Journal of Water and Environmental Nanotechnology
Volume:3 Issue: 2, Spring 2018

The aim of this study was to expand an ecofriendly route for the fabrication of spherical shape silver nanoparticles (AgNPs) using an aqueous extract of Leucaena leucocephala L. leaves to act as stabilizing and reducing agent. Several biomolecules present in plant extract are accountable for single step reduction of metal ions into nanoparticles. The synthesized AgNPs were characterized by X-ray diffraction (XRD) profile, Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Energy-dispersive X-ray spectroscopy (EDS) and Photoluminescence. Besides these, AgNPs evinced potent antibacterial, antimalarial and antimycobacterial activity against Pseudomonas aeruginosa, Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Salmonella typhi, Bacillus subtilis, Plasmodium falciparum and Mycobacterium tuberculosis. The results suggest that the efficiently synthesized AgNPs can be used as potential candidates for various medicinal applications in bionanotechnology based industries.

The present study reports one step green synthesis of silver nanoparticles using Gymnema sylvestre aqueous extract at room temperature and their usage in the photodegradation of methyl orange dye. The silver nanoparticles are synthesized using an aqueous extract of stem and root of Gymnema sylvestre. UV-Visible spectral analysis showed absorbance peak at 430 nm with special reference to the excitation of surfaces plasmon vibration by silver nanoparticles. FT-IR analysis of nanoparticles reveals the presence of molecular functional groups such as amides, phenolic compounds, and carboxylic acid. These phytochemicals act capping and stabilizing agents for silver nanoparticles. EDAX elemental analysis shows the presence of silver as the main element in synthesized nanoparticles. The average crystalline size of silver nanoparticles was found to be 25.3 nm and 9.97 nm for Stem-AgNPs and Root-AgNPs respectively by Scherer formula. XRD patterns also suggest the occurrence of crystalline silver ions. Further, photocatalytic degradation of methyl orange was measured spectrophotometrically by using silver nanoparticles as nanocatalyst under solar light effect. The results revealed that biosynthesized silver nanoparticles using G. sylvestyre was found to be notable in degrading methyl orange dye under the influence of sunlight.

This paper describes the photocatalytic degradation of Reactive Blue 19 (RB-19) and Reactive Red 76 (RR-76) dyes pollutant in the industrial wastewater using TiO2, C-doped TiO2(C-TiO2), S-doped TiO2 (S-TiO2) and C,S co-doped TiO2 (C,S-TiO2)nanoparticles as photocatalysts, which were synthesized via sol-gel process. The prepared photocatalysts were characterized by scanning electron microscopy (SEM), X-Ray diffraction (XRD), Fourier transformer infra-red spectroscopy (FTIR), Energy dispersive spectroscopy (EDAX) and ultraviolet-visible absorption spectroscopy (UV-Vis). The dyes degradation was investigated under several experimental parameters such as pH, catalyst load, dye concentration, shaking speed, irradiation time and catalyst recovery. The photocatalytic dose was found to be 1.6 g/L and the efficiency of RB-19 and RR-76 photocatalytic degradation attained 100 % after 1 h irradiation time under visible light. The chemical oxygen demand (COD) values were determined for wastewater and treated wastewater. Toxicity and biological activity of the treated and untreated wastewater on marine aquatic organisms rotifer, artemia and Vibrio parahaemolyticus were investigated.

In this communication, an advanced, simultaneous mass and heat transfer model has been developed to take a meticulous glance on the influences of different parameters on Persian Gulf seawater desalination using Sweeping Gas Membrane Distillation (SGMD) technique. This essay focuses on the increasing the distillate flux by investigation of the physical properties and feed temperature of the sweeping gas membrane distillation on the seawater desalination. The effects of operating parameters, including feed temperature, salt concentration, sweeping gas temperature, and heat transfer coefficient on the distillate flux of the Persian Gulf seawater have been investigated. The effect of feed temperature on temperature polarization has also been studied. By increasing the feed temperature from 25 oC to 60 oC, the temperature polarization increases and the polarization coefficient (TPC) decreases; for instance, for membranes with PP, the TPC decreases from 0.95 to 0.905. By increasing the feed temperature, higher fluxes are achieved for both the gas velocities. Therefore, by increasing the feed temperature from 50 oC up to 80 oC, the distillate flux grows 9 times. Also, the distillate flux for membrane with PVDF as polymer increased from 0 to 4.2 by increasing the feed temperature from 40 oC to 70 oC. The model predictions show a small error of 3.6% with the experimental data reported in literature which indicates the reliability of simulated results.

Heavy metals pollution in the environment is one of the serious problems in the field of water and wastewater management. In this study; calcium carbonate nanoparticles, synthesized by an efficient and novel method, were used as an adsorbent for the removal of lead and iron from aqueous solutions. To study the mechanism of adsorption, the kinetic and isotherm models were examined. The adsorption kinetics of process was found to follow a pseudo-second-order equation. The maximum monolayer adsorption capacities of calcium carbonate nanoparticles calculated from Langmuir isotherm were found to be 1210±30 mg/g for Pb(II) and 845±8 mg/g for Fe(II) ions, respectively. The response surface methodology based on three variable Box-Behnken design was utilized to evaluate the effects of temperature (25-65 oC) and initial metal concentration (10-200 mg/L) on the sorption process. The optimum conditions for the removal process using calcium carbonate nanoparticles were found to be 200 mg/L at 25 oC. Experimental data demonstrated that a precipitation transformation mechanism rather than adsorption enhances the removal efficiency.

In the current research work the Iranian natural zeolite (clinoptililite) was modified with Cobalt Hexacyanoferrate nanopatricles. The natural and Cobalt Hexacyanoferrat modifed zeolites were characterized by FTIR and SEM techniques  and were empolyed as an adsorbent for removal Cd(II) ions from aqueous sloution. The adsorption expriments were performed in bach mode. The Cd(II) sorption capacity of Cobalt Hexacyanoferrat modified zeolite was 51 mg g-1. The effect of influceing factors such as time, temperature and initial concentration were investigated. A fast sorption was observed in the initial contact time and equilibrium was achieved in less than 100 min. The equilibrium adsorption data for Cd (II) were better fitted to the Longmuir adsorption isotherm model. The increase in temperature has a slight positive effect on the uptake of Cd(II) ions. The results indicated that the Cobalt Hexacyanoferrate nanopatricles modified natural zeolite has effective potential for the adsorption of Cd(II)  from the wastewater.

The purpose of this investigation is to study the influence of Spruce sawdust (SD) coated by magnesium oxide (MgO) nanoparticles in the removing of methylene blue (MB) from an aqueous solution which is in a batch system. The adsorbent was characterized by FTIR, FE-SEM, BET and XRD analysis. The high adsorption potential of SD-MgO nano-biocomposite was revealed by these findings, therefore, it is usable for dye-containing wastewater treatment. By investigating the impact of particular conditions like MB concentrations, the dose of adsorbent and pH, it became possible to confirm the effectiveness of the process. The OOP (which stands for Optimum Operating Parameters) were evaluated by RSM (which stands for Response Surface Methodology) which is based on BBD (Box-Behnken design) and is used for removing MB dye. The adsorbent dosage is the highest effective degree of the individual factor on MB removal. Maximum removal of MB dye was detected at pH 11 with 3.50 g L-1 adsorbent dosage. The surface area of 0.873 m2 g-1 and mesoporous adsorbent prepared gave good adsorption capacity of 26.657 mg g-1 for MB. Furthermore, in order to predict the empirical variables’ significance, the variances’ analysis (ANOVA) was used. The predicated removal efficiency which is proved to be the potency of the process and its effectiveness was found to be 94.05%. Different equilibrium and kinetic models were utilized to the experimental data. Both Pseudo-second order kinetic model and Freundlich adsorption isotherm showed the better fitness to the experimental data.

Effect of crystallization time and temperature on the membrane structure and performance has been investigated for Nano-pore Hydroxysodalite (HS) zeolite membranes. Molar composition of the starting gel of the HS zeolite membranes were: SiO2/Al2O3=1.0-5.0, Na2O/Al2O3=15-65, and H2O/Al2O3=500-1500. X-ray diffraction (XRD) patterns of the membranes exhibited peaks corresponding to the support and the zeolite. The crystal species was characterized by XRD and the morphology of the supports subjected to crystallization was characterized by Scanning Electron Microscopy (SEM). Separation performance of HS zeolite membranes was studied for water-Ethanol mixtures using pervaporation (PV). The membranes showed good selectivity towards water in the water-Ethanol mixtures. Water permeates faster because of its preferential adsorption into the Nano-pores of the hydrophilic zeolite membrane. In PV of water-Ethanol mixtures, the membrane exhibits a hydrophilic behavior, with a high selectivity towards water and a good flux. The best flux and separation factor of the membranes were 2.05 kg/m2.h and 10000, respectively. Effect of operating condition (temperature, flow rate and pressure) on the membrane performance was investigated for HS zeolite membranes grown onto seeded mullite supports. Finally, a comprehensive 2D model was developed for the PV of water-Ethanol mixture through HS zeolite membrane using Finite Element Method (FEM). Effect of varying dimensional factors, temperature and feed flow rate on the PV performance was studied.  The proposed model was masterfully capable of predicting concentration distribution within two sub-domains of feed and membrane.