Activated spent tea (AST) was prepared and characterized by using different techniques such as BET, FTIR and SEM. It is used for methylene blue (MB) dye removal from aqueous solution in a batch system. Experimental results showed that natural basic pH, increased initial dye concentration, and high temperature favored the adsorption. Analysis based on the artificial neural network (ANN) indicated that the adsorbent dose and time with the relative importance of 30.03 and 35.44%, respectively, appeared to be the most influential parameters in the MB adsorption. The adsorption of MB was relatively fast and the Avrami fractional order and pseudo-second-order kinetic models showed satisfactory fit with the experimental data. The equilibrium data were well fitted by the Langmuir and Liu isotherm models, with a maximum sorption capacity of 104.2 mg/g. Also, the obtained values of thermodynamic parameters showed that the adsorption of MB onto AST is endothermic and spontaneous. The results of this study indicated that AST was a reliable adsorbent for removing cationic dyes from wastewater.
Background Few studies have examined nano-sized plastic particulates (NPs) exposure in relation to oxidative stress and biochemical responses in rodents, commonly used for toxicity evaluations on which to base risk assessment for humans.Methods Here we explored possible oxidative stress and biochemical responses of five weeks oral exposure to polystyrene (PS) nanoparticles (1, 3, 6 and 10 mg/kg body weight per day) in male rats. We used variance analysis and variance explained statistic eta-squared (𝜂2) to estimate the strength of relationships worked out. The whole body scanning further provided insight into the bio-distribution of nanoplastics upon oral exposure.Results Results demonstrated the accumulation of PS-NPs through whole body and also a dose-dependent increase in the production of reactive oxygen species (ROS). Significant alterations in antioxidant responses including serum levels of catalase, superoxide dismutase (SOD), and total glutathione content were noticed, pointing towards a perturbation of redox state induced by the exposure conditions. Acetylcholinesterase level in highest dose group was about 40 percent lower than those in control group. Biochemical parameters viz. glucose, cortisol, lipase, lactate, lactate dehydrogenase (LDH), alkaline phosphatase, gamma-glutamyl transpeptidase (GGT), triglycerides, and urea showed a significant increase, while total protein, albumin and globulin levels showed an appreciable decline.Conclusion The pattern of associations noticed with AChE activity and biochemical responses in our study suggests the possibility that a neurobehavioral effect or dysfunctions in energy metabolism, or both, may be the potential mode of action, possibly through stress response as well as liver function. Perturbations of creatinine and uric acid levels are indeed plausible biological explanations for the association with kidney dysfunction. Although we provided a new scientific clue for exploring the biological effects of plastics nanoparticles, the results warrant additional research with a larger sample size. The suggested potential mechanisms also remains to be investigated.
Background: Zero-valent iron (ZVI) can effectively activate persulfate (PS) generating free sulfate radicals (SO 4 •-), thereby presenting a promising technology to degrade recalcitrant organic contaminants such as para-chlorophenol (PCP) in wastewater. Objectives: The current study aimed to examine the feasibility and application of ZVI/PS system through batch experiments to degrade PCP of petrochemical effluent, which its treatment is included in The United States environmental protection agency (USEPA) priority pollutant list. Materials and Methods: Effects of dosages of ZVI (0.056-2.8 g/L), ZVI to PS molar ratio (0.1-5.0), PS concentration (2.5-25.0 mM/L), pH = (3.0-11.0), contact time (5-240 minutes), and ZVI reusability (three cycles) on PCP degradation were examined. Results: The results showed that the PCP degradation increased with an increase in ZVI dosage from 0.056 to 1.4 g/L, an increase in persulfate concentration from 2.5 to 15.0 mM/L, and an increase in ZVI to PS molar ratio from 0.1 to 2.5. The optimal initial pH for PCP removal was 5.0 and the maximum removal efficiency of 70% was achieved within 120 minutes. Moreover, the ZVI catalyst was reused until the third cycle to activate the persulfate and degrade PCP. However, the degradation efficiency of PCP gradually decreased to 51.7% when the ZVI reuse time increased. Conclusions: The results indicate that using ZVI/PS system is not an efficient enough method to treat petrochemical effluent, due to the complexity of petrochemical wastewater matrix and high-total dissolved solids (TDS) content, as well.
Hery’s trichloramine sampling procedure has been widely used to determine trichloramine exposure in indoor swimming pools. This method consists of pumping air at a 1 L/min flow rate for 2 hours through a Teflon prefilter and two quartz fibre filters. Modified Hery methods have been reported using different sampling pump flow rates and types of prefilters. This study aims to evaluate the effects of different cassette assemblies and sampling flow rates on the levels of measured trichloramine. Laboratory tests were performed using a trichloramine production set-up designed for this study. Workplace measurements were carried out in four indoor swimming pools. Different prefiltering strategies were used: no prefilter, glass prefilter or Teflon prefilter in the sampling cassette, and an original separable prefilter cassette is presented in this study. In this new assembly method, the prefilter is placed in a cassette alone and connected with a Tygon tube to the main cassette that has two impregnated fibre filters. Laboratory tests indicated that in the situation of trichloramine concentrations higher than 1 mg/m³, the trichloramine percentage captured on the first filter could pass the value of 75%, which demonstrates the possible loss of material during the sampling. The investigation of the prefilter effect on sampling strategy using different cassette assemblies revealed that using a separable cassette assembly could prevent overestimating the trichloramine levels. Furthermore, there were no significant differences between measured TCA concentrations at different flow rates (from 0.5 L/min to 2 L/min) in swimming pools.
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