics and adsorption/desorption were studied through batch sorption experiments in ten typical volcanic ash-derived soils from Andisol and Ultisol orders. Two kinetic models were used to fit the experimental data: i. Models that allowed establishment of principally kinetic parameters and modeling of the adsorption process, and ii. Models described solute transport mechanisms commonly used for remediation purposes. Adsorption kinetic data were best fitted by the pseudo-second-order kinetic model and Two-Site Nonequilibrium model. These models suggest that mechanisms are complex due to rapid surface adsorption in ultisols with mass transfer controlling adsorption kinetics across the boundary layer, as indicated by the highhand lowt1/2values. High intraparticle diffusion into macropores and micropores was observed for Andisols. The Freundlich model accurately represented adsorption equilibrium data in all cases (R2 > 0.9580) with comparatively higher adsorption capacity on Andisols. Kf values (2.50-52.28 µg1-1/n mL1/n g-1) and hysteresis were significant in all studied soils. Taken together, these data suggest that Glyphosate may be adsorbed more on Andisol soils in comparison to Ultisols.

Identification of potential trypanothione reductase inhibitors among commercially available ß-carboline derivatives using chemical space, lead-like and drug-like filters, pharmacophore models and molecular docking.

American trypanosomiasis or Chagas disease caused by the protozoan Trypanosoma cruzi (T. cruzi) is an important endemic trypanosomiasis in Central and South America. This disease was considered to be a priority in the global plan to combat neglected tropical diseases, 2008-2015, which indicates that there is an urgent need to develop more effective drugs. The development of new chemotherapeutic agents against Chagas disease can be related to an important biochemical feature of T. cruzi: its redox defense system. This system is based on trypanothione ([Formula: see text],[Formula: see text]-bis(glutathyonil)spermidine) and trypanothione reductase (TR), which are rather unique to trypanosomes and completely absent in mammalian cells. In this regard, tricyclic compounds have been studied extensively due to their ability to inhibit the T. cruzi TR. However, synthetic derivatives of natural products, such as [Formula: see text]-carboline derivatives ([Formula: see text]-CDs), as potential TR inhibitors, has received little attention. This study presents an analysis of the structural and physicochemical properties of commercially available [Formula: see text]-CDs in relation to compounds tested against T. cruzi in previously reported enzymatic assays and shows that [Formula: see text]-CDs cover chemical space that has not been considered for the design of TR inhibitors. Moreover, this study presents a ligand-based approach to discover potential TR inhibitors among commercially available [Formula: see text]-CDs, which could lead to the generation of promising [Formula: see text]-CD candidates.

Sorption kinetics of diuron on volcanic ash derived soils.

Diuron sorption kinetic was studied in Andisols, Inceptisol and Ultisols soils in view of their distinctive physical and chemical properties: acidic pH and variable surface charge. Two types of kinetic models were used to fit the experimental dates: those that allow to establish principal kinetic parameters and modeling of sorption process (pseudo-first-order, pseudo-second-order), and some ones frequently used to describe solute transport mechanisms of organic compounds on different sorbents intended for remediation purposes (Elovich equation, intraparticle diffusion, Boyd, and two-site nonequilibrium models). The best fit was obtained with the pseudo-second-order model. The rate constant and the initial rate constant values obtained through this model demonstrated the behavior of Diuron in each soil, in Andisols were observed the highest values for both parameters. The application of the models to describe solute transport mechanisms allowed establishing that in all soils the mass transfer controls the sorption kinetic across the boundary layer and intraparticle diffusion into macropores and micropores. The slowest sorption rate was observed on Ultisols, behavior which must be taken into account when the leaching potential of Diuron is considered.