Cementitious materials are commonly used to reinforce the bearing capacity of silty soils. However, there is very little data about how changes in arsenic (As) leaching from silty soils caused by the addition of cementitious materials. Therefore, batch leaching tests were conducted using As-bearing silty soil under different pH conditions. The pH was adjusted by changing the amount of slag cement added or the concentration of sodium hydroxide. This allows us to evaluate the effects of cement on As leaching. In addition, two different additives were applied to reduce As migration. The results show that high concentration of calcium ion (Ca²⁺) in leachates of soil-cement mixture has a significant effect in reducing the mobility of As even under hyperalkaline pH conditions. Arsenic immobilized by Ca²⁺ was observed in two patterns. The first mechanism was the help of Ca²⁺ to reduce the negative electrical potential on the surface of (hydr)oxide minerals under high pH conditions, thereby reducing the mobility of As by adsorption and coagulation of fresh precipitates of Fe and Al hydroxides. The second was the precipitation of calcium carbonate. This precipitate either directly adsorb/co-precipitate As or lower the concentration of strong competing ion, silica, both of which reduced the As mobility. When Ca- or Mg-based additive was added to the silty soil-cement mixture, As concentration in the leachate decreased. These findings are useful in developing sustainable soil-cement reinforcement techniques to avoid contamination.

A novel adsorbent PN-Fe₃O₄-IDA was developed by the chemical modification of magnetic peanut husk with iminodiacetic acid (IDA) and its efficacy for the sequestration of cationic dyes assessed using methylene blue (MB) as a model. This modification process enhanced the adsorption capacity of peanut husk as an adsorbent for dye sequestration and at the same time greatly minimized the adverse effects associated with its use in the pristine state. Results from the batch adsorption studies indicated that the uptake of MB onto PN-Fe₃O₄-IDA increased with MB concentration, contact time, temperature and pH whereas it decreased in the presence of some common salts. The pseudo-second-order kinetic model was observed to best describe the adsorption process which may greatly be influenced by the intra particle diffusion mass transfer. A maximum monolayer adsorption capacity of 43.5 mg g⁻¹ was observed at 313 K according to the Langmuir model. There was good property of regeneration for MB-loaded PN-Fe₃O₄-IDA. Based on these results, as well as other unique features such as easy separation and preparation under benign environmental conditions, PN-Fe₃O₄-IDA exhibits great potential for the removal of MB and other cationic pollutants in practical applications with easy separation from solution using external magnet. Graphical abstract

Harmattan dust and traffic-related pollution have been a serious environmental concern in the West African sub-region. In order to further contribute to the understanding of ambient levels of atmospheric pollution and chemical composition in the region, this study monitored harmattan dust and traffic-related particulate matter at four locations across southwestern (Ile-Ife) and north-western (Zaria) geo-political zones of Nigeria. The collected samples were characterized for their chemical composition using Energy-Dispersive X-Ray Fluorescence spectrometer equipped with an optimized secondary target x-ray excitation conditions (Al, CaF₂, Fe, Ge, Zr, Mo, Ag, Al₂O₃). The objectives are to assess spatio-temporal mass concentrations, chemical footprints, enrichment factors, elemental correlations, and ratios at all locations. The X-ray analytical method was validated with a NIST SRM 2783 air particulate standard, and detection limits for each chemical specie were determined. Validation results showed good reproducibility of the certified reference material with relative standard deviations of the elements much lower by about 1–13% than the corresponding reference values. Mass concentrations reached up to 2200 μgm⁻³ in the north and 1500 μgm⁻³ in the south. The range of mean concentration of crustal marker elements were Al (5–27 μgm⁻³), Si (5–856 μgm⁻³), Ca (0.78–13 μgm⁻³), and Fe (2–13 μgm⁻³), and were most abundant during the harmattan particularly in the southwestern region. Highest mean concentration values of 380, 810, and 420 ngm⁻³ were recorded for Cr, Cu, and Pb respectively at the traffic corridor which also recorded the highest enrichment factors. Black carbon and elemental concentrations contributed between 1 to 54% and 9 to 94% across the locations respectively. Backward trajectories of atmospheric flow over the locations showed two dominant sources; dust laden source from the Sahara desert and maritime flow over the Gulf of Guinea. This study found that chemical footprints (Al, Si, K, Ca, Ti, and Fe) of harmattan-related dust were more correlated (r² between 0.88 and 0.99) than those attributed to dust re-suspension at the traffic location.

Among all female sex hormones, 17β-estradiol (E2) has been most often detected in discharge water from animal farms. The objectives of this study were to evaluate the performance of UV/heat-activated persulfate to degrade E2 and the technical feasibility to use this system for treating real wastewater. As an individual persulfate (PS) homogeneous activator, UV-activated PS removed E2 better than using low heat (40 °C) and solar irradiation to activate PS. When both UV and heat (25–65 °C) were used to activate PS, the Arrhenius equation represented well the observed rate constant, with activation energy of 118.07 kJ mol⁻¹. Inorganic ion concentrations increased the degradation rate. These ions included Cl⁻ (3500 mg L⁻¹), which increased rates by 18.1%, HCO₃⁻ (250 mg L⁻¹) by 4.6%, and NO₃⁻ (5 mg L⁻¹) by 7.9%. However, lesser impacts on degradation kinetics were observed at higher concentrations for all constituents due to SO₄·⁻ scavenging by the formed radicals such as Cl₂·⁻, Cl·, HCO₃·, CO₃·⁻, and NO₃·. The E2 degradation observed rate constant (kₒbₛ) was highest at pH 3. Although both synthetic wastewater and real wastewater showed inhibitory effects due to UV blocking from turbidity and the existence of the –COOH and –OH functional groups that acted as radical scavengers, E2 degradation was still observed. The overall results provided proof-of-concept that UV/heat-activated PS can be applied to treat E2 in wastewater containing a high organic content and can minimize the chemical and operating costs, as solar irradiation provides the heating source.

Photocatalytic oxidation (PCO) has been described as an advanced technology to remove toxic volatile organic compounds (VOCs) and airborne microorganisms from indoor air environments. This technique is economic, stable, safe, and capable to remove a wide variety of organic contaminants under UV irradiation. This study presents a case study on the effect of a fabricated filter in the removal of toluene at 26 mg/L and disinfection of ambient air under a given operating condition. The principal goals of this study were to synthesize Ag nanoparticles/TiO₂ filter for the first time via the deposition of Ag nanoparticles on a commercial immobilized TiO₂ tissue sheet by impregnation technique and to investigate the performance of this prepared Ag/TiO₂ tissue based filter system for toluene removal as well as to remove airborne microorganisms from indoor air. The results illustrated that under the experimental conditions, Ag/TiO₂-based filter was able to disinfect well the microorganisms. The performance of Ag/TiO₂ filter shows two different stages; the first one is a slight adsorption phase in dark with approximately 15% of toluene removal within 60 min. The second stage is a photooxidation phase under UV irradiation in which the toluene removal efficiency was significantly enhanced with extension of the operational time and reached 97% during this stage. Additionally, the Ag/TiO₂ filter has a higher disinfection capacity of airborne microorganisms that completely removed to reach 100% after 300 min of application. This filter could be practically introduced as an effective system in industrial, hospital, and home applications for air purification. Graphical abstract

Aflatoxicosis is a serious health condition resulted from aflatoxin (AF)-producing fungi. Major health threats resulted from AFs and reflect on the livestock industry with great economic losses. There are limited scientific evidences concerning the AFs in ruminant, therefore it is important to evaluate AFs health hazards in cattle. Here, we investigate biochemical, oxidative stress, and postmortem changes associated with unexpected acute bovine aflatoxicosis. Seventy-two cattle were suffered from aflatoxisocis. Depression and inappetence were predominant clinical findings of the diseased animals. Analysis of feedstuffs revealed presence of aflatoxin B1 (AFB1). The AF-intoxicated animals showed a significant increase in alanine amino transferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), serum creatinine (SCr), catalase (CAT), and malondialdehyde (MDA) levels. Moreover, a significant decrease in total protein (TP), magnesium (Mg), and reduced glutathione (GSH) were also seen. Hepatomegaly, enlarged gallbladder as well as congestion of the intestine and kidney were observed. This study elucidates the critical and constructive measurements needed for the prevention of the AFs hazardous effects to livestock for the future control of AF outbreaks. Conducting series of diagnostic assays reflect the marked health condition alterations in the biochemical and antioxidant status of the AF-intoxicated cattle.

A novel titanium dioxide/activated carbon (TiO₂/AC) composite where AC derived from oil palm empty fruit bunch (EFB) was synthesised by using sol–gel method. All the samples were characterised by using X-ray diffraction (XRD), scanning electron microscopy-energy dispersive X-ray (SEM-EDX), Fourier transformed infrared (FTIR), thermogravimetric analysis (TGA) and surface analyser. SEM analysis showed that TiO₂ particles were successfully embedded and well distributed on the AC surface. The elemental composition analysis found that the TiO₂/AC composite contained titanium (Ti), oxygen (O) and carbon (C) atoms. Meanwhile, the appearance of new band at about 960 cm⁻¹ which assigned to the Ti–O stretching was observed in the FTIR spectra when the AC was incorporated into TiO₂. TGA analysis showed that the weight loss of 32 wt.% from 150 to 550 °C was due to the decomposition of amorphous carbon layers and loss of hydroxyl groups on TiO₂. It was found that the TiO₂/AC composite had better performance in the sonocatalytic degradation of malachite green as compared to the individual AC and TiO₂ because the TiO₂/AC composite had dual functionality and huge number of active sites which could promote the mass transfer of dye molecules towards catalyst surface. By using 1.5 g/L of TiO₂/AC composite which calcined at 700 °C on 100 mL of 200 mg/L of malachite green at solution pH of 7, a degradation efficiency of 87.11% had been achieved after 30 min of ultrasonic irradiation. A lower chemical oxygen demand (COD) removal (81.75%) was observed because the structured dye molecules underwent mineralisation process during the sonocatalytic degradation to generate intermediate compounds. The TiO₂/AC composite was able to be recycled and still achieved a high degradation efficiency of 76.78% after second catalytic cycle as compared to the fresh TiO₂/AC composite with degradation efficiency of 87.11%. In conclusion, the TiO₂/AC composite had high reusability and promising for practical applications in textile industry.

Air pollution can generate changes in the morphology, physiology, and behavior of several animals, including birds, which, when responding to such environmental changes, can be used as biomonitors. Quantitative and qualitative analyses of erythrocyte nuclear anomalies comprise a useful tool for biomonitoring, with anucleated erythrocytes, called erythroplastids, being particularly significant. The objectives of the present study were to quantify the presence of erythroplastids in Antilophia galeata and relate their presence to distance from the nearest urban environment. Blood smears were analyzed for 80 individuals of A. galeata captured between June 2013 and October 2018 in five Cerrado forest fragments of different sizes and with different influences from urbanization. The quantity of erythroplastids differed among areas, with it being greater in fragments within a proximity with urban, and less in highly preserved areas far from an urban environment. Quantification of erythroplastids in A. galeata proved to be a useful tool for monitoring air quality.

Very little information is available on the stressed growth of Microcystis imposed by arsenate (As(V)) under different phosphorus (P) regimes. In this study, we examined the growth characteristics and arsenic transformation of four Microcystis species exposed under As(V) with two P sources involving dissolved inorganic phosphorus (IP) and organophosphate (D-glucose-6-phosphate disodium salt, GP). Results showed that all the four chosen Microcystis species could grow and reproduce with GP as the only P source, and the difference was insignificant when compared with IP. From optical density (OD), chlorophyll a (Chla), and actual quantum yield (Yield), the tolerance to As(V) of the chosen species was following as FACHB 905 > FACHB 1028 > FACHB 1334 > FACHB 912. Specifically, the 96 h EC₅₀ of As(V) for FACHB 905 in IP was approx. 4 orders of magnitude higher than that in GP, but for other three algal species, the 96 h EC₅₀ values were similar under the two given different P conditions. Furthermore, all antioxidant enzyme activities of superoxide dismutase (SOD), peroxide dismutase (POD), glutathione S-transferases (GSTs), and metalloproteinase (MTs) in algal cells were significantly increased in GP conditions. Moreover, the enzyme activities of AKP, GSTs, and MTs were inhibited with increasing As(V) levels under both IP and GP conditions. In addition, arsenite (As(III)) and methylated As of monomethylarsonic acid (MMA) and dimethylthioarsinic acid (DMA) were found in FACHB 912 and FACHB 1334 media, indicating that these Microcystis could detoxify As(V) by As biotransformation under IP and GP conditions. Specifically, As(V) reduction was elevated in media of FACHB 1334 and FACHB 905, but was decreased in media of FACHB 912 under GP conditions. Our results highlight the different P sources that impact the toxic effects of arsenate exposure on Microcystis and subsequent As biotransformation.

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC₅₀ of 45.8 mg L⁻¹) and moderate effects (LD₅₀ of 99.8 μg adult⁻¹) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD₅₀ values of 68.9 and 61.2 μg larva⁻¹, respectively. Based on our results, the essential oil from A. campestris may be further considered a candidate ingredient for developing botanical larvicides.