RESUMEN

This work aims to produce bio-surfactant using a brewery waste (trub) as a strategy to reduce production costs related to the substrate, as well as to provide an eco-friendly destination for this residue. Trub is obtained during the boiling of the wort, being mainly composed of proteins and reducing sugars. To evaluate important process parameters on bio-surfactant production, a full factorial design (24) was elaborated, having agitation rate and concentrations of trub, yeast extract, and peptone as independent variables. The highest bio-surfactant concentration achieved was 100.76 mg L-1, where FTIR and Maldi-ToF-MS confirmed functional groups characteristic of peptides and isomers of surfactin in the bio-surfactant extract. Trub, agitation and yeast extract showed statistically significant effects on the response variable (surface tension), where an increase in the agitation rate and in the concentration of yeast extract demonstrated a positive impact on the production of bio-surfactant.

Asunto(s)

RESUMEN

Eco-responsible flame retardant treatments with some resistance to washing are of considerable interest in the sale and applications of technical garments and home textiles. Thus, in the present study, a nano-hybrid composite based on kaolinite-TiO2 was prepared and incorporated into the fibers of cotton fabric through a more sustainable route compared to existing commercial processes. SEM analyses revealed a mineral covering of the treated cotton fibers, which do not propagate flames when exposed to fire and have a self-extinguishing behavior after the heat source removal. The method proved to be efficient in obtaining a cotton product with high fireproof performance. It was observed that after functionalization, the fabric showed a thermal degradation 41% less at 800 °C, an increase in the residue formation, and a reduction of about 85% in peak heat release measured by PCFC. Some resistance to washing was noticed, and the mechanical resistance of fibers was preserved.

RESUMEN

The effluent from the textile industry is a complex mixture of recalcitrant molecules that can harm the environment and human health. Biological treatments are usually applied for this wastewater, particularly activated sludge, due to its high efficiency, and low implementation and operation costs. However, the activated sludge microbiome is rarely well-known. In general, activated sludges are composed of Acidobacteria, Bacillus, Clostridium, Pseudomonas, Proteobacteria, and Streptococcus, in which Bacillus and Pseudomonas are highlighted for bacterial dye degradation. Consequently, the process is not carried out under optimum conditions (treatment yield). Therefore, this review aims to contextualize the potential environmental impacts of azo dye-containing wastewater from the textile industry, including toxicity, activated sludge microbiome identification, in particular using the matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) as a novel, rapid and accurate strategy for the identification of activated sludge microbiome (potential to enhance treatment yield).

Asunto(s)

RESUMEN

This paper presents the synthesis of a hybrid material through the use of natural pozzolan and titanium(IV) isopropoxide using the sol-gel method and its application in the photocatalytic hexavalent chromium reduction. The characterization data indicated a mesoporous material possessing a surface area of 271.7 m2 g-1. The morphology studies (SEM and TEM) showed nanosheet hybrid structures. The analysis of DRUV, FTIR, XRD, and Mössbauer spectroscopy provides a different electronic structure of the synthetized material when compared with the originals, proving the hybridization process between pozzolan and titanium(IV) isopropoxide. The photocatalytic reduction of Cr(VI) to Cr(III) using the hybrid material showed a better performance than conventional photocatalysts (precursor and TiO2-P25). Operational conditions such as chromium initial concentration (0.02-0.20 mM), solution pH (3-6), and type of scavenger (citric or tartaric acid) were evaluated in order to determine the best experimental conditions for the Cr(VI) photoreduction. At their optimum (catalyst load of 15 mg L-1, tartaric acid as scavenger, [scavenger]0/[Cr(VI)]0 M ratio = 3:1, pH 3, and 25 °C), the total photoreduction of 0.20 mM Cr(VI) was achieved in 180 min. The novel hybrid materials synthesized from pozzolan and titanium(IV) isopropoxide showed to be a potential catalyst for the Cr(VI) reduction in aqueous solution. Graphical abstract.

Asunto(s)

RESUMEN

Rhodococcus sp. has a broad catabolic diversity and unique enzymatic capabilities, and it is able to adapt under extreme conditions. Thereby, the production of this remarkable bacterium has a great biotechnological and industrial importance. In this sense, we sought to improve the R. erythropolis ATCC 4277 growth through a central composite design, by varying the components of nutrient medium (glucose, malt extract, yeast extract, CaCO3), temperature, and agitation. It was found that the concentrations of glucose and malt extract are not statistically significant, being reduced of 4.0 and 10.0 g L-1 to 2.0 and 5.0 g L-1, respectively. The CaCO3 concentration and temperature were also diminished of 2.0 to 1.16 g L-1and 28 to 23.7 °C, respectively. Optimal growth conditions provided a 240% increase in final biomass concentration, an increment in specific growth rate, and a growth yield coefficient about five times greater. Application of the optimal conditions in biodesulfurization and biodenitrogenation processes showed that desulfurization capability is not associated with optimal growth conditions; however, it was achieved a 47% of nitrogen removal in the assay containing 10% (w/w) of heavy gas oil. Graphical Abstract ᅟ.

Asunto(s)

RESUMEN

The biodegradation kinetics of BTX compounds (benzene, toluene, and xylene) individually and as mixtures was studied using models with different levels of sophistication. To compare the performance of the unstructured models applied in this work we used experimental data obtained here and some results published in the literature. The system description was based on the material balances of key components for batch operations, where the Monod and Andrews models were applied to predict the biodegradation of individual substrates. To simulate the biodegradation kinetics of substrate mixtures, models of substrate inhibition were applied along with the Sum Kinetics with Interaction Parameters (SKIP) models, where for two-component association toluene-xylene SKIP model presented better performance and for tri-component association benzene-toluene-xylene, the uncompetitive inhibition model was better. The kinetic parameters were estimated via a global search method known as Particle Swarm Optimization (PSO). The main result of this study is that the sophisticated biodegradation kinetics of BTX mixtures can be successfully described by applying the SKIP model, with the main advantage being the consideration of the substrate interactions.

Asunto(s)

RESUMEN

The removal of dyes present in industrial effluent has received great attention in the past few years. This is partly due to increasing environmental awareness and the implementation of ever stricter environmental rules. However, some treatments for color removal from these effluents do not guarantee the absence of other secondary toxic substances, often originating from the treatment process itself. The aim of this study is to evaluate the toxicity level of the adsorbent Neem, used in adsorption processes for color removal, as well as that of the dye solution before and after the adsorption process. The toxicity tests were carried out according to the Environment Agency FATMA regulation no. 017/02. They consisted of exposing representative microorganisms from the environment, for a certain time interval, to several concentrations of one or more substances, under different environmental conditions, and then evaluating the toxic effects. The results show that the Neem leaf extract had a harmful affect on the test organism used. Thus, it is recommended that the leaf extract is removed prior to effluent treatment, since the results of this study indicate that this will reduce the toxicity of the effluent and also improve the efficiency of the adsorption process.

Asunto(s)

RESUMEN

The enzyme peroxidase is known for its capacity to remove phenolic compounds and aromatic amines from aqueous solutions and also to decolorize textile effluents. This study evaluates the potential of the enzyme horseradish peroxidase (HRP) in the decolorization of textile dyes and effluents. Some factors such as pH and the amount of H(2)O(2) and the enzyme were evaluated in order to determine the optimum conditions for the enzyme performance. For the dyes tested, the results indicated that the decolorization of the dye Remazol Turquoise Blue G 133% was approximately 59%, and 94% for the Lanaset Blue 2R; for the textile effluent, the decolorization was 52%. The tests for toxicity towards Daphnia magna showed that there was a reduction in toxicity after the enzymatic treatment. However, the toxicity of the textile effluent showed no change towards Artemia salina after the enzyme treatment. This study verifies the viability of the use of the enzyme horseradish peroxidase in the biodegradation of textile dyes.

Asunto(s)