Mahboobeh Zarei; Majid Baghdadi; Fatemeh Yazdian; Nasser Mehrdadi
Abstract
In this study, an optimized composite of expanded graphite /g-C3N4 /phenylenediamine was synthesized and characterized by SEM, FESEM, EDS, XRD, and BET methods.The composite was prepared with an optimized combination using response surface methodology (RSM) as a proper adsorbent for eliminating heavy ...
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In this study, an optimized composite of expanded graphite /g-C3N4 /phenylenediamine was synthesized and characterized by SEM, FESEM, EDS, XRD, and BET methods.The composite was prepared with an optimized combination using response surface methodology (RSM) as a proper adsorbent for eliminating heavy metals from water samples. The evaluation of the final adsorbent was accomplished by removing metal ions like Pb2+ and Cd2+. Under the optimum adsorption conditions for Pb2+ and Cd2+ (pH:5, adsorbent dosage:2 g/L, and Time:60 min), elimination efficiencies were 78.4% for Cd2+ and 71.35% for Pb2+. pH was the most important factor that influenced the adsorption rate. A short contact time for maximum removal efficiency was reported because of the porous structure of the constructed composite. As a result of the absorptive construction, the equilibrium showed a satisfactory agreement with the Freundlich model. The kinetic evaluations showed that the adsorption process of both heavy metals fitted the pseudo-second-order model. Furthermore, the results of thermodynamic studies indicated that the adsorption was an endothermic and spontaneous process. A series of regeneration experiments (5 cycles) was directed to evaluate the adsorbent reusability. The results presented that it was a suitable adsorbent for heavy metal uptake from aquatic solutions.
Saba Abdolalian; Farhad Qaderi
Abstract
The use of ultrasound is one of the most studied methods in treatment of water and wastewater. This study was going to remove pollutants from the supernatant of excess sludge by using of ultrasound. Initial raw supernatant with COD equal to 1600 mg/L and phosphorous equal to 80 mg/L was exposed to ultrasound. ...
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The use of ultrasound is one of the most studied methods in treatment of water and wastewater. This study was going to remove pollutants from the supernatant of excess sludge by using of ultrasound. Initial raw supernatant with COD equal to 1600 mg/L and phosphorous equal to 80 mg/L was exposed to ultrasound. The experimental design was used to determine the experiments with variables including time (1.5-9.5 h), ultrasonic power (40-360 w), and the volume of sample (20-180 mL). COD and phosphorous were the responses, those were investigated in this research. Based on the Response Surface Methodology (RSM), a model for COD and phosphorous removal was obtained with a 95 % confidence interval. The optimized removal of COD (97.39 %) and phosphorous (98.73 %) was observed. According to the results, ultrasonic waves is a good way to remove COD and phosphorus from sludge. This method can be used in wastewater treatment plants for treatment of supernatant of excess sludge.
Jacques Munyegaju; Hakizimana Jean Nepo; Buscotin Horax Beakou; Valerien Mutambyi; Uwitonze Nestor
Abstract
Textile industries consume a lot of water through their various textile production processes. Increased demand for textile products, ultimately increases the formation of wastewater, which labels the textile industry a main source of severe pollution problems worldwide. The agricultural wastes used for ...
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Textile industries consume a lot of water through their various textile production processes. Increased demand for textile products, ultimately increases the formation of wastewater, which labels the textile industry a main source of severe pollution problems worldwide. The agricultural wastes used for adsorbing pollutants were revealed to be efficient and economical adsorbents with high potential for removing dyes from polluted water. In this study, the synthetic textile effluent was simulated using Orange 2 sodium salt (OSS) dye mixed with tap water. The treatment of OSS dye solution by adsorption process was conducted in a batch reactor employing the avocado seeds activated carbon (ASAC). The impacts of temperature, adsorption contact time, OSS dye initial concentration, ASAC biosorbent dosage, and OSS solution pH on the adsorption efficiency were explored and optimized by the Box Behnken design (BBD) of Response surface methodology (RSM). The optimum conditions for the dye removal were: temperature 40°C, adsorbent dosage 0.1g and initial dye concentration 10 mg/L. The yield of the OSS dye removal resulted to 96.5%. The OSS dye adsorption has best fitted with the Freundlich isotherm of adsorption (R2 = 0.9922), suggesting the occurrence of a multilayer adsorption on the non-homogeneous surfaces of the ASAC. The kinetic study fitted with the kinetic model of Pseudo-second order. Also, the dye adsorption thermodynamics manifested that the adsorption of OSS dye was feasible and spontaneous with negative Gibbs free energy changes (-ΔGo) such as -2.18KJ/mol at 303K, -3.18KJ/mol at 308K, -3.58KJ/mol at 313K and -7.32KJ/mol at 323K. The adsorption was endothermic with positive enthalpy change (+74.73KJ/mol). The entropy study resulted in 0.25KJ/molK, revealing the augmenting chaos at the interface of the sorbent and dye solution during adsorption process. The use of avocado seeds as biosorbent enables the valorization of this agro-waste and waste management alongside efficient textile effluent treatment.
