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- Bhatnagar, Amit, et al.
(författare)
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Coconut based biosorbents for water treatment : A review of the recent literature
- 2010
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Ingår i: Advances in Colloid and Interface Science. - : Elsevier BV. - 0001-8686 .- 1873-3727. ; 160:1-2, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Biosorption is an emerging technique for water treatment utilizing abundantly available biomaterials (especially agricultural wastes). Among several agricultural wastes studied as biosorbents for water treatment, coconut has been of great importance as various parts of this tree (e.g. coir, shell, etc.) have been extensively studied as biosorbents for the removal of diverse type of pollutants from water. Coconut-based agricultural wastes have gained wide attention as effective biosorbents due to low-cost and significant adsorption potential for the removal of various aquatic pollutants. In this review, an extensive list of coconut-based biosorbents from vast literature has been compiled and their adsorption capacities for various aquatic pollutants as available in the literature are presented. Available abundantly, high biosorption capacity, cost-effectiveness and renewability are the important factors making these materials as economical alternatives for water treatment and waste remediation. This paper presents a state of the art review of coconut-based biosorbents used for water pollution control, highlighting and discussing key advancement on the preparation of novel adsorbents utilizing coconut wastes, its major challenges together with the future prospective. It is evident from the literature survey that coconut-based biosorbents have shown good potential for the removal of various aquatic pollutants. However, still there is a need to find out the practical utility of such developed adsorbents on commercial scale, leading to the superior improvement of pollution control and environmental preservation.
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- Bhatnagar, Amit, et al.
(författare)
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Optimization of nickel biosorption by chemically modified brown macroalgae (Pelvetia canaliculata)
- 2012
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 193, s. 256-266
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Tidskriftsartikel (refereegranskat)abstract
- In the present work, various forms of algae Pelvetia canaliculata were prepared by different chemical modifications, in order to get the best form of algae for the maximum uptake of nickel. Potentiometric titration revealed that the carboxyl groups were more abundant (3.9 mmol/g) as compared to hydroxyl groups (2.0 mmol/g) on the biosorbent surface. Fourier transform infrared (FUR) analysis of algae was done to identify the role of different functional groups present on algae surface during nickel biosorption. The protonated algae showed least sorption of nickel suggesting that after acid treatment, some of the binding sites were destroyed. Among the various forms of prepared algae. Na-algae prepared directly from raw algae (without protonation) showed highest uptake of nickel. The release of sodium ions during the uptake of nickel ions has shown that the current biosorption mechanism involves ion-exchange being a stoichiometrical ratio of 2:1 between sodium and nickel ions.
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- Bhatnagar, Amit, et al.
(författare)
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Review on the use of red mud as adsorbent for the removal of toxicpollutants from water and wastewater
- 2011
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Ingår i: Environmental technology. - : Informa UK Limited. - 0959-3330 .- 1479-487X. ; 32:3, s. 231-249
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Tidskriftsartikel (refereegranskat)abstract
- Red mud (an aluminium industry waste) has received wide attention as an effective adsorbent for water pollution control, showing significant adsorption potential for the removal of various aquatic pollutants. In this review, an extensive list of red‐mud‐based adsorbents has been compiled and their adsorption capacities (maximum uptake value of the adsorbent for the pollutant or adsorbate being removed) for various aquatic pollutants (metal ions, dyes, phenolic compounds, inorganic anions) are presented. The review provides a summary of recent information obtained using batch studies and deals with the adsorption mechanisms involved. It is evident from the literature survey that red mud has been found to be efficient for the removal of various aquatic pollutants, especially arsenic and phosphate. However, there is still a need to investigate the practical utility of these adsorbents on a commercial scale.
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- Bhatnagar, Amit, et al.
(författare)
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Valorisation of marine Pelvetia canaliculata Ochrophyta for separation and recovery of nickel from water: equilibrium and kinetics modeling on Na-loaded algae
- 2012
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 200, s. 365-372
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, biosorption of Ni2+ by Na-loaded (raw algae treated with NaCl), algae Pelvetia canaliculata Ochrophyta, was studied in a batch system. Kinetics and equilibrium experiments were conducted at different pH values (2.0, 3.0 and 4.0). The metal uptake capacity decreased by decreasing the solution pH, suggesting that competition exists between hydrogen ions, present in high concentrations at low pH values, and metal ions. An ion-exchange model, considering two different binding sites, sulfonic and carboxylic groups, was developed to describe equilibrium data. A mass transfer model, considering intraparticle resistance was also developed to describe kinetics in a batch system. The release of sodium ions during the uptake of nickel ions revealed that the biosorption mechanism involved ion-exchange between sodium and nickel ions with a stoichiometrical ratio of 2:1. Nickel showed higher affinity to the sulfonic groups than for carboxylic ones of algae biomass. Kinetic results show that hydrogen ions diffuse faster as compared to nickel and sodium ions. The maximum uptake capacity of Na-loaded algae, P. canaliculata, for Ni2+ was found to be ca. 100 mg/g at pH 4.0.
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- Santo, C.E., et al.
(författare)
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Optimization of coagulation-flocculation and flotation parameters for the treatment of a petroleum refinery effluent from a Portuguese Plant
- 2012
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 183, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- Petroleum refineries generate significant amounts of wastewater which have to be treated and processed before their discharge into water streams. The refinery wastewater treatment plants (WWTPPs) employ physico-chemical processes to achieve effluents of satisfactory oil content to be further treated by biological processes. In the present study, coagulation-flocculation and flotation processes are optimised to reduce the concentrations of organic matter, oil and grease and other contaminants in order to obtain an effluent with suitable characteristics ready to be treated by an aerobic biological process. PAX-18 (17% Al2O3), aluminium sulphate (Al-2(SO4)(3)) and ferric sulphate (Fe-2(SO4)(3)) are chosen for affecting coagulation-flocculation as a primary treatment. NALCO 71408 is employed as flocculant. Treatment efficiency is evaluated in terms of chemical oxygen demand (COD), total organic carbon (TOC) and turbidity measurements. The experiments are conducted both in discontinuous and continuous mode to assess the feasibility of the process. Flotation is investigated as a post-treatment process for the removal of emulsified hydrocarbons and satisfactory results are obtained.
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| 9. |
- Santo, C.E., et al.
(författare)
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Sulphide removal from petroleum refinery wastewaters by catalytic oxidation
- 2012
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Ingår i: Desalination and Water Treatment. - : Informa UK Limited. - 1944-3994 .- 1944-3986. ; 46:1-3, s. 256-263
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Tidskriftsartikel (refereegranskat)abstract
- The catalytic oxidation of sulphides present in oil refinery wastewaters was investigated in the present study. The wastewaters were obtained from the wastewater treatment plant of the oil refinery in Matosinhos (Portugal), Galp Energia. Air, NaOCl and H2O2 were chosen as oxidants and Fe3+ and Mn2+ as the two catalysts to assess the effective combination of catalyst-oxidant for sulphide removal after oil separation in parallel plate interceptors. Primarily, air (oxygen) was used as the oxidant and the efficiency of two catalysts (Fe3+ and Mn2+) for sulphide removal was evaluated. Experimental data suggested that Fe3+ catalysed sulphide removal in the presence of oxygen was more effective than Mn2+ catalysed reaction. In a subsequent study, oxygen was replaced by NaOCl and H2O2, and the potential of various catalyst-oxidant combinations, NaOCl + [Fe3+], NaOCl + [Mn2+], H2O2 + [Fe3+], H2O2 + [Mn2+], was assessed. The NaOCl + [Fe3+] combination achieved the maximum sulphide oxidation. Pseudo-first-order and pseudo-second-order reaction models were fitted to the kinetic experimental data. The influence of temperature on the kinetic rate was also investigated.
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| 10. |
- Vilar, V.J.P., et al.
(författare)
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Insights into trivalent chromium biosorption onto protonated brownalgae Pelvetiacanaliculata: distribution of chromium ionic species on thebinding sites
- 2012
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Ingår i: Chemical Engineering Journal. - : Elsevier. - 1385-8947 .- 1873-3212. ; 200-202, s. 140-148
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, biosorption of trivalent chromium by protonated brown algae, Pelvetia canaliculata, was studied in batch system. FTIR analyses provided information about the possible binding groups present in the algae, as carboxylic, hydroxyl and sulfonate groups. Potentiometric acid–base titrations showed a heterogeneous distribution of two major binding groups, carboxyl and hydroxyl ones, following the Quasi-Gaussian affinity constant distribution suggested by Sips, which allowed to estimate the maximum amount of acidic functional groups (2.26 ± 0.02 mmol g−1) and proton binding parameters () for an ionic strength of 0.2 M. The trivalent chromium removal was found to increase with pH and the maximum chromium uptake was observed at pH 4.0 (∼0.6 mmol/g), corresponding to 1.34 meq/g, since at that pH, 25.8% of total chromium is in the Cr3+ form and 72.7% as CrOH2+. An equilibrium model incorporating the hydrolysis reactions that chromium undergoes in the aqueous phase was able to predict the chromium biosorption at different pH values and chromium concentrations, enabling the prediction of the distribution of chromium ionic species on the binding sites. A mass transfer model provided a good representation of the chromium biosorption kinetics, resulting in intraparticle homogeneous diffusion coefficients of 4.6 × 10−7 cm2/s for Cr3+ and 1.8 × 10−8 cm2/s for CrOH2+. The distribution of chromium ionic species in the solution and on the binding sites was also predicted by the kinetic model.
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