Ligand-less in situ surfactant-based solid phase extraction for preconcentration of silver from natural water samples prior to its determination by atomic absorption spectroscopy

A simple and rapid ligand-less in situ surfactant-based solid phase extraction method for preconcentration of silver from water samples is developed. In this method, a cationic surfactant containing a proper alkyl group (n-dodecyltrimethylammonium bromide) is dissolved in the aqueous sample and then a proper ion-pairing agent (ClO₄^?) is added. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed and used for adsorption of silver carbonate. After centrifugation, the sediment is dissolved in 2.0 mL 1 M HNO₃ in ethanol and then aspirated directly into the flame atomic absorption spectrometer. Variables affecting the extraction efficiencies such as pH, concentrations of surfactant and CO₃^2?, ion pair concentration, and extraction time, are optimized. Under such conditions, the calibration curve is linear from 3 to 700 μg L^?1. Detection limit is 1.1 μg L^?1 with an enrichment factor of 37. The relative standard deviation for eight replicate measurements of 100 μg L^?1 is 2.1%. The method has been applied for the determination of silver in water samples.     

Positive environmental effects of the coronavirus 2020 episode: a review

Environment, Development and Sustainability - The outbreak of COVID-19 has made a global catastrophic situation that caused 1,039,406 deaths out of 35,347,404 infections, and it will also cause...     

Challenges of higher education related to e-learning in developing countries during COVID-19 spread: a review of the perspectives of students,instructors, policymakers,and ICT experts

The COVID-19 pandemic brought about many critical issues in all aspects such as economy, environment, health, and lifestyle, but people always try to find some response to crisis in different conditions. E-learning is defined as an elaborate response aiming at continuing education during the COVID-19 pandemic. It seems that developed countries have established and adjusted their technological infrastructures for the transition from a face-to-face education to a digital one. In contrast, developing countries were not completely prepared for this transition. Improper and deficient technological and practical fundamentals have been causing problems for all students, instructors, and other involved individuals. Therefore, we reviewed the challenges that have arisen from e-learning during the COVID-19 outbreak in different parts of tertiary education focusing on underprivileged countries.

     

A critical review of state-of-the-art electrocoagulation technique applied to COD-rich industrial wastewaters

Environmental Science and Pollution Research - Electrocoagulation (EC) is one of the emerging technologies in groundwater and wastewater treatment as it combines the benefits of coagulation,...     

Rapid photodegradation and detection of zolpidem over β-SnWO4 and α-SnWO4 nanoparticles: optimization and mechanism

Environmental Science and Pollution Research - We reported the tin (II) tungstate nanoparticles as the photocatalyst and sensor modifier that were synthesized via chemical precipitation reaction...     

Synthesizing of magnesium and nickel nanoparticles from spent methane dry reforming catalyst using sol–gel method: process flow diagram development

Journal of Material Cycles and Waste Management - This study aims to recover Ni and Mg from spent catalysts of dry methane reforming. Huge amounts of spent catalyst are produced every year....     

Presence of heavy metals in drinking water resources of Iran: a systematic review and meta-analysis

Environmental Science and Pollution Research - Water quality is one of the most important indices for public health especially for drinking water consumptions. This study was conducted to survey...     

Contaminants of emerging concern: a review of new approach in AOP technologies

The presence of contaminants of emerging concern (CECs) such as pharmaceuticals and personal care products (PPCPs), endocrine-disrupting compounds (EDCs), flame retardants (FRs), pesticides, and artificial sweeteners (ASWs) in the aquatic environments remains a major challenge to the environment and human health. In this review, the classification and occurrence of emerging contaminants in aquatic environments were discussed in detail. It is well documented that CECs are susceptible to poor removal during the conventional wastewater treatment plants, which introduce them back to the environment ranging from nanogram per liter (e.g., carbamazepine) up to milligram per liter (e.g., acesulfame) concentration level. Meanwhile, a deep insight into the application of advanced oxidation processes (AOPs) on mitigation of the CECs from aquatic environment was presented. In this regard, the utilization of various treatment technologies based on AOPs including ozonation, Fenton processes, sonochemical, and TiO₂ heterogeneous photocatalysis was reviewed. Additionally, some innovations (e.g., visible light heterogeneous photocatalysis, electro-Fenton) concerning the AOPs and the combined utilization of AOPs (e.g., sono-Fenton) were documented.     

Energy flow modeling and sensitivity analysis of inputs for canola production in Iran

This study examines energy use patterns and the relationship between energy inputs and yield for canola production in Golestan province of Iran. Data used in this study were obtained from 130 randomly selected canola farms using a face to face survey. The results revealed that total energy of 17,786.36 MJ ha⁻¹ was required for canola production and fertilizer, diesel fuel and electricity were the main energy consuming inputs. Energy use efficiency and energy productivity were 3.02 and 0.12 kg MJ⁻¹, respectively. Moreover, in specifying a functional relationship the Cobb-Douglas production function was applied and the results showed that machinery, fertilizer, diesel fuel and water for irrigation energies significantly contributed to yield. Also, the marginal physical productivity (MPP) technique was applied to analyze the sensitivity of energy inputs. It was found that, canola production had more sensitivity on machinery, fertilizer and water for irrigation energies; so that an additional use of 1 MJ from each of the machinery, total fertilizer and water for irrigation would lead to an increase in production by 0.93, 0.61 and 0.24 kg, respectively. However, electricity and seed energies were contributed negatively to yield, which may result in inverse effect on yield and impose risks to the environment.     

Ultrasound-assistant preparation of Cu-SAPO-34 nanocatalyst for selective catalytic reduction of NO by NH3

The influence of the various preparation methods of Cu-SAPO-34 nanocatalysts on the selective catalytic reduction of NO with NH₃ under excess oxygen was studied. Cu-SAPO-34 nanocatalysts were prepared by using four techniques: conventional impregnation (IM), ultrasound-enhanced impregnation (UIM), conventional deposition precipitation (DP) using NaOH and homogeneous deposition precipitation (HDP) using urea. These catalysts were characterized in detail by various techniques such as N₂-sorption, XRD, TEM, H₂-TPR, NH₃-TPD and XPS to understand the catalyst structure, the nature and the dispersed state of the copper species, and the acid sites for NH₃ adsorption. All of the nanocatalysts showed high activities for NO removal. However, the activities were different and followed the sequence of Cu-SAPO-34 (UIM) > Cu-SAPO-34 (HDP) > Cu-SAPO-34 (IM) > Cu-SAPO-34 (DP). Based on the obtained results, it was concluded that the NO conversion on Cu-SAPO-34 nanocatalysts was mainly related to the high reducibility of the isolated Cu^2 + ions and CuO species, the number of the acid sites and the dispersion of CuO species on SAPO-34.