Methods for preparation and activation of activated carbon: a review

Activated carbon refers to a wide range of carbonised materials of high degree of porosity and high surface area. Activated carbon has many applications in the environment and industry for the removal, retrieval, separation and modification of various compounds in liquid and gas phases. Selection of the chemical activator agent is a major step controlling the performance and applicability of activated carbon. Here, we review chemical activators used to produce activated carbon. We compare the impregnation method with the physical mixing method used in activating with alkali hydroxides. We selected 81 articles from Google Scholar, PubMed, Scopus, Science Direct, Embase and Medlin databases. Eighteen articles report the activation with potassium hydroxide, 17 with phosphoric acid, 15 with zinc chloride, 11 with potassium carbonate, nine with sodium hydroxide, and 11 with new activating agents. Activation with phosphoric acid is commonly used for lignocellulosic material and at lower temperatures. Zinc chloride generates more surface area than phosphoric acid but is used less due to environmental concerns. Potassium carbonate, in comparison with potassium hydroxide, produces higher yields and a higher surface area for the adsorption of large pollutant molecules such as dyes. Activating with potassium hydroxide in terms of surface area and efficiency shows better results than sodium hydroxide for various applications. Also, the comparison of the physical mixing method and the impregnation method in activation with alkali metals indicates that the activated carbon obtained through physical mixing had a higher porosity than the activated carbon produced by the impregnation method. © 2020, Springer Nature Switzerland AG

A global systematic, review-meta analysis and ecological risk assessment of ciprofloxacin in river water

The presence of antibiotics and their metabolites such as ciprofloxacin (CIP) in water resources attracted notable attention as a new international health concern. A systematic and review-meta analysis was performed to evaluate the concentration of CIP in the rivers along with the related ecological risk assessment. PubMed, Scopus and Embase databases were screened to retrieve the related articles among 1 January 1983 to 10 July 2018. Fifty-five articles (58 studies of data reports) comprising 1,886 samples from 20 countries were included. Furthermore, the meta-analysis was performed by the aid of a random effects model (REM) to estimate pooled concentration with 95 confidence intervals (CI). According to findings, the concentration of CIP in the river downstream of untreated wastewater was higher than other rivers located downstream of treated wastewater. Also, the meta-analysis of data based on year of study subgroup demonstrated that over time, the concentration of CIP in the rivers was increased. The ecological risk assessment showed that people settled in some regions of South Africa was at a potential (HQ: 1�10 value) adverse ecological risk of CIP in the river. Therefore immediate control plans besides appropriate removal techniques should be approached for complete eradication of antibiotics like CIP. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

The concentration and risk assessment of potentially toxic elements (PTEs) in unrefined salt: a case study of Aran and Bidgol Lake, Iran

Sediment salt or unrefined salt is among the widely used ingredients in a variety of eastern food products while the contamination of this product with properties potentially toxic elements (PTEs) due to their bio-bioaccumulation and persistence can endanger the health of consumers. In this regard, in the current investigation, 62 samples of salt sediment were collected from Aran and Bidgol Lake and the concentration of As, Cd, Ni, and Pb were measured by the aid of an inductively coupled plasma-mass spectrometry (ICP-MS). Also, the non-carcinogenic and carcinogenic risks for the adults and children consumers were estimated by the aid of the Monte Carlo Simulation (MCS) method. According to findings, the rank order of PTEs based of their concentration was As (0.41 mg/kg) > Ni (0.22 mg/kg) > Cd (0.17 mg/kg) > Pb (0.15 mg/kg), while the rank order of PTEs according to target hazard quotient (THQ) for the adult�s consumers were calculated as As (0.285) > Cd (0.030) > Pb (0.017) > Ni (0.007) and for children was As (1.471) > Cd (0.170) > Pb (0.072) > Ni (0.035). Also, the cancer risk (CR) due to As in the adults and children was measured as 1.27E-4 and 6.19E-4, respectively. The non-carcinogenic health risk demonstrated that all consumers (adults and children) are at the safe range (TTHQ < 1); however, consumers are at cancer risk due to ingestion of As via salt consumption (CR > 10�4). Therefore, the continuous and careful monitoring for control entrance sources of As into salt sediment of Aran and Bidgol lake is essential. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

The concentration of potentially hazardous elements (PHEs) in the muscle of blue crabs (Callinectes sapidus) and associated health risk

In this study, the concentration of potentially hazardous elements (PHEs) in the muscle of Blue crabs (Callinectes sapidus) from the Strait of Hormuz was analyzed and following the health risk in the consumers by uncertainty and sensitivity analysis in the Monte Carlo simulation (MCS) technique was estimated. Fifty-eight blue card samples (male blue crabs = 33 samples; female blue crabs = 25 samples) were collected in the Strait of Hormuz from May to September 2020 for analysis of Nickel (Ni), Lead (Pb), Cadmium (Cd), and Iron (Fe) using Flame Absorption Spectrometer (FAAS). The order of PHEs in the in muscle male blue crabs was Fe (414.37 ± 288.07 μg/kg.ww) > Pb (238.78 ± 87.83 μg/kg.ww) > Ni (92.57 ± 39.72 μg/kg.ww) > Cd (52.73 ± 18.39 μg/kg.ww) and in female blue crabs Fe (461.16 ± 320.56 μg/kg.ww) > Pb (230.79 ± 125.59 μg/kg.ww) > Ni (84.13 ± 46.07 μg/kg.ww) > Cd (67.412 ± 43.93 μg/kg.ww). The concentration of PHEs muscle of male blue crabs and female blue crabs was not significantly different (P-value > 0.05). Uncertainty of non-carcinogenic risk revealed that P95 of total target hazard quotient (TTHQ) in the adult and children consumers due to ingestion male blue crabs was 5.30E-3 and 1.08E-3, respectively, and P95 of TTHQ in the adult and children due to ingestion female blue crabs was 7.05E-3 and 1.20E-3, respectively. P95 of TTHQ in both adult and children consumers was lower than one value. Therefore, consumers are at the acceptable range of the non-carcinogenic risk due to ingestion muscle of male and female blue crabs in Bandar Abbas. Although the non-carcinogenic risk of blue crab was in the safe range, due to the increase in its consumption and the increase of pollution sources in the Persian Gulf, it is recommended to monitor PHEs in Blue's muscle crabs. © 2021 Elsevier Lt