جستجوی مقالات مرتبط با کلیدواژه "environment" در نشریات گروه "شیمی"

Emerging heavy metal contamination of the environment urges researchers to implement effective resolutions against the toxic heavy metal resources worldwide. Waste biomass is expected to gain rapid scientific and industrial interest due to its excellent properties in heavy metal remediation. Biomass-derived carbon resources have attracted researchers’ attention worldwide. The biomass-derived carbon possessed versatile characteristics such as porosity, high surface area, higher graphitisation degree, etc. Much literature has discussed using carbon-based materials, including biochar, activated carbon, graphene, graphene oxide, carbon nanotubes, and carbon black for heavy metal remediation. Although improvements, modifications, and additions in their corresponding mechanisms still need to be understood. This review provides insight into recent approaches, progresses, challenges, and opportunities in the remediation of the heavy metal polluted environment using biomass-derived activated carbon and carbon materials. The mechanisms of biomass-derived carbon remediation of heavy metals included physical, chemical, and nanotechnological processes-based absorption. In addition, applying biomass in agricultural activities is an excellent alternative to synthetic fertilisers and pesticides to overcome the deposition of heavy metals in soil and water bodies. Furthermore, future progress, current research advances, challenges, and opportunities are discussed to promote biomass-derived carbon materials applications in heavy metal remediation for circular economy and eco-friendliness.

In this paper, the quantities of nanomaterials used in the construction industry in Iran in recent years have been estimated. Then the amounts of nanomaterials in different environments of water, air, soil, and municipal wastewater from 2015 to 2019 in Iran have been estimated. The results show that during these few years, the amount of imports of nanoparticles has been more than its production. This study shows that the highest concentrations of nanoparticles in different environments are SiO2, TiO2, Fe2O3, and carbon nanotube, respectively. While the concentration of TiO2 nanoparticles, carbon nanotubes, and Fe2O3 in different environments has increased with a gentle slope during five years. This could be due to the increasing use of these nanoparticles in the industry without control and the lack of appropriate filters to prevent nanoparticles from entering the environment. The results of this study show that during five years, the concentrations of SiO2, TiO2, carbon nanotube, Fe2O3 nanoparticles has increased by about 4%, 30%, 28%, and 45% in water and %11, 16%, 27% and 29% in air, respectively. Also, their concentrations in soil %23, 18%, 43% and 52% and in municipal wastewater %30, 27%, 37% and 61%, respectively.

Pesticides are helping to meet up the demand for population growth in today's agriculture. They are also being utilized for numerous issues including domestic pests control, home gardening, and disease vectors. Though, they are extremely poisonous in nature. They also cast false impact on surroundings. When used for the agricultural purpose, their toxic residues are continually left behind, and thus forming a major origin of pollution. The unwanted risky chemical groups are contaminating natural assets at a shocking rate. Agricultural pesticides left behinds are among the most harmful contaminants to the soil and water. Removing them from wastewaters is critical as they have bioaccumulation potential, toxicity, and a high persistence. Pesticides have long been used to improve manufacturing efficiency and extend the shelf-life of food goods. Their residues should be removed from food products and waters to limit human pesticide exposure. To remove pesticides, various processes are usually employed which include the adsorption process, membrane processes, and improved oxidation reactions, while microorganisms degrade them naturally i.e. bioremediation/biodegradation. Many organic and inorganic materials have been fabricated for rapid and complete degradation of pesticides. Semiconductor materials contribute to the pesticide oxidation and reduction because they have a proclivity for producing radicals through the charge separation. This review focuses on the pesticides’ taxonomy, functioning, their associated risks to human and environment, and degradation methods involving the current discoveries and progress in the utilization of several approaches for their probable removal from wastewater. The advanced oxidation, adsorption, bioremediation, photocatalysis, semiconductor materials, phytoremediation, and membrane technologies are some of these processes discussed in this investigation. In the upcoming researches, it will be required to generate the novel concepts in the current farming that will reduce the need of toxic pesticides and enable manufacturing of selective to target and less persistent pesticides.

Soil pollution has increasing risks for human health and environment. Heavy elements are considered among the most important pollutants in the environment, which have been highly concerned in the last few decades. The accumulation of heavy elements in the soil, especially in agricultural fields, is gradual and the concentration of heavy elements can reach a level that threatens human food security. Every year, thousands of tons of these elements, which are caused by urban, industrial, and agricultural activities, enter the soil. The study of different researchers inside the country shows that the intensification of industrial activities, on one hand, and the non-compliance of environmental issues and standards by some of the industrial owners, on the other hand, has caused environmental pollution in some areas of the country. Soil is one of the important components of earth's bio-travel and plays an important role in the health of humans and animals. Soil not only plays an important role in the production of food and clothing, but also has a significant effect on maintaining the environmental quality. Therefore, soil contamination by chemicals is one of the most important biological issues. In the last few decades, with the progress of industry, the amount of toxic elements in the soil has been increased. Municipal and industrial effluents, solid wastes from various urban, industrial and agricultural activities, various fertilizers, and chemical poisons are important sources of soil pollution with toxic elements.

Humic acid (HA) has a complex chemical composition and the ability to chelate, adsorb, and exchange ions with organic and inorganic contaminants in bodies of water, which worsens water quality and poses a threat to human health and the environment. In this research, an Ultraviolet-activated sodium perborate (UV/SPB) symbiotic method (UV/SPB) was developed to eliminate humic acid in water. The major synergistic and degradative processes of the humic acid were investigated, as well as the impact of the starting humic acid concentration, sodium perborate dose, and primary pH value on the humic acid elimination. Results indicate that just 0.5 % and 1.5 % of humic acid were eliminated mostly by sole UV and sole sodium perborate (SPB) methods, respectively. More effectively than other methods, UV/SPB removed humic acid with an efficiency of 88.83%. An experiment using free radicals to mask them revealed that the primary catalyst for humic acid removal is the hydroxyl radical generated by sodium perborate activation. The excitation-emission matrix spectroscopy, Ultraviolet-visible absorption (UV-Vis) spectrum, absorbance ratio values, specific Ultraviolet-visible absorbance values (SUVA), and UV/SPB method performance findings demonstrated the UV/SPB method’s capability to degrade and mineralize humic acid.

Determination of environmental pollution in the surface water is very important. So, in this study, determination, and health risk assessment were evaluated. The pollutions such as anions, cations, and heavy metals were analyzed in surface water by photometer spectrometry and atomic absorption spectrometry (AAS). Other parameters such as pH and TDS were determined. The results showed us, the electrical conductivity (EC) in this study falls between 100.68 ± 1.0 - 194.74 ±1.4 μs cm-1 in the dry and wet season. The pH value in this study for the two seasons varied from 5.57±0.22 to 5.73±0.28 which shows a little acidity. In the current study, TDS for wet and dry seasons goes from 122.17±1.74 mg L-1 to 63.80±0.86 mg L-1. This may conceivably be a sign of typical pollution from the runoff of soils in the study area. The high phosphate levels in both wet and dry seasons are recorded from 60.74±0.61 to 60.27±0.38 mg L-1 in both seasons. Iron values observed range from 8.42±0.06 to 6.28±0.11 mg L-1 in the wet and dry season, Cu was recorded between 0.08±0.01 - 0.07±0.01 mg L-1, Mn recorded from 0.07±0.01 to 0.06±0.01 mg L-1, Zn recorded between 2.29±0.09 - 1.15±0.09 mg L-1, and Pb recorded from 0.69±0.09 to 0.40±0.18 mg L-1 while Cd and Ni were not detected in the study. Water quality index (WQI) values were determined as 549 for wet and 328 for the dry season, the hazard indices for both seasons are below one. The outcomes in this present study showed that the level of Pb in the surface water could present a carcinogenic risk to both adults and children. All heavy metals results were validated by electrothermal atomic absorption spectrometry (ET-AAS).

There are several techniques for removing contaminants from water and wastewater. In the meantime, the surface adsorption is one of the simplest, the most effective, and economical methods for wastewater treatment. This review article refers to the recent research on the removal of various contaminants with various adsorbents from water and wastewater. Knowing the conducted research and background of the research topic can greatly help the study progress and achieve new logical results. Awareness of the previous research on the subject puts the study path in the continuation of the prior studies and is nothing duplicate and separated from them. Here are some examples of research from both internal and external sources on the subject of research. The movement of groundwater due to the complexity and irregularity of boundary conditions and the heterogeneity of the porous environment can rarely be studied by analytical methods. Therefore, in order to solve groundwater problems, either numerical methods should be used or experimental models should be used in problems where the governing equations also have errors. Experimental models can be divided into two parts, physical or allegorical, which were studied in detail in previous sections. Since the equation governing the lattice models is the same as the equation governing groundwater in saturation, but its structure is not like the real porous medium, this model can therefore be considered as an allegorical model.