Antonio Zuorro

Recovery of natural antioxidants from spent coffee grounds.

Spent coffee grounds (SCG) were extracted with an environmentally friendly procedure and analyzed to evaluate the recovery of relevant natural antioxidants for use as nutritional supplements, foods, or cosmetic additives. SCG were characterized in terms of their total phenolic content by the Folin-Ciocalteu procedure and antioxidant activity by the DPPH scavenging assay. Flavonoid content was also determined by a colorimetric assay. The total phenolic content was strongly correlated with the DPPH scavenging activity, suggesting that phenolic compounds are mainly responsible for the antioxidant activity of SCG. An UHPLC-PDA-TOF-MS system was used to separate, identify, and quantify phenolic and nonphenolic compounds in the SCG extracts. Important amounts of chlorogenic acids (CGA) and related compounds as well as caffeine (CAF) evidenced the high potential of SCG, a waste material that is widely available in the world, as a source of natural phenolic antioxidants.

Enzyme-assisted extraction of lycopene from tomato processing waste

A central composite design was used to optimize the enzyme-assisted extraction of lycopene from the peel fraction of tomato processing waste. Tomato skins were pretreated by a food-grade enzyme preparation with pectinolytic and cellulolytic activities and then subjected to hexane extraction. The factors investigated included extraction temperature (10-50 °C), pretreatment time (0.5-6.5 h), extraction time (0.5-4.5 h), enzyme solution-to-solid ratio (10-50 dm³/kg) and enzyme load (0-0.2 kg/kg). Overall, an 8- to 18-fold increase in lycopene recovery was observed compared to the untreated plant material. From a response surface analysis of the data, a second-degree polynomial equation was developed which provided the following optimal extraction conditions: T=30 °C, extraction time=3.18 h and enzyme load=0.16 kg/kg. The obtained results strongly support the idea of using cell-wall degrading enzymes as an effective means for recovering lycopene from tomato waste.

Response surface methodology (RSM) analysis of photodegradation of sulfonated diazo dye Reactive Green 19 by UV/H2O2 process.

A central composite design was used to investigate the influence of the main process parameters on the degradation of Reactive Green 19 (RG19) azo dye by the UV/H2O2 treatment. The combined use of UV radiation and H2O2 resulted in the decolorization and dearomatization of the dye. They were monitored by measuring the spectral changes occurring, respectively, in the visible and UV regions of the dye spectrum. RG19 degradation was found to be practically complete over a time of 15-60 min, for decolorization, and 50-200 min, for dearomatization, depending on the applied conditions. Both processes followed apparent first-order kinetics. The associated rate constants were used as the response variables and their dependence on initial dye and H2O2 concentrations, pH and reaction time was investigated by the response surface methodology. Response surface plots for the decolorization and dearomatization processes were very similar in shape. For both processes, the initial dye and H2O2 concentrations were the key factors controlling dye degradation.

Evaluation of UV/H2O2 advanced oxidation process (AOP) for the degradation of diazo dye Reactive Green 19 in aqueous solution

ABSTRACTThe azo dye Reactive Green 19 (RG19) is extensively used for dyeing textiles due to its cost effectiveness and excellent fastness properties. Treatment of wastewaters containing this dye by conventional methods is often inadequate because of its resistance to biological and chemical degradation. In this study, the suitability of an advanced oxidation process based on the use of UV radiation and hydrogen peroxide to degrade RG19 was investigated. Analysis of degradation data showed that the decolorization process followed pseudo-first-order kinetics. The existence of an optimum pH and H2O2 dose was also observed. Under the best conditions, complete decolorization of the dye solution was achieved in about 20 min. Total organic carbon (TOC) measurements showed that mineralization was slower than decolorization, but over 63% of TOC was removed in 90 min. Overall, the results obtained indicate that the UV/H2O2 treatment can be an effective method for the removal of RG19 from textile effluents.

Fluoride Removal from Water by Adsorption on a High Alumina Content Bauxite

Drinking water contamination by fluoride is recognized as a major public health problem in many parts of the world. In fact, although fluoride is an essential trace element for animals and humans, excessive fluoride intake may cause adverse health effects. In this study we investigated the potential of a natural, high alumina content, bauxite for the removal of fluoride from contaminated water. Both batch and continuous experiments were performed. In continuous-flow column experiments, the effects of inlet fluoride concentration (5–50 mg L

Removal of Lead from Aqueous Solutions by Spent Tea Leaves

Spent tea leaves from black and green tea were assessed for their potential to remove lead (II) from contaminated waters. Batch adsorption experiments made at temperatures between 5 and 40 °C and lead ion concentrations between 0.01 and 2 g/L showed that removal efficiencies higher than 95% can easily be achieved. The results were only marginally affected by the type of tea waste. At low lead loading the adsorption equilibrium was well described by the Langmuir equation, with a maximum adsorption capacity of 85–100 mg/g. A comparison with other adsorbents provided the following order for lead removal efficiency: black tea, coffee grounds > green tea > Fuller’s earth > activated carbon.

Enhanced lipid recovery from Nannochloropsis microalgae by treatment with optimized cell wall degrading enzyme mixtures

A statistical mixture design approach was used to investigate the effects of cell wall degrading enzymes on the recovery of lipids from Nannochloropsis sp. A preliminary screening of potentially suitable enzyme preparations, including lysozyme, cellulase and different types of hemicellulases, was carried out. The most effective preparations were then taken as basic components for the formulation of enzyme mixtures. Optimized ternary mixtures consisting of cellulase and two hemicellulases were obtained which allowed the recovery of up to 37.2g of lipids per 100g of dry biomass. SEM and TEM images of the enzymatically treated microalga revealed extensive cell damage, with degradation of the cell wall and release of intracellular material. Overall, the results obtained demonstrate that the mixture design method can be used to prepare cell wall degrading enzyme cocktails that can significantly improve the recovery of lipids or other valuable components from microalgae.

Use of cell wall degrading enzymes for the production of high-quality functional products from tomato processing waste

The feasibility of using tomato pomace, the solid waste resulting from the industrial processing of tomatoes, to produce a tomato oleoresin and a lycopene-enriched seed oil was investigated. The oil was obtained by cold-pressing the seeds, while the oleoresin was produced by pretreating the peel fraction of the waste with cell wall degrading enzymes. The latter consisted of polygalacturonase, pectin methylesterase, cellulase and hemicellulase. The enzymatic treatment followed by hexane extraction and solvent evaporation allowed the production of an oleoresin with a lycopene content of about 7% by weight. The oleoresin was incorporated in different proportions into tomato seed oil so as to obtain a functional oil with a lycopene content ranging from 30 to 600 ppm. The lycopene-enriched oil was characterized by official analytical methods and its potential use in the nutraceutical and cosmetic sectors was discussed.

Spent Tea Leaves as a Potential Low-cost Adsorbent for the Removal of Azo Dyes from Wastewater

Spent tea leaves (STL), a solid waste that is available in large amounts worldwide, was investigated as a potential low-cost adsorbent for the removal of two azo dyes, Reactive Green 19 (RG19) and Reactive Violet 5 (RV5), from contaminated waters. Preliminary experiments conducted on untreated STL showed that this material exhibited very low removal efficiencies (<10 %). By contrast, thermal activation of STL (200 to 400 °C for up to 2 h) resulted in a significant increase in dye adsorption. After thermal exposure of STL to 300 °C for 1 hour, removal efficiencies of 98.8 % and 72.8 % were observed, respectively, for RG19 and RV5. Characterization of the adsorbent by TG/DTA and FTIR measurements showed that structural and chemical changes occurred in the lignocellulosic material which were probably responsible for the enhancement in adsorption capacity. These results strongly support the use of activated STL as a low-cost alternative to conventional adsorbents.

Enhanced antibacterial and anti-quorum sensing activities of triclosan by complexation with modified β-cyclodextrins

Triclosan (TCS), an antimicrobial agent widely used in consumer and medical products, was complexed with 2-hydroxypropyl-β-cyclodextrin (HPβCD) and methyl-β-cyclodextrin (MβCD). Phase-solubility studies indicated that inclusion complexes of 1:1 stoichiometry were formed and allowed estimation of the associated equilibrium constants and free-energy changes. At the highest cyclodextrin concentrations investigated, an almost 20-fold increase in the apparent water solubility of TCS was determined. Susceptibility tests against Escherichia coli and Staphylococcus aureus showed that the TCS–HPβCD and TCS–MβCD complexes exhibited antibacterial properties higher than those of uncomplexed TCS. The two complexes were also found capable of interfering with cell-to-cell communication mechanisms in the C. violaceum model system relying on N-acylhomoserine lactone autoinducers. The inhibitory activity of TCS increased significantly upon inclusion of the drug in HPβCD or MβCD, with small differences between the two CDs. The results obtained suggest that the investigated complexes could be used for treating infections caused by TCS-susceptible pathogens or for preventing biofilm formation on indwelling medical devices such as catheters, stents and orthopedic implants.