Uranium wastewater treatment has been performed by adsorption method using Mg(OH)₂-impregnated activated carbon. Research purposes are to determine (i) uptake capacity of the adsorption isotherm of uranium in Mg(OH)₂-impregnated activated carbon, (ii) mathematical correlation of uranium (VI) adsorption rate, and (iii) effect of the impregnation ratio of adsorbent to uranium removal efficiency. Adsorbent was synthesized through several stages, i.e., pyrolysis of coconut shell (400 °C), chemical activation using NaOH, and impregnation process using varied solutions of MgCl₂ (600 °C). The materials were characterized comprehensively using FTIR, BET, XRF, and XRD. The parameters studied in this research were adsorption temperature (T), average particle diameter of adsorbent (d), mass ratio of adsorbent to wastewater solution (r), and impregnation ratio of Mg(OH)₂/activated carbon. The results shown that equilibrium data are well fitted with the Langmuir isotherm model with the maximum adsorption capacity about 85 mg/g at 303 K and dimensionless constant separation factor (RL) value about 0.7. The adsorption rate was increased by increasing the adsorption temperature, mass ratio of adsorbent to wastewater solution, and the decrease of particle diameter of adsorbent with mathematical equation of the uranium (VI) adsorption rate as:[Formula: see text]In addition, the results also shown that increasing the impregnation ratio from 0.3 to 1.0 can increase the uranium removal efficiency up to 67.3%.

A growing number of electrochemical oxidation system was employed for the degradation of refractory contaminants. In this study, a boron-doped diamond (BDD) anode/Ti cathode equipped in the differential column batch reactor (DCBR) was utilized for electrochemical oxidation of ciprofloxacin (CIP). The feed solution within the DCBR system was confirmed as a uniform flow state through a computational fluid dynamics (CFD) simulation analysis. The results showed that the BDD anode/Ti cathode electrochemical system was with a high efficiency oxidation performance when treating the CIP contaminant. The CIP was completely degraded within 20 min, and over 50% DOC removed after 120 min. Therefore, two-stage electrochemical oxidation mechanism was proposed. Four major factors, the initial concentration, current density, pH, and electrolyte concentration, on the CIP degradation efficiency were systematically investigated. The CIP degradation curve followed pseudo first-order degradation kinetics. The electric efficiency per order (EE/O) of the electrochemical oxidation system was calculated to determine an optimal operation condition. Moreover, the oxidation intermediates were identified with a mass spectrometry (LC/MS/MS) and the degradation pathways were proposed in this study. The destruction of quinolone moiety and piperazine ring and fluorine substitution were the three possible degradation pathways during BDD anode oxidation process.

Cyproconazole is a triazole fungicide used to protect a diverse range of fruits, vegetables, and grain crops. As such, it has the potential to enter aquatic environments and affect non-target organisms. The objective of this study was to assess the acute toxicity of the triazole fungicide cyproconazole to zebrafish embryos by assessing mortality, developmental defects, morphological abnormality, oxidative respiration, and locomotor activity following a 96-h exposure. Zebrafish embryos at 6-h post-fertilization (hpf) were exposed to either a solvent control (0.1% DMSO, v/v), or one dose of 10, 25, 50, 100, 250, and 500 μM cyproconazole for 96 h. Data indicated that cyproconazole exhibited low toxicity to zebrafish embryos, with a 96-h LC₅₀ value of 90.6 μM (~ 26.4 mg/L). Zebrafish embryos/larvae displayed a significant decrease in spontaneous movement, hatching rate, and heartbeats/20 s with 50, 100, and 250 μM cyproconazole exposure. Malformations (i.e., pericardial edema, yolk sac edema, tail deformation, and spine deformation) were also detected in zebrafish exposed to ≥ 50 μM cyproconazole, with significant increases in cumulative deformity rate at 48, 72, and 96 hpf. In addition, a 20–30% decrease in basal and oligomycin-induced ATP respiration was observed after 24-h exposure to 500 μM cyproconazole in embryos. To determine if cyproconazole affected locomotor activity, a dark photokinesis assay was conducted in larvae following 7-day exposure to 1, 10, and 25 μM cyproconazole in two independent trials. Activity in the dark period was decreased for zebrafish exposed to 25 μM cyproconazole in the first trial, and hypoactivity was also observed in zebrafish exposed to 1 μM cyproconazole in a second trial, suggesting that cyproconazole can affect locomotor activity. These data improve understanding of the toxicity of cyproconazole in developing zebrafish and contribute to environmental risk assessments for the triazole fungicides on aquatic organisms. We report that, based on the overall endpoints assessed, cyproconazole exhibits low risk for developing fish embryos, as many effects were observed above environmentally-relevant levels.

Two-dimensional HPLC (2D-HPLC) recently has received great attention due to providing high resolving power and higher peak capacities than that of 1D-HPLC, especially dealing with a wide spectrum of sample matrices containing several components. In this work, an on-line heart-cutting two-dimensional liquid chromatography (2D-LC) method was developed using monolithic columns coupled with reversed-phase liquid chromatography (RPLC). 2D-HPLC was successfully carried out using affinity-based monolithic columns at first dimension (20 cm × 4.6 mm I.D.) followed by a Pinnacle II PAH column (50 mm × 4.6 mm I.D.) at the second dimension. Furthermore, good linearity was observed for the correlation of the benzo[a]pyrene (BaP) molecule against the peak areas (R² = 0.994) in the concentration range of 0.01–1.0 ng/mL in 30 min. The limit of detection and the limit of quantification were found to be 4.0 pg/mL and 12.0 pg/mL, respectively. Both the intra-day and inter-day precision at 0.01 and 0.1 ng/mL spiked concentrations were below than 2.35% RSD whereas the means of the recovery data of the BaP from the water samples were found to be in the range of 93.71–98.65%. These results demonstrate that the 2D-HPLC system, developed by the combination of the P(HEMA-MAPA) column and Pinnacle II PAH column, is reliable, stable, and well qualified in the extraction of polycyclic aromatic hydrocarbons from the water samples.

To elucidate the inhibitory effects of different herbicides on soil nitrification, eight widely used herbicides, i.e., acetochlor, atrazine, dicamba, isoproturon, paraquat, puma, tribenuron-methyl, and 2,4-dichlorophenoxyacetic acid butyl ester (2,4-Dbe), which represent different chemical taxonomy were selected. Our results indicated that herbicide 2,4-Dbe displayed the best inhibitory effect on nitrification, followed by puma and tribenuron-methyl, whereas the remaining five herbicides exhibited less effect when 10 mg of active ingredient (A.I.) of every herbicide per kg of soil was applied in vegetable-planting soil. The inhibition appeared when 5–100 mg of A.I. 2,4-Dbe was employed, which was enhanced with an increment in its dose in both vegetable-planting and fluvo-aquic soils. However, the inhibitory effect of 10 mg of A. I. 2,4-Dbe exhibited obvious differences in these two types of soils, where the duration of inhibition was shorter as it only continued about a week in fluvo-aquic and calcic cambisols soils with strong nitrification activity but poorer effect as compared to 10 mg of dicyandiamide (DCD). In contrast, the duration of inhibition exceeded 2 months in dryland red and shajiang black soils with a weak nitrification activity which was equivalent to DCD. In addition, comparing with five nitrification inhibitors, 10 mg of 2,4-Dbe had better inhibition than the substituted pyrimidine (AM) and sulfocarbamide (SU), but was equivalent to DCD, nitrapirin, and 3,4-dimethylpyrazole phosphate (DMPP) at their recommended application rates in dryland red soil. These obtained data clearly indicated that 2,4-Dbe could play a stronger role as a nitrification inhibitor in soils.

Worldwide, reef building corals are being degraded due to increasing anthropogenic pressure, and as a result, macroalgal cover is being increased. Hence, mechanism of coral–algal interaction, differential coral response to algal overgrowth, is critical from every geographical location to predict future coral dynamics. This paper documents the frequency of coral–algal (Halimeda) interactions, differential coral response to algal interaction. We found difference in susceptibility among coral genera to competitive effects. Out of 970 coral colonies surveyed, 36.7% were in contact with Halimeda sp. Most frequent contact was observed in Porites (57%) followed by Favites 28% (n = 60), Acropora 26% (n = 48), Platygyra 5% (n = 5) and Symphyllia 4.2% (n = 3). Frequent discoloration and tissue loss were only observed in Porites. Continuous monitoring revealed that long-term algal physical contact prevents light required for polyp for photosynthesis and stops coral feeding ability. In this study, we also found mutual exclusion between Halimeda and coral recruit. Out of 180 coral colonies (size class between 5 and 15 cm) comprised of Favites (n = 74), Acropora (n = 20), Favia (n = 79) and Porites (n = 7) surveyed, none of them were found in Halimeda-dominated sites. The documented effects of recruitment exclusion and tissue mortality followed by algal interaction on major reef building corals (Porites) could affect replenishing process and health of the remaining healthy corals in the Palk Bay reef if algal proliferation rate is not controlled through proper management strategies.

New optical tools are proposed for the real-time diagnosis of water quality without traditional sampling and laboratory physico-chemical analysis. In particular, the optical decision-making system is developed as an operational tool for in-situ assessment of water quality in natural water areas. Specifically, three versions of this system are analyzed using 8-channel and 35-channel photometric devices and a 128-channel spectroelipsometric device. The spectral images obtained from these devices are the basis for the diagnosis of water quality by using new algorithms to detect these spectral images. In more detail, four algorithms are developed to identify optical spectral images of water objects. The effectiveness of these optical tools is demonstrated in experimental water quality control sites in water systems operating under different climatic conditions. Finally, the results for the determination of the various pollutants at the surface of these water bodies are presented.

A challenge in side-stream treatment of anaerobic digester supernatant is that the effluent does not meet discharge standards. To address this challenge, this study tested tubular multichannel ceramic microfiltration (MF) and ultrafiltration (UF) membranes for the post-treatment of anaerobic digester supernatant. Pollutant rejection (total suspended solids (TSS), COD, total nitrogen (TN), and total phosphorus (TP)), color removal, and membrane susceptibility to fouling were determined at various transmembrane pressures (TMPs) (0.2, 0.3, 0.4, 0.5 MPa). Both methods completely removed TSS. In MF, COD was removed with 48–76% efficiency at 0.2–0.4 MPa. In UF, COD removal efficiency was slightly higher, reaching 83.7% at 0.4 MPa. With both methods, pollutant removal did not increase at TMP of 0.5 MPa. With both MF and UF, color was reduced by 54–100%, irrespective of the TMP. At 0.2–0.4 MPa, membrane resistance was lower and permeate flux was much higher with MF than UF. At 0.5 MPa, the methods differed only slightly from each other. Due to the larger cut-off, flux decline was slower in MF (0.7 h⁻¹) than in UF (1.1 h⁻¹), as the larger pore-size favors less foulant deposition. Thus, taking into account rejection efficiency, capacity, washing frequency, and cost (pressure), these results indicate that MF at 0.4 MPa is the most effective variant for post-treatment of anaerobic digester supernatant. With this variant, the almost colorless permeate contained 25 mg COD/L, no TSS, 55 mg TN/L (75% in the form of nitrites and nitrates), and 8.5 mg TP/L, thus meeting criteria for water to be used in irrigation or algae cultivation.

Polycyclic aromatic hydrocarbons (PAHs) upset the basic biological parameters of the soil, such as enzymatic activity, which can be used to identify the direction and intensity of organic and mineral substance transformation in the soil environment. The aim of this study was to determine the impact of soil contamination with naphthalene, phenanthrene, anthracene and pyrene at rates of 0–4000 mg kg⁻¹ DM (dry matter) of soil on the activity of acid phosphatase and alkaline phosphatase. An analysis was also conducted on how some organic substances, such as cellulose, sucrose and compost at rates of 0 and 9 g kg⁻¹ DM alleviate the PAH impact on the enzymes under study. The experiment was carried out in a laboratory with loamy sand as the soil material. Phosphatase resistance (RS) and soil resilience (RL) were calculated. The enzyme activity was found to depend significantly on the PAH rate, time of PAH deposition in soil and the type of organic substance added to the soil. The activity of acid and alkaline phosphatase increased with the degree of soil contamination with PAHs. Naphthalene had the greatest stimulating effect on enzyme activity. Biostimulation of soil with cellulose, sucrose and compost had a positive effect on acid and alkaline phosphatase activity, with cellulose and compost being the most effective in boosting acid and alkaline phosphatase activity, respectively. Naphthalene had the greatest effect on acid and alkaline phosphatase resistance and pyrene had the least effect. Low RL indices indicate that the presence of PAHs permanently disturbed the activity of acid and alkaline phosphatase.

This research work is focused on the synthesis, characterization, and application of cost-effective biochar–biopolymeric hybrid adsorbents from waste agricultural biomass and sodium alginate. The adsorbents were characterized by BET (Brunauer–Emmett–Teller), FTIR (Fourier transform infrared), XRD (X-ray diffraction), FESEM (field emission scanning electron microscopy), and bulk density measurement. The performance of the synthesized hybrid adsorbents has been tested for the removal of aqueous phase Ni²⁺ and Cu²⁺ metal ions at a concentration range of 25 to 100 mg/L, adsorbent dose of 1–3 g/L, and system temperature of 298–308 K, respectively. The effect of various physicochemical process parameters such as solution pH, adsorbent dose, initial metal ion concentration, temperature, and presence of salts on metal ion adsorption has been studied here, and experimental process parameters are being optimized by response surface methodology (RSM). The model was fitted well with the experimental data. Various kinetic models, namely, pseudo-first-order, pseudo-second-order, and Weber–Morris, have been fitted with batch experimental data, and the mechanism of adsorption has been identified. The maximum Langmuir monolayer adsorption capacity for Cu²⁺ and Ni²⁺ were 112 and 156 mg/g, respectively, which are comparative to other published adsorbent’s capacity data under similar experimental conditions. Thermodynamic parameter studies showed that the system was endothermic and spontaneous in nature.