Yellow Clay Research Articles

Heavy metal adsorption on yellow loam clay modified by biomass- and biochar-decomposed liquids from Ficus microcarpa

In studing the heavy metal adsorption effect of decomposed liquid (Dl) on yellow loam clay (C), biomass-Dl (BmDl) and biochar-Dl (BcDl) from Ficus microcarpa leaves were used to modify C. The different Dl-modified Cs (Dl-Cs) were characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. A batch method was used to study the adsorption kinetics and thermodynamics of Pb(II) and Cd(II), as well as the effects of decomposition time, modification ratio, pH, temperature, and ionic strength on the adsorption process. Results of microscopic morphology indicated that Dl was modified on the C surface, and it changed the surface properties. The adsorption isotherms of Pb(II) and Cd(II) by different Dl-Cs conformed to the Langmuir and Freundlich model, with the maximum adsorption capacity (qm) maintained at 65.64–163.89mmol/kg (BmDl-Cs) and 77.68–235.63mmol/kg (BcDl-Cs). Under the same conditions, the peak value of qm was reached at decomposition time of 14 days and 50% of Dl modification. pH = 6, ionic strength of 0.1mol/L, and 30 ℃ were the optimum conditions for the adsorption of Pb(II) and Cd(II) by different Dl-Cs. Pb(II) and Cd(II) adsorption was a spontaneous, endothermic, and entropy-increasing process, and pseudo-first-order kinetic equation was suitable to characterize adsorption.

PREPARATION AND CHARACTERIZATION OF POLYMER INCLUSION MEMBRANES BASED ON BIODEGRADABLE CELLULOSE/ALGERIAN CLAY FOR HEAVY METALS REMOVAL FROM WASTEWATER

Separation membranes have gained attention as promising options for water and wastewater treatment due to their financial sustainability, and eco-friendliness. However, practical challenges have limited their application in water separation. To overcome these limitations, inorganic-organic hybrid membranes have been developed in this study. The present work deals with two attractive aspects: (i) economical, through the valorization of a local clay (Algerian kaolin), and (ii) environmental, which is based on the membrane selectivity for metal ions. The principal objective of this work is the development of enhanced nanocomposite membranes. It is achieved with low costs, based on cellulose triacetate (CTA) as a polymeric matrix modified by the addition of a lamellar filler, i.e. yellow clay obtained from Jijel, located in the east of Algeria, and plasticized by dioctyl phthalate (DOP). A further objective of this paper was the treatment of wastewater polluted by lead (Pb2+) and cadmium (Cd2+). The prepared membranes were characterized by various characterization techniques, including scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). All synthetized membranes had an amorphous structure, with homogeneous pore morphology and distribution. Moreover, the presence of nanocomposite clay showed effective integration into the membrane matrix and led to a significant improvement in thermal resistance. These membranes were applied to treat a synthetic aqueous solution contaminated with heavy metals, namely Pb2+ and Cd2+. The results revealed a rejection rate higher than 50%, suggesting the potential effectiveness of a stable and environmentally sustainable polymer inclusion membrane system for water purification.

High-strength tile production from yellow clay with high silicon dioxide content and its reflection in ultraviolet and visible regions

Presently, there is an increasing global demand for high-quality raw materials in tile production owing to rapid urbanization. In addition, the issues of insufficient reserves and low-quality clays are resolved by exploring the potential of environmentally friendly Bilecik yellow clay with high SiO2 content. In this study, the feasibility of producing high-strength earthen tiles from yellow clay, which has a higher SiO2 content than that of commercially used clays, is investigated. X-ray diffraction, field-emission scanning electron microscopy, and X-ray fluorescence spectroscopy are employed to analyze yellow clay. The tiles are produced in the Hatipoglu Günes Tile and Brick Industry Inc. factories. Galette tiles are obtained using a vacuum press device. Then, the galette tiles are fired at temperatures of 900, 950, and 1000 °C in an electric and Hoffman furnace. The tile fired at 1000 °C exhibits the highest transformed flexural strength (305.371 kg/cm2), which is 2.55 times higher than that specified in the TS EN 1304:2016 standard (Turkish standard-European norm). In addition, reflectance measurements are performed in ultraviolet and visible regions through UV–VIS and Fourier-transform infrared spectroscopy; the results confirmed that the galette tiles are reflected in the UV-C region. Therefore, it can be concluded that galette tiles exhibit sterilization and disinfectant effects under appropriate conditions. The usability of yellow clay with high SiO2 content in industry, the availability of high-strength products, and its production stages will create an important database for literature.

Acid resistance of alkali-activated binders based on clays from phosphate mining by-products

This paper outlines the results of studying the resistance of alkali-activated materials (AAM), based on calcined yellow clay from phosphate mine by-products as a precursor, to an acid attack (with sulfuric and phosphoric acids, 5 %, pH ≈ 0,8–2). Calcined yellow clay (YC850) is used as the source of aluminosilicates, containing montmorillonite, dolomite, and quartz. The alkali-activation of such materials allows the determination of an adequate valorization way and evaluating their durability leads to defining the range of application. The residual compressive strengths were measured after 1, 2, and 4 weeks of immersion in those acids. The deterioration suffered by the paste specimens was examined using different techniques.The degree of deterioration differs from one acid to another; in sulfuric acid, the strengths decrease from 47 MPa to 10.6 MPa presenting 77.4 %. While in phosphoric acid, the decrease was about 36.2 % (30 MPa) after 28 days of attack. This detriment in the strengths is associated with changes not only in the microstructure but also with the alteration of the reaction products, mainly the binding gels C-A-S-H and (C,N)-A-S-H, which undergoes dealumination and decalcification. What is more, the chemical attack involves several reactions; calcium coming from the precursor reacts with the sulfates (in the H2SO4 attack) inducing the precipitation of gypsum, which is responsible for the significant strength loss. In addition, the dissolution of crystalline minerals, such as periclase and gehlenite (present in the precursor) generates higher porosity explaining the obtained results.

Composites with Immobilized Bioactive Spirulina on an Inorganic Substrate (Yellow Clay, Hydroxyapatite, SiO2, TiO2, ZnO).

In order to improve the structural properties of clays and composites of powdered spirulina, clay, nanosilica, hydroxyapatite, TiO2 and ZnO were used as an additive for mechanical processing. As a result, composites with natural nanostructured materials (NNM) are prepared with improved structural properties and bioactivity. The mixtures based on NNM with crystalline kaolinite, clays and admixtures were processed in a knife mill. The materials were characterized using FTIR spectroscopy, nitrogen adsorption and desorption, SEM release of bioactive components (anthocyanin 0,004-0,07 mg/g; chlorophyll 20-29 mg/g), composite toxicity level (below 25%), particle size measurement and surface charge density, zeta potential. Adsorption enthalpies during the formation of an intermolecular complex during the interactions of an anthocyanin molecule with the appropriate component of the composite were also calculated. There are regularities in the characteristics depending on the type of NNM, particle morphology and textural features of solids. The morphological and structural properties of the components changed slighty in the blends because the processing was conducted under relatively low mechanical stress. The morphological, textural and structural characteristics of the composites as well as the transformation to a nanostructured state, assume great bioactive activity of the composites, interesting for practical applications in medicine and cosmetics.

An Archaeometric Study of the Iron Age Ceramics from Quinta do Almaraz Archaeologic Site (8th to 5th Centuries BC)—Colour and Mineralogical Characterization

The ceramic pastes of ca. 31 samples recovered from the Almaraz archaeological site, located in the south bench of Tagus River, were studied in detail using XRF, micro-Raman and GSDR spectroscopies, as well as the XRD technique. The ceramic sherds could be grouped into six categories, red slip tableware, decorated tableware, yellow slip tableware, grey tableware, common tableware, and handmade pottery. Our studies of the mineralogic composition of the sherds’ body indicate all ceramics were produced locally, using siliceous clays in most cases and calcareous clays in a few ones. Micro-Raman and ground state diffuse reflectance absorption spectroscopy provided useful information regarding the materials used to produce the coloured ceramics: hematite and brookite for the red slip and decorated ceramics, jacobsite or carbon black for the black decoration or grey ceramics. For the yellow slip tableware, a simple engobe rich in yellow clay was used. XRF spectroscopic studies provided the elemental composition of all samples, and biplots of the potassium (K) versus calcium (Ca) contents, normalized to the silicon content of each ceramic paste, clearly show Pliocene and Miocene local clays sources were used to produce most ceramics. Only one sherd can be considered a Lisbon production.

Development of eco-friendly clay ceramics using rice husk ash as a secondary mineral source of quartz

The study focuses on the sustainable reuse of waste ceramic materials, particularly rice husk ash (RHA), as a secondary mineral source in ceramics production. RHA's potential to replace primary raw clays in making ceramic blocks and bricks is explored. RHA is categorized as Class II-A non-inert waste, limiting its use to controlled applications like the ceramic industry due to environmental and health risks. The study assesses the feasibility of incorporating RHA into three different types of clay: yellow and black plastic clays (plastic) and sandy clay. Waste classification according to environmental and health risks follows ABNT NBR 10004/2004 guidelines. Various analytical techniques, including X-ray fluorescence, X-ray diffractometry, differential thermal analysis, and thermogravimetric analysis, were employed to characterize the materials. Laser diffraction measured the particle size distribution of the clays. In addition to the conventional ceramics industry standard formulation (STD), the study prepared five different mixtures with varying RHA and clay contents. These mixtures underwent evaluation for properties such as thermal shrinkage, density, porosity, water absorption, and diametral mechanical strength, with resistance reliability assessed using Weibull distributions. Results indicated that introducing over 15% RHA into clay ceramics led to excessive water absorption, rendering it unsuitable. Consequently, an 8.3% RHA content was chosen to manufacture hollow ceramic blocks for non-load-bearing masonry. This industrial test demonstrated favorable processing conditions compared to the STD, highlighting RHA's potential as an alternative raw material for the ceramic industry, contributing to sustainable development.

Characterization and Suitability Assessment of Ameskroud Clay Deposits for Ceramic Applications

The identification of natural clay deposit parameters is critical for the development of ceramics. This research underscores the essential role of understanding clay properties in producing high‐quality ceramics and represents a comprehensive characterization methodology, shedding light on the untapped potential of natural clay deposits for ceramic applications. This study investigates red clays from the Triassic, as well as yellow and gray clays from the Cretaceous period, collected from the western High Atlas of Morocco (Ameskroud). The characterization of clays from this geographic region is innovative, as they have not been previously investigated for their suitability within ceramic applications. The investigation encompasses an examination of the geological context, mineralogy, chemical composition, and physicochemical attributes of these clays. Furthermore, the thermal behavior, firing characteristics, and compressive strength of the clay samples were assessed when fired at 900°C, 1000°C, and 1100°C. Mineralogical analysis reveals that illite predominates with relatively low levels of kaolinite and chlorite. The primary chemical constituent is SiO2, followed by Al2O3 and Fe2O3. Notably, yellow clay exhibits a significant CaO content exceeding 10%. At 1100°C, the clay specimens exhibit reduced water absorption rates (ranging from 9.88% to 17.1%) and enhanced mechanical performance, with compressive strengths ranging from 22.33 MPa to 36.07 MPa, attributable to the sintering process. The findings affirm that the raw clays sourced from the Ameskroud region possess characteristics suitable for various ceramic applications, making them ideal candidates for the production of dense bricks and ceramic tiles.

Thermal characteristics analyses of clay bricks with wheat straw additives

The production technology of the environmentally polluting baked bricks suggests that they can be replaced by bricks that are produced in an ecologically clean environment, such as the unbaked ones. In the present research work, different brick samples were made and studied, built with clay, sand and agricultural waste raw materials. With the development of the construction industry and increasing environmental requirements, research studies in the field continue to improve the thermal characteristics of the new construction materials. Thus, in the presented work bricks were made, which are a mixture of yellow clay and sand with added 5, 10, 15 and 20% wheat straw. The finished bricks are 0.35/0.08/0.17 m in size. Then, non-destructive measurements were carried out and thermal conductivity coefficient (k), specific heat capacity (Cp), thermal diffusivity (a) and density (ρ) were determined. The results of the measurements show that as the amount of wheat straw increases, the thermal characteristics of the samples improve. Finally, it is proved that the use of unbacked bricks from local clays and the utilization of binders from agricultural waste raw materials, will help to improve the energy performance of the produced environmentally friendly and economically beneficial structural building materials.

Elaboration and characterization of physicochemical properties and mineralogical study of natural clay (M'sila area).

Clays are used in a wide variety of fields (e.g. construction, pharmaceuticals, agriculture, etc.),motivating experts and scientists to study the physical-chemical properties of clays and their mineralcomposition, and to improve their use in their specific fields. Given its importance in the field of use, ourresearch focused on studying the mineral composition of natural clays and their physical-chemicalproperties. Physical-chemical properties studied - we obtained only a yellow clay with a pH of 7.47, the W% of 1.38% is lower. The Ig swelling index (1.55%) swells slightly. The clay characterization method wasrevealed by FTIR in agreement with the results revealed by the analysis. The existence of kaolinite andquartz is well confirmed (Si-O bond deformation and Si-O elongation vibration band signatures of quartzlocated at 470.4 cm-1, 712 cm-1and 798, 4 cm-1). Kaolinite or Si-group quartz at 1025cm-1) The thermalstability of the clay was monitored by ATG thermogravimetric analysis, which made it possible to track theloss of sample mass as a function of temperature (total loss of clay was approx. 5.56%). the spectral analysisof the d X-ray diffraction (XRD) indicates that it is composed of quartz, calcite and dolomite, whichexplains why our clay is heterogeneous, the mineralogical composition of the clay fraction of our materialis quartz (12.68%) and calcite (50.35%) The results of the elemental chemical analysis (XRF) show thatsilica (26.42%) and calcium oxide (28.58%) are the major oxides in our sample.

Plastic behaviour of clay materials for the manufacture of fast-drying red ceramics

AbstractFast drying (~60 min) is useful for optimizing production processes by increasing productivity and reducing costs and environmental impacts, especially in red ceramic industries in Brazil. However, suitable clays are necessary and, currently, studies focused on the plastic behaviour of clays with compositions suitable for extrusion, especially for fast drying, are scarce. Therefore, in this study, three different clays from the same mineral deposit were studied for producing clay-based structural products via fast drying. The clays were characterized according to their chemical, mineralogical and thermal properties, particle size, cation-exchange capacity, specific surface area and open pore volume distribution. Ten formulations were developed using a simplex-centroid mixture design of experiments and their plasticity index (PI) values were determined. The response surfaces of the formulations were evaluated according to their PI, while the formation characteristics were determined according to their extrusion workability factor values. Formulations F5 (50.0 wt.% yellow clay and 50.0 wt.% green clay) and F8 (66.6 wt.% yellow clay, 16.7 wt.% grey clay and 16.7 wt.% green clay; PI = 15.5–16.6%) displayed optimal extrusion properties, followed by formulations F7 (33.3 wt.% yellow clay, 33.3 wt.% grey clay and 33.3 wt.% green clay) and F10 (16.7 wt.% yellow clay, 16.7 wt.% grey clay and 66.6 wt.% green clay; PI = 13.8–14.2%), which are within acceptable extrusion index values. Thus, the chosen formulations have significant potential for use in the manufacture of fast-drying red ceramics.

Study on the uniaxial compression constitutive relationship of modified yellow mud from minority dwelling in western Sichuan, China

Abstract More than 2 billion people around the world still use raw earth architecture, in countries like Nepal, India, and Iran. In China, the proportion of people living in earthen structures rose to 36%, some of them in western Sichuan. Minority dwellings in western Sichuan, China, use local stone and yellow mud as building materials and have been used for thousands of years. Because yellow mud is a brittle material with poor mechanical properties, and because the region is prone to earthquakes, the walls are highly susceptible to damage under seismic action. To improve the mechanical properties of yellow mud, the yellow mud of Taoping Qiang Village in western Sichuan was studied and modified. Uniaxial compressive tests were conducted on the modified specimens, and the existing ontogenetic equations of raw soil-based materials were analyzed and optimized. Finally, we developed the constitutive models for yellow clay and modified yellow clay in the western Sichuan area, which can be used for different kinds of modified materials through the variation of parameters. The results show that the compressive strength of yellow clay is improved by adding the modified materials. The optimized constitutive model can better fit the test curves, which can provide a basis for theoretical calculations and seismic mitigation of minority residential structures in western Sichuan or similar structural systems.

Earthing Resistance and Poldzolic Soil Resistivity at PT. Perta Samtan Gas Field Extraction Plant Prabumulih

It is important to undertake research at the location of PT. Perta Samtan Gas Field Extraction Plant Prabumulih with Podzolik soil type (yellow gravel clay) and analysis in order to prevent work accidents and the risk of fire caused by leakage current at the gas processing extraction installation. Direct measurement of soil resistance value is used as the basis for the methodology, which is followed by literature study as background information and technical comprehension of experimental research. The outcomes of the research study are then compared using Comsol simulation with the computational method of computational finite element analysis of the resulting resistance. According to the data, the resistivity of the podzolic soil was 214.4 Ωm, while the Comsol simulation yielded a resistance value per meter of 209.1 Ω and 196.7Ω, respectively. The Comsol simulation demonstrates that, in order to obtain a ground resistance value of 1 ohm on a Single rod system with Fe material, it is necessary to optimize the depth of the grounding electrode, which can range from 3 meters to 1053 meters d. In the simulation, the results of soil resistance measurements and the Comsol Multiphysics application are obtained, and the difference is calculated with a percentage error of 1.62%.

Immunological mechanisms of anti-inflammatory action of modified yellow clay in the experiment

BACKGROUND: Modern scientific search and reasonable introduction of new balneofactors into sanatorium-resort recreational technologies are conditioned by the results of fundamental research. Experimental balneology is faced with the tasks of investigating poorly studied natural sources that are potentially capable of having therapeutic and preventive properties.
 AIM: is to evaluate immunological mechanisms of anti-inflammatory action of external balneological medicine based on natural clays to study their therapeutic effectiveness in diseases of musculoskeletal system of degenerative-dystrophic nature.
 MATERIAL AND METHODS: An experimental study was conducted with the participation of 79 laboratory animals (male rats, Wistar line) distributed by simple sampling into 5 groups: in the control group 1 (n=15) there were healthy animals (intact); in the 2nd group (n=13) the animals had adjuvant arthritis (AA) without exposure; the 3rd group (n=17) had an adjuvant arthritis model and Tambukan dirt; in the 4th group (n=17) there was model adjuvant arthritis and a course of yellow clay, the 5th group (n=17) had model adjuvant arthritis and a course of modified clay. The anti-inflammatory effects of native and modified external balneological medicine were examined by evaluating the response of immune-competent cells of peripheral blood in reproducing chronic inflammation in adjuvant arthritis model.
 RESULTS: The conducted studies have shown that the external use of modified yellow clay in the form of balneological medicine Glinofir is comparable to the effect of Tambukan dirt. According to the immune marker analysis there was a significant change in population lymphocyte structure in peripheral blood as a result of adjuvant arthritis modeling, namely, the number of B-lymphocytes increased (2.5 times; p 0.02) with simultaneous reduction of total T-lymphocytes (2.5 times; p 0.05); the level of circulating immune complexes showed a tendency to increase with the animals of the group with adjuvant arthritis model without treatment (59.84.18 units in adjuvant arthritis and 52.43.44 units with healthy animals; p=0.1).
 CONCLUSION: According to the results of the experimental studies, Glinofir which has immune-modulatory and anti-inflammatory effects can be recommended for subsequent introduction into clinical practice as the treatment and medical rehabilitation of patients with diseases of musculoskeletal system of degenerative-dystrophic nature.

Application of Yellow Clay Powder for Efficient Treatment of Cyanobacterium Microcystis sp. - Laden Source Water in Drinking Water Treatment Facility

Objectives : This study evaluated the effect of dosing yellow clay powder as a sedimentation aid when <i>Microcystis</i> sp. bloomed.Methods : Pre-oxidation (chlorination and ozonation) treatment and coagulation/precipitation experiments of <i>Microcystis</i> sp. - laden source water were performed with a jar-tester. Treatment efficiency was evaluated by analyzing the turbidity and particulate matter of the supernatant after sedimentation according to the presence or not of pre-oxidation, the concentrations of yellow clay powder, and polyamine dosing.Results and Discussion : As a result of evaluating the turbidity and particulate matter of the supernatant after coagulation/sedimentation according to the dosing concentrations of yellow clay powder, the turbidity of the supernatant decreased as the dosing concentrations of yellow clay powder increased regardless of the presence or not of pre-oxidation. In particular, when pre-oxidation was not performed, both turbidity and particulate matter of the supernatant after sedimentation were significantly reduced. In addition, without pre-oxidation, when yellow clay powder (50 mg/L) and polyamine (1.0 mg/L) were dosed together, turbidity was reduced by 25% and the amount of particulate matter by 41% compared to utilizing pre-oxidation. Regarding the concentrating efficiency of sedimentation sludge, when yellow clay powder was added, concentrating efficiency increased by more than 31~38% regardless of pre-oxidation treatment compared to when yellow clay powder was not added. However, with pre-oxidation, the concentrating efficiency decreased by about 27~34% under the same yellow clay powder and polyamine dosing conditions compared to without pre-oxidation.Conclusion : When yellow clay powder was added to <i>Microcystis</i> sp. - laden source water, turbidity and particulate matter were effectively reduced after coagulation/sedimentation regardless of the presence or not of pre-oxidation. In particular, when pre-oxidation was not performed, the turbidity and particulate matter after coagulation/sedimentation were significantly reduced as compared with utilizing pre-oxidation, and using yellow clay powder together with a polyamine reduced turbidity and particulate matter the most. In addition, the sludge concentration of <i>Microcystis</i> sp. - containing sludge with low concentrating efficiency was increased by dosing yellow clay powder.

Lithostratigraphy and sedimentology across the Cretaceous/Tertiary boundary in the Flyschgosau (Eastern Alps, Austria)

Detailed lithological profiles across the Cretaceous/Tertiary boundary (K/T) in the flyschoid Gosau Formation at Gosau (Elendgraben) and Gams (Knappengraben) are presented. The revised low sediment accumulation rates in the lowermost Danian correspond to those calculated by Smit & Hertogen (1980) for the Caravaca section. The estimated longer time-span for the deposition of the K/T boundary layers of 6-11 ka seems to be more realistic. The sediment at the K/T in the Gosau area was deposited under reducing conditions (Reissner et al. 1985). Peak levels of the siderophile elements do not coincide at Gosau and Gams. A diachronism of events is therefore assumed. The gradual decline of CaCO3 and some major element oxides beginning 4 cm below the K/T boundary and also a 1 mm thin yellow clay layer 10 mm underneath the boundary clay at Gams suggest multiple events and could be the result of a period of increased volcanism.

A Characteristic Analysis on Clay Pigments of Mural Paintings in Sri Lanka

Sri Lanka has four types of mural painting styles; Classic, Late Classic, Kandyan, and Southern styles, but there is little research on scientific analysis for mural paintings. In this study, we analyze white, yellow, and red clay pigments which were collected from ancient producing sites. Analyzing pigment samples shows that samples are containing aluminum oxide(Al<sub>2</sub>O<sub>3</sub>) and silicon dioxide(SiO<sub>2</sub>) which are connected to the soil. And a degree of iron oxidation determines yellow or red colors. To understand the characteristics of clay pigment samples, we go over previous pigment analyses of mural paintings in Sri Lanka. Kaolin is identified after the 17<sup>th</sup> century, yellow and red ochre are applied in early periods, Classic and Late Classic styles. The change in raw materials of pigments occurred in the 17<sup>th</sup> century.

Properties and Durability of Cement Mortar Using Calcium Stearate and Natural Pozzolan for Concrete Surface Treatment.

Applying a concrete surface treatment method (epoxy or primer) can prevent water from penetrating concrete through surface pores. However, if the concrete surface is damaged, the subsequent reconstruction can be expensive and time-consuming. Concrete that is resistant to internal and external water has been extensively developed and used to supplement the surface treatment method. Herein, we prepared specimens by mixing cement mortar with fatty-acid-salt-based calcium stearate attached to two natural pozzolanic materials—diatomite and yellow clay. The physical tests measured (1) the air content, (2) flow test, (3) compressive strength, and (4) activity Factor. Durability experiments were performed on (1) the contact angle, (2) chloride ion diffusion coefficient, and (3) water absorption test. The results revealed that the compressive strength of concrete decreased as the calcium stearate content increased. Furthermore, it was confirmed that the contact angle of the test piece using the pozzolanic substance and calcium stearate was twice as high. It was confirmed that the sand test specimen had the highest water absorption rate, and the DT3% had the lowest. (Sand%: 11.8 > OPC: 6.5 > DT3%: 2.4), the chloride diffusion coefficient also showed similar results. (Sand%: 12.5 > OPC: 8.4 > DT1%: 8.8)Due to its unique insolubility, calcium stearate retards hydrate formation when mixed alone and negates compressive strength loss when combined with pozzolanic mixtures rich in SiO2 and Al2O3. Furthermore, the ideal method for producing water-resistant cement mortar is to evenly disperse calcium stearate in the porous powder of cement mortar.

Effects of aerated subsurface drip irrigation on rhizosphere soil environment and pepper (Capsicum annum L.) growth in three soil types

ABSTRACT Aerated subsurface drip irrigation (ASDI) has been considered an effective method to unlock the growth potential of crops. An experiment was undertaken to monitor the effects of three aeration rates (40% aeration rate, 15% aeration rate, CK: no-aeration) on rhizosphere soil environment and growth parameters of pepper in three soil types (YC: yellow clay, SL: silt loam, HL: heavy loam). ASDI significantly increased the soil enzyme and microbial abundance, and enhanced the soil respiration compared to the control. ASDI significantly increased the pepper yield, fruit quality, and biomass of stem and leaf. The 40% aeration rate was more beneficial to these parameters than that of 15% aeration rate in YC and SL, whereas, in HL, the 40% was less effective than 15% aeration rate. Soil type significantly affected pepper rhizosphere soil environment and the yield, quality, and biomass of stem and leaf. The benefits of ASDI in YC were better than those in SL and HL. However, aeration rate and soil type had no significant effects on the fresh/dry weight of pepper root. The recommended ASDI patterns for pepper in YC and SL were 40% aeration rates, while in HL it was the 15% aeration rate.

Flow patterns and aquifer recharge controls under Amazon rainforest influence: The case of the Alter do Chão aquifer system

The present study clarifies the role of rainforests in the recharge processes of the Alter do Chão Aquifer System in the outcropping region based on a dataset collected in reference areas. Different methods and techniques commonly applied to hydrogeology studies were integrated to achieve this objective, including soil profile description (in field and laboratory), potentiometric analysis, hydrochemistry data, and stable isotopic evaluation. The Alter do Chão Aquifer System occurs as an unconfined and semiconfined groundwater reservoir in the Amazonian plateau regions, with the following profile sequence: topsoil (higher porosity and hydraulic conductivity), yellow clay (mean porosity of 18% with small pore throats, resulting in lower hydraulic conductivity), aluminous iron crusts, and solid bauxite (highest hydraulic conductivity values resulting from porosity values from 30 to 45%), and at the bottom, the mottled stratified argillite (acting as an aquitard layer, with leaky confining attributes). The relief pattern with high plateau areas cut by shallow and deeper valleys allows regional and local hydrogeological flow systems. The dense forest cover acts as a vital recharge control due to bioturbation by the roots, observed up to 15 m deep. This bioturbation causes preferential flow zones and is responsible for increasing the hydraulic conductivity in the pelitic layers. Oxygen and deuterium stable isotope data demonstrate that recharge is due to rainwater infiltration because the local groundwater line is plotted next to or over the regional meteoric water line. Tritium data indicate that the aquifer is supplied by relatively recent rainfall or at least by mixtures containing recent rainwater. The conceptual flow model for the semiconfined and unconfined portions of the Alter do Chão Aquifer System is represented by the following processes: infiltration of large volumes of rainwater, high loss by forestry evapotranspiration, loss by interflow at the interfaces of contrasting hydraulic conductivity layers, and local loss due to regional lateral flow to the discharge areas. Considering a 1 km2 polygon, it is possible to determine a recharge amount of at least 236,400 and 350,000 m3/year for the semiconfined and unconfined portions of the aquifer, respectively.