Photocatalytic degradation of amoxicillin and tetracycline by template synthesized nano-structured Ce3+@TiO2 thin film catalyst.

Contamination of the aquatic environment with pharmaceutical compounds is a serious environmental concern. The present investigation aims to utilize the Ce3+/TiO2 thin film catalyst to remove of potential antibiotics (amoxicillin and tetracycline) using the less harmful UV-A radiations. Reduced cerium ion-doped TiO2 is obtained by a simple one-step facile template method using polyethylene glycol as the templating agent. The synthesized catalysts Ce3+@TiO2 (non-template) and Ce3+@TiO2(T) (template) were characterized by spectroscopic methods. The XPS reaffirms the reduced Ce3+ dispersed within the titania network, and the AFM showed the surface roughness of the thin films. Detailed physicochemical analyses were conducted to deduce the degradation mechanism, and repeated use of the thin film photocatalyst showed enhanced stability. Significant mineralization of the antibiotics indicates the potential applicability of the photocatalytic catalyst. Furthermore, the presence of Ce3+ significantly restricted the recombination of electron/hole pairs in the photo-excited TiO2 semiconductor and showed enhanced photocatalytic degradation of the antibiotics proceeded predominantly through the •OH.

Correction to: Influence of iron mining activity on heavy metal contamination in the sediments of the Aqyazi River, Iran.

The original version of this article unfortunately contained an error in the affiliation section and missing acknowledgment statement.

Influence of iron mining activity on heavy metal contamination in the sediments of the Aqyazi River, Iran.

In order to investigate the degree of contamination of heavy metals (As, Cd, Cr, Cu, Fe, Pb, and Ni) in the Aqyazi River in Iran, sediment samples were collected from the river receiving wastewater from an iron-manufacturing plant. For this study, contamination indices, geoaccumulation index (Igeo), contamination factor (CF), and pollution load index (PLI), were used to assess contamination by the heavy metals. The results of the Igeo indicated that the sediments were moderately contaminated by Cu and strongly to extremely contaminated by Cd. Based on spatial distribution of concentrations and the Igeo, mining activity was the source of Cu and Cd in the Aqyazi River. Furthermore, the elevated Igeo of Cd at upmost northern station was not influenced by the mining activity, suggesting that there may be another upstream anthropogenic source of Cd. The CF values indicated the same trend as the Igeo. The PLI was calculated using all the metals analyzed in this study, and displayed that the sediments were not polluted. However, the PLI was re-calculated using only Cu and Cd and indicated that the sediments were polluted. Our results suggest further studies to trace another source of Cd upstream of the Aqyazi River and to investigate influence of the river waters on accumulation of heavy metals in soils and vegetables downstream.

Application of cadmium-doped ZnO for the solar photocatalytic degradation of phenol.

In this study, photocatalysis of phenol was studied using Cd-ZnO nanorods, which were synthesized by a hydrothermal method. The Cd-ZnO photocatalyst was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy, and Fourier transform infrared (FT-IR) and UV-Vis spectroscopy. XRD patterns exhibit diffraction peaks indexed to the hexagonal wurtzite structures with the P63mc space group. SEM images showed that the average size of the Cd-ZnO nanorods was about 90 nm. Moreover, the nanorods were not agglomerated and were well-dispersed in the aqueous medium. FT-IR analysis confirmed that a surface modifier (n-butylamine) did not add any functional groups onto the Cd-ZnO nanorods. The dopant used in this study showed reduction of the bandgap energy between valence and conduction of the photocatalyst. In addition, effect of various operational parameters including type of photocatalyst, pH, initial concentration of phenol, amount of photocatalyst, and irradiation time on the photocatalytic degradation of phenol has been investigated. The highest phenol removal was achieved using 1% Cd-ZnO for 20 mg/l phenol at pH 7, 3 g/l photocatalyst, 120 min contact time, and 0.01 mole H2O2.

Chemical and toxicological assessment of arsenic sorption onto Fe-sericite composite powder and beads.

Batch sorption and leaching of arsenic (1-30mgL-1) on Fe-sericite composite powder and beads were investigated in this study. Fe-sericite composite powder was made from natural sericite modified with iron, and alginate was used to transform the powder into beads. The maximum sorption capacities of the Fe-sericite composite powder (15.04 and 13.21mgg-1 for As(III) and As(V), respectively) were higher than those of the corresponding beads (9.02 and 7.11mgg-1 for As(III) and As(V), respectively) owing to the higher specific surface area of the powder. In addition, the leaching amounts of As(III) from Fe-sericite composite beads (≤ 15.03%) were higher than those of the corresponding powder (≤ 5.71%). However, acute toxicity of As(III)-sorbed Fe-sericite composite beads toward Daphnia magna was not significantly different from that of the corresponding powder (p > 0.05). Considering higher uptake of the powder particles by the daphnids, Fe-sericite composite beads seem to be a more appropriate and safer sorbent for arsenic removal in practical application. Based on Fe content, Fe-sericite composite beads had similar or higher maximum sorption capacities (71.19 and 56.11mgg-1 Fe for As(III) and As(V), respectively) than those of previously reported sorbents.

Adhesion of Acanthamoeba on Cosmetic Contact Lenses.

BACKGROUND: This study aimed to evaluate the adhesion of Acanthamoeba trophozoites on cosmetic contact lenses (CLs) with and without CL care multipurpose solution (MPS) treatment. METHODS: Acanthamoeba lugdunensis L3a trophozoites were inoculated onto disks trimmed from CLs: 1-day Acuvue moist, 1-day Acuvue define, Acuvue 2, and Acuvue 2 define. After 18-hour inoculation, the number of adherent trophozoites was counted under phase contrast microscopy. The effects of MPS, Opti-Free Express, soaking CLs for 6 hours, on Acanthamoeba adhesion were analyzed. Scanning electron microscopic examination was performed for assessment of Acanthamoeba attached on the lens surface. RESULTS: Acanthamoeba trophozoites showed greater adhesion to cosmetic CL (P = 0.017 for 1-day CL and P = 0.009 for 2-week CL) although there was no significant difference between the types of cosmetic CL. On all lenses, the number of adherent Acanthamoeba was significantly reduced after treatment with MPS (P < 0.001 for 1-day Acuvue moist, P = 0.046 for 1-day Acuvue define, P < 0.001 for Acuvue 2, and P = 0.015 for Acuvue 2 define), but there was still significant difference between conventional and cosmetic CLs (P = 0.003 for 1-day CL and P < 0.001 for 2-week CL, respectively). More attachment of Acanthamoeba was observed on colored area and the acanthopodia of Acanthamoeba was placed on the rough surface of colored area. CONCLUSION: Acanthamoeba showed a greater affinity for cosmetic CL and mostly attached on colored area. Although MPS that contained myristamidopropyl dimethylamine reduced the adhesion rate, there was a significant difference between conventional and cosmetic CLs.

Nanocomposite thin films Ag0(NP)/TiO2 in the efficient removal of micro-pollutants from aqueous solutions: A case study of tetracycline and sulfamethoxazole removal.

The aim of this communication is to synthesize novel Nanocomposite thin film materials (Ag0(NP)/TiO2) using the template process. Surface morphology of materials was obtained by the Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) analyses. The presence of doped Ag-nanoparticles was confirmed by the TEM images along with the SEM-EDX analyses. The Atomic Force Microscopic images were demonstrated the surface roughness and thickness of Nanocomposite thin films. X-ray diffraction analysis confirmed that TiO2 was predominantly present to its anatase mineral phase. The Fourier Transform Infra-red analysis conducted to obtain the functional groups present with the solid. The specific surface area and pore sizes of Nanocomposites were obtained by the BET (Brunauer, Emmett, and Teller) analysis. Further, the Nanocomposite thin film photocatalysts were successfully employed in the degradation of emerging micro-pollutants viz., the antibiotics tetracycline and sulfamethoxazole from aqueous solutions using less harmful UV-A light (λmax 330 nm). The effect of solution pH (pH 4.0-8.0) and pollutant concentrations (1.0 mg/L-20.0 mg/L (for tetracycline) and (0.5 mg/L-15.0 mg/L (for sulfamethoxazole)) was extensively studied in the photocatalytic removal of these antibiotics. A significant decrease in percentage of non-purgeable organic carbon removal indicated that the micro-pollutants was substantially mineralized by the photocatalytic treatment. The stability of thin film was assessed by the repeated use of Nanocomposite thin films and results were indicated that the degradation of tetracycline or sulfamethoxazole was almost unaffected at least for six cycles of photocatalytic operations. The presence of several cations and anions in the degradation of these antibiotics was studied. Additionally, the presence of 2-propanol and EDTA inhibited significantly the degradation of these micro-pollutants i.e., the percentage of degradation was decreased by 31.8 and 24.2% (for tetracycline) and 42.8 and 39.9% (for sulfamethoxazole), respectively. This indicated that the degradation of tetracycline or sulfamethoxazole was predominantly proceeded by the OH radicals; generated at the valance and conduction band of semiconductor. Similarly, the presence of sodium azide inhibited the percentage removal of these antibiotics.

Enhanced biomass production through optimization of carbon source and utilization of wastewater as a nutrient source.

The study aimed to utilize the domestic wastewater as nutrient feedstock for mixotrophic cultivation of microalgae by evaluating appropriate carbon source. The microalgae Chlorella vulgaris was cultivated in municipal wastewater under various carbon sources (glucose, glycerol, and acetate), followed by optimization of appropriate carbon source concentration to augment the biomass, lipid, and carbohydrate contents. Under optimized conditions, namely of 5 g/L glucose, C. vulgaris showed higher increments of biomass with 1.39 g/L dry cell weight achieving biomass productivity of 0.13 g/L/d. The biomass accumulated 19.29 ± 1.83% total lipid, 41.4 ± 1.46% carbohydrate, and 33.06 ± 1.87% proteins. Moreover, the cultivation of Chlorella sp. in glucose-supplemented wastewater removed 96.9% chemical oxygen demand, 65.3% total nitrogen, and 71.2% total phosphate. The fatty acid methyl ester obtained showed higher amount (61.94%) of saturated fatty acid methyl esters associated with the improved fuel properties. These results suggest that mixotrophic cultivation using glucose offers great potential in the production of renewable biomass, wastewater treatment, and consequent production of high-value microalgal oil.

Integration of microalgal cultivation system for wastewater remediation and sustainable biomass production.

Untreated wastewaters have been a great concern and can cause major pollution problems for environment. Conventional approaches for treating wastewater involve tremendous capital cost, have major short comings and are not sustainable. Microalgae culture offers an interesting step for wastewater treatment. Microalgae serve the dual purpose of phycoremediation along with the production of potentially valuable biomass, which can be used for several purposes. The ability of microalgae to accumulate nitrogen, phosphorus, heavy metals and other toxic compounds can be integrated with wastewater treatment system to offer an elegant solution towards tertiary and quaternary treatment. The current review explores possible role of microalgal based wastewater treatment and explores the current progress, key challenges, limitations and future prospects with special emphasis on strategies involved in harvesting, boosting biomass and lipid yield.

Effect of the N/P ratio on biomass productivity and nutrient removal from municipal wastewater.

The aim of this study is to investigate the effect of the N/P ratio on biomass growth with the simultaneous removal of nutrients from municipal wastewaters. An optical panel photobioreactor is employed for this investigation because it provides a uniform light distribution within the reactor, which enhances the efficiency of the reactor in the cultivation of microalgae. The N/P ratio is varied over a wide range, i.e., from 5 to 30, for the assessment of its effect on biomass productivity. There is not a strong correlation between biomass productivity and TN removal, and these factors do not seem to be proportional in the wastewater using the microalgae we employed. In contrast, the TP removal depends greatly on both the N/P ratio and biomass productivity. The optimum value of the N/P ratio for biomass productivity in and nutrient removal from municipal wastewater treatment using microalgae varies from 5 to 30, depending on the ecological conditions in the wastewater.

Harvesting of microalgae species using Mg-sericite flocculant.

In this study, Mg-sericite was used as a flocculant to harvest freshwater microalgae Chlorella vulgaris. Mg-sericite separated successfully >99% of the C. vulgaris at the following optimal parameters: sericite and MgCl2 ratio (S/M ratio) of 45 to 15, mixing time of 5 min, mixing rate 100 to 150 rpm and settling time of 5 min. The harvesting efficiency was pH dependent. The highest harvesting efficiency (99 ± 0.3%) was obtained at S/M ratio 40 and pH 9-11. These results indicated that a biopolymer, Mg-sericite, can be a promising flocculant due to its high efficiency, low-dose requirements, and short mixing and settling times. In addition, Mg-sericite does not contaminate the growth medium, which can be recycled to reduce not only the cost and the demand for water, but also the extra operational costs for reusing the growth medium. This harvesting method is helpful to lower the production cost of algae for biodiesel.

A mini review: photobioreactors for large scale algal cultivation.

Microalgae cultivation has gained much interest in terms of the production of foods, biofuels, and bioactive compounds and offers a great potential option for cleaning the environment through CO2 sequestration and wastewater treatment. Although open pond cultivation is most affordable option, there tends to be insufficient control on growth conditions and the risk of contamination. In contrast, while providing minimal risk of contamination, closed photobioreactors offer better control on culture conditions, such as: CO2 supply, water supply, optimal temperatures, efficient exposure to light, culture density, pH levels, and mixing rates. For a large scale production of biomass, efficient photobioreactors are required. This review paper describes general design considerations pertaining to photobioreactor systems, in order to cultivate microalgae for biomass production. It also discusses the current challenges in designing of photobioreactors for the production of low-cost biomass.

Effect of optical panel thickness for nutrient removal and cultivation of microalgae in the photobioreactor.

The aim of this study was to quantitatively evaluate the effect of the illumination area and the thickness of the optical panel (OP) on the biomass growth of Chlorella vulgaris (C. vulgaris) algae with simultaneous removal of nutrients. For this purpose, three different thicknesses of OPs were used and designated as follows: 4 mm v-cut OP (Run 1), 6 mm v-cut OP (Run 2) and 8 mm v-cut OP (Run 3). The results indicated that the Run 2 and Run 3 samples possessed higher chlorophyll content, as calculated per cell and per unit area of the cell volume, and a shorter doubling time compared to the Run 1 samples. The growth of the biomass using Run 2 and Run 3 was approximately 11.18 %, and this growth was higher than that of Run 1. Furthermore, higher nutrient removal was observed with Run 2 than Run 1. The nutrient removal, biomass growth and specific growth rate for the Run 2 and Run 3 fractions were found to be almost identical. However, in terms of economic consideration, Run 2 with simultaneous nutrient removal was more effective than Run 1 and Run 3 in cultivating the microalgae C. vulgaris.

A novel optical panel photobioreactor for cultivation of microalgae.

In this study, a novel optical panel photobioreactor (OPPBR) equipped with a V-cut/or flat optical panel (OP) and a light source, i.e., light-emitting diodes (LEDs) was developed. The performance of this OPPBR was assessed using cultures of Chlorella vulgaris. Growth rates of biomass were compared in bioreactors operated separately using a V-cut OP, or a flat-plate OP both equipped with LEDs or a fluorescent light source without any OP. The experiments were conducted at neutral pH (7.2 ± 0.3) with an initial cell concentration of 0.15 ± 0.05 g L(-1), at 23 ± 1 °C under dark and light cycles of 8 and 16 h, respectively, using LEDs and fluorescent lamps for 11 days. The results demonstrated that the amount of biomass produced using the V-cut OP was three times higher than the flat-plate OP and five times higher than without the OP. Parametric studies demonstrated that a distance of 3 mm between the OP and the LEDs produced the highest illumination uniformity, i.e., 65.7% for the flat-plate OP and 87.6% for the V-cut OP. The OPPBR system can be scaled up and could be used to enhance biomass production using an LED and OP combination.

Photocatalytic removal of Escherichia coli from aquatic solutions using synthesized ZnO nanoparticles: a kinetic study.

Development of effective and low-cost disinfection technology is needed to address the problems caused by an outbreak of harmful microorganisms. In this work, an effective photocatalytic removal of Gram-negative bacteria Escherichia coli from aqueous solution was reported by using ZnO nanoparticles under UV light irradiation. The effect of various parameters such as solution pH, ZnO dosage, contact time and initial E. coli concentration were investigated. Maximum photocatalytic disinfection was observed at neutral pH because of the reduced photocatalytic activity of ZnO at low and high pH values originated from either acidic/photochemical corrosion of the catalyst and/or surface passivation with Zn(OH)(2). As the ZnO dosage increased, the photocatalytic disappearance of E. coli was continuously enhanced, but was gradually decreased above 2 g/L of ZnO due to the increased blockage of the incident UV light used. The optimum ZnO dosage was determined as 1 g/L. Photocatalytic removal of E. coli decreased as initial E. coli concentration increased. Three kinetic models (zero-, first- and second-order equations) were used to correlate the experimental data and to determine the kinetic parameters.

Efficient and selective use of functionalized material in the decontamination of water: removal of emerging micro-pollutants from aqueous wastes.

The contamination of the aquatic environment with emerging micro-pollutants is a serious global concern. The aim of this investigation was to synthesize novel functionalized material (BNAPTES) precursor to natural bentonite in a single pot facile synthetic route. The material was utilized for efficient and selective removal of tetracycline (TC) and triclosan (TCS) in aqueous wastes. The grafting of silane was confirmed with the FT-IR (Fourier Transform Infra-Red) analysis and the EDX (Energy Dispersive X-ray) analysis showed the incorporation of amino group with the bentonite. The structural changes of clay due to silane grafting were studied with the help of XRD (X-ray Diffraction) and BET (Brunner-Emmett-Teller) surface area analyses. Batch adsorption studies showed that functionalized clay significantly increased the selectivity and adsorption capacity of bentonite for TC and TCS. The Langmuir monolayer adsorption capacity was found to be 15.36 and 17.15 mg/g for TC and TCS, respectively. The rapid uptake of TC and TCS by functionalized material followed pseudo-second-rate kinetics. Further, a total of 78% of TC and 73% of TCS were removed within 5 min of contact and the adsorption equilibrium was achieved within 120  min. The influence of background electrolytes and co-existing ions indicated that TC and TCS were selective towards BNAPTES. The loading capacities of the column packed with BNAPTES were found to be 56.00 and 44.42 mg/g for TC and TCS, respectively. Further, BNAPTES was found efficient even in real water treatment since the attenuation of TC and TCS was not affected significantly in the real water matrix.

Machine learning-based modeling of malachite green adsorption on hydrochar derived from hydrothermal fulvification of wheat straw.

This study investigated the efficiency of hydrochar derived from hydrothermal fulvification of wheat straw in adsorbing malachite green (MG) dye. The characterizations of the hydrochar samples were determined using various analytical techniques like SEM, EDX, FTIR, X-ray spectroscopy, BET surface area analysis, ICP-OES for the determination of inorganic elements, elemental analysis through ultimate analysis, and HPLC for the content of sugars, organic acids, and aromatics. Adsorption experiments demonstrated that hydrochar exhibited superior removal efficiency compared to feedstock. The removal efficiency of 91 % was obtained when a hydrochar dosage of 2 g L-1 was used for 20 mg L-1 of dye concentration in a period of 90 min. The results showed that the study data followed the Freundlich isotherms as well as the pseudo-second order kinetic model. Moreover, the determined activation energy of 7.9 kJ mol-1 indicated that the MG adsorption was a physical and endothermic process that increased at elevated temperatures. The study also employed an artificial neural network (ANN), a machine learning approach that achieved remarkable R2 (0.98 and 0.99) for training and validation dataset, indicating high accuracy in simulating MG adsorption by hydrochar. The model's sensitivity analysis demonstrated that the adsorbent dosage exerted the most substantial influence on the adsorption process, with MG concentration, pH, and time following in decreasing order of impact.

An induced annual modulation signature in COSINE-100 data by DAMA/LIBRA's analysis method.

The DAMA/LIBRA collaboration has reported the observation of an annual modulation in the event rate that has been attributed to dark matter interactions over the last two decades. However, even though tremendous efforts to detect similar dark matter interactions were pursued, no definitive evidence has been observed to corroborate the DAMA/LIBRA signal. Many studies assuming various dark matter models have attempted to reconcile DAMA/LIBRA's modulation signals and null results from other experiments, however no clear conclusion can be drawn. Apart from the dark matter hypothesis, several studies have examined the possibility that the modulation is induced by variations in detector's environment or their specific analysis methods. In particular, a recent study presents a possible cause of the annual modulation from an analysis method adopted by the DAMA/LIBRA experiment in which the observed annual modulation could be reproduced by a slowly varying time-dependent background. Here, we study the COSINE-100 data using an analysis method similar to the one adopted by the DAMA/LIBRA experiment and observe a significant annual modulation, however the modulation phase is almost opposite to that of the DAMA/LIBRA data. Assuming the same background composition for COSINE-100 and DAMA/LIBRA, simulated experiments for the DAMA/LIBRA without dark matter signals also provide significant annual modulation with an amplitude similar to DAMA/LIBRA with opposite phase. Even though this observation does not directly explain the DAMA/LIBRA results directly, this interesting phenomenon motivates more profound studies of the time-dependent DAMA/LIBRA background data.

Biomass-derived materials in the remediation of heavy-metal contaminated water: removal of Cadmium(II) and copper(II) from aqueous solutions.

Manganese-coated activated carbon (MCAC) and activated carbon were used in batch experiments for the removal of cadmium(II) and copper(II). Results showed that uptake of Cd(II) and Cu(II) was unaffected by increases in pH (3.0 to 8.5) or concentration (1 to 20 mg/L). Increased ionic strength (from 0.001 to 1 M NaNO3), however, significantly affected the uptake of Cd(II); adsorption of Cu(II) was not affected. Freundlich adsorption isotherm results indicated that MCAC possessed higher sorption capacity than activated carbon. Second-order rate constants were found to be 0.0386 for activated carbon and 0.0633 g/mg x min for MCAC for Cd(II) and 0.0774 for AC and 0.1223 g/mg x min for MCAC for Cu(II). Column experiments showed that maximum sorption capacity of MCAC was 39.48 mg/g for Cu(II) and 12.21 mg/g for Cd(II).

Effects of potassium and magnesium in the enhanced biological phosphorus removal process using a membrane bioreactor.

This study assessed the role of potassium (K+), magnesium (Mg2+), and calcium (Ca2+) ions in the enhanced biological phosphorus removal (EBPR) from wastewaters using a membrane bioreactor (MBR). A linear relationship in the anaerobic and aerobic/ anoxic phases for P(uptake) versus P(release) was obtained using the known equation deltaP(uptake) = a x deltaP(release)+ b, where the constants "a" and "b" were found to be 0.44 and 8.40, respectively. Both potassium and magnesium were soluble with phosphate in the anaerobic phase, but they accumulated again during the successive aerobic/anoxic phase. The linear correlation coefficients (R2) of K+/PO4-P and Mg2/PO4-P were calculated as 0.6682 and 0.8884, respectively. The molar ratio of C(K/P) during anaerobic phosphorus release was observed to be 0.20 mol/mol, whereas C(Mg/P) was 0.21 mol/mol. Furthermore, unlike potassium and magnesium, calcium was not co-transported with phosphorus during the release and uptake processes.