Removal of Sulfate and Metals from Wastewater of a Mining Enterprise by a Dual Sorbent System: A Case Study

This paper presents the results of wastewater treatment at a mining enterprise developing a complex ore deposit in the Murmansk region, Russia. The main pollutants are sulfate, manganese, and strontium. For this complex wastewater treatment, a two-stage scheme was proposed and tested using two sorbents (at a pH of 6): an aminated peat biosorbent to remove sulfate and a commercial sorbent based on the mineral brucite to remove metals. Optimal conditions were established for purifying the wastewater of sulfate and manganese and strontium ions to the level of maximum available concentrations in water bodies for fishery purposes.

     

Three-dimensional sodium phosphinates derived from a bis-functionalized phosphinic acid

The synthesis and crystal structures of two three-dimensional sodium phosphinates are reported. While [Na₂{(CH₂OH)₂PO₂}₂(H₂O)]_n (1) is formed from the direct reaction of bis(hydroxylmethyl)phosphinic acid with NaOH, the addition of 1,10-phenanthroline to the above reaction mixture results in the formation of [Na₂{(CH₂OH)₂PO₂}₂]_n (2). The basic structural unit of the 3D polymeric networks in both 1 and 2 is a dimeric Na₂L₂ moiety. In case of 1, these units are interconnected through coordination via phosphoryl and alcoholic oxygen atoms to eventually result in a three-dimensional network. However in the case of 2, only the phosphoryl oxygen is responsible for gluing the Na₂L₂ dimeric units into a three-dimensional framework.     

Efficient organic solvent and oil sorbent co-polyesters: Poly-9-octadecenylacrylate/methacrylate with 1-hexene

In this work, highly absorbent cross linked co-polymer gels of cis-9-octadecen-1-ol with acrylic/methacrylic acid and 1-hexene in different molar ratios were synthesized by thermal polymerization techniques and studied. The polymers were characterized by Fourier Transform-Infrared Spectroscopy, Thermogravimetric analysis and Scanning Electron Microscopy techniques. Their non-ionic nature was verified with the help of transport number measurement by Wagner polarization technique. The polymers were found to have very high swelling capacities in organic solvents like chloroform, tetrahydrofuran, ethanol, diethylether, thiophene, pyridine, and benzene. These gels show maximum swelling for chloroform which reaches up to 750%. The swelling capacities for different oils like kerosene, gasoline, engine oil, and silicon oil, are also favorable. The swelling kinetics confirmed that the swelling followed second order kinetics. The chloroform retention time was also checked which established that the gels can be recycled and reused again and again. An experiment showing removal of kerosene from kerosene/water mixture is also performed. This confirms that these gels can be used in removing organic contaminants and oil from water and can help in water purification and environmental cleanup purposes.     

A cycle simulation model for predicting the performance of a diesel engine fuelled by diesel and biodiesel blends

Among the alternative fuels, biodiesel and its blends are considered suitable and the most promising fuel for diesel engine. The properties of biodiesel are found similar to that of diesel. Many researchers have experimentally evaluated the performance characteristics of conventional diesel engines fuelled by biodiesel and its blends. However, experiments require enormous effort, money and time. Hence, a cycle simulation model incorporating a thermodynamic based single zone combustion model is developed to predict the performance of diesel engine. The effect of engine speed and compression ratio on brake power and brake thermal efficiency is analysed through the model. The fuel considered for the analysis are diesel, 20%, 40%, 60% blending of diesel and biodiesel derived from Karanja oil (Pongamia Glabra). The model predicts similar performance with diesel, 20% and 40% blending. However, with 60% blending, it reveals better performance in terms of brake power and brake thermal efficiency.     

Тhe Еffectiveness of Metal and Metalloid Sorption from Mining Influenced Waters by Natural and Modified Peat

This study investigated the sorption behaviour of natural (N peat) and HCl-acid-modified peat (HCl peat) for contaminants in water collected at a mine site in northern Finland. Batch sorption experiments were conducted at room temperature and at 5 °C. Characterization of the sorbents by FTIR and XPS revealed no substantial change in the peat’s functional groups due to the acid treatment. Generally, the N peat was a more efficient sorbent for the mine water, although the HCl peat exhibited better nickel uptake capacity (21 mg Ni/g) than the N peat (16 mg Ni/g) from synthetic water. This is attributed to the lower equilibrium pH in samples treated with the HCl peat as well as the water’s different chemical composition. At room temperature, the N peat removed As(V) (80%) and Ni (85%) at low dosage (1–2 g/L), whereas the HCl peat presented good removal of As(V) (80%) at low dosage (1 g/L) but did not achieve satisfactory removal of Ni, even at a higher dosage (4 g/L). The performance of both sorbents was significantly affected by contact time. Ni removal by N peat increased substantially with contact time whereas removals achieved by HCl peat increased slightly up to 60 min, but decreased significantly at 24 h. Unlike with HCl peat, the N peat was less efficient in the experiments conducted at 5 °C. Overall, for both sorbents, As(V) and Ni were the most efficiently removed contaminants from the mine water. HCl peat had slightly better settling properties, however, both products settled poorly, thus rendering the studied mixing and settling system unsuitable for the proposed application. Nevertheless, both peat products, and especially the N peat, exhibited high contaminant removal potential and could represent a cost-effective and sustainable option for mine water treatment.     

Agar immobilized yeast cells in tubular reactor for ethanol production

Saccharomyces cerevisiae cells were immobilized in agar gel and used in a tubular reactor for conversion of cane molasses to ethanol at 30 degrees C, pH 4.5. Reactor was used in a continuous operation to test the operational stability and ethanol productivity. After 100 days of continuous fermentation at a dilution rate of 0.67 hr-1, some deactivation of cells was observed, but ethanol productivity was recovered by reactivating the cells by sparging air intermittently. It was found that intermittent reactivation during continuous operation was very important for satisfactory performance of the reactor. During operation, gel beads maintained their rigidity. Maximum ethanol concentration (94.9 g/L) was obtained with a feed containing 255 g/L reducing sugar, at a dilution rate of 0.2 hr-1. Maximum volumetric productivity (79.5 g ethanol /L/hr), specific ethanol productivity (0.58 g ethanol/g cells/hr), specific sugar uptake rate (1.12 g sugar/g cells/hr) and ethanol yield coefficient (0.43 g ethanol/g sugar) were obtained with a feed containing 195 g/L reducing sugar at a dilution rate of 1.33 hr-1.     

D.C. electrical properties of vacuum-deposited CdTe films

The current-voltage characteristics of vacuum-deposited CdTe films were studied as a function of film thickness (2500–13000 Å) at various temperatures (0–110°C). The d.c. conduction mechanism was explained using a modified Poole-Frenkel equation.