Experimental Study on the Damage and Deterioration Behaviour of Deep Soft Rock under Water-Rock Interaction

The ageing disintegration, the damage, and failure mechanism of water-saturated soft rock are of significance to hazard prevention for deep mining. In this paper, indoor experiments, including disintegration behaviour tests in water, uniaxial compression failure tests of rock samples with different water contents, and variations in the microstructure of mudstone under saturated water contents, were conducted. The investigation results show that the saturated water content of mudstone is 16.96% and that the rock mass bursts completely after being immersed in water for 72 h. With increasing water content, the uniaxial strength and elastic modulus at the prepeak stage present significant attenuation. However, Poisson’s ratio varies little, which indicates that the swelling of cemented mudstone is not obvious when meeting water. In addition, the failure pattern of mudstone changes from overall splitting failure to block fragmentation failure. Due to ion-exchange adsorption and the wedging action of water molecules, the edge of contact between particles changes from staggered to smooth, which leads to the expansion of pores, the loosening of mudstone structures, and a decrease in mechanical strength. Therefore, the diffusion, migration, and particle expansion of illite and other clay minerals in mudstone are the main factors leading to the structural damage and strength reduction of weakly cemented rock under water-rock interactions.

HIGHLY EFFICIENT REMOVAL OF COPPER(II) IONS FROM AQUEOUS SOLUTION BY NICKEL 2-ETHYLIMIDAZOLATE

Nickel 2-ethylimidazolate was obtained and characterized, which is used in this work as a sorbent for the removal of copper (II) ions. The sample characterization was carried out by scanning electron microscopy, low-temperature nitrogen adsorption. It was found that the obtained sorbent is a microheterogeneous material with the size of individual particles in the range of 0.4-0.7 μm. Nitrogen adsorption isotherms in the pores of nickel 2-ethylimidazolate were obtained. It was found that when processing the experimental data in linear coordinates of TVFM, linearization is reached in coordinates lnV-lnPs/P, which indicates the predominance of mesopores in the structure of nickel 2-ethylimidazolate. The total pore volume was determined from the TVFM linear coordinates. It was 0.21 cm3/g. According to obtained differential pore size distribution, the most probable average pore radius corresponds to 7.5 nm. One of the main characteristics of nickel 2-ethylimidazolate as a sorbent, the surface area was determined by the A.V. Kiselev method and amounted to 703.56 m2/g. The efficiency verification of using nickel 2-ethylimidazolate in the heavy metal ions sorption processes was carried out by removal of copper(II) ions from aqueous solutions by the limited solution volume method at different contact times. The copper(II) sorption kinetics in the presence of nickel 2-ethylimidazolate was studied by processing experimental data in the first and second orders linear coordinates. It was found that the adsorption kinetics of copper(II) ions is described by a second order model, which indicated ion-exchange adsorption. Equilibrium adsorption capacity in the sorbent-solution system is reached at a contact time of 90-120 min.

Recent Approaches for Chemical Speciation and Analysis by Electrospray Ionization (ESI) Mass Spectrometry

In recent years, the chemical speciation of several species has been increasingly monitored and investigated, employing electrospray ionization mass spectrometry (ESI-MS). This soft ionization technique gently desolvates weak metal–ligand complexes, taking them in the high vacuum sectors of mass spectrometric instrumentation. It is, thus, possible to collect information on their structure, energetics, and fragmentation pathways. For this reason, this technique is frequently chosen in a synergistic approach to investigate competitive ligand exchange-adsorption otherwise analyzed by cathodic stripping voltammetry (CLE-ACSV). ESI-MS analyses require a careful experimental design as measurement may face instrumental artifacts such as ESI adduct formation, fragmentation, and sometimes reduction reactions. Furthermore, ESI source differences of ionization efficiencies among the detected species can be misleading. In this mini-review are collected and critically reported the most recent approaches adopted to mitigate or eliminate these limitations and to show the potential of this analytical technique.

Lithium Recovery from Water Resources by Ion Exchange and Sorption Method

Demand to lithium rising swiftly as increasing due to its rapidly increasing dosages diverse applications such as rechargeable batteries, light aircraft alloys, and nuclear fusion. Lithium demand is expected to triple by 2025 driven by battery applications, specifically electric vehicles. To ensure the growing consumption of lithium, it is necessary to increase the production of lithium from different resources. Natural lithium resources mainly associate within granite pegmatite type deposit (spodumene and petalite ores), salt lake brines, seawater, and geothermal water. Among them, the reserves of lithium resources in salt lake brine, seawater, and geothermal water are in 70–80% of the total, which are excellent raw materials for lithium extraction. Compared to the minerals, the extraction of lithium from water resources is promising because this aqueous lithium recovery is more abundant, more environmentally friendly, and cost-effective. There are many ways to recover lithium from water resources. Among existing methods, the adsorption method is more promising on the way of manufacture. Therefore, the important progress on ion-exchange adsorption methods for lithium recovery from water resources searched ways, were summarized in detail, and the new trends in the future were also carried out.

Derivation and application of a generalised exchange-adsorption isotherm for the adsorption of hydrophobic compounds on soils

A general adsorption model able to provide a good description of the multilayer adsorption of ions and molecular compounds under any circumstances is proposed in this paper. In order to reach this goal, a general form of isotherm was deduced based on the Gapon equation and classical isotherm forms. The adsorption of molecular compounds with diverse hydrophobicity and acid-base characteristics were investigated and validated with a new model for the adsorption of four pesticides on different soils. The adsorption capacity and adsorption energy estimated by the new model were found to be related to the organic matter content of the soil. Great differences were found in the isotherm parameters (A_i, K_i, and n_i) among both the soils and compounds investigated here.

Integrated Stirred-Tank Bioreactor with Internal Adsorption for the Removal of Ammonium to Enhance the Cultivation Performance of gdhA Derivative Pasteurella multocida B:2

Growth of mutant gdhA Pasteurella multocida B:2 was inhibited by the accumulation of a by-product, namely ammonium in the culture medium during fermentation. The removal of this by-product during the cultivation of mutant gdhA P. multocida B:2 in a 2 L stirred-tank bioreactor integrated with an internal column using cation-exchange adsorption resin for the improvement of cell viability was studied. Different types of bioreactor system (dispersed and internal) with resins were successfully used for ammonium removal at different agitation speeds. The cultivation in a bioreactor integrated with an internal column demonstrated a significant improvement in growth performance of mutant gdhA P. multocida B:2 (1.05 × 1011 cfu/mL), which was 1.6-fold and 8.4-fold as compared to cultivation with dispersed resin (7.2 × 1010 cfu/mL) and cultivation without resin (1.25 × 1010 cfu/mL), respectively. The accumulation of ammonium in culture medium without resin (801 mg/L) was 1.24-fold and 1.37-fold higher than culture with dispersed resin (642.50 mg/L) and culture in the bioreactor integrated with internal adsorption (586.50 mg/L), respectively. Results from this study demonstrated that cultivation in a bioreactor integrated with the internal adsorption column in order to remove ammonium could reduce the inhibitory effect of this by-product and improve the growth performance of mutant gdhA P. multocida B:2.

Synthesis, Characterization, and Properties of Sulfonated Chitosan for Protein Adsorption

Chitosan sulfate was prepared and characterized as a new chromatography media for protein separation. The degree of sulfonation of chitosan could be well controlled and impacted under conditions in the synthesis process. The prepared chitosan sulfate shows improved binding capacity with proteins. Sulfonated chitosan shows improved ion-exchange adsorption properties with proteins, which could have good potential in protein purification.