RESUMO
Emerging pollutants, including pharmaceuticals and personal care products, have been detected in surface and groundwaters. The adsorption of paracetamol and ibuprofen, two widespread drugs, has been studied in aqueous medium, using a ceramic-derived carbon (CeDC) and a commercial activated carbon (CoAC). CeDC yielded a BET surface area of 895 m2 g-1, a bimodal pore size distribution (13.2 and 35 nm) and a total pore volume of 1.99 cm3 g-1. CoAC had an approximate surface area of 1000 m2 g-1, a homogeneous pore size distribution and a total pore volume of 0.42 cm3 g-1. Kinetic and equilibrium tests were carried out in batch systems to study the materials' sorption performances. The intraparticle diffusion model best fitted the experimental kinetic data. The maximum ibuprofen sorption capacities were 120 mg g-1 and 133 mg g-1 for CoAC and CeDC, respectively, whereas no major differences on the maximum paracetamol sorption capacities (qm) were observed among the sorbents (150-159 mg g-1). Therefore, CeDC, synthesized easily from a ceramic composite, improved time and sorption capacity of paracetamol and ibuprofen compared to the commercial activated carbon, indicating the potential of the developed carbon as an emerging pollutant sorbent material.
RESUMO
A biocomposite system was developed and tested for the removal of the azo dye Reactive Red (RR195) from wastewater. The biocomposite was synthesized using ceramic particles containing 75% alumina which were coated using chitosan cross-linked with oxalic acid. The biocomposite showed high performance at low pH (maximum adsorption capacity = 345.3mg.g-1 at pH=2.0). The physicochemical and structure characteristics of the matrix were evaluated by Z-potential, FTIR-ATR, SEM-EDS, XRD, and porosity. Langmuir sorption isotherm and pseudosecond-order model gave the best fit. The electrostatic interaction between RR195 (due to the sulfonate groups) and the free amino groups of chitosan, enabled successive desorption/regeneration cycles. The maximum removal percentage (>80%) occurred at pH=2.0 due to the cross-linking effect. Experiments at different temperatures allowed the calculation of thermodynamic parameters (ΔG, ΔS, ΔH); adsorption was spontaneous, exothermic, and enthalpy controlled. The presence of inorganic ions ([Formula: see text] ) was analyzed during the adsorption process. This novel biocomposite can be applied as a cost-effective and environmentally friendly adsorbent for anionic azo dye removal from wastewater. The application of chitosan cross-linked with oxalic acid as a coating of the ceramic support enhanced the adsorption capacity and enabled its use under acidic conditions without solubilization.
