Study of flocculation performance and mechanism of ultrafine montmorillonite particles with NPAM

Abstract

Ultrafine montmorillonite particles are the main clay minerals in industrial wastewater. In order to explore the flocculation performance and mechanism of flocculant with montmorillonite, the effects of nonionic polyacrylamide (NPAM) dosage and molecular weight on flocculation effect were studied using a flocculation sedimentation experiment. The morphology of flocs was observed by metallographic microscope and scanning electron microscope, and the microscopic adsorption mechanism was studied utilizing density functional theory (DFT). The results show that the best reagent system for the montmorillonite sample is that the molecular weight of NPAM is 14 million and the added amount is 100 g/t. The floc size increases with rising NPAM dosage, forming a unique multilevel compact space network structure through polymer bridging. The adsorption energy of acrylamide on the Na-( 001) surface of montmorillonite is -108.81 kJ/mol, which is significantly higher than -50.66 kJ/mol on the None-(001) surface. Hydrogen bonding is not the main reason for the adsorption of acrylamide on the montmorillonite surface. NPAM mainly causes the flocculation and sedimentation of montmorillonite through the processes of polymer bridging and electrostatic attraction. This study can provide a theoretical basis for the design and synthesis of new flocculants.

Mechanism of the Absent Air Column in Three Products Hydrocyclone Screen (TPHS): Experiment and Simulation

“…Both grids of the maximum cell skewness were below 0.8, which indicate the excellent grid quality. According to our investigation [16], the above grid regulations could create economical grid-independence. The experimental procedure for the detection of the air column in TPHS can be described as follows.…”

“…Both grids of the maximum cell skewness were below 0.8, which indicate the excellent grid quality. According to our investigation [16], the above grid regulations could create economical grid-independence.…”

“…Firstly, the high-definition camera (type: Dantec Flow Sense EO 4M, Dantec Dynamics A/S, Copenhagen, Denmark) was placed about 0.5 m in front of the cube shell, and then the lens was focused on the TPHS (see the red dotted rectangle in Analogous to other innovative cyclones [7,15], since TPHS is a derivative of a hydrocyclone, the characteristics of fluid flow should have a crucial impact on the particle classification. Afterwards, the advanced technology including the particle image velocimetry (PIV) test and the computational fluid dynamics (CFD) simulation have been used to explore the fluid flow of TPHS [16]. The result illustrates the lower tangential and higher radial velocity in TPHS than that in CH.…”

“…The previous investigations also indicate that the occurrence of an air column drastically reduces the efficiency of separation [17,18], which can be attributed to the fact that the air core could lead to more energy consumption and ineffective particle separation, and thus some efforts were considered to eliminate the air core for better device performance [19][20][21]. Since TPHS can be considered as one kind of cyclone, the absent air core should promote particle separation [16]. The prior works exhibit some general understanding for TPHS, however, the details of the eliminated air column have not been yet explored and remain unknown.…”

Comparison between response surface methodology and artificial neural network: Application in three‐product hydrocyclones

“…[13] One possible modification is the introduction of a third outlet flow to the HC, resulting in a three-product cyclone (TPC), which can present one overflow and two underflows [14] or two overflows and one underflow. [15] This application can be an alternative to solve problems with size classification without using multi-stage HCs in series or parallel. [16] Obeng and Morrell [17] described a new type of cyclone, called the Julius Kruttschnitt three-product cyclone (JK TPC) (Figure 1), developed at the Julius Kruttschnitt Mineral Research Centre (JKMRC).…”