Explore the functional applications of Attapulgite clay

Attapulgite is a kind of natural one-dimensional nanomaterial. Attapulgite has unique nanorod-like crystals, nanochannels and reactive groups on the surface, and has been widely used in many fields including agriculture, chemical engineering, environmental protection, adsorption materials and composites. Recently, the disaggregation of the crystal bundles of attapulgite into mono-dispersed ones has been achieved, while keeping their environment-friendly property. This has changed attapulgite from clay mineral to a very interesting nanomaterial. With unique nanorods-like crystals and nanochannels, attapulgite can be used to prepare nanocomposites via the crystals and reactive groups on the surface, and also can be used to prepare hybrid materials via the nanochannels. Attapulgite is the new focus for the preparation of diverse functional materials. Thus, it is now pertinent to give an overview of the recent progress in the field. First, we hope to overview the structure and physicochemical properties of attapulgite.....focus on the development of attapulgite-based functional materials (e.g., adsorbents, colloidal materials, hybrid materials, polymer/attapulgite composites, bio-inspired materials, catalysts and energy materials) and recycling of attapulgite. 

Attapulgite is an oral, nonabsorbed medication that is used in the management of diarrhea. It works by adsorbing (binding) large numbers of bacteria and toxins and reducing the loss of water. Attapulgite reduces the number of bowel movements, improves the consistency of loose or watery stools, and relieves the gastrointestinal cramping that often is associated with diarrhea

The adsorption of the cationic surfactant, cetyltrimethylammonium chloride (CTMA) from aqueous solutions on attapulgite was studied. Attapulgite is a clay mineral that has many applications, especially in agriculture and industry. It has not been studied extensively compared with other clay minerals for its sorption properties in environmental appl..

The present study investigated the effects of attapulgite supplementation in sow diets during gestation and lactation on sow performance. The study comprised two reproductive phases (cycles) in two commercial farrow to finish farms: Farm A (capacity: 550 sows) and Farm B (capacity: 220 sows). The treatment groups were: a) control group (CN): the sows were fed a common gestation or lactation diet; b) attapulgite group (AT): the sows were fed the CN diet supplemented with attapulgite at 0,7% level; c) attapulgite plus group (AT+): the sows were fed the CN diet supplemented with attapulgite (0.7%) and a mix of enzymes, live yeast and amino acids (0.1%), at a total of 0.8% level... Regarding sow parameters, sow body weight loss during lactation tended to be greater in AT sows compared to CN sows during cycle 1 in Farm B and was greater in AT and AT+ than CN sows in Farm A that completed both cycles (P=0.063 and P=0.023, respectively). A greater litter size 24h postpartum was observed in favour of AT compared to CN group during cycle 1 in Farm A and in sows that completed both cycles in Farm A (P=0.001 and P= 0.011, respectively). Litter size at weaning was greater in sows from the AT group than CN during cycle 1 and 2 in Farm A, in cycle 1 in Farm B and in sows that completed both cycles in Farm A (P=0.004, P=0.037, P=0.037, and P=0.022, respectively). Piglet weight at weaning and average daily gain during lactation were greater in AT group than CN and AT+ in sows that completed both cycles in Farm A (P=0.049 and P=0.040 respectively). Notable similar effects, although not statistically significant, were also observed in Farm B. This field study suggests that attapulgite supplementation in sow diets can improve performance indexes. 

 Batch adsorption experiments were investigated to remove the radioactive isotope Cs-137 from the real radioactive wastewater. The attapulgite natural clay mineral was characterized and adopted as an adsorbent in a batch adsorption system. Equilibrium was reached after 2 h with a Cs-137 removal efficiency of 97% for attapulgite. The kinetics of Cs-137 adsorption on the attapulgite clay surface were evaluated. The pseudo-second-order kinetic model produced an excellent fit with the experimental kinetic data for attapulgite, indicating that attapulgite was the best adsorption medium.

Anoxic filtration is a system that has been developed and trialled over many years by Dr. Kevin Novac Ph.D.  Water clarity in pictures of ponds that are using it is amazing.  Not only will this system remove ammonia directly from pond water before it can be turned into nitrate, but it also has areas where friendly facultative bugs can live and remove any nitrate that has been produced by nitrogen cycle bugs elsewhere in the pond. The basis of the system is a 24 inch-deep pond, full of what are called Biocenosis Baskets. These baskets are nothing more complicated than a planting basket full of Kitty Litter [Attapulgite clay] with a volcanic material called Laterite poured into a depression in the centre. Some of the baskets must be planted, but all baskets may be planted, according to taste. Dr. Novak is an American, and Kitty Litter is a common American brand name.  In the UK, an equivalent is Fuller’s Earth.

The development of polymeric nanocomposites using clay minerals as a Nano filler is of great interest to researchers and industry.. this strategy improves the thermal and mechanical performance and changes the surface finishing and the processing characteristics. The Attapulgite  (ATP) has a large surface area, strong absorption capacity superior to any other natural mineral, good mechanical resistance and thermal stability. These properties make ATP an ideal candidate for reinforcing polymeric materials.

The most common means of reducing the particle size of solids is by grinding, a process which can affect the surface properties and the behavior of the solid in later stages (granulation, compaction, etc.), and which can influence the end-use properties of the final product. Inverse gas chromatography (IGC) measurements were used here to evaluate the influence of grinding, in a ball mill, on attapulgite. ....The stability of the surface energy with respect to the grinding process was seen to be related to the particular fibrous structure of the attapulgite clay.

Immobilized microorganisms especially bacteria are most used rather than free cells to be protected from the environmental conditions when being used for the bioremediation of environmental pollutants. Herein, two marine’s bacterial isolates were tested for their ability to decompose crude oil. The optimum conditions for effective bacterial degradation e.g., pH, temperature, and inoculum size were investigated. PVA-alginate-clay composite hydrogel beads with different types of incorporated mineral clays were prepared and tested as bacterial carrier for potential bioremediation. Results showed that... attapulgite clay-containing beads recorded maximum degradation% as 78.8 and 75% for both bacterial isolates, when added to immobilization matrices and these percentages could be enhanced under optimal conditions. 

Attapulgite (ATP) is a natural hydrophilic clay mineral known for its reactive -OH groups on the surface and having a layer chain like structure with exchangeable cations in its framework channel. It was reported by Zhu et al. [18] that modified hydrophobic ATP through cation exchange showed high absorption capacity and selectivity to organic solvents and oils owing to its mesoporous structure and hydrophobic treatment which allow it to be effectively applied for crude oil biodegradation issues. ...

A composite proton exchange membrane chitosan (CS)/attapulgite (ATP) was prepared with the organic–inorganic compounding of ATP and CS. The composite membranes were characterized by scanning electron microscope (SEM), X‐ray diffraction (XRD), and fourier transform infrared spectroscopy (FTIR). The mechanical properties, thermal stability, water uptake, and proton conductivity of the composite membranes were fully investigated. The composite membranes exhibited an enhanced mechanical property, dimensional and thermal stability compared to CS membrane, owing to the interface interaction between ATP and CS. The maximum tensile strength of 53.1 MPa and decomposition temperature of 223.4°C was obtained, respectively. More importantly, the proton conductivity of the composite membrane is also enhanced, the composite membrane with 4 wt% ATP content (CS/ATP‐4) exhibited the highest proton conductivity of 26.2 mS cm−1 at 80°C with 100% relative humidity, which is 25.1% higher than pure CS membrane. These results may explore a simple and green strategy to prepare CS‐based PEMs, which have a great potential in the application of proton exchange membrane fuel cells.

Pollution from heavy-metal ions has become a major challenge to the global fight against environmental pollution. Given the availability of various low-cost and environmentally friendly adsorbents, adsorption has become the most efficient technology for the removal of heavy metals from water. In this study, attapulgite (ATP) was directly functionalized by coupling with an aminosilane agent. Analysis showed this maneuver provided a suitable adsorbent for the removal of lead ion (Pb2+) from an aqueous solution. The effects of several parameters including solution pH, contacting time, adsorbent dosage, and initial Pb2+ ion concentration were investigated. Batch sorption results showed that the adsorption process was rapid and over 98% of Pb2+ was removed within 30 min at the optimal pH 4.0. The maximum adsorption capacity at 25°C, calculated by the Langmuir isotherm, was 82.17, 78.80, 61.13, and 28.56 mg/g for γ-divinyltriaminepropyl-methyldimethoxylsilane-grafted attapulgite (KH-103-ATP), γ-aminopropyl-methyldiethoxysilane-grafted attapulgite (KH-912-ATP), N-(β-aminoethyl-γ-aminopropyl)-methyl-dimethoxysilane-grafted attapulgite (KH-602-ATP), and ATP, respectively. Moreover, molecular dynamics simulations of adsorption behaviors of heavy-metal ions at attapulgite surfaces (010) modified by aminosilane agents were carried out. Both the PMF value and diffusion coefficient of metal ions suggest that KH-103-ATP owns the highest rate constant and capacity compared with the other two. And the analysis of free energy and results of XPS characterization revealed that Pb2+ formed covalent bonds with the nitrogen atom of aminosilane agents.

​Heavy-metal contamination is widespread in agricultural soils worldwide, especially paddy soils contaminated by Cd. Amendment-induced immobilization of heavy metals is an attractive and effective technique, provided that cost-effective materials are used. This field experiment compared three alkaline passivators (attapulgite, processed oyster shell powder, and mixed soil conditioner) at a rate of 2.25 t ha-1 for their effectiveness in decreasing Cd bioavailability in soils and accumulation in rice plants in a paddy field contaminated by Cd (0.38 Cd mg kg-1). The utilization of attapulgite and processed oyster shell powder decreased labile fractions but increased stable fractions of Cd in soils through ion exchange, precipitation and complexation. The addition of attapulgite decreased the concentration of bioavailable Cd in both bulk and rhizosphere soils, whereas the amendment of processed oyster shell powder decreased it only in bulk soil. The Cd accumulation in rice plants correlated significantly with acid-soluble and residual Cd fractions in the rhizosphere soil but not in the bulk soil. The addition of attapulgite and processed oyster shell powder decreased Cd accumulation in rice grains from 0.26 mg kg-1 to 0.14 and 0.19 mg kg-1, respectively, meeting the National Food Safety Standard (< 0.20 mg kg-1). However, the mixed soil conditioner did not decrease the Cd accumulation in rice shoots or grains. This study demonstrated that attapulgite and processed oyster shell powder were economic agents in reducing Cd accumulation in rice grains.

As most pesticides are either insoluble or only slightly soluble in water and must be applied in relatively small amounts over large areas, they are formulated in such a way that a highly concentrated organic chemical can be put into a convenient-to-use and effective form for field use by blending it with additives and inert carriers. The formulation must be easy and economical to use, do the job it is meant for, have an adequate shelf-life, and have no undesirable side effects.....

In 1976 nearly 300,000 tons of various clays were delivered to pesticide manufacturers in the United States alone for use in pesticide formulations (U.S. Department of Agriculture 1976). Of this amount, over 65% was attapulgite. The predominance of attapulgite in the formulation of pesticides in preference to more common clay minerals such as kaolinite and montmorillonite stems from the fact that it is not easily flocculated by electrolytes and does not cake at high relative humidities but remains free-flowing (HADEN and SCHWINT1967).

Slow-release fertilizers could improve the productivity of field crops and reduce environmental pollution. So far, no slow-release fertilizers are suited for maize cultivation in semiarid areas of China. Therefore, we tested attapulgite-coated fertilizers. Attapulgite-coated fertilizers were prepared by dividing chemical fertilizers into three parts according to the nutrient demand of maize in its three main growth stages and coating each part with a layer of attapulgite. This design is novel and unique, satisfying the demands of maize throughout the whole growing season with slow release of nutrients from the coated layers. A field experiment was conducted in 2010 and 2011, using three fertilizer rates, in kg/ha: 94.22 nitrogen (N) and 22.49 phosphorus (P), 139.09 N and 38.98 P, and 254.23 N and 50.98 P. Five types of fertilizers were compared: 20 and 30 % attapulgite-coated chemical fertilizer, 20 and 30 % attapulgite-mixed chemical fertilizer, and chemical fertilizer only. The results show that the soil mineral N and available P of attapulgite-coated fertilizer has a slow-release behavior that allows a better synchronization between nutrient availability and plant needs. Attapulgite-coated fertilizer increased the grain yield by 15.1–18.4 %. The use of attapulgite-coated fertilizers also improved partial factor productivity of N fertilizer by 10.0–26.7 % and P fertilizer by 11.0–26.7 %, compared with the control fertilized without coated formulates. Given their good performance, the attapulgite-coated fertilizers could be a promising alternative slow-release fertilizer for sustainable agriculture in semiarid areas.

To improve fertilizer use efficiency and minimize its negative impact on environment, a slow-release nitrogen and boron fertilizer with water-retention was prepared. Wheat straw was used as skeletal material in copolymerization on which acrylic acid monomer can be grafted to form superabsorbent composite. Urea and borax were introduced to provide nitrogen (N) and boron (B) nutrients, respectively. The product possessed a core/shell structure. Its core was urea in attapulgite and alginate matrix, and the shell was chemically modified wheat straw-g-poly(acrylic acid)/attapulgite (CMWS-g-PAA/APT) superabsorbent composite containing urea and borax. The effects of the amount of cross-linker, initiator, chemically modified wheat straw and attapulgite on water absorbency were investigated and optimized. The water absorbency of superabsorbent synthesized under optimal conditions was 186 g g−1 in tap water. Ammonia-selective electrode and inductively coupled plasma results showed that the contents of the nitrogen and boron of the product were 23.3% and 0.65%, respectively. The water retention capacity and the slow-release behavior of N and B of the product were investigated. The results showed that the product with slow-release and water-retention capacity, being economical, nontoxic in soil and environment-friendly, could be found good application in agriculture and horticultural.

​Heavy-metal contamination is widespread in agricultural soils worldwide, especially paddy soils contaminated by Cd. Amendment-induced immobilization of heavy metals is an attractive and effective technique, provided that cost-effective materials are used. This field experiment compared three alkaline passivators (attapulgite, processed oyster shell powder, and mixed soil conditioner) at a rate of 2.25 t ha-1 for their effectiveness in decreasing Cd bioavailability in soils and accumulation in rice plants in a paddy field contaminated by Cd (0.38 Cd mg kg-1). The utilization of attapulgite and processed oyster shell powder decreased labile fractions but increased stable fractions of Cd in soils through ion exchange, precipitation and complexation. The addition of attapulgite decreased the concentration of bioavailable Cd in both bulk and rhizosphere soils, whereas the amendment of processed oyster shell powder decreased it only in bulk soil. The Cd accumulation in rice plants correlated significantly with acid-soluble and residual Cd fractions in the rhizosphere soil but not in the bulk soil. The addition of attapulgite and processed oyster shell powder decreased Cd accumulation in rice grains from 0.26 mg kg-1 to 0.14 and 0.19 mg kg-1, respectively, meeting the National Food Safety Standard (< 0.20 mg kg-1). However, the mixed soil conditioner did not decrease the Cd accumulation in rice shoots or grains. This study demonstrated that attapulgite and processed oyster shell powder were economic agents in reducing Cd accumulation in rice grains.