seyedeh bahareh azimi

The use of natural adsorbents in wastewater treatment is one of the efficient methods that, due to the availability of raw materials, the cost of the process is significantly reduced. Various natural organic and inorganic compounds can be used as adsorbents in this field. Contamination of water resources with aromatic compounds is one of the environmental problems that has attracted the attention of researchers. In general, phenolic compounds and their derivatives have harmful effects on living organisms even in low concentrations because the nitro aromatic componds have toxicity and mutagenic nature. According to the studies conducted in this field, the adsorption method using biochar can be a suitable method for removing aromatic compounds from the aqueous media.

In this study, due to the production of a large amount of biomass in Iran, the use of these compounds in the preparation of biochar as an adsorbent and its application to remove nitro phenol from water have been investigated. For this purpose, straw and stubble of pirozi garden of Tehran has been used as biomass. A laboratory system that is designed and constructed for this purpose, was used to prepare biochar. Biochar was prepared at a temperature of 350 °C and was used as an adsorbent after washing and drying. In order to assesse the general characteristics of the prepared biochar, surface morphology was performed by SEM analysis, surface chemical characteristics was assessed by FTIR analysis, heavy metal content was investigated by MOOPAM method using atomic absorption spectroscopy, and specific surface area of the produced biochar was checked by BET analysis. Also, the process has been modeled and optimized statistically using the CCD method.

Examining the characteristics of the prepared biochar showed that the prepared biochar has nano structure, which will lead to an increase in the surface area. Based on the results, specific surface area was 0.42 m2/g, the porosity volume was 0.04 cm3/g, and the average diameter of the holes was 361.76 nm. Also, the analysis of heavy metals in the produced biochar showed that the measured metal values are less than the allowable range of presence of heavy metals in biochar based on the IBI standard. After designing the experiment and performing the relevant experiments, statistical analysis was performed on the results. The results of statistical analysis showed that the process is well fitted with a quadratic model and has good accuracy. According to the prediction of the model, after 60 minutes of the process, this adsorbent can remove about 84.8% of nitrophenol with an initial concentration of 16.2 ppm, at pH = 4.2, using 47.12 mg of adsorbent per 100 ml of solution. In order to confirm the correct performance of the model, the process was experimentally checked under optimal conditions, and the average removal efficiency was 82.7%.

According to the obtained results, biochar as a natural material can be used as an adsorbent to remove nitroaromatic compounds. Also, the use of biochar, in addition to wastewater treatment, it leads to biomass waste management.

Wind erosion and thunderstorms bring about significant adverse consequences, including air pollution, reduced visibility, wear and tear of industrial machinery, soil structure destruction, and adverse effects on soil fertility. In recent years, the aerosol pollution caused by sand storms has turned into a serious health threat for Iranian people. In addition to being detrimental to human health, the adverse consequences mentioned above will also cause many problems for ecosystem processes. That is why the fight against erosion has received worldwide attention. The application of mulch is a method widely used to control wind erosion and stabilize sand grit and dust hotspots. Mulch is defined as any natural and artificial material that is promoted and applied to the soil surface together with crop residues, plastic films, asphalt, emulsion mulch, oil, petroleum residue, nano-clay matters, and livestock manure. Therefore, this study sought to examine the chemical properties of soils covered by two emulsion mulches.

This experimental study was conducted in some parts of large desert areas located in Aran and Bidgol counties. The treatment items examined in this study were the type of mulch, time of mulch application, and soil depth. In addition to harvesting soil samples covered with mulch, control soil samples were also collected for comparison. PH, EC, concentration of cations (Ca, Mg, K and Na), and anions (NO3, HCO3, SO4, Cl) were other parameters examined in this study.

The results showed that the application of emulsion mulch reduced the soil's pH and EC. In fact, reducing soil salinity leads to a decrease in soil cations and anions concentration, providing suitable conditions for plant growth and establishment by maintaining moisture and reducing evaporation. It was also found that moisture in soils covered by emulsion mulches was significantly higher than that of the control soil during the study period (12 months), reducing the concentration of cations. Considering the fact that the presence of emulsion mulch in the soil surface leads to a decrease in its concentration of cations compared to that of the control soil, this study's analysis of the dominant sodium cation in soil showed a significant decrease in treatment mulch compared to that of the control mulch. Moreover, the concentration of chlorine and sulfate anions was found to have decreased after the application of emulsion mulch, resulting in the creation of suitable conditions for plant cultivation in the region. In contrast, the study found that bicarbonate concentration in the soil increased due to the presence of carbon in the emulsion mulch structure compared to that of the control soil sample.

There was a significant decrease in the amount of salinity in the soil treated with both types of mulch compared to the control soil that received no mulch, the amount of which increased over time. The main reason for the reduction of salinity in the soil treated with the two types of mulch could be the reduced water evaporation from the soil surface caused by an increase in the soil's moisture. Code 1 emulsion mulch was more efficient in maintaining the soil moisture than the other type of mulch. Increasing moisture affects the soil's aggregation by increasing the adhesion between particles and, therefore, the velocity of wind erosion threshold will be decreased. Furthermore, the study found a decrease in the pH of the soil covered by mulches. This decrease in pH was more evident in surface samples, indicating a relative decrease in pH than that of the subsoil.As soil salinity decreases after mulch application, the concentration of cations is also expected to decrease. Among the cations examined in this study, the soil's dominant sodium cation suggested a significant decrease in treated emulsion mulch compared to that of the control mulch. Possessing a lower sand percentage, Code 2 emulsion mulch was found to have a more decreasing effect on the cation concentration after 12 months of its application. The study's results also revealed a reduction in the concentration of all studied cations, which occurred 12 months after the application of Code 2 emulsion mulch, while the concentration of the cations had not changed after six months of the application of the mulch.  The study also found that chlorine and sulfate anions significantly reduced in the studied anions of the treated soils. The final results of this study suggested that both types of applied mulch could contribute to reducing the effects of harmful cations and anions on plant growth and that the application of the mulches would allow more plants to be grown in such areas. Moreover, the results of long-term tests showed the efficacy of the two applied mulches in terms of their stability.

In this research, the removal efficiency of an Acid Brown-14 as azo dye was carried out by an adsorbing method using a magnetic-activated carbon adsorbent, through which separation of adsorbent could be performed by a magnet at the end of the process. A second-order reduced polynomial model is used for method and optimization. Based on the model foresight, the process can remove the dye up to 82 % under the optimum situations of the primary pH = 4.6, [Dye] = 20 ppm, and [Ads.] = 791 ppm at room temperature. An experimentally accurate assessment of the model revealed that the model has a good agreement with the model prediction.

In this study, surficial sediments along 9 stations (from Bilqan to Dizin and Varangeh_e Rood) were collected seasonally along 2017-2018 and water quality was assessed using enrichment index (EF) and Pollution load index (PLI).The percentages of sand, silt, clay in the sediment samples were determined (78, 17 and 5 respectively). The mean of Al, As, Cu, Fe, Ni, Pb, Cr, Zn, V, TP and TN in the sediment samples were 7.35±1.99%, 8.0±1.2 ppm, 41.0±30.2ppm, 3.56±0.53% , 24.33±4.87 ppm, 5.9-13.6 ppm and 21.8-28.8 ppm, 15.9±5.99 ppm, 36.08±11.45 ppm , 68.08±08.6 ppm, 88.9±23.3 ppm, 0.1±0.05% and 0.42±0.07% respectively. Based on cluster analysis, Asara and Shahrestanak (group1); Pool-e Khab and Gachsar(group2), Bilqhan, Varangh_e Rood, Hassankader and Dizin (group3); and Pool_e Choobi (group4) categorized into separate groups. In general, the concentration of nutrients and heavy metals in the stations did not exceed the PEL and SEL. The enrichment index for both chromium (0.2) and iron (0.8) showed a degree of non-enrichment at all stations. Other metals showed a low degree of enrichment and have low enrichment levels and, in terms of arsenic concentration, EF have been moderate to severe (4.9±1.1). According to the PLI index (1.35-1.9), all stations were more than one, so it can be concluded that all of them were polluted.

In this study, firstly, the process of changes in land coverage/usage was determined through satellite image analysis in the Dohezar and Sehezar forested landscape in Tonekabon County, Mazandaran Province during the years of 1984-2016 .Then, impacts of changes in land coverage/usage on the quantity of carbon sequestration and storage were mapped, quantified and valued using InVEST carbon model within the same time period. The result showed that dense and low-dense forest cover have been decreased by 18 and 55 percent, respectively during three decades, while semi-dense forest has been increased by 63 percent. It was also found that the effects of these structural changes in forest cover have reduced carbon sequestration capacity by 1927474 tons. This reduction has caused a loss of 53,137,258.80 US $ (equivalent to 568,568,699,160 billion rials) over three decades.