Nitrate removal from aqueous solutions by magnetic nanoparticle

Introduction: Due to causing methemoglobinemia, different cancers, and teratogen effects in human nitrate contamination of water resources has become a critical environmental problem Therefore, the aim of this work was to determine the optimum condition of nitrate sorption onto magnetic nanoparticle

Materials and Methods: The removal of nitrate from aqueous solutions by magnetic nanoparticles has been studied through using batch adsorption method. X-ray diffraction [XRD], Transmission Electron Microscopy [TEM], and Scanning Electron Microscopy [SEM] was applied to characterize the synthesized Fe[3]O[4]. The effect of pH, nano-magnetic, adsorbent dose, initial concentration of nitrate, and contact time were investigated

Results: According to SEM and TEM images, the adsorbent particles were nanosized and spheroidal; the sizes were about 20-30 nm. The experiments' results indicated that the optimum adsorbent dose was 750 mg in 1000 ml of solution, with a contact time of 90 min, while the optimum pH was 9. The kinetic models for nitrate adsorption showed rapid sorption dynamics by both first-order kinetic [R2 = 0.97] and second-order kinetic [R2 = 0.96] models. Nitrate adsorption equilibrium data were fitted well to the Freundlich isotherm than Langmuir isotherm

Conclusion: The results showed that, magnetic nanoparticles can be used as a low cost and efficient adsorbent for removal of nitrate from aqueous solutions

Effect of physical and chemical operating parameters on anaerobic digestion of manure and biogas production: a review

Introduction: The need for food produced from animal husbandry has made it a growing industry which result in increment of livestock waste. On the basis of environmental and economic considerations, these materials require treatment and management. Anaerobic digestion and creation of biogas are the most effective methods of waste management. Several parameters affect the anaerobic digestion of animal wastes which should be studied in order to optimize the biogas production of reactors

Materials and Methods: The parameters affecting the performance of anaerobic processes in different scientific databases within 1984 -2016 were searched and related information were obtained

Results: A wide range of reactors with retention times of 0.5 to 140 days and organic loading rates from 0.11 to 7.5 grams per liter of organic matter in a day were studied based on the Volatile Solid [VS] in different temperature range. Also, studies conducted on mixing, co-digestion, changes in pH and ammonia content of the substrate, C/N ratio, as well as the effect of chemical interference were investigated

Conclusion: High COD removal decrease of VS were achieved in the range of 80-95 % and 65- 92 % respectively in bioreactors. The produced methane was also 48 mmol L[-1] to 4681.3 m[3] per month for reactors with a volume of 120 ml to 1330 m[3] achieved respectively at 37 and 55[degree]C from the Mesophilic and thermophilic temperatures. Results summarized on the physical and chemical conditions in this paper, can be used to study the effective parameters and optimize conditions used in biogas production

review of the performance of carbon nanotubes in reducing environmental pollution

Introduction: In recent times, one of the most important purposes of sustainable development has been defined as the protection of environmental health. Using appropriate and innovative infrastructures such as nanotechnology is a solution to walk along the path of sustainable development and solves many environmental problems. The purpose of this study is to review the application of carbon nanotubes in the removal of environmental pollutants, based on conducted studies

Materials and Methods: All scientific data related to the issue were collected from scientific databases of Google Scholar, Scopus, Elsevier, and SID to evaluate and conduct the study. Keywords such as carbon nanotubes, environmental pollutant, sustainable development, and environmental health were used. 85 articles were also used in this review research [1993-2016]

Results: Based on the evaluated studies, the results indicated that common methods of sewage treatment are not enough to remove the mentioned environmental pollutants completely. In the mentioned methods, despite high decomposition, the amount of mineralization has been reduced and the toxicity of wastewaters has remained unchanged or has increased. Adsorption has been propounded due to its simplicity and lower energy consumption compared with other methods. Carbon nanotubes [CNTs] are unique one-dimensional macromolecules which have high thermal resistance and chemical stability. Adsorption through CNT as the adsorbent in the treatment of drinking water and sewage polluted with pharmaceutical, petroleum, heavy metal, and leachate pollutants has been studied widely

Conclusion: This study indicated CNT as effective adsorbents that have high potential to protect the environment and promote sustainable development