To investigate the adsorptive properties of a local laterite deposited in Chenzhou, Hunan province, China, the adsorptive properties of the natural laterite were investigated by batch technique in this study. The effects of contact time, pH, ionic strength, temperature, and the concentration on adsorption properties were also analyzed. The obtained experimental results show that the main mineral composition of laterite is kaolinite and montmorillonite. The adsorption process achieved equilibrium within 60 minutes and 90 minutes for Sr(II) and Cr(VI), respectively. The adsorption capacities for Cr(VI) and Sr(II) by the laterite were about 7.25 mg·g-1 and 8.35 mg·g-1 under the given experimental conditions, respectively. The equilibrium adsorption data were fitted to the second-order kinetic equation. The adsorption capacity for Sr(II) onto the laterite increased with increasing pH from 3–11 but decreased with increasing ionic strength from 0.001 to 1.0 M NaCl. The Sr(II) adsorption reaction on laterite was endothermic and the process of adsorption was favored at high temperature. Similarly, the adsorption capacity for Cr(VI) onto the laterite increased with increasing pH from 3–11, however, the ionic strength and temperature had an insignificant effect on Cr(VI) adsorption. The adsorption of Cr(VI) and Sr(II) was dominated by ion exchange and surface complexation in this work. Furthermore, the Langmuir and Freundlich adsorption isotherm model was used for the description of the adsorption process. The results suggest that the studied laterite samples can be effectively used for the treatment of contaminated wastewaters.
The purpose of the study was to analyse the effect of changes in the composition of raw material and agglomeration on sorption properties of a multi-component food, in the example of a powdered cocoa beverage. The basic composition of the mixtures was 20% of cocoa and 80% of sucrose. A change in raw material composition involved partial or total replacement of sucrose with a mixture of glucose and fructose, or with maltodextrin. Analysis of sorption properties demonstrated variability in the course of isotherms of water vapour sorption for components of the powdered cocoa beverage. Limiting water activity (aw) was determined for the value of 0.529. The conducted analysis detected no significant effect of agglomeration on water content in the tested products. However, a significant change in the raw material composition was demonstrated.
This paper presents an experimental study on Cochineal Red A dye adsorptive removal by yeast. Batch equilibrium and kinetic tests were conducted in constant temperature of 30 ◦C for the dye’s initial concentration range of 0.02–0.50 g/L (pH = 3 and 10) and 0.02–0.35 g/L (pH = 7:6). The equilibrium was reached after 105–120 min. Yeast demonstrated the adsorption capacity of 10.16 mg/g for acidic environment (pH = 3) and slightly lower values (8.13 mg/g and 8.38 mg/g respectively) for neutral (pH = 7:6) and alkaline environment (pH = 10). The experimental equilibrium results were fitted with Langmuir, Freundlich, Sips and Toth isotherm models. Most of them (Freundlich model being the exception) were proven sufficient for the experimental data correlation. The adsorption kinetic studies showed that the pseudo-second order model fits better the experimental data than the pseudo-first- order model. Results achieved from intra-particle diffusion model indicate that powdered yeast are a nonporous adsorbent. The percentage of solution discoloration reached a maximum value of 75% at pH = 3 for an initial dye concentration of 0.02 g/L.
The sorption isotherm and sorption kinetics of NH4+ by the Fen River reservoir sediment were investigated for a better understanding of the NH4+ sorption characteristics and parameters. The results showed that Q (adsorption content) increased with the increase of Ceq (equilibrium concentration), sorption isotherms could be described by Freundlich equation (R2 from 0.97 to 0.99). Cation exchange capacity (CEC) had a significant correlation with the parameters K and n (R2 was 0.85 and 0.95, respectively). The ENC0 (Ceq as Q was zero) of S1, S2, S3 and S4 was 1.25, 0.57, 1.15 and 1.14 mg L-1, respectively, and they were less than the NH4+ concentrations in reservoir water. The sediments released NH4+ to the Fen River reservoir water and acted as a pollution source, in the form of complex and heterogeneous adsorbents. The NH4+ adsorption kinetic process was composed of ‘fast’ and ‘slow’ reaction patterns and could be fitted using both Elovich equation and Pseudo second-equation. More than one-step may be involved in the NH4+ sorption processes, and interior diffusion was not dominant ion action.
The compost derived from cellulosic material coming from the Public Utility Company in Zabrze
(Poland) was investigated for its capability for adsorbing acid dyes from aqueous solution at various concentrations of the dyes and the compost dosages. Four acid dyes were investigated: Acid Red 18 (AR-18), Acid Blue
9 (AB-9), Acid Green 16 (AG-16) and Acid Black 1 (ABk-1). The adsorption isotherms were determined by
comparing the experimental data with the isotherm models (Freundlich, Langmuir and Dubinin–Radushkevich
models). The sorption capacity of the compost depended on the initial concentrations of dyes in the solution,
compost dosage, and on the structure of dyes. The maximum sorption capacities of the compost for adsorbing
particular dyes may be ordered as follows: ABk-1 > AG-16 > AB-9 > AR-18. The amounts of bound and the
percentages of removed acid dyes from effluent depended on the adsorbent dosage. The growth of the dye removal percentages with growing adsorbent mass may be attributed to the growth of the adsorbent uptake surface
with growth of the adsorbent mass. The dyes were bound onto the surface of compost through the electrostatic
interaction between the surface (negatively charged at pH > pHPZC) and the dye cations (AG-16), and/or through
the hydrogen bond between the functional groups of the humic matter in compost (–OH, –COOH) and the
functional surface groups of AR-18, AB-9 and ABk-1 dyes (–OH, –NH2
). At the experiment conditions, the
Freundlich and Dubinin-Raduskevich adsorption isotherm models fitted the equilibrium data very well (much
better than the Langmuir one). The values of 1/n in the Freundlich equation and E in the Dubinin-Raduskevich
one indicate the favourable adsorption. The studied compost may be used as a low-cost sorbent for the removal
of acid dyes from wastewater released by textile industries. However, elevated values of chemical oxygen demand (COD) in the final solutions may enhance the solubility of humic compounds.
Production processes of hot forging most often look similar [1-3]. Forging in several operations, usually in three or four. Most often the first operation is upsetting or flattening (sometimes rolling). The last operation is finishing forging. This applies to the production of steel forgings for the automotive, agricultural and other similar industries. Typical production proceeds as follows: the forgings are cleaned (shot-blasted) and then heat treatment is performed. It can be normalization, hardening and tempering, etc. After the heat treatment, forgings are checked and subjected to strength and microscopic tests, hardness tests, impact tests. The type of tests depends on the recipient. The process described in the work takes place in three operations. The heat treatment used so far is hardening and tempering. An attempt was made to change the heat treatment technology for a selected product made of 42CrMo4 steel (1.7225) (4140). An isothermal annealing test was carried out at different temperatures and for different times. The possibility of using heat from the forging process in heat treatment processes for the described product has been confirmed.
In the present study, the novel quaternary ammonium salt (QAS+), 1-methyl-di-octyl-1 phenyl ammonium iodide (QAS1), was synthesized by complete alkylation reaction. Sodium montmorillonite (Mt) was modified via an ion-exchange reaction with QAS1+. The modified material and quarternary ammonium salt (Mt1 and QAS1) were analyzed by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Removal capacity of hydrophobic organic pollutants such as 4-nitrophenol (4-NP) and 2,4-dinitrophenol (2,4-DNP) from solution media of synthesized organoclay was evaluated. The optimum conditions and batch kinetics of adsorption of 4-nitrophenol and 2,4-dinitrophenol from aqueous solutions are reported. It was shown that the adsorption capacity decreased in the order 4-NP> 2,4-DNP. The total mass loss during the drying process was 66% and 78%, respectively. Thermodynamic parameters enthalpy (∆H0) and entropy (∆S0) and the mean free energy (E) for the adsorption of nitrophenol compounds (NCP) were determined.
The reliable and rapid diagnosis of infectious animal diseases presents an exceptionally im- portant aspect when considering their control and prevention. The paper describes the compara- tive evaluation of two rapid isothermal amplification methods for diagnosis of African swine fever (ASF). The robustness of loop-mediated isothermal amplification (LAMP) and the cross-priming amplification (CPA) were compared using samples obtained from ASF confirmed animals. Both assays were evaluated in order to define their diagnostic capabilities in terms of ASF diagnosis and reproducibility of the results. Investigations showed no cross-reactivity for other pig patho- gens and no significant differences in the specificity of both assays. The sensitivity of LAMP reached 90%, while that of CPA was 70%. In conclusion, both methods are suitable for imple- mentation in preliminary ASF diagnosis but further improvements are required to enhance their diagnostic sensitivity.
Enterotoxigenic Escherichia coli (ETEC) is the causative agent of a wide range of diseases, which are the important cause of illness and mortality in piglets. ETEC strains expressing F4 fimbriae are frequently associated with post-weaning diarrhea (PWD) and lead to great economic losses in swine production industry worldwide. The aim of this study was to establish a rapid and effective isothermal amplification method for detection of F4 fimbriae. Loop-mediated isothermal amplification (LAMP), Polymerase spiral reaction (PSR) and cross-priming ampli- fication (CPA) were used to develop and optimize the detection method first time. Subsequently, the specificity and sensitivity of these methods were evaluated, and the clinical samples were detected with these methods. All the F4-positive samples could produce ladder-like amplifica- tions products and lead the chromogenic substrate SYBR Green I produce green fluorescence, while in blank control and negative samples lack of this pattern or remained orange. The sensi- tivity of LAMP and CPA were 10 times higher than PSR method. Meanwhile, these three methods were validated with clinical samples, 7 were found positive, while 125 samples were negative, the testing results were consisted with the real-time PCR method. These findings suggested that the isothermal amplification based on the F4 fimbriae is a rapid, effective and sensitive method under resource constrains.