Calcined Umbonium vestiarium snail shell as an efficient adsorbent for treatment of wastewater containing Co (II).

In the present study, the Umbonium vestiarium snail shell (UVS) was used as an abundant and low-cost resource for the removal of Co (II) from aqueous solution. The characteristics of calcined Umbonium vestiarium snail shell (CUVS) were analyzed using FTIR, SEM, MAP, EDAX, and BET analyses. The results showed that the specific surface area of the CUVS was obtained 17.02 m2/g which was an acceptable amount. The presence of Co (II) in the adsorbent structure was confirmed by EDAX, and Map analyses after Co (II) adsorption showed that the adsorbent successfully adsorbed Co (II) from aqueous solution. The effect of different parameters such as, contact time, initial concentration of cobalt ion, the adsorbent dose, and pH value was also investigated. The maximum efficiency of cobalt ion adsorption was measured 93.87% at a pH value of 6, contact time of 80 min, the adsorbent dose of 3 g/L, and initial ion concentration of 10 mg/L. Also, Langmuir, Freundlich, and D-R isotherm models were used to determine the most appropriate isotherm model for cobalt ion adsorption. The adsorption equilibrium data were better fitted with the Langmuir model with a maximum adsorption capacity of 93.46 mg/g. Additionally, the average free energy of adsorption was evaluated in the amount of 1.4085 KJ/mol, revealing a physical adsorption. Moreover, the kinetic behavior study showed that the experimental data follow the pseudo second order kinetic model to the value of correlation coefficient.

Amendment of Caulerpa sertularioides marine alga with sulfur-containing materials to accelerate Cu removal from aqueous media.

This study reports a new approach of alga amendment in a live mode. The Caulerpa sertularioides alga was modified with sulfur-containing materials of methionine (C5H11NO2S) and sodium sulfate (Na2SO4) to more concentrate the sulfur content of the yielded biomass (adsorbent). The simple and amended C. sertularioides alga was fully characterized with FTIR, SEM, EDX, BET, BJH, and pHzpc techniques. The copper adsorption from aqueous media was done by three adsorbents of C. sertularioides-simple (CSS), C. sertularioides-Na2SO4 (CSN), and C. sertularioides-C5H11NO2S (CSC). The parameters of pH (2-6), adsorbent dosage (2-10 g/L), and contact time (3-80 min) were optimized at 5, 5 g/L, and 60 min, respectively. According to Langmuir isotherm (the best-fitted model), the maximum adsorption capacity of CSN (98.04 mg/g) was obtained 2.4 times higher than CSC (40.73 mg/g) and 9.5 times higher than CSS (10.29 mg/g). The Cu adsorption process by the adsorbents was best-fitted pseudo-second-order kinetic model. The CSN, CSC, and CSS biomasses were successfully reused 5, 4, and 4 times, respectively. The thermodynamic study revealed that the copper adsorption process by CSN is exothermic and non-spontaneous. Finally, the suitability of adsorbents prepared from algae was tested by cleaning a simulated wastewater.

Occurrence, distribution, and potential sources of antibiotics pollution in the water-sediment of the northern coastline of the Persian Gulf, Iran.

Occurrence and frequency of six most prescribed antibiotics (tetracycline, norfloxacin, azithromycin, anhydro erythromycin, cephalexin, and amoxicillin) were assessed in three wastewater treatment plants (WWTPs), and in water and sediments of the Persian Gulf at Bushehr coastline, Iran. The antibiotics concentration in the influent and effluent of septic tank (the hospital WWTP), activated sludge (the hospital WWTP), and stabilization pond (municipal WWTP) ranged between 7.89 and 149.63, 13.49-198.47, 6.55-16.37 ng/L, respectively. Conventional treatment resulted in incomplete removal of most of the studied antibiotics. Furthermore, the activated sludge was more effective in terms of antibiotic elimination compared to the stabilization pond or septic tank. The mean concentration of antibiotics ranged 1.21-51.50 ng/L in seawater and 1.40-25.32 ng/g in sediments during summer and winter. Norfloxacin was the dominant detected antibiotic in seawater, sediments, and influent of two hospital WWTPs. Seasonal comparisons showed significant differences for erythromycin and amoxicillin concentrations in seawater. Spatial variation indicated the role of physicochemical properties on distribution of antibiotics in seawater and sediments. The results emphasize the need to pay attention to antibiotic contamination in water and sediments of the Persian Gulf.