Abstract
Here, Box-Behnken design (BBD) approaches were utilised to optimise synthesis methodology for the chitosan-calcite rich adsorbent (CCM) made from fishery-food waste material (crab carapace), using low-temperature activation and potassium hydroxide (KOH). The effect of activation temperature, activation time and impregnation ratio was studied. The final adsorbent material was evaluated for its phosphorus (P) removal efficiency from liquid phase. Results showed that impregnation ratio was the most significant individual factor as this acted to increase surface deacetylation of the chitin (to chitosan) and increased the number of amine groups (–NH2) in the chitosan chain. P removal efficiency approached 75.89% (at initial P concentration of 20 mg/L) under optimised experimental conditions, i.e. where the impregnation ratio for KOH:carapace (g/g) was 1:1, the activation temperature was 105 °C and the activation time was 150 min. Predicted responses were in good agreement with the experimental data. Additionally, the pristine and CCM material were further analysed using scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), Brunauer-Emmett-Teller technique (BET), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and thermal gravimetric analysis (TGA). Characterisation showed enhancements in surface chemistry (introducing positively charged amine groups), textural properties and thermal stability of the CCM.
Highlights
IntroductionFaculty of Technical Sciences, Department of Environmental Engineering and Occupational Safety and Health, University of Novi Sad, Novi Sad, Serbia
Responsible Editor: Tito Roberto Cadaval JrElectronic supplementary material The online version of this article contains supplementary material, which is available to authorized users.Environmental Research Institute, University of the Highlands and Islands, Thurso, Caithness, Scotland KW14 7JD, UKFaculty of Technical Sciences, Department of Environmental Engineering and Occupational Safety and Health, University of Novi Sad, Novi Sad, SerbiaSchool of Chemistry, University of Edinburgh, David Brewster Rd, Edinburgh EH9 3FJ, UKFaculty of Science, Department of Chemistry, Biochemistry and Environmental Protection, University of Novi Sad, Trg Dositeja Obradovića 3, Novi Sad, SerbiaPhosphorus (P) is an essential macro nutrient for plants and animals, but excessive dissolved orthophosphate ions in aquatic ecosystems can lead to a deterioration in habitat quality due to eutrophication (Mitrogiannis et al 2017)
Our results indicate that IR (ratio of KOH: carapace (g/g) - 1:1) had the greatest impact on resultant removal efficiency
Summary
Faculty of Technical Sciences, Department of Environmental Engineering and Occupational Safety and Health, University of Novi Sad, Novi Sad, Serbia. Faculty of Science, Department of Chemistry, Biochemistry and Environmental Protection, University of Novi Sad, Trg Dositeja Obradovića 3, Novi Sad, Serbia. Various techniques have been used for P removal from Prich effluents, including chemical precipitation and crystallisation (Huang et al 2017), biological treatment (Yang et al 2018), membrane technology (Furuya et al 2017), constructed wetlands (Du et al 2017), ion exchange (Bui et al 2018) and adsorption (Yu et al 2017). Physicochemical methods to remove P during water treatment are either too expensive (i.e. membrane processes), whilst chemical precipitation is costly due to the need for additional metal salts (such as iron). Whilst biological processes are low cost, removal efficiency is commonly < 30%; additional P removal techniques may be required
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