Displacement washing of softwood pulp cooked to various levels of residual lignin content

This study investigates the influence of the degree of delignification of kraft spruce pulp cooked at seven different kappa numbers, ranging from 18.1 to 50.1, on the efficiency of displacement washing under laboratory conditions. Although the pulp bed is a polydispersive and heterogeneous system, the correlation dependence of the wash yield and bed efficiency on the Péclet number and the kappa number of the pulp showed that washing efficiency increased not only with an increasing Péclet number, but also with an increasing kappa number. The linear dependence between the mean residence time of the solute lignin in the bed and the space time, which reflects the residence time of the wash liquid in the pulp bed, was found for all levels of the kappa number. Washing also reduced the kappa number and the residual lignin content in the pulp fibers.

Fungal α-amylase entrapped in agar-agar organic matrix “beads” enhances fabric starch-desizing potentials and α-amylase-detergent compatibility

Aureobasidium pullulans α-amylase (ApAmy) mixed with melted agar-agar solution and drop-wisely added to a mixture of organic solvent solution allowed for the entrapment of the α-amylase in the agar-agar organic matrix as beads. The immobilized ApAmy’s characteristics and wash performance were elucidated in comparison with the soluble ApAmy. Agar-agar at 2.0 % (w/v) and toluene: chloroform at 3:1 resulted in the highest immobilization yield retaining about 98% residual activity after ten catalytic cycles. The optimum temperature and pH for the immobilized enzyme were 60ºC and 6.5 respectively. The immobilized ApAmy hydrolysed branched and linear substrates thus establishing its broad substrate specificity. Relatively, the immobilized ApAmy (iApAmy) was more tolerant to organic solvents than the free enzyme. The iApAmy was mildly inhibited by cobalt but metals such as zinc, manganese, calcium and sodium enhanced the free and immobilized ApAmy activity. The iApAmy had a higher washing efficiency (77%) in the presence of detergents than the free enzyme (68%) and control (36%). The iApAmy showed good potentials as a detergent additive and from its characteristics, it could be useful in other industrial applications.

Efficiency of coal washing process and Harrington desirability function

The technological efficiency of the coal washing process is traditionally assessed by the correlation between the practically achieved results of this coal washing at a coal dressing plant and the theoretically possible ones defined by the laboratory testing to define the coal washability. However, the laboratory assessment of coal washability is a labor-intensive process and cannot be used for on-line control. The article considers the possibility of introducing a performance evaluation indicator using parameters traditionally defined in operational control schemes. This indicator is based on the well-known function of qualitative process evaluation based on several parameters, i.e. the Harrington's desirability function. The proposed efficiency indicator was calculated based on the qualitative and quantitative parameters of washing thirty different coals using the conventional processing scheme. Evaluation of the proposed efficiency indicator was made by comparing it with the traditionally used efficiency indicators. The evaluation results showed that the proposed indicator is more informative, because it also allows to take into account the compliance of the ash content during washing with the specified parameter, as well as to evaluate the efficiency of the washing process more objectively than the traditionally used clean coal yield indicator. Within a given ash content of the clean coal there exists a correlation with the performance indicators recommended for assessment of the washing efficiency. Given the specific features of the desirability function, the indicator makes it possible to qualitatively assess the coal washing process and determine the optimal value..

Research progress of viscoelastic surfactants for enhanced oil recovery

Although new energy has been widely used in our lives, oil is still one of the main energy sources in the world. After the application of traditional oil recovery methods, there are still a large number of oil layers that have not been exploited, and there is still a need to further increase oil recovery to meet the urgent need for oil in the world economic development. Chemically enhanced oil recovery (CEOR) is considered to be a kind of effective enhanced oil recovery technology, which has achieved good results in the field, but these technologies cannot simultaneously effectively improve oil sweep efficiency, oil washing efficiency, good injectability, and reservoir environment adaptability. Viscoelastic surfactants (VES) have unique micelle structure and aggregation behavior, high efficiency in reducing the interfacial tension of oil and water, and the most important and unique viscoelasticity, etc., which has attracted the attention of academics and field experts and introduced into the technical research of enhanced oil recovery. In this paper, the mechanism and research status of viscoelastic surfactant flooding are discussed in detail and focused, and the results of viscoelastic surfactant flooding experiments under different conditions are summarized. Finally, the problems to be solved by viscoelastic surfactant flooding are introduced, and the countermeasures to solve the problems are put forward. This overview presents extensive information about viscoelastic surfactant flooding used for EOR, and is intended to help researchers and professionals in this field understand the current situation.

Feasibility of a Chemical Washing Method for Treating Soil Enriched with Fluorine Derived from Mica

High levels of fluorine in soil may pose health risks and require remediation. In this study, the feasibility of using a practical chemical washing method for the removal of fluorine from an enriched soil was evaluated. The chemical washing procedures were optimized through experimental analyses of various washing solutions and washing conditions (i.e., washing solution concentration, solid–liquid ratio, agitation speed, and reaction time). Additionally, the effects of techniques for improving the washing efficiency, such as ultrasonic washing, aeration, and multi-stage washing, were evaluated. Herein, among all applied methodologies, the maximum washing efficiency achieved for the total fluorine present in soil was only 6.2%, which indicated that chemical washing was inefficient in remediating this particular soil. Further sequential extraction analysis showed that the fluorine in this soil was present in a chemically stable form (residual fraction), possibly because of the presence of mica minerals. It was demonstrated that chemical washing may not be effective for remediating soils containing such chemically stable forms of fluorine. In these cases, other physical-based remediation technologies or risk management approaches may be more suitable.

Temperature-resistant and salt-tolerant mixed surfactant system for EOR in the Tahe Oilfield

A new temperature-resistant and salt-tolerant mixed surfactant system (referred to as the SS system) for enhancing oil recovery at the Tahe Oilfield (Xinjiang, China) was evaluated. Based on the analysis of the crude oil, the formation water and rock components in the Tahe Oilfield, the long-term thermal stability, salt tolerance and the ability to change the wettability, interfacial activity and oil washing efficiency of the mixed surfactant system were studied. The system contains the anionic surfactant SDB and another cationic surfactant SDY. When the total mass concentration of the SS solution is 0.15 wt%, m(SDB)/m(SDY) ratio is 1 to 1, and excellent efficiencies are achieved for oil washing for five kinds of Tahe Oilfield crude oils (more than 60%). In addition, after adding cationic surfactant, the adsorption capacity of the surfactant is further reduced, reaching 0.261 mg/g. The oil displacement experiments indicate that under a temperature of 150 °C and a salinity of 24.6 × 104 mg/L, the SS system enhances the oil recovery by over 10% after water flooding. The SS anionic–cationic surfactant system is first presented in the open literature that can be successfully applied to obtain predictions of Tahe Oilfield carbonate reservoirs with a high temperature and high salinity.

Factors affecting chemical heat washing efficiency of oily sludge and Demulsification Mechanism

Oily sludge belongs to the hazardous waste specified in the national hazardous waste list. It will directly or indirectly threaten the ecological environment and human health. This paper introduces the advantages of chemical hot washing of oily sludge. This paper discusses the main factors affecting the treatment effect, Demulsification Mechanism and research progress in the treatment of oily sludge by chemical thermal washing, and puts forward some suggestions on the future research and development direction of oily sludge utilization and disposal.