scholarly journals Improved Shear Strength Performance of Compacted Rubberized Clays Treated with Sodium Alginate Biopolymer

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 764
Author(s):  
Amin Soltani ◽  
Ramin Raeesi ◽  
Abbas Taheri ◽  
An Deng ◽  
Mehdi Mirzababaei
Keyword(s):  
Sodium Alginate ◽  
Clay Content ◽  
Soil Mass ◽  
Experimental Program ◽  
High Plasticity ◽  
Content Increase ◽  
Sem Images ◽  
Strength Performance ◽  
Environmentally Sustainable ◽  
Soil Clay Content

This study examines the potential use of sodium alginate (SA) biopolymer as an environmentally sustainable agent for the stabilization of rubberized soil blends prepared using a high plasticity clay soil and tire-derived ground rubber (GR). The experimental program consisted of uniaxial compression and scanning electron microscopy (SEM) tests; the former was performed on three soil–GR blends (with GR-to-soil mass ratios of 0%, 5% and 10%) compacted (and cured for 1, 4, 7 and 14 d) employing distilled water and three SA solutions—prepared at SA-to-water (mass-to-volume) dosage ratios of 5, 10 and 15 g/L—as the compaction liquid. For any given GR content, the greater the SA dosage and/or the longer the curing duration, the higher the uniaxial compressive strength (UCS), with only minor added benefits beyond seven days of curing. This behaviour was attributed to the formation and propagation of so-called “cationic bridges” (developed as a result of a “Ca2+/Mg2+ ⟷ Na+ cation exchange/substitution” process among the clay and SA components) between adjacent clay surfaces over time, inducing flocculation of the clay particles. This clay amending mechanism was further verified by means of representative SEM images. Finally, the addition of (and content increase in) GR—which translates to partially replacing the soil clay content with GR particles and hence reducing the number of available attraction sites for the SA molecules to form additional cationic bridges—was found to moderately offset the efficiency of SA treatment.

scholarly journals Shear strength characteristics of a sand clay liner

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Muawia Dafalla ◽  
Abdullah Shaker ◽  
Tamer Elkady ◽  
Abdullah Almajed ◽  
Mosleh Al-Shamrani
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Pore Water Pressure ◽  
Axial Strain ◽  
Water Pressure ◽  
Clay Content ◽  
Triaxial Tests ◽  
High Plasticity ◽  
Content Increase ◽  
Triaxial Cell

Abstract This study investigated shear strength behaviour of compacted sand–clay mixtures used as liners, with 10%, 20%, and 30% clay contents. A natural high-plasticity and highly expansive clay found in the eastern province of Saudi Arabia was used. A series of consolidated undrained triaxial tests and pore water pressure measurements of saturated samples with various clay contents and confining pressures was conducted using a computer-controlled Bishop and Wesley triaxial cell. The unit was equipped with pressure volume controllers and a pressure transducer for measuring sample volume changes and excess pore water pressure. The experimental test results indicate that clay content and confining pressure significantly affect stress strain response curves, pore water pressure generation curves, and steady-state shear strength. Sand–clay mixtures with clay content less than 10% showed a tendency toward contractive behaviour. The failure line slope increased in accordance with clay content increase. The deviator stress versus axial strain of saturated sand–clay mixtures indicated a hyperbolic trend. The stress ratio versus axial strain representation was more informative for the shear strength behaviour assessment. Clay content did not significantly affect critical-state friction angle. Scanning electron microscope images of the sand-clay mixtures with different clay contents are presented.

scholarly journals Eudragit S-100 coated sodium alginate microspheres of naproxen sodium: Formulation, optimization and in vitro evaluation / Alginatne mikrosfere naproksen natrija obložene Eudragitom S-100: Priprava, optimizacija i in vitro vrednovanje

2012 ◽  
Vol 62 (4) ◽  
pp. 529-545 ◽  
Author(s):  
Anuj Chawla ◽  
Pooja Sharma ◽  
Pravin Pawar
Keyword(s):  
Drug Release ◽  
Sodium Alginate ◽  
Naproxen Sodium ◽  
Drug Loading ◽  
Size Analysis ◽  
Scanning Calorimetry ◽  
Sem Images ◽  
S 100 ◽  
Eudragit S 100

The aim of the study was to prepare site specific drug delivery of naproxen sodium using sodium alginate and Eudragit S-100 as a mucoadhesive and pH-sensitive polymer, respectively. Core microspheres of alginate were prepared by a modified emulsification method followed by cross-linking with CaCl2, which was further coated with the pH dependent polymer Eudragit S-100 (2.5 or 5 %) to prevent drug release in the upper gastrointestinal environment. Microspheres were characterized by FT-IR spectroscopy, X-ray diffraction, differential scanning calorimetry and evaluated by scanning electron microscopy, particle size analysis, drug loading efficiency, in vitro mucoadhesive time study and in vitro drug release study in different simulated gastric fluids. Stability studies of the optimized formulation were carried out for 6 months. SEM images revealed that the surface morphology was rough and smooth for core and coated microspheres, respectively. Core microspheres showed better mucoadhesion compared to coated microspheres when applied to the mucosal surface of freshly excised goat colon. The optimized batch of core microspheres and coated microspheres exhibited 98.42 ± 0.96 and 95.58 ± 0.74 % drug release, respectively. Drug release from all sodium alginate microsphere formulations followed Higuchi kinetics. Moreover, drug release from Eudragit S-100 coated microspheres followed the Korsmeyer-Peppas equation with a Fickian kinetics mechanism. Stability study suggested that the degradation rate constant of microspheres was minimal, indicating 2 years shelf life of the formulation.

scholarly journals Remaining phosphorus and sodium fluoride pH in soils with different clay contents and clay mineralogies

2004 ◽  
Vol 39 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Marcelo Eduardo Alves ◽  
Arquimedes Lavorenti
Keyword(s):  
Buffer Capacity ◽  
Ammonium Oxalate ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Response Curves ◽  
Solution Ph ◽  
Ph Values ◽  
Soil Clay ◽  
Soil Clay Content ◽  
Discriminatory Capacity

The remaining phosphorus (Prem) has been used for estimating the phosphorus buffer capacity (PBC) of soils of some Brazilian regions. Furthermore, the remaining phosphorus can also be used for estimating P, S and Zn soil critical levels determined with PBC-sensible extractants and for defining P and S levels to be used not only in P and S adsorption studies but also for the establishment of P and S response curves. The objective of this work was to evaluate the effects of soil clay content and clay mineralogy on Prem and its relationship with pH values measured in saturated NaF solution (pH NaF). Ammonium-oxalate-extractable aluminum exerts the major impacts on both Prem and pH NaF, which, in turn, are less dependent on soil clay content. Although Prem and pH NaF have consistent correlation, the former has a soil-PBC discriminatory capacity much greater than pH NaF.

scholarly journals P-sorption and desorption in Savanna Brazilian soils as a support for phosphorus fertilizer management

2013 ◽  
Vol 37 (6) ◽  
pp. 521-530 ◽  
Author(s):  
Flávio Araújo Pinto ◽  
Edicarlos Damacena de Souza ◽  
Helder Barbosa Paulino ◽  
Nilton Curi ◽  
Marco Aurélio Carbone Carneiro
Keyword(s):  
Clay Content ◽  
Soil Characteristics ◽  
Fertilizer Management ◽  
Phosphorus Fertilizer ◽  
Phosphorus Adsorption ◽  
P Sorption ◽  
Brazilian Soils ◽  
Soil Clay ◽  
Sand Base ◽  
Soil Clay Content

Phosphorus (P) sorption by soils is a phenomenon that varies depending on soil characteristics, influencing its intensity and magnitude, which makes it a source or drain of P. The objective of this study was to determine the Maximum Phosphorus Adsorption Capacity (MPAC) and desorption of P from soils under native Savanna Brazilian and verify the correlation between MPAC and P Capacity Factor (PCF) with the chemical and physical properties of these soils. The study was conducted in seven soils under native Savannas. The Langmuir isotherms were adjusted from the values obtained in sorption assays, being evaluated the MPAC, the energy adsorption (EA) and PCF, which was calculated according to the levels of P-adsorbed and P-sorbed. Values of MPAC were classified as high in most soils, ranging from 283 up to 2635 mg kg-1 of P in the soil and were correlated with soil organic matter, clay, silt, sand, base saturation and pH. The PCF was higher in soils where the MPAC was also higher. The use of only one attribute of soil (clay content) as a criterion for the recommendation of phosphated fertilization, as routinely done, is susceptible to errors, needing the use of more attributes for a more accurate recommendation, as a function of the complexity of the interactions involved in the process.

scholarly journals EVALUATION OF BACTERIAL CELLULOSE-SODIUM ALGINATE FORWARD OSMOSIS MEMBRANE FOR WATER RECOVERY

2018 ◽  
Vol 80 (3-2) ◽  
Author(s):  
Ngan T. B. Dang ◽  
Liza B. Patacsil ◽  
Aileen H. Orbecido ◽  
Ramon Christian P. Eusebio ◽  
Arnel B. Beltran
Keyword(s):  
Contact Angle ◽  
Bacterial Cellulose ◽  
Sodium Alginate ◽  
Water Flux ◽  
Forward Osmosis ◽  
Composite Membranes ◽  
Membrane Thickness ◽  
Water Recovery ◽  
Sem Images ◽  
Salt Rejection

Water resources are very important to sustain life. However, these resources have been subjected to stress due to population growth, economic and industrial growth, pollution and climate change. With these, the recovery of water from sources such as wastewater, dirty water, floodwater and seawater is a sustainable alternative. The potential of recovering water from these sources could be done by utilizing forward osmosis, a membrane process that exploits the natural osmotic pressure gradient between solutions which requires low energy operation. This study evaluated the potential of forward osmosis (FO) composite membranes fabricated from bacterial cellulose (BC) and modified with sodium alginate. The membranes were evaluated for water flux and salt rejection. The effect of alginate concentrations and impregnation temperatures were evaluated using 0.6 M sodium chloride solution as feed and 2 M glucose solution as the draw solution. The membranes were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and Contact Angle Meter (CAM). The use of sodium alginate in BC membrane showed a thicker membrane (38.3 μm to 67.6 μm), denser structure (shown in the SEM images), and more hydrophilic (contact angle ranges from 28.39° to 32.97°) compared to the pristine BC membrane (thickness = 12.8 μm and contact angle = 66.13°). Furthermore, the alginate modification lowered the water flux of the BC membrane from 9.283 L/m2-h (LMH) to value ranging from 2.314 to 4.797 LMH but the improvement in salt rejection was prominent (up to 98.57%).

Surface soil clay content mapping at large scales using multispectral (VNIR–SWIR) ASTER data

2018 ◽  
Vol 40 (4) ◽  
pp. 1506-1533
Author(s):  
Anis Gasmi ◽  
Cécile Gomez ◽  
Philippe Lagacherie ◽  
Hédi Zouari
Keyword(s):  
Surface Soil ◽  
Clay Content ◽  
Aster Data ◽  
Soil Clay ◽  
Soil Clay Content

scholarly journals Factors Affecting Microbial Formation of Nitrate-Nitrogen in Soil and Their Effects on Fertilizer Nitrogen Use Efficiency

2001 ◽  
Vol 1 ◽  
pp. 122-129 ◽  
Author(s):  
Alan Olness ◽  
Dian Lopez ◽  
David Archer ◽  
Jason Cordes ◽  
Colin Sweeney ◽  
...  
Keyword(s):  
Organic Matter ◽  
Decision Aid ◽  
Pore Space ◽  
Organic Matter Content ◽  
Clay Content ◽  
Matter Content ◽  
N Fertilizer ◽  
Nitrate N ◽  
Soil Clay ◽  
Soil Clay Content

Mineralization of soil organic matter is governed by predictable factors with nitrate-N as the end product. Crop production interrupts the natural balance, accelerates mineralization of N, and elevates levels of nitrate-N in soil. Six factors determine nitrate-N levels in soils: soil clay content, bulk density, organic matter content, pH, temperature, and rainfall. Maximal rates of N mineralization require an optimal level of air-filled pore space. Optimal air-filled pore space depends on soil clay content, soil organic matter content, soil bulk density, and rainfall. Pore space is partitioned into water- and air-filled space. A maximal rate of nitrate formation occurs at a pH of 6.7 and rather modest mineralization rates occur at pH 5.0 and 8.0. Predictions of the soil nitrate-N concentrations with a relative precision of 1 to 4 μg N g–1of soil were obtained with a computerized N fertilizer decision aid. Grain yields obtained using the N fertilizer decision aid were not measurably different from those using adjacent farmer practices, but N fertilizer use was reduced by >10%. Predicting mineralization in this manner allows optimal N applications to be determined for site-specific soil and weather conditions.

scholarly journals DEVELOPMENT OF SODIUM ALGINATE COATED NANOPARTICLES OF METRONIDAZOLE FOR THE TREATMENT OF PERIODONTITIS

2019 ◽  
pp. 105-110 ◽  
Author(s):  
MUKUL SINGH ◽  
GAURAV JAIN
Keyword(s):  
Particle Size ◽  
Sodium Alginate ◽  
Biological Membrane ◽  
Spherical Shape ◽  
Prolonged Treatment ◽  
Prolonged Action ◽  
Sem Images ◽  
Mean Particle Size ◽  
Coated Nanoparticles ◽  
Acceptable Range

Objective: The present study was aimed to develop metronidazole (MNZ) loaded poly lactic-co-glycolic acid (PLGA) based mucoadhesive nanoparticles (NPs) in prolonged treatment in periodontitis. Methods: Nanoparticles were prepared by using single (SE) and double (DE) emulsion method to determine the suitability of methods. Prepared NPs were evaluated for surface morpholgy, mean particle size, polydispersity index, zeta potential, mucoadhesion ability and invitro-drug release, Results: SEM images confirmed that NPs were of spherical shape and smooth surface. Mean particle size, of MNZ loaded NPs were found 583.28±18.22 and 872.72±63.18 prepared by SE and DE method. Similarly, polidispersity index (0.68±0.1 and 0.83±0.06) and zeta potention (-33.29±0.7 and-31.28.0.6) was found in acceptable range. Prepared NPs were surface treated with Sodium alginate (SA) to increase mucoadhesive property. It was observe that particles remain adhere till 24 hr with biological membrane. Prepared NPs allow release of MNZ upto 24 h in sustained manner. Conclusion: This study confirms that the prepared MNZ loaded NPs may be used as an better alternate with addition application such as prolonged action thus improved patient compliance.

Survival and biomass of exotic earthworms, Aporrectodea spp. (Lumbricidae), when introduced to pastures in south-eastern Australia

1999 ◽  
Vol 50 (7) ◽  
pp. 1233 ◽  
Author(s):  
G. H. Baker ◽  
P. J. Carter ◽  
V. J. Barrett
Keyword(s):  
South Australia ◽  
Clay Content ◽  
Total Biomass ◽  
Soil P ◽  
South Eastern ◽  
Inoculation Density ◽  
Eastern Australia ◽  
Exotic Earthworms ◽  
Soil Clay Content ◽  
South Eastern Australia

The earthworm fauna of pastures in south-eastern Australia is dominated by exotic lumbricid earthworms, in particular the endogeic species, Aporrectodea caliginosa and A. trapezoides. Anecic species such as A. longa are very rare. All 3 species were introduced within cages in 10 pastures on a range of soil types within the region. Five months later, A. longa had generally survived the best and A. trapezoides the worst. The survivals and weights of individual worms varied between sites for all 3 species. The survivals of A. caliginosa and A. longa, and to a lesser extent A. trapezoides, were positively correlated with soil clay content. The weights of A. caliginosa and A. longa, but not A. trapezoides, were positively correlated with soil P content. The survivals and weights of A. longa and A. trapezoides and the weights only of A. caliginosa decreased with increasing inoculation density, suggesting increased intraspecific competition for resources, particularly in the first two species. A. longa reduced the abundance and biomass of the exotic acanthodrilid earthworm, Microscolex dubius, at one site, and the total biomass of 3 native megascolecid species at another, when these latter species occurred as contaminants in A. longa cages. The addition of lime had no effect on the survivals and weights of A. caliginosa, A. longa, and A. trapezoides, although the soils were acid at the sites tested. The addition of sheep dung increased the survival and weights of some species at some sites. Mechanical disturbance of the soil within cages reduced the survivals of A. longa and A. trapezoides. A. longa was released without being caged at 25 sites within one pasture in South Australia. Four years later, it was recovered at all release points. A. longa has the potential to colonise pastures widely throughout the higher rainfall regions of south-eastern Australia.

Failure Mechanisms of Pipelines Subjected to Loss of Support Under Deep Burial Conditions

2004 ◽  
Author(s):  
Yuri D. Costa ◽  
Jorge G. Zornberg ◽  
Benedito S. Bueno ◽  
Carina L. Costa
Keyword(s):  
Vertical Section ◽  
Failure Mechanisms ◽  
Soil Mass ◽  
Experimental Program ◽  
Rigid Base ◽  
Failure Patterns ◽  
Slip Surfaces ◽  
Deep Burial ◽  
Flexible Pipes ◽  
Adjacent Soil

This paper investigates the failure mechanisms of pipelines subjected to a localized loss of support. An experimental program was conducted, which consisted of a series of four centrifuge model tests containing an aluminum tube embedded in a pure dry sand backfill that was placed over an underlying rectangular rigid base moving downwards during the test. All models were built taking advantage of the longitudinal symmetry of the problem. The prototype pipe had a diameter (D) of 1.1 m and a soil cover height of about 5 D, characterizing deep burial conditions. Failure patterns were observed within a vertical section comprising the central axis of the pipe and also in four distinct vertical transverse sections along the length of the pipe in the region of ground loss. The influence of pipe stiffness and backfill density on the behavior of the system was assessed. The transverse sections showed fully developed slip surfaces starting in the vicinity of the edge of the void towards the adjacent soil mass. The mode of failure of the flexible pipes took the form of a severe deformation at the region of the shoulder and a reversal of curvature at the invert due to over-deflection. This situation was more critical in the central section. The damage experienced by the flexible pipes was noticeably more pronounced when using the looser backfill, whereas only negligible deflections were observed when using the denser backfill. The experimental results were compared with analytical predictions, which showed to be highly unconservative for the case loose backfill.

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