The aim of this work was to study the adsorption and removal of chromium (VI) ions contained in aqueous solutions using a chitosan-based hydrogel synthesized via chemical crosslinking of radical chitosan, polyacrylic acid, and N,N'-methylenebisacrylamide. Fourier-transform infrared spectroscopy confirmed the hydrogel synthesis and presence of reactive functional groups for the adsorption of chromium (VI) ions. The chromium (VI) adsorption mechanism was evaluated using non-linear Langmuir, Freundlich, Redlich-Peterson, and Sips isotherms, with the best fit found by the non-linear Redlich-Peterson isotherm. The maximum chromium (VI) adsorption capacities of the chitosan-based hydrogel were 73.14 and 93.03 mg metal per g dried hydrogel, according to the non-linear Langmuir and Sips isotherm models, respectively. The best kinetic fit was found with the pseudo-nth order kinetic model. The chromium (VI) removal percentage at pH 4.5 and 100 mg L initial metal concentration was 94.72%. The results obtained in this contribution can be useful for future works involving scale-up of a water and wastewater treatment method from a pilot plant to full-scale plant.

The burial of bodies is a potentially polluting activity. Taking this into consideration, the aim of the present study was to verify the compliance of two cemeteries with environmental legislation and to quantify the concentrations of heavy metals in soils affected by burial activities. Physicochemical characterization of the soil was performed by analyzing control samples from areas near the cemeteries. Concentrations of cadmium, lead, chromium, nickel, zinc and copper were determined using high-resolution continuum source atomic absorption spectrometry. The two cemeteries had unsatisfactory properties for the retention of metal cations, with clay percentages ranging from 15.40 to 41.40% and sand percentages ranging from 28.75 to 66.85%. The control samples presented low cation exchange capacity (12.27 to 22.73 cmolc/dm³) and high aluminum (Al3+) saturation (66.74 to 90.16%). Although neither of the two cemeteries had concentrations above the limits established for the metals analyzed by Resolution No. 420/2009 of the National Environment Council, the contaminants may be leaching to groundwater due to inadequate soil characteristics.

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O município de Bom Retiro/SC se caracteriza por intensa atividade agropecuária. Essas atividades podem impactar os recursos naturais, devido a utilização de agrotóxicos e fertilizantes que podem conter metais, causando diversos impactos ambientais. Com este estudo, objetivou-se caracterizar os sedimentos das áreas rurais influenciadas por atividades agropecuárias no município de Bom Retiro/SC. Para representação significativa da área, foram realizadas coletas de sedimentos em 25 pontos influenciados diretamente pelas referidas atividades. Os metais pesados cádmio (Cd), cobre (Cu), cromo (Cr), ferro (Fe), níquel (Ni), chumbo (Pb) e zinco (Zn) foram determinados por Espectrometria de Absorção Atômica de Alta Resolução com Fonte Contínua (ARFC EAA). Os sedimentos superficiais apresentaram concentrações de Cu, Cr, Fe, Ni, Pb e Zn, mas todos os pontos estavam enquadrados pela Resolução CONAMA n° 454/2012 como nível 1.

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