Phosphorus (P) is a nutrient necessary for agricultural production and a potential originator for eutrophication in water bodies, resulting in qualitative changes; it may also affect the aquatic ecosystem and human health. In addition, as a finite resource, the importance of studying strategies to remove it from water is evident, thus making possible its recycling. Many studies have used powdered materials, including biochars, for P water decontamination; however, the difficulty of separating and collecting these materials from water after adsorption may be difficult. Therefore, using hybrid materials in which the fine particles (powder) are impregnated into larger, solid particles by means of a polymeric host can facilitate collection and reuse after P adsorption. In this context, this study aimed the synthesis and characterization of a new hybrid film formed by the biopolymer cellulose acetate (CA) and biochar (FAC-B) for P adsorption in aqueous solution. We obtained biochar from the pyrolysis of carrot residue (Daucus carota L.) and doped it with magnesium. As a biodegradable polymer and the most abundant natural polysaccharide in the environment, using CA as a biochar support material is an environmentally friendly alternative. We prepared the CA film with the casting method, and the biochar was inserted into the filmogenic solution in the same amount as the CA. The film was characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), molecular absorption spectroscopy in the infrared region with an attenuated total reflectance (FTIR/ATR) accessory, and X-ray Photoelectron Spectroscopy (XPS). We evaluated the thickness, weight, density, H₂O uptake and H₂O solubility of the produced FAC-B. The maximum adsorption capacity of P by FAC-B was 21.57 mg g⁻¹, in agreement with the Langmuir isotherm model. The adsorption value suggests that the film has the potential to be used as an efficient P adsorbent in water.

Study regionThe study was developed for fhe Pomba River Basin, which is located in southeast region of Brazil in the continent of South America.Study focusThis study aimed to (a) calibrate and validate the SWAT model for a sub-basin of Pomba River Basin, (b) validate it for use with upstream and downstream control sections and (c) validate it for sub-basins other than the one where calibration was performed. This was done with the goal of having a model that can be used for the estimation of water availability and the planning of soil use and occupation. The model was calibrated by trial and error during the period from January 1996 through December 1999, while validation was conducted during the period from January 2000 through December 2004. Estimated the maximum, average and minimum annual daily streamflows were evaluated based on the paired t-test and linear regression analysis.New hydrological insightsThe SWAT model was qualified for simulating the Pomba River sub-basin in the sites where rainfall representation was reasonable to good. The model can be used in the simulation of maximum, average and minimum annual daily streamflow based on the paired t-test, contributing with the water resources management of region, although the model still needs to be improved, mainly in the representativeness of rainfall, to give better estimates of extreme values