Journal of Water and Environmental Nanotechnology
Year:2020 | Volume:5 | Issue:2|Papers Count:8

The etiological factors for increased risk of endocrine and reproductive disorders remain largely unclear but a huge number of data from in vitro, in vivo, and epidemiological studies, support the association of their incidence and prevalence with long term exposure to endocrine-disrupting chemicals /agrochemicals in the modern world. Engineered Nanomaterials (ENMs) could be considered as new alternatives to overcome the environmental challenges of endocrine-disrupting pesticides and fertilizers and to reduce human health risks of cancer and endocrine toxicity based on their unique physicochemical properties. Carbon nanotubes (CNTs) are the initiative members of the big family of ENMs used for developing "Nanotechnology-Based Agrochemical" but despite remarkable detoxifying effects mediated by CNTs, several controversies and key questions address the toxicity and endocrine-disrupting properties of these authoritative agents which may introduce to the global markets a new generation of as nano fertilizers, nano adsorbents, and nano pesticides soon. The actual issue stems from a limited number of studies invalid toxicology models on CNTs related endocrine disruption and absence of systematic reviews on CNTs exposure-mediated endocrine health hazards especially concerning epidemiological and human data. In this direction this systematic review focused on the following sub-topics: (1) an overview on CNTs applications as novel agrochemicals (2) environmental risks and benefits of CNTs 3) toxicokinetic and toxicodynamic of CNTs (4) contribution of CNTs in the pathogenesis of obesity, diabetes and cardiovascular effects 4) evidence on the involvement of CNTs in developmental and reproductive toxicities from in vitro and in vivo studies (5) conclusions and perspectives.

Activated Montmorillonite (AM) reveals as a low-cost and efficient adsorbent for the adsorption of nicotine and pyridine from aqueous solutions. In this study, the influence of several operation conditions (initial compounds concentration, volumetric flow rate, and height of bed) on the shape of breakthrough curves and the mass transfer resistance was evaluated. Adsorption experiments were developed to determine the adsorption isotherm of the system, then the adsorption of pyridine and nicotine onto activated Montmorillonite in single and binary systems has been studied using fixed-bed adsorption column. In continuous adsorption, Results show that the maximum nicotine uptake 0. 68 mmol/g of AM was achieved through electrostatic attraction and hydrogen bond at a pH = 6. 3, a flow rate of 1 ml/min and a height of bed equal to 12 mm. In binary mixtures, zeolite adsorption is governed primarily by the size of pollutants present in water. Thus, the bigger compound (in this case, Nicotine), was adsorbed more easily than the pyridine present in the mixture. Experimental data were fitted according to Fowler Guggenheim for the isotherms and Wolborska model for the breakthroughs. AM was regenerated by ethanol and the results show that about 94% of the adsorption capacity is maintained after three times of cyclic adsorptiondesorption process.

At present, the synthetic compounds are wide choice as indicators in various acid-base titrations. Due to strict environmental regulations, search for eco-friendly compounds as an effective indicator of various acid-base titrations was started. The current vocation highlights the exploit of Areca catechu seed extract as an efficacious indicator for various acid-base titrations and to determine their Ka values. The Areca catechu seed is easily available and easy to extract. The extraction performed using the Soxhlet extraction apparatus. UV-Vis spectroscopy, FT-IR spectroscopy, XRD, physical properties (density, viscosity, surface tension, and refractive index) and qualitative phytochemical screening was performed for the proper identification of the Areca catechu seed extract. The Areca catechu seed extract exhibits sharp color change at the endpoint during the various acid-base titrations. The specific contrast between their colors in both the acid and alkali media made species present in the Areca catechu seed extract suitable for the eco-friendly indicator for four acid-base titrations. The endpoint obtained by the extract of Areca catechu seed coincides with the endpoint obtained by the standard synthetic indicator. Areca catechu seed is found to be economical, useful, accurate, simple, and eco-friendly.

The catalytic wet peroxide oxidation of phenol from aqueous wastewater and COD reduction over CuMn2 and Cu-Co2 nano mixed oxides are reported. The effects of process variables of pH, reaction time, and hydrogen peroxide dosage were investigated in the process over both catalysts. The catalysts were characterized by X-ray diffraction (XRD) and it was concluded that the mixed oxides are in the form of the spinel structure. However, a little bit CuO was found in the mixed oxides. The morphology and particle size of the catalysts were investigated by scanning electron microscope (SEM). The morphologies and particle size of the catalyst were approximately the same with an average range of 40-60 nm. The catalytic results indicated the higher activity of CuCo2 O4 spinel. The phenol oxidation on Cu-Co2 oxide was 82% after 40 min, whereas on the Cu-Mn2 oxide was 78% even after 50 min. The COD reduction The higher activity and reusability of the Cu-Co2 catalyst is attributed to the high synergistic effect between CuO particles and Cu-Co2 spinel, promoting phenol degradation.

The present study was performed on the adsorption of 2, 4-Dichlorophenoxyacetic acid from aqueous solutions by amine-modified magnetic nanoparticles. The adsorbent was synthesized by the coprecipitation method. The adsorbent properties of Fe3 O4 @SiO2-NH2 were investigated using XRD, FTIR, TGA, VSM, and TEM. Adsorbent efficacy was studied by investigating the effect of pH, initial concentration of pollutants, and adsorbent dose, and times. Finally, kinetics equations and isotherms models were used to describe the data. The results showed that the highest removal percentage was observed at pH 6 and the initial concentration of 20 mg/l of 2, 4-Dichlorophenoxyacetic acid. The adsorption capacity was increased by 65. 3% bypassing the time from the beginning of the process to 60 min. The results from the study of isotherms and adsorption kinetics presented that the sorption procedure follows the pseudo-second-order kinetics and the Langmuir isotherm with R2> 99. The maximum adsorption capacity of Fe3 O4 @SiO2-NH2 is 116. 3 mg/g. Besides, thermodynamic studies have shown that the adsorption process in the present study is endothermic and spontaneous. The experiments showed that Fe3 O4 @ SiO2-NH2 synthesized nanoparticles could be an excellent method to remove 2, 4-Dichlorophenoxyacetic acid contaminants from the aqueous solutions due to the high efficiency, simplicity, and lack of secondary contamination in the solution.

Remediation of soils polluted with heavy metals or petroleum hydrocarbons is one of the environmental problems. This research aimed to evaluate the effect of carbon nanotubes, zeolite, and AMF on triticale Ni concentration in a soil co-contaminated with diesel fuel and Ni. Treatments consisted of applying multiwalled carbon nanotubes (MWCNs) and zeolite at the rates of 0, 1 and 2 % (W/W) in a Ni-polluted soil (0, 75 and 150 mg Ni/kg soil) which was naturally polluted with diesel fuel under cultivation of triticale plant inoculated with AMF. After 70 days, plants were harvested and soil and plant Ni concentration were measured using atomic absorption spectroscopy (AAS). Soil microbial respiration and degradation of diesel fuel were also measured. Applying 2 % (W/W) zeolite and MWCNs significantly increased the diesel fuel degradation in soil by 12. 3% and 14. 5 %, respectively, while the plant Ni concentration was decreased by 8. 9 % and 13. 1%, respectively. Increasing soil pollution with Ni from 0 to 75 mg/kg soil significantly decreased the degradation of diesel fuel in the soil under cultivation of plant inoculated with AMF by 14. 4%. In addition, the soil microbial respiration was also decreased by 11. 8%. The results of this study showed that the application of zeolite and MWCNs had a significant effect on increasing diesel fuel degradation in heavy metal polluted soil that is a positive point in environmental studies.

This research work aims to investigate the sorption characteristic of synthesized polypyrrole/ polyaniline (PPy/PANI) nanofiber for Cu(II) removal from paper mill wastewater. The sorption is carried out by a batch method. The structural characterization of this sorbent was performed by SEM and FTIR analysis. The optimum conditions of copper sorption from paper mill wastewater onto PPy/PANI were found to be: pH=6, contact time 12min and 0. 4 g of sorbent in 100ml in wastewater. The kinetic studies showed that the sorption process was well described by the pseudo-second-order kinetic model. Also, Langmuir isotherm provided the best fit to the equilibrium data. Also, the effect of temperature on the process was found that the temperature has a positive effect on the process. Thermodynamic parameters showed that the sorption of copper onto nanofiber was feasible, spontaneous, and endothermic understudied conditions.

Reactive Black 5 is a toxic dye that has adverse effects on the environmental ecosystems and the health of human beings. Therefore, its removal is very important. Among the reported methods adsorption gathered huge attention in recent years because of its simplicity and low-cost. In this review paper, the removal of reactive black 5 by adsorption method from wastewaters was evaluated and all of the achievements from the past to the present were discussed in detail. The influence of important operational parameters on the adsorption efficiency of reactive black 5 such as pH, temperature, adsorbent dosage, and initial dye concentration was investigated. In addition, the reported adsorbents for reactive black 5 were divided into different groups based on their nature (like nanostructures, natural materials, by-products, and chitosanbased adsorbents) and their important characteristics, including adsorption capacity, removal percentage, initial dye concentration, repeatability, the synthesis cost, and optimized experimental parameters are compared with each other in detail. Moreover, important conclusions have been made from the surveyed literature and some suggestions are proposed for future works.