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Acrylamide (AA) is routinely used in laboratories and industries, and its disposal is always a problem; consequently, offering an alternative for their treatment contributes to conducting research in a responsible way. Therefore, in this work, acrylamide solutions were degraded by ultraviolet radiation and hydrogen peroxide (H2O2), and their toxicity was evaluated using a Desmodesmus quadricauda microalgae growth assay. The AA solutions were exposed to different dosages of H2O2 and different exposure times to UV radiation. The degradation was evaluated by liquid chromatography, which allowed the identification of the acrylamide peak and subsequent by-product peaks. A 100% degradation of the 1.5 mg L-1 AA solution with UV/H2O2 (0.034 g L-1) was achieved in just 10 min. The by-products formed did not inhibit the growth of D. quadricauda microalgae. The number of D. quadricauda individuals that grew in acrylamide solutions exposed to 20 and 30 min of UV radiation, with 0.034 g L-1 of H2O2, was very similar to the number of individuals that grew in the control solution. Thus, the treatment proposed in this work using H2O2 combined with ultraviolet radiation degraded acrylamide into by-products with reduced toxicity.

The work aims to synthesize and characterize vegetal charcoal (or biochar) from Syzygium cumini (AC-SC), evaluating the adsorption capacity for dexamethasone drug (DEX) removal, using the kinetic and equilibrium adsorption. The samples were characterized by N

The present work aims to evaluate the removal capacity of Rhodamine B dye (RhB) using nano-porous chitosan (NC) from shrimp shells. NC was characterized by XRD, SEM-EDS, N

The pollution of wastewater with dyes has become a serious environmental problem around the world. In this context, the work aims to synthesize and characterize a supported nanocatalyst (NZ-180) from rice husk (RH) and alum sludge (AS) incorporating silver (AgNPs@NZ-180) and titanium nanoparticles (TiNPs@NZ-180) for Rhodamine B (RhB) dye degradation, under UV and visible irradiation. Central rotatable composite design (CRCD) was used to determine ideal conditions, using nanocatalyst and dye concentration such as input variables and degradation percentage like response variable. Samples were characterized by XRD, SEM-EDS, N2 porosimetry, DLS, and zeta potential analyses. TiNPs@NZ-180 showed the best photocatalytic activity (62.62 and 50.82% under UV and visible irradiation, respectively). Specific surface area has increased from 35.90 to 418.90 m2 g−1 for NZ-180 and TiNPs@NZ-180, respectively. Photocatalytic performance of TiNPs@NZ-180 has reduced to 8 and 10% after 5 cycles under UV and visible light irradiation. Ideal conditions found by CRCD were 2.75 g L−1 and 20 mg L−1 for nanocatalyst and RhB concentrations, respectively. Therefore, (agro)industrial waste present such an alternative material for application in the removal of wastewater with dyes, which helps in the reduction of the impact of chemicals/pollutants on human and animal health.

Olive biomass waste (Olea europaea L.) is a by-product of vegetable oil extraction processing produced in ever-increasing quantities, becoming an environmental liability when not destination or treated correctly. Thus, the work aimed to study the application of olive biomass waste to preparation of adsorbent material (biochar) to rhodamine B (RhB) dye removal. For the preparation of the biochar, activation/carbonization process was used, where for chemical activation, the ZnCl2 was used as activating reagent, in the proportion of 1:2 w/w, and for the carbonization, used a heating rate of 10 °C min−1 to 600 °C for 240 min. Materials were characterized by X-ray diffraction (XRD), zeta potential (ZP), and Fourier transform infrared spectroscopy (FTIR), and its adsorption potential to remove RhB dye from aqueous media was verified, through kinetic, equilibrium, and thermodynamic study. About kinetic adsorption, the pseudo-first-order model showed satisfactorily represented. Moreover, Freundlich model was suitable to represent the adsorption equilibrium of the RhB dye. The maximum value for adsorption capacity was 263.71 mg g–1, and the adsorption process was thermodynamically spontaneous, favorable, and endothermic. Therefore, the olive biomass waste can be considered a potential adsorbent for the wastewater treatment with dyes, mainly.

Rhodamine B (RhB) is a cationic organic dye widely used industrially, mainly in the textile and food industries. Then, the work aims to study on the photocatalytic degradation of RhB dye, under UV and visible radiation, using photocatalyst silica-based materials synthesized by sol-gel route with different solvents (ethanol and n-propanol) and catalysts (C12H27N, HNO3, NH4OH, and NaOH) to the hydrolysis and condensation of tetraorthosilicate (TEOS). In addition, the effect of doping with silver nanoparticles (AgNPs) was evaluated on the photocatalytic activity. The samples were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), N2 porosimetry, zeta potential measurements (ZP), and Fourier transform infrared spectroscopy (FTIR). To evaluate the photocatalytic activity, photocatalytic tests were carried out in a stirred batch reactor, with the photocatalyst in suspension, under ultraviolet and visible radiation, and the target molecule chosen was the Rhodamine B dye (RhB). The photocatalyst Si–HNO3–AgNPs showed the best photocatalytic activity with a degradation of the RhB dye of 90.16% (k = 0.0198 min−1, under ultraviolet radiation) and 82.79% (k = 0.0148 min−1, under visible radiation), after 120 min of reaction; while under the same conditions, the commercial catalyst TiO2 (P25) showed a degradation of 50.02% and 42.14%, respectively.

Nicotine, a highly toxic alkaloid, has been detected in effluents, surface and groundwater and even bottled mineral water. The present work studied the photocatalytic degradation of nicotine in aqueous solution, under ultraviolet irradiation. The experiments were carried out using commercial (ZnO, TiO2) and non-conventional catalysts, which were prepared from industrial and laboratory waste. Two experimental designs (CCD) were performed for both commercial catalysts, and initial nicotine concentration, catalyst concentration and initial solution pH effects were studied. Then, the synthesized catalysts were tested under the optimal conditions which were found through CCDs. Using commercial catalysts, about 98% of the alkaloid was degraded by ZnO, and 88% by TiO2, in 1h. Among the non-conventional catalysts, the highest photocatalytic degradation (44%) was achieved using the catalyst prepared from a petrochemical industry residue.

Foundry sands from the iron foundry industry were employed as a support source for photocatalysts. TiCl4 was used as the titanium precursor in the preparation of the supported photocatalysts. The solids were characterized by scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, diffuse reflectance spectroscopy in the ultraviolet range, small-angle X-ray scattering, nitrogen porosimetry, and zeta potential measurements. The prepared catalyst systems contained Ti, Al, Fe, K, Na, or Cu. All systems were also found to contain carbon. The systems were evaluated in the photodegradation of rhodamine B. For comparative reasons, P25 (Degussa) was also employed as a catalyst. Among the tested systems, the greatest percent dye degradation occurred with ultraviolet (65 %) and visible (38 %) radiation, whereas under the same conditions, the commercial P25 catalyst achieved 93 and 14 % degradation, respectively, for the ultraviolet and visible radiation.

Dexamethasone and guaifenesin were comparatively degraded under UV and visible radiation in the presence of a supported photocatalyst generated from petrochemical residue. For comparative reasons, photochemical tests were also conducted in the presence of commercial titania (P25). The photoelectrochemical behavior of the supported photocatalyst was examined using cyclic voltammetry and differential pulse voltammetry in the dark and under LED irradiation. This photodegradation study indicates the highest drug degradation values were observed for guaifenesin under UV (48.6 %) and visible (45.2 %) radiation with the synthesized photocatalyst. Under the same conditions, the commercial P25 catalyst achieved 66.3 and 50.2 % of the degradation under UV and visible radiation, respectively. Exploratory tests with tap water samples revealed that the system may be sensitive to other analytes present in these environmental samples.