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This research was undertaken to evaluate the usability of ferric(III) hydroxide for phosphate removal from sewage. Batch adsorption experiments, partly fixed bed column experiments, were conducted to study the influence of various factors, competing anions and contact time on the adsorption of phosphate on ferric(III) hydroxide. Processing ferric iron in the form of akaganeite (β-FeOOH) greatly increased the adsorption capacity for phosphate. The optimum phosphate removal was observed in the pHeq ≤ 6.0. All results from this study demonstrate the potential usability of β-FeOOH as a good phosphate-selective adsorbent for the phosphate removal system for a sewage treatment plant. HIGHLIGHTS Recovery of phosphate from sewage and wastewater to control eutrophication.; To develop phosphate-selective absorbents.; The potential usability of β-FeOOH as phosphate-selective adsorbent.; β-FeOOH can be applied for the phosphate removal system.; The phosphate adsorption capacity was increased to β-FeOOH>PA rein>Fe(OH)3.;

This study investigates the potential of electrospun polyacrylonitrile (PAN) nanofibers chemically modified with ethylenediamine (EDA) as effective adsorbents for nitrate-nitrogen (NO3-N) removal from wastewater. The nanofibers treated with 100% EDA at 95°C exhibited the highest adsorption capacity of 47 mg/g at 5 h of reaction time, whereas those at 80°C showed an increased adsorption capacity over time, reaching 46 mg/g after 15 h. Optimal NO3-N adsorption was observed in the weakly acidic pH range (3-6). This study also explored the field applicability and regeneration potential of PAN-EDA nanofibers. An adsorption-regeneration experiment involving fixed-bed columns showed promising results, with the adsorbent's performance sustained over multiple uses. Overall, this study concluded that PAN-EDA nanofibers are effective and reusable adsorbents for nitrate removal, paving the way for more sustainable wastewater treatment strategies. [ABSTRACT FROM AUTHOR]

This study investigated the possibility of using potassium titanate oxide (K2Ti4O9) and acrylic acid-grafted polypropylene fabric (PP-g-AA) as adsorbents capable of removing strontium from aqueous solutions. K2Ti4O9 showed the highest rate of strontium removal in the weak alkaline range, while the PP-g-AA increased strontium removal in the neutral range. Moreover, the adsorption capacity of the K2Ti4O9 was not affected by the coexistence of K and Na ions, while the adsorption capacity decreased when Ca and Mg ions were present at the same concentration as that of strontium. When coexisted at the same concentration as strontium, Na, K, Ca, and Mg ions strongly reduced the adsorption capacity of the PP-g-AA. The results also indicated that the adsorption of strontium on K2Ti4O9 was consistent with both the Langmuir and Freundlich adsorption isotherms. In contrast, the adsorption of strontium on the PP-g-AA was more consistent with the Langmuir isotherm model. Moreover, the adsorption equilibrium time of K2Ti4O9 was generally 12 h, while that of the PP-g-AA was 5 h, indicating that the adsorption rates were consistent with the pseudo-second order kinetics model. K2Ti4O9 and the PP-g-AA could be regenerated by simple washing with 0.5 N HCl. [ABSTRACT FROM AUTHOR]

The objective of this study is to evaluate the applicability of adsorption models for predicting the properties of adsorbents. The kinetics of the adsorption of NO3- ions on a PP-g-AA-Am non-woven fabric have been investigated under equilibrium conditions in both batch and fixed bed column processes. The adsorption equilibrium experiments in the batch process were carried out under different adsorbate concentration and adsorbent dosage conditions and the results were analyzed using adsorption isotherm models, energy models, and kinetic models. The results of the analysis indicate that the adsorption occurring at a fixed adsorbate concentration with a varying adsorbent dosage occur more easily compared to those under a fixed adsorbent dosage with a varying adsorbate concentration. In the second part of the study, the experimental data obtained using fixed bed columns were fit to Bed Depth Service Time, Bohart-Adams, Clark, and Wolborska models, to predict the breakthrough curves and determine the column kinetic parameters. The adsorption properties of the NO3- ions on the PP-g-AA-Am non-woven fabric were differently described by different models for both the batch and fixed bed column process. Therefore, it appears reasonable to assume that the adsorption properties were dominated by multiple mechanisms, depending on the experimental conditions. [ABSTRACT FROM AUTHOR]