For the first time, the present study removes ions of mercury, in the form of Hg (I) and Hg (II) ions, from aqueous solutions by adsorbing them onto titanium dioxide nanoparticles. The effects of various parameters, such as solution's initial pH, temperature, sorbent dosage, initial mercury concentration, and contact time have been examined on the adsorption process. The experimental results have been compared with Langmuir, Freundlich, and Temkin adsorption isotherms. The maximum adsorption, obtained for Hg (I) and Hg (II) ions, have been 97.5% and 98.6%, respectively. Also, it has been shown that the Langmuir isotherm has better fitting with the equilibrium data than the Freundlich and Temkin isotherms. Thermodynamic parameters of the adsorption, such as and  have been calculated, the negative values of which show that the mercury ions adsorption is an exothermic process and that randomness is decreased, respectively. The study of adsorption kinetics shows that the adsorption of Hg (I) and (II) ions with TiO2 nanoparticles is pseudo-second order.

A wide range of chemicals and dyes are being used in textile industry, and are often found in the wastewater produced. This study attempts to investigate the reduction of COD, TSS, and dye in effluents from the dyeing and washing unit of textile industry, using electrocoagulation process. The reactor is equipped with 10 iron electrodes, connected to a direct current (DC) source in a monopolar electrode configuration. In each stage of the experiment, 2.5 l of the effluent enters the reactor and the effects of a number of important operational parameters such as voltage, pH, and reaction time is studied on the removal of COD, TSS, and dye parameters. Results show that the optimum operational conditions are reaction time of 120 min, voltage of 30 V, and pH of 7, which reduces COD, TSS, and dye by 87%, 91%, and 98%, respectively. Therefore, it has been concluded that the efficiency of pollutants removal from the wastewater improves as voltage and reaction time are increased.

Petroleum refining industries produce large amounts of toxic effluents, causing environmental pollution. Iran is an oil-rich country that encounters oil pollution in its soil and water. Bioremediation of these pollutants is an appropriate solution to tackle them, compared to physical and chemical remediation methods. There are some factors that increase the rate of biodegradation; therefore, this study aims to determine the rate of gasoil bioremediation by two indigenous bacterial isolates (from oil-contaminated soils of an oil refinery south of Tehran) in two different media, namely soil and soil-sawdust mixture. The two superior indigenous bacteria has been isolated through three steps with results indicating that in an optimal environmental condition (temperature= 27±2 °C, humidity of 60%, water holding capacity, and daily manual aeration), bacterial isolates are able to degrade about 78.87% and 93.53% of gasoil during 45 days in soil and soil-sawdust mixture media, respectively. These results imply the role of sawdust in improving aeration, water holding capacity, and-consequently- increasing bioavailability of gasoil to bacteria.

The present study investigates the transesterification of corn oil with methanol over two oxides of MgO and ZnO at 65 ͦC and 1 atm. These two catalysts have been prepared via a conventional co-precipitation process. As for MgO, the corresponding mixed metal nitrate solution has been mixed and heated at the presence of urea. ZnO has also been synthesized by co-precipitation of metal acetate at the presence of oxalic acid and ethanol. The catalysts then have been characterized by means of X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM). XRD results indicate high purity for both catalysts. Also, catalytic activity has been evaluated in methanol reflux temperature through corn oil transesterification, with the impacts of reaction variables, like catalyst amount, methanol/oil molar ratio, and reaction time on biodiesel yield, investigated by means of HNMR spectrum. Under appropriate transesterification conditions at 65 °C (catalyst amount= 5%, methanol/ oil ratio= 20, and reaction time= 10 hr), an ME content of 62.61% can be achieved, using MgO catalyst. Similarly, the experiments have been repeated to achieve the best yield, using ZnO catalyst, with the highest rate, equal to 53.1%, obtained in 9% of catalyst and methanol/oil ratio of 30 over 10 hr. Furthermore, reusability of ZnO and MgO has been evaluated in transesterification reaction.

Conserving water resources and protecting them from pollution are of high account in the natural cycle of our life. This study has tried to determine the refining potential and capacity of water hyacinth (Eichhornia crassipes) in order to remove the cadmium from water, studying the influence of factors such as initial concentration of cadmium, contact time, absorbent mass, and pH. Results have shown that the best efficiency of cadmium, more than 99%, was obtained in the optimum conditions (i.e. retention time of 30 hours, adsorbent dose of three plants (12 stems), and pH=6.6). By increasing the initial concentration of cadmium from 0.28 to 8.28 mg/L, the elimination efficiency did not change; moreover, by increasing the absorbent mass, the elimination efficiency increased from 98.4 to 99.8 and the lowest retention time was obtained for the balance. All experiments have been repeated three times, showing in the end that water hyacinth is able to absorb cadmium up to 8.28 mg/L. This process follows Freundlich isotherm (R2=0.98). Results of this study indicate that this plant can grow well at high levels of cadmium and the growth of water hyacinth is better in the presence of cadmium than control conditions (city water). Finally, it can be concluded that it is necessary to provide a reliable, cheap, and fast method to eliminate pollution. Eichhornia crassipes, a promising plant with great functionality, can be used as a refiner in order to eliminate the heavy metals in wastewater (sewage) effluents, particularly industrial sewage.

This study presents the natural dye recovery from various biodegradable temple and household wastes. The raw material for colour extraction consisted residual flowers and garlands from various temples as well as onion and vegetables peels from vegetable markets, university hostels, and households, which were washed, dried, crushed, and sieved. The extracted natural colours were produced by means of ultra-sonication, and were dried in the spray drier, being characterized by FT-IR and UV-Vis Spectrophotometers. They were used to dye various fabrics such as cotton, silk, and wool, not to mention different mordents. It was found out that the remaining residue, left after dye extraction, was rich in nutrients, hence, it could be further used as the resource material, itself. As a result, we explored these residual wastes for vermicomposting and biochar production, which can be further employed as an organic fertilizer for agriculture. Overall, the present waste management approach will lead to a closed-loop environmental management through waste reduction and reutilization. It will also provide value-added materials for economic gains from waste. Thus, it can be promoted as a potential mechanism to maintain the environmental sustainability at wider scales.

Petroleum-polluted soil samples from Ahvaz oilfield were enriched, using three methods to detect microorganisms with different dibenzothiophene degradation capabilities. Strain NISOC-03, a nitrate-reducing, oxidase negative, catalase, citrate, and urease positive, gram negative rod, showed interesting dibenzothiophene desulfurization behavior, designated as Entreobacter sp. strain NISOC-03 based on phenotype and genotype analyses. Gas chromatography, biomass measurement, and Gibb’s assay showed that in the presence of benzoate as the carbon source, strain NISOC-03 utilized 64% of 0.8 mM dibenzothiophene, producing 0.27 mM phenyl phenol during the exponential growth phase, though the produced phenyl phenol was degraded in the stationary growth phase. In the presence of glucose as the carbon source, however, strain NISOC-03 metabolized only 19.6% of 0.8 mM dibenzothiophene. Furthermore, replacing glucose with ethanol or glycerol led to the same reduction of the dibenzothiophene utilization. It is thus concluded that the chemistry of the potential carbon source(s) in the culture medium has a significant influence on the quality and the rate of dibenzothiophene metablization, and the enrichment designation has a very vital effect on the biodegradation efficiency of the isolated microorganisms.

This study utilizes a decade long (2005-2014) monthly data of Total Column Tropospheric Ozone (TCTO) in Dubson units to evaluate the spatial and temporal trend of LAO over some major cities of West Africa, namely Lagos, Accra, Niamey, Abuja, Bamako, Dakar, Agadez, Conakry, Kano, and Ouagadougou which are either capital cites or major commercial hubs, where the population ranges from 0.09 million (Agadez, Niger) to over 9 million (Kano and Lagos, Nigeria). The mean (long term average) of TCTO in Lagos (Nigeria) was 34.4±0.6 DU (α=5%) for the entire period, being the highest in all major cities of this study. The lowest TCTO, 30.4±0.5 DU (α=5%), occurred in Bamako (Mali). It was also observed that the concentrations of TCTO vary seasonally. The seasonal changes in TCTO was investigated by categorizing months of the year to very dry months of December, January, and February (DJF), onset of rainy season months of March, April, and May (MAM), wet season months of June, July, and August (JJA), and end of rainy season months of September, October, and November (SON). Seasonal mean of TCTO is higher in all cities, close to the coast during DJF, and cities, north of latitude 12o N, during MAM, compared to rest of the seasons. Elevated TCTO concentrations can be attributed to transport mixing, due to the flow direction of well-known wind regime over the study area. This was established from the analysis of correlation coefficient between the mean of zonal, meridional winds, vertical wind speeds and divergence, and TCTO over region.

Plastics, one of the most abundant materials in the world today, are one of the main sources of pollution. People’s perception of using and disposing plastic bags is primordial as they tend to be a major part of household solid waste. This study aims to determine community’s perception of usage and disposal of plastic bags in Eastern Ethiopia. A quantitative cross-sectional study has been conducted in Harar city of Eastern Ethiopia, using a multi-stage statistical sampling technique. The data concerning all variables have been collected via pretested questionnaire and observational checklist with a response rate of 91% which has then been into SPSS and analyzed by STATA 11.0. About 51% open dump their plastic bag wastes. It has been shown that the majority (88.7%) of the responders perceived plastic bags as having environmental impacts, with 82.8% feeling a growth in their plastic bags utilization and about 54% thinking that plastic bags should be banned. It has also been illustrated that perception of plastic bags' environmental impacts and the willingness to pay for solid waste collection service has an association with plastic bag utilization. This study has found that utilization and open dumping of plastic bags rests at a significantly higher level. Community’s perceptions regarding environmental impacts of plastic bags have been at a higher level, which still requires consideration. A considerably high number of residents believe that utilization of plastic bag should be continued; therefore, a great emphasis should be given to bringing the desired attitudinal change.

The present study aims to analyze the existing indoor environmental conditions of Firozabad City along with its impact on people’s health by going through the correlative index of indoor environment’s determinant and different diseases, faced by the people. In order to measure spatial disparities, the statistical technique, i.e. the standard score additive model (Z- score), has been applied to develop a composite score for each set of indicators in order to arrive at the general environmental and health condition of the study area as a whole. The analysis reveals that high intensity of indoor pollution and disease are reported in peripheral and old parts of the city. Preventive measures, likely to have deleterious health effects and improve such harmful environmental conditions, should be adopted. Enhanced use of clean fuel and national uniform housing codes or guidelines that address factors, affecting indoor air quality, makes up the current need.