Eggshell waste as adsorbent was successfully used for the removal of Cd(II) ions from model synthetic aqueous solutions. Batch biosorption studies were conducted in order to evaluate the effect of various parameters, such as: contact time and initial metal ion concentration. The changes in the morphological structure were evaluated by TEM and SEM analysis. The experimental isotherm data were analysed using Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherm equations, using regression analysis linear and non-linear form. Langmuir model was found to be in better correlation with experimental data (R 2 =0.99). Biosorption kinetics data were tested using pseudo-first-order, pseudo-second-order, intra-particle and liquid film diffusion models. Kinetics studies showed that the biosorption followed a pseudo-secondorder reaction. Removal efficiencies up to 92 % and a maximum adsorption capacity of 8.2 mg/g Cd(II) were obtained experimentally and 7.14 mg/g Cd(II) were obtained from Langmuir isotherm model. The percentage of metal sorption (C i =11 mg/L, E,(%)=92.42), EDS analyses, and bioconcentration factor were also calculated. The investigation findings suggested that the physical adsorption is controlling the adsorption rate. Results of this study indicate that eggshell waste can be effectively used for the removal of Cd(II) ions from aquatic environments. The process is feasible, reliable and eco-friendly.
Concentrations of PCBs, DDTs, toxaphene, chlordanes, dieldrin, and mercury were determined in smallmouth bass (Micropterus dolomieui) collected from Fumee Lake, a remote lake in the Upper Peninsula of Michigan. An ecological hazard assessment was conducted to determine potential impacts of contaminants on bald eagles and mink eating fish from this lake. Concentrations of organochlorines, except toxaphene, and mercury in smallmouth bass were similar to those found in fish from Lake Superior, where atmospheric inputs are the primary sources. Bioaccumulation was indicated by a positive correlation between fish weight and contaminant concentrations for organochlorines, while mercury concentrations did not appear to correspond predictably to body weight. Concentrations of mercury and PCBs in smallmouth bass were sufficiently great to be of concern regarding their consumption by eagles or mink.
The aim of this study was to investigate the concentrations and pollution levels of heavy metals, organochlorine pesticides, and polycyclic aromatic hydrocarbons in marine sediments from the Leghorn Harbor (Italy) on the Mediterranean Sea. The phytoextraction capacity of three aquatic plants Salvinia natans, Vallisneria spiralis, and Cabomba aquatica was also tested in the removal of lead and copper, present in high concentration in these sediments. The average detectable concentrations of metals accumulated by the plants in the studied area were as follows: >3.328 ± 0.032 mg/kg dry weight (DW) of Pb and 2.641 ± 0.014 mg/kg DW of Cu for S. natans, >3.107 ± 0.034 g/kg DW for V. spiralis, and >2.400 ± 0.029 mg/kg DW for C. aquatica. The occurrence of pesticides was also analyzed in the sediment sample by gas chromatography coupled with mass spectrometry (GC/MS). Due to its metal and organic compound accumulation patterns, S. natans is a potential candidate in phytoextraction strategies.
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