Woody residues of the grape production chain as an alternative precursor of high porous activated carbon with remarkable performance for naproxen uptake from water

Environmental Science and Pollution Research - Activated carbon prepared from grape branches was used as a remarkable adsorbent to uptake naproxen and treat a synthetic mixture from aqueous...     

Radionuclide release and transport from nuclear underground tests performed at Mururoa and Fangataufa--predictions under uncertainty

In the context of a study by the International Geomechanical Commission (IGC) and the International Atomic Energy Agency (IAEA) on the effects of nuclear tests at the atolls of Mururoa and Fangataufa, release to the biosphere is estimated for 35 radionuclides originating from 147 nuclear underground tests. Based on a qualitatively characterised hydrogeological situation of atolls and relatively scarce site-specific data, a model chain was developed to conservatively estimate the radionuclide fluxes via groundwater, from their sources, the explosion cavities, towards the biosphere, the ocean or lagoon. Finite element hydro-thermal modelling was used to describe water flow. Parameters were calibrated by a very few measured pre-test temperature profiles in bore holes. The impact of the tests on groundwater flow and mechanical impact on rock was considered. Estimates were made to quantify spatial extensions and temporal evolution of impact by using measurements on refilling rate of the cavities. Tests were categorised according to their specific yield and location although detailed data were missing. A base case parameter set was defined for the hydraulic conditions and for the initial radionuclide inventory of individual tests. Models were used to describe the concentration of radionuclides in the cavities as a function of time. Radionuclide transport from the cavities to the biosphere was represented by two different approaches: a double porosity model for the fractured volcanic rock and a single porosity model for the overlaying, highly porous carbonates. Results consist of conservative estimates on radionuclide release into the environment, or concentration in the lagoon or ocean water. Their sensitivity was investigated using different models and parameters. A few measured data (concentrations in a few cavities, in the deep carbonates and in the lagoons for selected radionuclides, such as 3H, 14C, 36Cl, 90Sr, 129I, 137Cs239 240Pu and 241Am) were available for a comparison with the calculations. In view of the lack and uncertainty of site-specific data, the agreement is of acceptable quality.     

Effective removal of non-steroidal anti-inflammatory drug from wastewater by adsorption process using acid-treated Fagopyrum esculentum husk

Environmental Science and Pollution Research - In this work, buckwheat husks (Fagopyrum esculentum) were modified by acid treatment and posteriorly employed to remove the ketoprofen in batch...     

Radionuclide release and transport from nuclear underground tests performed at Mururoa and Fangataufa — predictions under uncertainty

In the context of a study by the International Geomechanical Commission (IGC) and the International Atomic Energy Agency (IAEA) on the effects of nuclear tests at the atolls of Mururoa and Fangataufa, release to the biosphere is estimated for 35 radionuclides originating from 147 nuclear underground tests. Based on a qualitatively characterised hydrogeological situation of atolls and relatively scarce site-specific data, a model chain was developed to conservatively estimate the radionuclide fluxes via groundwater, from their sources, the explosion cavities, towards the biosphere, the ocean or lagoon.Finite element hydro-thermal modelling was used to describe water flow. Parameters were calibrated by a very few measured pre-test temperature profiles in bore holes. The impact of the tests on groundwater flow and mechanical impact on rock was considered. Estimates were made to quantify spatial extensions and temporal evolution of impact by using measurements on refilling rate of the cavities. Tests were categorised according to their specific yield and location although detailed data were missing. A base case parameter set was defined for the hydraulic conditions and for the initial radionuclide inventory of individual tests. Models were used to describe the concentration of radionuclides in the cavities as a function of time. Radionuclide transport from the cavities to the biosphere was represented by two different approaches: a double porosity model for the fractured volcanic rock and a single porosity model for the overlaying, highly porous carbonates. Results consist of conservative estimates on radionuclide release into the environment, or concentration in the lagoon or ocean water. Their sensitivity was investigated using different models and parameters. A few measured data (concentrations in a few cavities, in the deep carbonates and in the lagoons for selected radionuclides, such as ³H, ¹⁴C, ³⁶Cl, ⁹⁰Sr, ¹²⁹I, ¹³⁷Cs²³⁹, ²⁴⁰Pu and ²⁴¹Am) were available for a comparison with the calculations. In view of the lack and uncertainty of site-specific data, the agreement is of acceptable quality.     

Transforming pods of the species Capparis flexuosa into effective biosorbent to remove blue methylene and bright blue in discontinuous and continuous systems

Environmental Science and Pollution Research - This study investigates, for the first time, the applicability of seed pods from Capparis flexuosa as an alternative biosorbent to remove methylene...     

Application of Cordia trichotoma sawdust as an effective biosorbent for removal of crystal violet from aqueous solution in batch system and fixed-bed column

Environmental Science and Pollution Research - In this work, for the first time, Cordia trichotoma sawdust, a residue derived from noble wood processing, was applied as an alternative biosorbent...     

Modelling of nonreactive tracer dipole tests in a shear zone at the Grimsel test site

The investigation of the migration of a high pH plume in a fractured shear zone is foreseen by a long-term experiment at the Grimsel rock laboratory. In order to characterise the initial conditions for the long-term experiment and to evaluate an optimal hydraulic in situ set-up, several dipole experiments with nonreacting tracers have been performed. The dipole experiments differ in geometry, pumping rates and orientation to the background water flow. Several single and double-porosity models have been applied to fit the results of these dipole tracer tests in order to extract values for some transport parameters and discriminate for certain transport processes. A two-dimensional porous medium approach was successfully used to fit tracer breakthrough curves measured for a dipole experiment. A model based on a one-dimensional dual porous medium approach was also successful, although the applied hydraulic dipole, with similar injection and extraction rates, suggests the existence of an extended two-dimensional flow field. For the two-dimensional porous medium approach, tracer breakthrough could only be fitted with a complex flow field geometry within the heterogeneous fractured shear zone. The heterogeneity was generated by heterogeneous porosity and hydraulic permeability distributions. Predictions for further dipole geometries and a sorbing tracer have been calculated by means of both models using the flow and transport parameters deduced from fits for a single dipole experiment. This allows for comparison with the measured breakthrough of sorbing tracers. The foreseen experiment with sorbing (radionuclide) tracers will help decide on the appropriate approach that should be used to describe such dipole experiments in this shear zone. Additionally, the migration and spreading of a solution with high pH has been calculated taking into account mineral dissolution and precipitation in a two-dimensional porous medium approach in order to estimate the amount and character of the mineral reactions induced by the interaction between the high pH solution and the rock.     

Migration of uranium(IV)/(VI) in the presence of humic acids in quartz sand: a laboratory column study

The migration behavior of U(IV) and U(VI) in the presence of humic acid was studied in a quartz sand system. Laboratory column experiments were performed using humic acid, U(VI) in humic acid absence, U(IV) and U(VI) in humic acid presence, and for comparison a conservative tracer. In experiments using humic acid, both redox species of U migrate nearly as fast as the conservative tracer. Humic acid accelerates the U(VI) breakthrough compared to the humic acid-free system. There are strong indications for a similar effect on the U(IV) transport. At the same time, a part of U(IV) and U(VI) associated with the humic acid is immobilized in the quartz sand due to humic colloid filtration thus producing a delaying effect. Tailing at a low concentration level was observed upon tracer elution. The experimental breakthrough curves were described by reactive transport modeling using equations for equilibrium and kinetic reactions. The present study demonstrates that humic acids can play an important role in the migration of actinides. As natural organic matter is ubiquitous in aquifer systems, the humic colloid-borne transport of actinides is of high relevance in performance assessment.     

Macro-fungal (Agaricus bisporus) wastes as an adsorbent in the removal of the acid red 97 and crystal violet dyes from ideal colored effluents

The wastes from the macro-fungus Agaricus bisporus were used as an eco-friendly and low-cost adsorbent for the treatment of colored effluents containing the recalcitrant dyes, acid red 97 (AR97) and crystal violet (CV). The macro-fungal waste presented an amorphous structure, composed of particles with different sizes and shapes. Also, it presents typical functional chemical groups of proteins and carbohydrates with a point of zero charge of 4.6. The optimum conditions for the dosage were found to be as follows: 0.5 g L⁻¹ with an initial pH at 2.0 for the AR97 and 8.0 for the CV. From the kinetic test, it was found that it took 210 min and an adsorption capacity of 165 mg g⁻¹ for the AR97. Concerning the CV kinetics, it took 120 min to reach the equilibrium and it achieved an adsorption capacity of 165.9 mg g⁻¹. The Elovich model was the most proper model for describing the experimental data, achieving an R² ≥ 0.997 and MSE ≤ 36.98 (mg g⁻¹)². The isotherm curves were best represented by the Langmuir model, predicting maximum adsorption capacity of 372.69 and 228.74 mg g⁻¹ for the AR97 and CV, respectively. The process was spontaneous and favorable for both dyes. The ∆H⁰ values were 9.53 and 10.69 kJ mol⁻¹ for AR97 and CV, respectively, indicating physical and endothermic adsorption. Overall, the wastes from Agaricus bisporus have the potential to adsorb cationic and anionic dyes, thus solving environmental problems related to water quality and residue disposal.