Granulated Powder Research Articles

Thick and dense nitrogen-doped hafnium carbide ultra-high temperature thermal protection coating for outstanding ablation resistance up to 2600 ℃

Transition metal carbon-nitrides, typically represented by HfCN, have become the latest progress among the ultra-high temperature ceramics. In this study, single-phase solid solution HfCN coating was successfully synthesized from spray granulated HfC-HfN composite powder followed by employing the dual solid solution effects of radio frequency inductively coupled plasma spheroidization and supersonic atmospheric plasma spraying processes. The coating was nearly dense (only 2.3% in porosity) with a high thickness of ~ 270 μm. Compared with HfC coating, the HfCN coating exhibited higher hardness and elastic modulus. After plasma ablation at a high heat flux of 8.2MW/m2 for 200s, the HfCN coating exhibited a surface temperature of up to 2600 ℃ and can firmly protect the refractory tungsten substrate from oxidation failure. This outstanding performance illustrates that doping N element in HfC crystal can effectively improve the energy barrier for oxidation reaction and oxygen adsorption compared with typical HfC coating.

Exploring pharmaceutical powder behavior in commercial-scale bin blending: A DEM simulation study

Bin blending is one of the main steps in pharmaceutical production processes. Commercial-scale production of expensive products typically does not allow to perform a large number of experiments in order to optimize the process. Alternatively, Discrete Element Method (DEM) simulations can be used to evaluate the powder behavior (flow and blending pattern) during blending, identify the risks (e.g., segregation), and provide solutions to mitigate them. In this work, DEM simulations are used to investigate the blending of two granulated powders in commercial-scale cone and cylindrical (hoop) blenders. The DEM contact model parameters were calibrated based on the experimental compression and ring shear tests for both granulated powders to mimic the bulk powder behavior in the simulations. The model's output was compared to the experiments in one of the blending cases. The blending efficiency in the cone blenders was evaluated considering the fill levels, the presence of baffles, the rotating directions, the filling order, and the bin sizes. Furthermore, for the hoop blenders, the effects of blender's angle, rotation speed, and filling order were addressed. The main findings of the work were that, in cone blenders, the blending can be improved by introducing baffles and changing in the rotational direction frequently. In hoop blenders, blending can be improved by increasing the inclination angle from the horizontal plane and the rotational speed.

Effect of steam curing on strength, durability and microstructure of concretes with and without mineral admixtures

This research explores the effect of steam curing on the strength, durability and microstructure of concretes with and without mineral admixtures of fly ash (FA) and ground granulated blast-furnace slag powder (SL). Two types of C55 strength grade concretes (one was pure cement concrete, the other was a concrete made by replacing part of the cement with 12% FA and 18% SL) were prepared and their compressive strength, chloride diffusion coefficient and carbonation depth under standard and steam-curing conditions were measured and compared. The phase composition and microstructure of the concretes under the two curing conditions were tested by X-ray diffraction, scanning electron microscopy and mercury intrusion porosimetry. The results showed that, on the one hand, compared with standard curing, steam curing is beneficial to the early strength, but not conducive to the later strength development and chloride permeability resistance of both types of concretes. Furthermore, for the steam-cured concrete, the 28 days carbonation depth of the forming surface is higher than that of the bottom surface. In addition, steam curing can reduce the carbonisation resistance of pure cement concrete and improve the carbonisation resistance of concrete mixed with FA and SL. On the other hand, composite mineral admixtures of FA and SL reduce the early strength and the carbonisation resistance of concrete cured by standard curing, but improve the later strength, the carbonisation resistance and chloride permeability resistance of concrete cured by steam curing. FA and SL are thermally activated under steam curing and can react with the calcium hydroxide formed by cement hydration in the early stage, which produces a larger amount of secondary hydration products to improve the pore structure and interfacial microstructure of the concrete with FA and SL. In this way, the adverse effects of steam curing on later strength and durability of concrete are significantly restrained by composite mineral admixtures of FA and SL.

Preparation of spherical Gd2Zr2O7 powders by RF induction thermal plasma process

Spherical Gd2Zr2O7 (GZO) powders with a uniform particle size distribution are successfully prepared using a novel industrial approach, which combines spray-drying process and thermal plasma sintering technology together. In this, GZO powders with pyrochlore structure as the main phase are first synthesized via a solid-state reactive route using a mixture of the milled Gd2O3 powders and ZrO2 powders as starting materials. The influence of sintering temperature on the microstructure of prepared powders is researched. Then, GZO granules are prepared after wet-grinding and spray-drying process, which exhibit a spherical shape with the average particle size of 46.5 μm. RF induction thermal plasma is finally used to sinter the granulated particles, and the influence of feeding rate on the properties of spherical powders is investigated. The apparent density of plasma sintered GZO spherical powders is increased from 1.53 g/cm3 to 2.29 g/cm3 when the feeding rate of granulated powders is 80 g/min, and further increased up to 3.90 g/cm3 when the feeding rate is 15 g/min. Such powders are in potential demand for plasma sprayed coatings and additive manufacturing techniques, and the successful synthesis of spherical GZO powders may guide the way toward the preparation of many other spherical rare earth zirconates powders.

Структура та властивості багатошарового металу, наплавленого електродними порошковими дротами з осердям із порошків феросплавів та гранульованих твердосплавних матеріалів

Comparative studies of the possibility of using granulated hard alloy powders as a charge of flux-cored wires for electric arc surfacing have been carried out. In the studies, granulated powder of the PG-R6M5 brand with a fraction of 50...300 μm was used. As a standard, a flux-cored wire was used, in the core of which there was a composition of powders of different ferroalloys of the same fraction. The content of the charge components in the core of the standard wire was selected and calculated so as to obtain a similar chemical composition to the wire containing granulated hard alloy powder. The test samples were obtained by layer-by-layer electric arc surfacing under the flux layer with flux-cored wires on low-carbon steel plates. To obtain identical dependences, the flux-cored wires had the same diameter and filling factor and differed only in the content of the core. The test samples were deposited under the same conditions with strict adherence to the deposition regimes, which were monitored using a high-speed analog-to-digital converter. It was determined that the use of granulated hard alloy powder as a charge of flux-cored wire has a positive effect on the melting characteristics of the wire and the stability of the welding process in general in comparison with the standard reference wire, the charge of which contains ferroalloys. This effect can be explained by the greater chemical purity of the granulated powder and the uniformity of the physicochemical properties of its particles in comparison with the powders of various ferroalloys. The determined features of the melting of the wire with a charge with granulated hard alloy powder have a positive effect on the quality of the formation of the multilayer deposited metal and its structure, leading to an increase in its homogeneity, some grinding of the grain and a decrease in the number and size of microdefects, which should positively affect the operational properties of the deposited metal. Keywords: electric arc surfacing, multilayer deposited metal, tool steels, granular hard alloy powder, ferroalloy, metal structure.

Powder wetting behavior and granule formation mechanism expansion in single-drop granulation

Single-drop granulation is performed under a variety of conditions to characterize the behavior that results from a liquid droplet impacting a powder bed. Drop impact velocity, liquid binder properties, powder bed consolidation status, and primary particle size are all demonstrated to have significant effects on the resulting granule formation mechanism. The process is broken down into a drop impact/drop deformation stage, a drop rebound stage, and a drop imbibition stage. These stages are often in competition with each other to determine the overall drop penetration behavior. Twelve granule formation mechanisms are identified and characterized in this study, in addition to two established granule formation mechanisms that were not observed in this work.

Anti-erosion ability and water retention of spreading PAM powder granules and spraying PAM gum liquid on inner dump

Anti-erosion ability and water retention of spreading PAM powder granules and spraying PAM gum liquid on inner dump

Comparative study of SiC fabrication through 3D-printing combining silicon infiltration based on granulated and non-granulated powders

Laser powder bed fusion (LPBF) combined with liquid silicon infiltration (LSI) holds promise for fabricating intricate SiSiC components. However, its suitability for producing SiC components without free silicon, crucial for acidic or alkaline resistance, remains uncertain. In this study, SiC components were fabricated through successive processes of LPBF, polycarbosilane impregnation (PI), carbonization, LSI, and acid etching using granulated and nongranulated SiC powders. Their properties were compared systematically. The results showed that PI treatment significantly improved the performance of samples made from non-granulated SiC; the bulk density and compressive strength after pyrolysis increased by 33 % and 325 %, respectively, and the bending strength after LSI increased by 26.2 %. These samples also exhibited a higher strength retention after acid etching. In contrast, PI treatment did not benefit the granulated SiC samples. Further analysis suggested that these differences stem from the distinct particle shapes and surface microstructures of granulated and nongranulated SiC, highlighting the need for process optimisation tailored to different SiC raw materials.

Preparation of spherical NiO-8YSZ composite powder through spray drying

Homogeneous sphere NiO-8YSZ composite powder with a narrow size distribution is significant for the fabrication of high-quality solid oxide fuel cell (SOFC) anodes. In this study, spray drying was used to prepare evenly distributed and spherical NiO-8YSZ composite particles used for the fabrication of SOFC anodes. The result showed that the particles prepared with a solid content of 65 wt %, atomizing pressure of 60 kPa, drying temperature of 180 °C, and sintering at 1200 °C for 2 h exhibited the best holistic quality with high sphericity (90 % over 0.84), narrow size distribution (D10 = 27.78 μm, D90 = 45.49 μm), high collection rate (70 %), and low content of unstable phases. The influence of these main parameters on the quality of the prepared particles was investigated and discussed as well. It was found that the solid content and the atomizing pressure demonstrated opposite effects on the particle size, with the former showing a positive correlation and the latter showing a negative correlation. The drying temperature decided the agglomeration degree of the prepared powder, which was involved in the presence of grape-like particles. In addition, the collection rate appeared to be positively correlated with the solid content and the atomizing pressure. The atmospheric plasma sprayed coating fabricated using the sprayed-dried powder prepared with the optimal parameters demonstrated significantly improved micromorphology and structure when compared with the coating fabricated using the mechanical mixed composite powder, which proved the prominent advantage of the powder produced through this spray drying method. All these progresses were considered good instructions for the studies on powder granulation and its applications in manufacturing high-quality coating materials.

Power of photo-stress analysis in unravelling the mechanics of granular materials and its applications in interdisciplinary research

Granular materials, such as various grains and granulated powders, are essential in numerous industrial applications and natural processes, including the chemical, pharmaceutical, food, and materials processing industries. They also play a significant role in geotechnical phenomena like the shear-driven collapses of embankments and landslides, which can lead to extensive damage and disruptions. Despite a significant surge in research activities and advancements in discrete element modelling (DEM) tools since the late 1970s, understanding the mechanical characteristics of granular materials remains complex. Experimental techniques such as photo stress analysis (PSA), Nuclear Magnetic Resonance (NMR), and X-ray tomography (XRT) offer valuable insights, yet there is still a lack of detailed information on how granular materials respond mechanically at the microscale under various loading conditions. This knowledge gap affects industrial product quality, equipment safety, production efficiency, operational costs, environmental compliance, and overall safety. In this paper, we initially focus on our scientific contributions to the development of photo stress analysis (PSA) in unravelling the load-transmission characteristics of granular materials of varying sizes and structures (two-dimensional and quasi-three-dimensional) under different mechanical loading environments and applications. Where relevant, discrete element modelling (DEM) complements PSA to enhance our understanding of granular mechanics. We then present the application of PSA to selected key interdisciplinary areas from our recent work, demonstrating the power of PSA. Despite current challenges in applying PSA to three-dimensional granular systems, the results reported here significantly advance our fundamental understanding of the particle-scale and micromechanical characteristics in granular mechanics and particulate engineering. This work highlights the potential of PSA in addressing various inter- and multidisciplinary research problems in the future.

Full Density Powder Metallurgical Cold Work Tool Steel through Nitrogen Sintering and Capsule-Free Hot Isostatic Pressing

Vanadis 4E (V4E) is a powder metallurgical cold work tool steel predominantly used in application with demand for wear resistance, high hardness, and toughness. It is of interest to have a processing route that enables full density starting from clean gas-atomized powder allowing component shaping capabilities. This study presents a process involving freeze granulation of powder to facilitate compaction by means of cold isostatic pressing, followed by sintering to allow for capsule-free hot isostatic pressing (HIP) and subsequent heat treatments of fully densified specimens. The sintering stage has been studied in particular, and it is shown how sintering in pure nitrogen at 1150 °C results in predominantly closed porosity, while sintering at 1200 °C gives near full density. Microstructural investigation shows that vanadium-rich carbonitride (MX) is formed as a result of the nitrogen uptake during sintering, with coarser appearance for the higher temperature. Nearly complete densification, approximately 7.80 ± 0.01 g/cm3, was achieved after sintering at 1200 °C, and after sintering at 1150 °C, followed by capsule-free HIP, hardening, and tempering. Irrespective of processing once the MX is formed, the nitrogen is locked into this phase and the austenite is stabilised, which means any tempering tends to result in a mixture of austenite and tempered martensite, the former being predominate during the sequential tempering, whereas martensite formation during cooling from austenitization temperatures becomes limited.

Welding and technological properties of flux-cored wire with the charge in the form of granulated powder

Welding and technological properties of flux-cored wire with the charge in the form of granulated powder

Sub-minute carbonization of polymer/carbon nanotube films by microwave induction heating for ultrafast preparation of hard carbon anodes for sodium-ion batteries

Hard carbons (HCs) are excellent anode materials for sodium-ion batteries (SIBs). However, the carbonization and granulation of HC powders involve complex processes and require considerable energy. Here, we developed a facile method for manufacturing HC anodes for SIBs via a novel microwave induction heating (MIH) process for polymer/single-walled carbon nanotube (SWCNT) films. Numerical simulations solving electromagnetic field and heat transfer problems revealed the MIH mechanism; the electric current induced by the applied microwave enables direct Joule heating of the SWCNT networks in the composite film. Consequently, the composite films could be heated to the target temperatures (800–1400 °C) and free-standing HC/SWCNT anodes could be prepared by applying MIH for only 30 s. Comparative analyses confirmed that ultrafast MIH is a reliable technique for producing HC anodes and can replace conventional carbonization processes which require a high-temperature furnace. Moreover, the HC/SWCNT anodes prepared by the ultrafast MIH were successfully applied to the SIB full cells. Finally, the feasibility of MIH for scalable roll-to-roll production of HC anodes was verified through local heating tests using a circular sheet larger than a resonator.

Исследование железоматричных композитов с карбидным упрочнением, полученных спеканием механоактивированных смесей титанидов железа с углеродом

Introduction. The addition of dispersed solid particles of refractory compounds (carbides, borides, silicides) to the structure of alloy is a widely used effective way to increase the wear resistance of steels and alloys. Composites with a matrix of iron-based alloys (steel and cast iron) strengthened by titanium carbide particles are of great practical interest. The main structural characteristics, which define hardness and wear resistance of the composites, are volume fraction, dispersion and morphology of the particles of the strengthening carbide phase. The structure of composites depends on the method of its preparation. The methods of powder metallurgy combined with preliminary mechanical activation of powder mixtures have become widespread. It is previously established that in mechanically activated powder mixtures of FTi35S5 ferrotitanium, consisting of 82 % of (Fe,Al)2Ti phase, and P-803 carbon black, a reaction occurs with the formation of a composite consisting of a steel binder and titanium carbide. The synthesis reaction of carbides occurs in a solid-phase mode at combustion’s temperatures of 900–950 °C. Therefore, there is no coarsening of the structure due to the growth of carbide particles, which is typical for reactions in the presence of a liquid phase. FTi35S5 alloy contains a plenty of impurities (silicon, aluminum and etc). The purpose of the work is to investigate the phase composition and structure of the products of the interaction of Fe2Ti and FeTi iron titanides with carbon under the conditions of reaction sintering of mechanically activated powder mixtures and to determine the possibility of synthesizing iron-matrix composites strengthened with submicron titanium carbide particles. Research methods. The structure and phase composition of sintered compacts from mechanically activated powders were studied by optical metallography, X-ray diffraction (XRD) and scanning electron microscopy (SEM) using determination of the elemental composition by energy-dispersive X-ray spectroscopy (EDX). Experimental technique. The reaction mixtures were prepared using intermetallic powders obtained by vacuum sintering of compacts from iron and titanium powder mixtures of 2Fe+Ti and Fe+Ti compositions. Carbon black was added to the intermetallic powders to convert all the titanium containing in the intermetallic compounds into carbide. The titanides – carbon black mixtures were processed by an Activator 2S planetary ball mill for 10 min milling time at a rotation speed of 755 rpm (40g). The mechanically activated mixtures were cold compacted into cylindrical samples with a diameter of 20 mm, which were sintered in vacuum at а temperature of 1,200 °C and an isothermal holding time of 60 minutes. Results and discussion. According to the results of X-ray diffraction analysis, almost all titanium contained in iron titanides reacts with carbon to form carbide and reduced iron. The sintering products of compacts of both compositions contain target phases: titanium carbide with a slight shift from the equiatomic ratio and α-iron, which has the lattice parameters close to the reference data, and also a few of other phases. The titanium carbide particles in the iron binder were identified on the back-scattered electron (BSE) images due to the tonal contrast: the heavy iron appears darker against the carbide, which is composed of lighter elements. According to EDX analysis, the relative content of titanium and carbon in the carbide particles indeed corresponds to the composition of non-stoichiometric titanium carbide. Conclusion. The composites including titanium carbide and α-iron binder were obtained by sintering of iron titanides and carbon (carbon black) mechanically activated powder mixtures. The granules of composite powders obtained by crushing of sintered compacts are of interest as feedstocks for wear-resistant coatings and additive technologies, as well as for manufacturing of dense materials by other compaction methods: spark plasma sintering (SPS) or hot pressing (HP).

Preparation and Evaluation of Metronidazole Tablets Produced with Different Binders Using Wet Granulation Method

In tablet formulation, binders are essential for ensuring proper powder mix, granulation and overall tablet quality. Variations in binder quality and concentration can impact drug bioavailability, strength and manufacturing processes. The inconsistency in bioavailability and therapeutic response of metronidazole from different manufacturers highlights the importance of binder selection in tablet formulation. This study evaluates the impact of different binding agents on tablet quality. The optimum binder concentration for each of the binders was assessed to obtain suitable concentration that was used to prepare metronidazole tablets. Metronidazole tablets were formulated with four different binder vis, acacia, gelatine, PVP, maize starch at 3% concentration using wet granulation method after which the tablet properties were evaluated. Metronidazole powder exhibited poor flow indices, as indicated by angle of repose: 39.92 ± 1.85, Carr’s compressibility index (CI): 20.13 ± 0.28 and Hausner’s ratio (Hr): 1.26 ± 0.01, whereas its granules exhibited good flow properties. The crushing strength (CS), friability (FR), disintegration time (DT) (CSFR/DT) ratio for batches showed values in 3% binder concentration, indicating higher strength as compared to other concentrations. There was a significant increase (P < 0.05) in the CSFR/DT ratio for gelatine (2.22) in formulation F2 compared to maize starch in Formulation F4. The formulated tablets with the various binders have met with the British Pharmacopeial criteria of 80% drug release from uncoated immediate-release tablets. Amongst the four binders, gelatine was found to be the best in the formulation of robust metronidazole tablets by wet granulation method at an optimised concentration of 3% w/w. Tablets produced with gelatin exhibited greater mechanical strength than those produced with other binders, while also demonstrating a slightly longer DT. Metronidazole tablets produced with gelatine have met the British Pharmacopeial requirements including an acceptable in-vitro drug release profile.

Tablet Shrouding Process Optimization with the Addition of Extended Fin to Improve Product Quality and Production Efficiency

In general, tablets are solid dose forms containing therapeutic substances, with or without fillers. Tablet compression is achieved by applying high pressure on powder (bulk) granules through a steel mold. The core tablet to be coated must meet certain standards because it will be moved and slammed repeatedly throughout the coating process. The extended fin is an additional fin that functions when the product is inserted into the coating pan and rotated, preventing the product from coming into direct contact with the coating pan wall during the coating process, resulting in friction and reactions that occur during the film coating process. For this reason, an expanded fin is inserted to reduce friction between the product and the pan coating machine's wall. The addition of the extended fin decreases friction between the drug and the machine wall, preventing the product coating process from reacting due to excessive friction with the machine wall. Additionally, the results of smoothness, glossiness, and color solidity are excellent. This resolves the issues that have previously lowered the proportion of production output.

Synthesis and coating properties of (La0.5Eu0.25Y0.25)2Zr2O7 ceramic powder

The (La0.5Eu0.25Y0.25)2Zr2O7 (LEYZ) ceramic powder for spraying was prepared and synthesised by combining spray granulation and solid phase reaction phase, and a double ceramic layer structure with (La0.5Eu0.25Y0.25)2Zr2O7 ceramic surface coating and YSZ intermediate coating was prepared by atmospheric plasma spraying. Experimental characterisation revealed that the moulding state of spray granulated powders was significantly influenced by the solid content. When the solid content is small, the viscosity of the slurry is insufficient, and the prepared powder has poor formability and small overall particle size. When the solid content is large, the slurry is too viscous, which easily leads to unfavourable conditions such as sticky walls. The best formability of the pelletised powder was obtained with a solid content of 55 wt-% and a binder content of 2.0 wt-%. Compared with La2Zr2O7 (LZ) ceramics, the fracture toughness of the rare-earth co-doped modified LEYZ ceramic coating was increased by 8.4% and the bond strength was increased by 49.9%, showing good toughness and crack resistance. Moreover, LEYZ coating has significantly better resistance to solid phase particle erosion than LZ coating, with 46.3% and 45.4% reduction in erosion rate at 45° and 90°, respectively.

High-strength 91W-6Ni-2Co-1Fe tungsten heavy alloys prepared by laser melting deposition using granulated powder

This study introduces a new approach for fabricating high-strength 91W-6Ni-2Co-1Fe tungsten heavy alloys (WHAs) using laser melting deposition (LMD) with a specially formulated granulated powder, characterized by near-spherical particles and a dense structure with fine W grains (2.6 μm). Thin plate samples were prepared using laser powers from 500 W to 900 W, revealing increased density at higher laser power, while the W grain size remains relatively stable. A near-fully dense sample (99% density) with the finest W grain size of 2.8 μm is obtained at a laser power of 900 W, while the highest hardness of 482 HV is achieved at 700 W. The contributions of the high cooling rate of LMD, the Co addition, as well as the use of fine-grained granulated powder to enhance the high strength are discussed. These findings offer significant insights into optimizing WHA fabrication using LMD, highlighting its potential in advanced materials engineering.

Numerical investigation on the densification of granulated porous indium tin oxide powders before compaction

Dense and uniform initial packing structures of powders are of key significance in powder metallurgy process, which can provide the precondition for the fabrication of high-performance components with low cost and high efficiency. In this paper, the packing densification of indium tin oxide (ITO) granulated micro powders with continuous size distributions and internal porosity under three-dimensional vibrations was numerically investigated by discrete element method (DEM). Firstly, the DEM model was validated by physical experiments, and the contact parameters between particles and the porosity therein were determined. Then the effects of operating parameters on the macro/micro properties (e.g., packing density, coordination number (CN), pores, and forces) of the packing structures were analyzed. Results show that the mean CN cannot intuitively reflect the packing structure due to the complex and varied inter-particle contacts caused by the inhomogeneity of the particle size in a multi-sized granular system. Additionally, the excellent packing structure of porous ITO particles is always obtained from low amplitude when the vibration intensity is the same. Corresponding mechanism analyses reveal that higher amplitude normally causes strong convective diffusion, leading to more pores in the packing. This increases the probability of wedging effect occurring during settling, thereby reducing the packing density. However, optimal packing quality with low amplitude can only be achieved when coupled with high frequency. Therefore, applying vibration is an effective way to achieve dense packing of porous spherical particles, especially at low amplitude and high-frequency operating conditions.

COMPARISON OF BRACKET WATER DESALINATION TESTS IN THE FORM OF POWDER, GRANULES AND GREEN ALGAE HYDROGEL

This research was motivated by the problem of lack of clean water around the coast of Rainbow Beach in Karawang because the water quality is poor and still brackish. Untreated brackish water poses a risk to human health if drunk for a long time and can trigger skin diseases if used for bathing. The well water taken is located in the Pelangi Coastal Area, Pedes Karawang. This research aims to test the ability of brackish water desalination using powder, granules, and three variations of green algae hydrogel. This research uses a quasi-experimental method by comparing it with zeolite as a standard for brackish water desalination. The research results show that the resulting hydrogel preparation has a solid, brittle shape, a dark green color, and a distinctive odor of green algae. The best viscosity value is in the H4 formula. All green algae hydrogel formulas have good pH values, while the best swelling ratio value is in the H2 formula, and the best gel fraction value is in the H4 formula. From the results of the research that has been carried out, it can be concluded that the hydrogel, granule, and green algae powder preparations can desalinate brackish water based on the results of pH, temperature, salinity, sodium ion, and magnesium ion tests compared with zeolite, where the 6 g hydrogel preparation shows the best desalination capability of brackish water at the three well sample points