Kaolinite Research Articles

Hypoplastic predictions of changes in undrained shear strength during episodic loading

Episodic loading patterns of undrained loading and consolidation are relevant to offshore foundation whole-life applications from variable metocean and operational conditions. In related finite-element simulations of foundation–soil interactions, the selected constitutive model then has to capture general trends of the soil response due to episodic loading, including changes in shear strength which affects the foundation's capacity. In this study, element test simulations using clay hypoplasticity were conducted to investigate the model's capability to capture general trends in the evolution of void ratio and undrained strength, which have been observed in direct simple shear (DSS) experiments on normally consolidated clay. Episodic loading in these DSS tests consisted of periods of undrained shear interspersed with consolidation and was applied to samples of normally consolidated kaolin clay. The clay hypoplastic constitutive model with the intergranular strain extension can be used to capture the response of normally consolidated clay subjected to episodic loading.

Comparison of Adsorption Capacity of Natural and Acid-activated Kaolinite Clay for Cesium ions from Aqueous Solution

Objectives : This study is to compare the removal efficiency of cesium ions in aqueous solutions by natural and acid-activated kaolinite clay.Methods : Natural kaolinite clay was acid-treated with H2SO4 (2M) at 80oC for 6 h under mechanical stirring. While activating natural kaolinite clay with acid, cations such as Al3+, Ca2+, Mg2+ and Fe3+ were partially eluted from the crystal lattice of natural kaolinite clay, and resulted in the increase in the surface area and the pore volume through the opening of crystal lattice. The surface area and the pore volume of acid-activated kaolinite clay were found to be roughly three times higher than natural kaolinite clay. The characteristics of natural and acid-activated kaolinite clay were observed by X-ray Fluorescence Spectroscopy, Energy Dispersive X-ray Spectroscopy, and BET Surface Area Analyzer.Results and Discussion : Generally, adsorption efficiency of Cs+ ion by acid-activated kaolinite clay showed much higher compared with natural kaolinite clay. At 50 mg L-1 of Cs+ ion concentration and the unit of dose in g L-1 , the adsorption efficiencies of Cs+ ion by natural and acid-activated kaolinite clay were 57.5% and 96.9%, respectively. The data obtained from this study were fitted to the adsorption isotherm and the kinetic models, respectively. It revealed that the Langmuir isotherm and the pseudo-second-order kinetic models described well the adsorption behavior of Cs+ ions on both natural and acid-activated kaolinite clay owing to their higher correlation coefficient R2. Based on the Langmuir isotherm coefficient Q, adsorption capacity of Cs+ ion by natural kaolinite clay and acid-activated kaolinite clay were 5.65 mg g-1 and 10.6 mg g-1, respectively.Conclusion : The results demonstrated that acid-activated kaolinite clay with acid treatment can be used as more effective adsorbent for the adsorption of Cs+ ions from aqueous solution than natural kaolinite clay.

Deep regolith weathering controls δ30Si composition of groundwater under contrasting landuse in tropical watersheds

Land use changes are known to alter terrestrial silicon cycling and the export of dissolved silicon from soil to fluvial systems, but the impact of such changes on groundwater systems remain unclear. In order to identify the processes responsible for groundwater geochemistry and to assess the impact of agricultural processes, we examined multiple isotopic tracers (δ30Si, oxygen (δ18O) and hydrogen (δ2H) isotopes) in groundwater, soil porewater and surface water from two contrasted watersheds having the same gneissic lithology, one forested (Mule Hole) and one intensely cultivated (Berambadi) in the Kabini basin in South India. In the cultivated watershed, groundwater exhibits high Cl− and NO3− concentrations indicative of fertilizer inputs and solute enrichment from evapotranspiration due to multiple groundwater pumping/recharge cycles. The DSi concentration in groundwater is significantly higher in the cultivated watershed (980 ± 313 μM) than in the forested one (711 ± 154 μM), indicating more intense evapotranspiration due to irrigation cycles. The groundwater δ30Si values ranged from 0.6 ‰ to 3.4 ‰ and exhibit no significant differences between cultivated (1.2 ± 0.5 ‰) and forested (1.0 ± 0.2 ‰) watersheds, indicating limited impact of land use and land cover. Groundwater also shows no significant seasonal differences in DSi and δ30Si within watersheds, indicating a buffer to seasonal recharge during wet season. The δ30Si of a majority of groundwater samples fits a steady-state open flow through system, with an isotopic fractionation factor (30ε) between precipitating phase and groundwater ranging from −1.0 ‰ and − 2.0 ‰, consistent with precipitation of kaolinite-type clays, dominant in the study area. The steady-state flow through system in groundwater can be interpreted as a continuous DSi input from mineral weathering reactions with a dynamic equilibrium between Si supply and precipitation of secondary phases. We also observe, in both watersheds, similar DSi and δ30Si values in local surface water that includes small streams and a river (406 ± 194 μM, 1.6 ± 0.3 ‰) and in soil porewater (514 ± 119 μM, 1.6 ± 0.2 ‰). Compared to soil porewater, groundwater exhibits significantly lower δ30Si signatures and higher DSi, reflecting the contribution of an isotopically light silicon source, resulting from water-rock interaction during percolation through the unsaturated zone. We assign this steady input of DSi to the weathering of primary silicate minerals in the regolith, such as Na-plagioclase, biotite and chlorite, with formation of kaolinite and smectites type clays. A simple isotopic mass balance suggests that deep regolith weathering can contribute to almost half of the DSi in groundwater. We conclude that silicon cycling in soil porewaters, and surface waters are directly impacted by land use, while the isotopic composition of groundwater remains unaffected. Our results indicate that Si isotopic signatures of weathering, adsorption, and plant uptake occurring in the shallow soil and saprolite horizons are partly overprinted and homogenized by the regolith weathering in the deep critical zone, irrespective of land use and seasonality.

Origins of complexity in the rheology of Soft Earth suspensions

When wet soil becomes fully saturated by intense rainfall, or is shaken by an earthquake, it may fluidize catastrophically. Sand-rich slurries are treated as granular suspensions, where the failure is related to an unjamming transition, and friction is controlled by particle concentration and pore pressure. Mud flows are modeled as gels, where yielding and shear-thinning behaviors arise from inter-particle attraction and clustering. Here we show that the full range of complex flow behaviors previously reported for natural debris flows can be reproduced with three ingredients: water, silica sand, and kaolin clay. Going from sand-rich to clay-rich suspensions, we observe continuous transition from brittle (Coulomb-like) to ductile (plastic) yielding. We propose a general constitutive relation for soil suspensions, with a particle rearrangement time that is controlled by yield stress and jamming distance. Our experimental results are supported by models for amorphous solids, suggesting that the paradigm of non-equilibrium phase transitions can help us understand and predict the complex behaviors of Soft Earth suspensions.

Assessment of Hast Bahar (Flowering Season) for Yield and Quality of Pomegranate at Farmer’s Field

An on-farm trail (OFT) on assessment of flowering season of pomegranate was tested. The experiment was conducted with three treatments comprising mrig bahar flowering as a control and hast bahar flowering with and without application of micronutrients and kaolin clay during June to February for three consecutive years from 2019–2022 in the different farmer fields at the Tharad taluka of Banskantha district, Gujarat, India. The treatment T1 Mrig bahar (June-July) flowering recorded the maximum total number of flowers (293.67) hermaphrodite flowers (108.9) and fruit setting (71.85%). Further, T1 exhibited the highest average number of fruits plant-1 (79.0) and maximum fruit yield (11.78 kg plant-1) followed by T3 and T2 treatments (10.14 kg plant-1 and 9.02 kg plant-1) respectively. In terms of total fruit yield, Treatment T1 exhibited the highest fruit yield of (9813 kg ha-1). Whereas, maximum individual fruit weight 179.44 g plant-1 and Total Soluble Solids (15.75°Brix) were found in Treatment T3. Moreover, treatment T3 Hast Bahar (Sept–Oct) flowering with foliar spray of micromix 0.2% and kaolin Clay 4.0%) has the lowest average fruit cracking (6.30%) and the lowest incidence of sunburn (8.80%) across the three years. However, treatment T1 recorded highest average fruit cracking (18.90%). Further, during the Mrig bahar season, incidence of leaf spots and fruit rot was observed higher compared to the Hast bahar flowering. In case of economics, treatment T3 obtained the highest average income of 411813 ha-1 as compared to treatment T2 and T3 ` 353074 ha-1 and 333425 ha-1, respectively.

Mineralogical Characterization and Geochemical Signatures of Supergene Kaolinitic Clay Deposits: Insight of Ropp Complex Kaolins, Northcentral Nigeria

This study presents the chemical and mineralogical composition of clay deposits and associated rock types within the Ropp Complex in order to assess the influence of parent lithology on the kaolinization, genesis, and utility of the deposit. Representative kaolin samples from E horizons of the weathering profiles and their bedrocks were collected from six sites in the Ropp Complex. Clay mineralogy was determined via the XRD technique, while a geochemical analysis was conducted using XRF, SEM coupled with EDS, and ICP-MS. The results showed that all kaolins dominantly contain kaolinite with a content of 77%–98% except for the AS1 kaolin with only minor kaolinite (20%) but mainly illite (65%). The notably lower crystallinity of kaolinite (HI value of 0.53–1.1) as well as its markedly small grain size is consistent with the formation of kaolinite from intensive chemical weathering of igneous rocks. The AS1 kaolin was probably formed from hydrothermal alteration in the burial stage due to the heating of groundwater by the late volcanism. Mobile trace elements (Sr, Ba, and Eu) exhibited a depletion trend, while immobile elements (Hf, Ta, Th) showed enrichment. The relatively more zirconium in kaolins implies the formation of low-temperature kaolinization. The notably high kaolinite content, accompanied by reasonable levels of Fe2O3 and TiO2, signifies a medium-grade quality. Furthermore, chondrite-normalized rare earth element (REE) patterns exhibit congruent trends in rocks and kaolin samples, indicating a relative enrichment in light rare earth elements (LREEs) alongside a discernible negative Eu anomaly. The abundant kaolinite and silicon–aluminum composition make the kaolins suitable for refractories, pharmaceutics, cosmetics, and supplementary cementitious material (SCM).

Kenneth Walters. 14 September 1934 — 28 March 2022

Kenneth (Ken) Walters was a leading international figure in the field of rheology. He applied his mathematical training to the analysis of many common test procedures, and contributed to the formulation of nonlinear constitutive equations for viscoelastic fluids. He also pioneered computational studies in rheology, and engaged in fruitful collaborations with industry—notably the oil and china clay industries. He was born in Swansea, South Wales, and he remained a devoted Welshman throughout his life. He studied under James Oldroyd at Swansea and was awarded the PhD degree in 1959. In 1960, after a stint in the USA, he was appointed as a lecturer at Aberystwyth, and he remained there until his death in 2022. He built a very strong research team at Aberystwyth, which became a dominant factor in the rheological scene in the United Kingdom. He was a keen promoter of rheology and assisted in the organization of many conferences and meetings. He was the founding editor of the Journal of Non-Newtonian Fluid Mechanics , and authored or co-authored four well-known books on rheology plus several tracts of a religious nature—Ken was always a devoted Christian. He was also a very able sportsman, especially at cricket and golf. He is survived by his wife Mary, three children and seven grandchildren.

ZnO‐doped kaolin nanoclay immobilized agar biopolymer for 2,4‐dinitrophenol photocatalytic degradation

AbstractThis study focuses on enhancing the properties of kaolin (Kao) clay by incorporating Zinc oxide nanoparticles (ZnO NPs) and further functionalizing with agar biopolymer, resulting in the formation of Agar/Kao@ZnO nanocomposite (NC). The synthesized material underwent comprehensive composition, structure, surface, and optical properties analysis to confirm the formation. The material was evaluated as a photocatalyst for the degradation of 2,4‐dinitrophenol (DNP) under visible light irradiation. The optimized conditions for the photocatalytic degradation of DNP were determined as irradiation time 50 minutes, pH 4, catalyst dose 20 mg, and DNP concentration of 25 mg L−1, resulting in degradation efficiency of 99.63%. Trapping experiment validated the significant role of hydroxyl (•OH) radicals as reactive oxidant species (ROS) in the degradation of DNP in the presence of visible light. Through four consecutive cycles of reusability experiments, it was confirmed that the synthesized material is highly stable and efficient for DNP degradation.

Novel low-carbon eco-concrete filled-FRP tubes under axial compression: Experimental behavior and analytical model

Concrete is essential in global construction but significantly contributes to carbon emissions, primarily due to cement production. The cement industry is adopting low-carbon practices, such as using supplementary cementitious materials (SCMs) to reduce emissions. Concrete prepared with calcined clay can achieve a carbon reduction effect of approximately 30 % compared to ordinary cement. Current studies highlight the reuse of kaolin clay, the predominant constituent of engineering sediment in Shenzhen, China, providing raw materials for sustainable low-carbon and eco-friendly concrete. However, high substitution rates of calcined clay can compromise concrete strength, posing a challenge for the application in load-bearing structures. This study proposed a novel low-carbon eco-friendly concrete (i.e., using calcined clay as supplementary cementitious materials) filled into FRP tubes (i.e., Low-Carbon Eco-Concrete-Filled FRP Tubes, termed LCE-CFFTs) aiming to enhance substitution rates of calcined clay and to improve compressive strength and ductility. This paper provides a detailed description of the preparation method, chemical reaction process, chemical composition, and microstructure of calcined clay. Experimental tests investigated the axial compressive performance of LCE-CFFTs, considering calcined clay substitution rates and FRP thickness as key parameters. The experimental work and theoretical analysis indicated that: the inclusion of 10 % and 40 % calcined clay led to a reduction in carbon emissions, resulting in a decrement of 5.8 % and 23.3 %, respectively; confinement provided by FRP tubes mitigated the reduction in axial compressive strength resulting from calcined clay inclusion, particularly evident at higher substitution rates (40 %); the effect of FRP tube confinement in improving peak stress and axial performance of LCE-CFFTs became more pronounced with higher calcined clay substitution rates; to more accurately predict the axial compressive behavior of LCE-CFFTs of this study, it is essential to consider the biaxial stress-strain state of filament-wound FRP tubes.

Design and characterisation of activated magnetic zeolite 4A from naturally occurring kaolin clay of Cameroonian origin for optimised dye removal by Fenton-like degradation

ABSTRACT The transformation of local clay material of Cameroonian origin into magnetic zeolite (Fe@Zeo-4A) for the degradation of acid-blue 90 in solution was investigate herein. The insertion of magnetic iron oxide particles into the zeolitic framework of Zeo-4A was achieved via hydrothermal synthesis. FT-IR spectroscopy, XRD and SEM confirmed the transformation of the clay into zeolite while EDX analysis and elemental mappings confirmed the presence of iron in the magnetic zeolite. Fe@Zeo-4A was strongly attracted to an external magnetic field. N2 adsorption-desorption studies revealed a considerable decrease in specific surface area and pore volume from the zeolite to the magnetic zeolite, suggesting the occupation of the pores of the zeolite by magnetite. The central composite design of the response surface methodology was used as optimisation approach for four parameters affecting the efficiency of degradation: solution pH, H2O2 concentration, initial dye concentration and time of stirring. ANOVA results revealed good correlation between the experimental and predicted results as well as the suitability of the linear regression model for describing the dye degradation process. An adjusted correlation coefficient of 85.17% was obtained for the dye degradation model. An optimal degradation percentage of 95.2% was obtained experimentally under optimal conditions of 7.6 for pH, 20 mg/L for dye concentration, 15.0 mol/L for [H2O2] and 15 min for time, in close agreement with a theoretical response of 96.6% predicted by the model. The magnetic zeolite was found to exhibit good stability over a wide pH range and lost only about 18% of its catalytic efficiency after five cycles of degradation experiments. Therefore, the novel magnetic zeolite-based material is an efficient Fenton catalyst for treating dye-contaminated wastewater.

On-bottom stability of a radial fin integrated surface-laid pipe-section against vertical penetration

This study focuses on the on-bottom stability of surface-laid submarine pipelines during vertical penetration under thermal-induced buckling. Submarine pipelines are susceptible to buckling due to their high slenderness ratio, and the resistance to such displacement relies on pipeline stiffness and soil resistance. To investigate this, laboratory model tests were conducted using a scaled-down pipe section placed on a clay bed. The clay bed was prepared with remoulded Kaolin clay, ensuring uniform moisture content, and the model pipe was scaled down from a typical industry prototype. These tests were conducted in 2D plane strain conditions within a tank, equipped with observation windows to monitor pipe movement and soil behaviour. A significant improvement in the pipe section's penetration resistance and on-bottom stability was observed after incorporating fin in the pipe. The addition of fins altered the earth pressure distribution beneath the vertically loaded pipe, leading to a larger failure mechanism in the adjacent soil. Furthermore, the soil-surface-heaving progressed towards the tank wall with increasing angular distance between the radial fins. Thus, the research demonstrated the effectiveness of radial fins in enhancing the stability and resistance of submarine pipelines against vertical penetration, shedding light on potential improvements in submarine pipeline design and deployment.

Synthesis of biobased Phosphorus-Nitrogen-Silicon ceramizable flame retardant and its flame retardancy effects on EPS

The rising interest in eco-friendly flame retardants marks a notable trend in the industry. However, the challenge remains that most flame retardants, while achieving high flame retardant properties, struggle to balance environmental sustainability and resource utilization. This work delves into the green synthesis and mechanism of action of ceramizable flame retardants. Using phytic acid (PA) and urea (U) as raw materials, ionic complexation assembly in water, employing polydopamine (PDA) as an adhesive, to develop an environmentally friendly, bio-based synergistic flame retardant (PAU) is conducted. Building upon this groundwork, the addition of the ceramic filler kaolin (KL) and the fluxing agent sodium carbonate (Na2CO3) physically modifies the PAU, resulting in a novel eco-friendly, bio-based, ceramifiable flame retardant (PAUK). Employing the prepared PAUK through an effective surface coating technique, a lightweight and scratch-resistant flame-retardant expanded polystyrene insulation board (EPS-PAUK) is created. The best EPS-PAUK composite in our study exhibits an oxygen index of 52.5, achieves a V-0 UL-94 rating, and features excellent smoke suppression and compression strength up to 67.8 kPa, while nearly maintaining the lightweight characteristics of the EPS insulation boards. This bio-based, ceramifiable flame retardant system offers a new approach for producing lightweight, highly efficient flame-retardant and high-performance polymers.

On the hydration of limestone calcined kaolinitic clay cement and energy-efficient production

Understanding hydration kinetics of cement composite incorporating calcined clay is crucial in further progressing low-carbon binder designs. However, due to diversity of clays and complex synergy with further limestone addition, it is challenging to predict the hydration process. In this study, a coupled kinetic-thermodynamic model is developed based on unified functional form to generate comprehensive hydration studies on cement binders including calcined kaolinitic clay and limestone. Dedicated model parameterisation analyses are performed, following available rapid, relevant, and reliable (R3) tests, to determine the kinetic models. Moreover, a numerical framework is proposed to describe the synergy in hydration of limestone calcined clay cement (LC3) utilising clays of diverse kaolinite contents. The model is demonstrated to be capable of generating robust hydration assessments on both binary and ternary systems. In enhancing the overall sustainability, the proposed hydration model is leveraged to gauge the energy-efficient production of LC3 binders utilising local resources.

Bioactive chitosan films: Integrating antibacterial, antioxidant, and antifungal properties in food packaging

In this work, chitosan was combined with bio-vanillin (BV) and kaolin clay (KC) to create a novel antifungal and biodegradable food packaging film. The chitosan/KC/BV film exhibited an antioxidant capacity of 80 % as measured by DPPH assay, which was significantly higher than that of the chitosan film which has 55.6 %). The film also demonstrated strong antimicrobial activity with a reduction of 90 % in the growth of E. coli and S. aureus compared to the control. Additionally, the chitosan/KC/BV film showed a 75 % reduction in fungal growth compared to chitosan film. Furthermore, the water vapor permeability of the chitosan film was reduced as 5.38 with the addition of KC/BV. The degradation study revealed that the chitosan/KC film degraded by 88 % within 20 days under composting conditions. Additionally, fresh-cut apple slices were used to examine the effectiveness of chitosan/KC/BV film as a packaging material. The fruit's weight loss and browning index showed satisfactory food preservation. Our research suggests that the chitosan/KC/BV film has great potential for use in the food sector due to its strong antioxidant, antimicrobial, and biodegradable properties.

Employing SHlNO_Glaze technology using local materials and applying it to high-temperature clays

This research is concerned with studying (SHlNO_Glaze technology using local materials), which consists of five chapters: The first chapter included a presentation of the research problem to find out what variables the technique causes when added to the surface of pottery? While the importance of the research came to increase scientific knowledge, in addition to the scarcity of its use, which makes it surrounded by a kind of mystery about the extent of its color and texture transformations, while the research aims to reveal the technical effects resulting in ceramic glass. The limits of the research include the addition of red earth and potassium feldspar. Calcium feldspar and soda ash, in addition to colored oxides, are high-temperature clays (1250 degrees Celsius). While the second chapter contained the theoretical framework and previous studies, this chapter reviewed the clays and their uses, as well as the types of clays found in their locations. It reviewed the structure of the glass and its compatibility with the pottery body and the classification of the glass in terms of chemical composition and maturation temperatures. This chapter also reviewed the coloring oxides through which it was identified. The researcher studied the oxides of copper, cobalt, iron, and tin, which determine the color and texture. This chapter also reviewed the techniques of special effects in porcelain glass, the firing atmospheres, and the types of reduction. The third chapter included the selection of materials added to the glass mixture based on colored oxides, which are considered the most common coloring oxides for potters, which are copper oxide (CuO), cobalt oxide (CoO), tin oxide (zn), and iron oxide (feo). In the golden ratios to the glass mixture, while fixing the ratios of the glass mixture and limiting the variable only to the chino, as it was applied to kaolin clay, the number of glazed models reached (12) models. As for the fourth chapter, it included the research sample, and the number of samples reached (12) samples representing the majority of the research population. They were reviewed with percentages and temperatures and were discussed according to each sample and its variable. The fifth chapter included conclusions, including :Adding recommendations, suggestions, sources, appendices, and a summary in English.

Effect of magnesia additive on the morphology and physico‐mechanical properties of kaolinitic clays ceramics

AbstractNigeria is rich in various minerals, including crude oil and solid minerals. However, despite this abundance, effectively utilizing these resources remains a challenge. Kaolin, also known as white China clay, is a crucial raw material used in industries such as ceramics, paper, paint, plastic, and welding electrodes. Despite its plentiful availability in Nigeria, kaolin has not been adequately exploited. Consequently, Nigeria spends approximately 14.35 million USD annually to import refined kaolin to meet local demand, due to the lack of capacity to process it to the required industrial standards. This study investigates the effect of magnesia (MgO) on the morphology and physico‐mechanical properties of kaolinitic clay ceramics using the slip‐casting method. Various analytical techniques were employed to examine the kaolin, including X‐ray fluorescence (XRF), X‐ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). Also, compressive and flexural tests were conducted. The XRF analysis revealed that all samples contained SiO2 (54.41%wt), Al2O3 (34.05%wt), and other trace elements. The main mineral phases identified were quartz, microcline, and orthoclase. Among the samples, 30–200 exhibited the highest compressive strength at 218 MPa, while the highest flexural rigidity was observed in sample 15–200. The results indicated that MgO significantly affected the properties of kaolin, as the control sample had a compressive strength of 59 MPa. The study also found that the quantities of additives should align with stoichiometric requirements. Results showed hypo‐stoichiometry in samples 30–600 and 15–400, and hyper‐stoichiometry in sample 60–200. XRF, XRD, and FTIR spectra confirmed the elemental and chemical compositions of the samples, while SEM analysis revealed the morphological structure. It was observed that increasing the magnesia content from 10% to 30% led to an increase in pore spaces within the samples. TGA analysis provided insights into the relationship between mass loss and temperature variation in the ceramic samples, While The DTG curves explain the endothermic phase changes over changes in temperature; at 50–150°C, loss of the water phase is complete, at 300–400°C burning of organic matter phase is achieved and at 500–700°C endothermic dihyroxylation phase begins forming armorphous meta‐kaolin.

Surface Modification of a Zeolite Microfiltration Membrane: Characterization and Application to the Treatment of Colored and oily Wastewaters

Membrane-based technologies used for water treatment can be an excellent alternative to handle wastewater including both conventional and emerging pollutants as they can provide technological (e.g., high quality of treated water) and economic (e.g., small footprint and low unit cost of production) advantages over other water treatment processes. Recently, low cost ceramic membranes fabricated from natural resources like kaolinitic clay, bentonite clay, phosphate are increasingly used owing to their low-cost starting materials, low sintering temperature and their excellent additional properties. Moreover, the modification of the surface by grafting process provides membranes appropriate for low UF process (dp < 10 nm) and suitable for micropollutants removal at relatively high permeate flux value which can be maintained during filtration due to antifouling characteristics of the UF active layer. In this work, the surface of microfiltration membranes made from natural zeolite was chemically modified by grafting with 1 H, 1 H, 2 H, 2 H-perfluorodecyltriethoxysilane molecule named PFAS. Various characterization methods and techniques, including scanning electron microscopy (SEM), mercury porosimetry, FTIR, TGA, and contact angle, were used to check the properties of the membranes surface before and after grafting. The grafted membranes pore size and porosity were reduced, as proved by SEM images. The determination of the water permeability shows a reduction from 1218 L.h−1.m−2.bar −1 to 204 L.h−1.m−2.bar −1 which confirm the surface densification. The application of the grafted membrane to the treatment of Indigo Blue (IB) colored solution and oily wastewater was investigated to evaluate the performances of this membrane in terms of permeate flux and pollutants retention. The filtration results revealed a good retention of color and oil, exceeding 95% for both parameters. Therefore, it is interesting to recommend this new low-cost membrane for the treatment of industrial wastewater containing recalcitrant pollutants such as color. The study of the effect of the treated colored solution on plant growth, shows that the presence of some residual nutrients required for crops growth, might make the IB treated water beneficial for irrigation purposes.

Synthesis of eco-friendly polyaniline-zeolite nanocomposite for pollutant remediation: Empowered by robust machine learning algorithm

The present research assesses the synthesis of an eco-friendly polyaniline and zeolite 4A (4 Armstrong) nanocomposite for enhanced adsorption of dye and heavy metal. Zeolite has been synthesized utilizing natural Kutch-sourced Kaolin clay. The materials synthesized were characterized via various instrumental techniques which confirms the formation of the desired materials. The composite exhibits superior performance in removing hazardous pollutants, demonstrating the removal of 98.5 % chromium in 12 min and 99.8% Congo red in 50 min, individually. Furthermore, for simultaneous removal, the composite continued displaying remarkable performance having a removal rate of 99% and 98.5 % for Congo red and chromium, respectively within 50 min, only. The nanocomposite follows the Freundlich isotherm model for chromium removal indicating physisorption and the Langmuir isotherm model for Congo removal signifying chemisorption. Artificial intelligence and machine learning (ML) techniques have been employed on the data set for the simulation of the adsorption percentage of the synthesized adsorbent. Various uncharted data visualizing techniques, including scatter plots, correlation coefficients, and mutual information were applied to explain the correlation between experimental variables. Conventional regression techniques showed poor performance with a high mean squared error (MSE) of 23 and an R2 value of 0.89. However, Bayesian optimization assisted ML model significantly improved the results. The Gaussian process with a polynomial function was the best performer, achieving an R2 value of 0.99 and mean squared error of 0.008. This research highlights the novel synthesis and effectiveness of the adsorbent materials, demonstrating the potential of machine learning in environmental remediation.

Enhancing fluidity and mechanical properties in Limestone Calcined Clay cements with one-third Portland clinker content

Limestone Calcined Clay Cements (LC3) are attracting considerable attention due to their low CO2 footprints and relatively fast hydration kinetics. LC3-50 formulations (approximately 50 % Portland clinker, 30 % kaolinitic calcined clay, 15 % limestone and 5 % gypsum) are being extensively investigated and the hydration chemistry, rheology, mechanical strength developments and durability performances are starting to be well established. LC3 binders with lower clinker factors are possible, offering an opportunity for further CO2 footprint reduction. However, these blends have been much less studied. This work contributes to fill this gap. Here, a LC3-35 binder (i.e. 35 % Portland clinker content) is investigated and its performances are compared to those of the original Portland cement (PC) and a standard LC3-50 binder. The effects of two superplasticizers and a strength-enhancing admixture are thoroughly investigated in mortars and pastes. Larger calcined clay contents result in an exacerbation of the slump retention problem, but this issue is solved by the use of a new superplasticizer. Moreover, the low mechanical strengths at early ages can be partly mitigated with a C-S-H nucleation seeding admixture. Employing the right admixtures, LC3-35 binders can develop strength values similar to those of neat PC and LC3-50 at 7 and 28 days. The laboratory X-ray powder diffraction results for LC3-35 pastes, when using the strength-enhancing admixture, show that C4AF exhibits an accelerated reaction rate, leading to the formation of larger amounts of AFt and AFm phases. Approximate mass balance calculations are carried out to estimate the metakaolin reaction degree. Finally, an environmental performance indicator is used to place the footprints of the reported binders within the LC3 landscape.

Investigation of the adsorption performance of aqueous solution of malachite green dye on kaolin clay

In this study, the removal of Malachite green (MG) dye, which has a toxic effect on the aquatic ecosystem, was carried out with kaolin clay, a natural and inexpensive material. In batch adsorption tests, the effects of pH, adsorbent dose, initial dye concentration and contact time were determined. Also, Pseudo first order and Pseudo second order kinetic models and Freundlich, Langmuir and Temkin isotherm models were tested. On the other hand, scanning electron microscope (SEM) and fourier transform infrared spectroscopy (FTIR) analyzes of raw and MG-loaded kaolin clay were performed. According to the results obtained, the most suitable kinetic and isotherm models were determined as Pseudo second order (R2: 0.999) and Freundlich (R2: 0.983), respectively. Additionally, the amount of MG dye removed per unit kaolin (qmax) was calculated as 16.36 mgMG/gkaolin. This study reveals the suitability of using kaolin clay in the adsorption of MG dye.