Chemoenzymatic Conversion of Biomass-Derived D-Xylose to Furfuryl Alcohol with Corn Stalk-Based Solid Acid Catalyst and Reductase Biocatalyst in a Deep Eutectic Solvent–Water System

In this work, the feasibility of chemoenzymatically transforming biomass-derived D-xylose to furfuryl alcohol was demonstrated in a tandem reaction with SO42−/SnO2-CS chemocatalyst and reductase biocatalyst in the deep eutectic solvent (DES)–water media. The high furfural yield (44.6%) was obtained by catalyzing biomass-derived D-xylose (75.0 g/L) in 20 min at 185 °C with SO42−/SnO2-CS (1.2 wt%) in DES ChCl:EG–water (5:95, v/v). Subsequently, recombinant E.coli CF cells harboring reductases transformed D-xylose-derived furfural (200.0 mM) to furfuryl alcohol in the yield of 35.7% (based on D-xylose) at 35 °C and pH 7.5 using HCOONa as cosubstrate in ChCl:EG–water. This chemoenzymatic cascade catalysis strategy could be employed for the sustainable production of value-added furan-based chemical from renewable bioresource.

H2-Based Processes for Fe and Al Recovery from Bauxite Residue (Red Mud): Comparing the Options

To tackle the challenge of bauxite residue (BR), generated during the alumina production, as well as to recover some of its metal content, three combinatory H2-based processes were utilized. Firstly, Greek BR was mixed with NaOH to produce water soluble Na-aluminates and was roasted under pure H2 gas in order to reduce the Fe+3 content. Then the first process combined water leaching and magnetic separation, the second water leaching and melting and the last included wet magnetic separation. The water media resulted in the dissolution of Na-aluminate phases and the production of Al, Na-ion rich leachates. From these, pregnant leaching solutions recovery of Al was 78%, 84% and for the third case it reached 91%. Concerning Na recovery, it could reach 94%. Both melting process and magnetic separation aimed for Fe recovery from the material. The former case however still needs to be optimized, here its concept is introduced. The magnetic fraction, after the dry magnetic separation, varied in Fe content from 31.57 wt.% to 38.50 wt.%, while after the wet magnetic separation it reached 31.85 wt.%.

Development of a Novel Adsorbent Prepared from Dredging Sediment for Effective Removal of Dye in Aqueous Solutions

This study proposed a novel and low-cost adsorbent prepared from dredging sediment (DSD) for effective removal of dye in aqueous solutions. The adsorption efficiency and behavior of the DSD adsorbent toward the crystal violet (CV), a cationic dye, were investigated via batch experiments. The results showed that DSD samples contain mainly clay minerals (illite and kaolinite) and other mineral phases. In addition, DSD is a mesoporous material (Vmesopore = 94.4%), and it exhibits a relatively high surface area (~39.1 m2/g). Adsorption experiments showed that the solution’s pH slightly affects the adsorption process, and a pH of 11 gave a maximum capacity of 27.2 mg/g. The kinetic data of CV dye adsorption is well described by the pseudo–second-order and the Avrami models. The Langmuir and Liu isotherm models provide the best fit for the adsorption equilibrium data. The monolayer adsorption capacity of Langmuir reached 183.6, 198.0, and 243.6 mg/g at 293, 308, and 323 K, respectively. It was also found that the adsorption process was spontaneous (−ΔG°), exothermic (−∆H°), and increased the randomness (+∆S°) during the adsorption operation. The primary mechanisms in CV dye adsorption were ion exchange and pore filling, whereas electrostatic attraction was a minor contribution. In addition, three steps involving intraparticle diffusion occur at the same time to control the adsorption process. The results of this study highlight the excellent efficiency of DSD material as an ecofriendly sorbent for toxic dyes from water media.

Direct Conversion of Cellulose Into 5-HMF By Transition-Metal Doped Montmorillonite Catalyst In Water

In this study, transition metal doped montmorillonite catalyts (Cr-MMT, Cu-MMT, Fe-MMT and Zn-MMT) were successfully synthesized by hydrothermal method and evaluated for the conversion of cellulose to 5-HMF in the water media. Metal-MMT catalysts were characterized by XRD, BET, Ammonia-TPD and pyridine-FTIR to investigate the properties of the samples. Using Cr-MMT, an efficient conversion of cellulose to 5-HMF was achieved in the water system, affording a conversion yield 93.47% and 5-HMF yield 9.07% within 6 h at 200oC.

Effect of medium type, light intensity, and photoperiod on the growth rate of microalgae Chlorococcum sp. local isolate

Microalgae are microscopic organisms that are living in a watery environment, whether in fresh or seawater. As photosynthetic organisms, microalgae are the primary oxygen producers in the water. Furthermore, microalgae have various benefits for the sustainability of human beings. Chlorococcum sp. is green microalgae found in freshwater, seawater, brackish water, or even in wastewater. Publication data on this microalga are limited, but this alga is known for its high lipid content. Previously, Chlorococcum sp. was isolated from the Ampenan Estuary of Lombok Island and grown in a liquid medium using Walne’s. The purpose of this study was to determine the optimum growth factors for the cultivation of Chlorococcum sp. The microalgae growth factors that were varied as treatments were the source of water medium used (distilled water, seawater, and saline water), the light intensity (2000, 25000, 3000, and 3500 lux), and the photoperiod (16: 8; 20:4; and 24:0 hours). Based on the research data, it is known that the type of water media is very influential on the productivity of microalgae. Where the highest growth of Chlorococcum sp. was produced in a medium containing saline water. In addition, the number of cells in the initial culture also affects the life span of microalgae. The treatment with the lowest initial cells caused the cell death phase to be extended, starting from the 11th day of culture. In conclusion, the optimal growth of Chlorococcum sp. occurred on the 5th day with a cell density of 323×104 cells/ml.

Can Oryzias Celebensis Embryo be Transported Dry?

Embryos of the genus Oryzias have long been used as sentinel organisms in ecotoxicological research. Compared with animal models from mammals, Oryzias embryo offers several advantages such as being cost-effective, more sensitive, rapid and produce very little waste. In ecotoxicological studies, it is necessary to have inter-laboratory calibration on used techniques between one laboratory and another, so that the used techniques are reliable. Inter-laboratory calibration between laboratories requires transferring embryos from one laboratory to another. For this purpose, research has been carried out to compare the survival of embryos reared in water and non-water (dry) media until they hatch. The results showed that the embryos reared with dry media hatched one day faster than those raised in water media. The dry-incubated embryo also had an average total length longer than those incubated with embryo rearing media (ERM). In this study, it was concluded that fish embryos of Oryzias celebensis could be transported dry for up to five days.