Seyed Mehdi Sajjadi
Abstract
Treatment of wastewater is a crucial step in reducing pollution from the textile and dyeing industries. One of the best techniques for dye removal is photocatalytic processes, and TiO2 is frequently employed in numerous wastewater treatment applications. In this study, different adsorption isotherm models ...
Read More
Treatment of wastewater is a crucial step in reducing pollution from the textile and dyeing industries. One of the best techniques for dye removal is photocatalytic processes, and TiO2 is frequently employed in numerous wastewater treatment applications. In this study, different adsorption isotherm models and experimental data from the removal of the methylene blue dye from wastewater by applying GO/TiO2/SiO2 nanocomposite were compared. The correlation coefficient values (R2) for the Langmuir isotherm type 1 (Hanes-Woolf), Temkin, and Freundlich were determined to be, respectively, 0.9957, 0.9823, and 0.9515. Additionally, the R2 values for the Redlich-Peterson, Sips, and Toth isotherms models were 0.9575, 0.9626, and 0.9629, respectively. Therefore, Langmuir isotherm type 1 has the highest R2 and is the best model for surface adsorption of methylene blue on GO/TiO2/SiO2 photocatalyst. As a result, monolayer adsorption was most likely dominating during the adsorption. Furthermore, this photocatalyst proved suitable for lower methylene blue concentrations and systems with lower temperature sensitivity.
Zahra Fadaei; Kurosh Rad-Moghadam; Parvaneh Pakravan
Abstract
This study explored the efficacy of a cost-efficient activated carbon (AC) derived from natural bitumen through chemical activation with phosphoric acid. The objective was to evaluate bitumen-based activated carbon (AC) potential as a novel adsorbent by integrating Cu (NO3)2.3H2O onto AC for the removal ...
Read More
This study explored the efficacy of a cost-efficient activated carbon (AC) derived from natural bitumen through chemical activation with phosphoric acid. The objective was to evaluate bitumen-based activated carbon (AC) potential as a novel adsorbent by integrating Cu (NO3)2.3H2O onto AC for the removal of harmful dyes from water-based solutions. Assessments of the adsorption capabilities of Cu@AC were conducted using representative samples of cationic and anionic dyes, namely methylene blue (MB) and methyl orange (MO). The incorporation of Cu onto the AC, leading to the formation of Cu@AC, resulted in a significant enhancement of the adsorption capacity of AC. The adsorption capacity of Cu@AC was measured using Brunauer–Emmett–Teller (BET) and iodine number measurements, with the most optimal Cu@AC sample exhibiting a BET surface area of 611 m2/g. Surface chemical properties were analyzed through FT-IR spectroscopy, while the microstructure of the produced Cu@AC was examined using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The efficiency of the adsorption process was influenced by factors such as pH, initial dye concentration, adsorbent dosage, and contact time. The most effective processing conditions for dye removal were determined as pH 11 for MB and pH 5 for MO, with an initial concentration of 25 mg/L, a 0.5 g/L adsorbent dosage, and a temperature of 333 K for a duration of 90 min. Under these optimized conditions, removal efficiencies exceeded 90% for MO and 80% for MB. The results demonstrated that Cu@AC has the potential to function as a cost-effective alternative to commercially available activated carbons for efficiently eliminating dyes from contaminated water.
Samaneh Salmani; Hassan Rezaei; Hajar Abyar
Abstract
Agricultural product processing generates substantial quantities of agricultural waste and their disposal has become a critical concern, threatening human health and the environment. The pyrolysis process is an upgrading technology for producing valuable products from waste feedstocks. Hence, the potential ...
Read More
Agricultural product processing generates substantial quantities of agricultural waste and their disposal has become a critical concern, threatening human health and the environment. The pyrolysis process is an upgrading technology for producing valuable products from waste feedstocks. Hence, the potential of eco-friendly biochar derived from cotton waste was comprehensively investigated for methylene blue removal. The cotton-based biochar contained various pore sizes and functional groups on the surface verified by SEM and FTIR analyses. The impacts of adsorbent dose, methylene blue concentration, temperature, pH, and contact time on the adsorption of methylene blue were assessed to highlight the efficiency of the cotton-based biochar. The results revealed >90% removal under 10 mg/l methylene blue concentration, 0.7 g adsorbent dose, pH of 6, and contact time of 60 min at a temperature of 20 ⁰C. The adsorption isotherm was well-fitted with the Freundlich model, indicating the multilayer methylene blue adsorption. The adsorption process was chemisorption and endothermic based on kinetic and thermodynamic modeling. Summing up, it can be suggested that the cotton-based biochar can be easily and efficiently applied for methylene blue removal from aqueous solutions, and further investigations are required to modify its specific surface area by a green synthesis approach.
Zohreh Jahannia; Hassan Rezaei; Hajar Abyar; Somayeh Namroodi
Abstract
Cost-effective dye wastewater treatment approaches are critically required for the long-term sustainability of textile industries. To fill the gaps, multiple high-potential adsorbents derived from biomass have been proposed. For this purpose, this study was conducted to present an applicable and cost-effective ...
Read More
Cost-effective dye wastewater treatment approaches are critically required for the long-term sustainability of textile industries. To fill the gaps, multiple high-potential adsorbents derived from biomass have been proposed. For this purpose, this study was conducted to present an applicable and cost-effective biochar synthesized from cow dung to remove methylene blue from the aqueous solutions. The potential of cow dung-based biochar was optimized under various pH, biochar dose, methylene blue concentration, contact time, and temperature. The maximum removal was 96% achieved at optimum conditions, 20 mg/l methylene blue concentration, 0.2 g biochar dose, pH of 6, and 90 min contact time at ambient temperature. The methylene blue adsorption process followed the Freundlich isotherm (R2=0.9827) and pseudo-second-order (R2=0.999) kinetic models, implying multilayered adsorption on the heterogenous surface and chemisorption mechanism, respectively. Furthermore, the adsorption process was spontaneous and exothermic due to negative Gibbs free energy (ΔG0) and enthalpy (ΔH0) with the reduction at randomness of methylene blue molecules and adsorbent interaction based on negative entropy (ΔS0). Regarding the high efficiency of cow dung-based biochar to adsorb methylene blue, it is recommended that further investigations consider the biochar activation and functionalization intending to upgrade its adsorption capacity.
