Indigenous Clay Research Articles

Comparative Assessment of Thermal Treatment for Mycotoxins Adsorption Potential of Indigenous Clay from Balochistan, Pakistan

The current study aimed to investigate the physical characteristics and mycotoxins (Aflatoxins B1 (AFB1) and Ochratoxin A (OTA) binding efficacy of indigenous clays before and after thermal treatment (calcination). The clay sample was collected from various mountainous areas of Balochistan, Pakistan. The samples were ground into a 360 mesh size and thermally treated initially at 200 °C and thereafter at 800 °C for 30 minutes with the help of a muffle furnace. XRD analysis revealed montmorillonite as the most commonly occurring group of clay minerals. The thermally treated clays showed that the binding potential was significantly (P <0.05) improved against mycotoxins. Enzyme-linked immunoassay (ELISA) determination showed significantly (P <0.05) lower residual concentrations of mycotoxins in thermally treated clays. The mycotoxin adsorption capacity (%) was found to be higher in the clay samples procured from Pishin (79.17% for AFB1 and 67.34% for OTA) and Bolan (62.0% for AFB1 and 50.17% for OTA). Calcination also caused a significant decrease in Cation Exchange Capacity (CEC) in some clay samples. Overall, the findings of the study showed that thermal treatment enhanced the in vitro binding capacity of clays against the studied mycotoxins. An increase in the mycotoxin binding capacity of the clays not only reduces the bioavailability of mycotoxins but also decreases their toxic effects. It is recommended that Balochistan clay have the potential to be used as an adsorbent for the removal of mycotoxins from the environment and animal feeds.

Catalytic Pyrolysis of Plastic Waste to Liquid Fuel Using Local Clay Catalyst

Plastics are nonbiodegradable, and safe disposal of this waste poses an environmental challenge all over the world. Catalytic pyrolysis is superior to thermal pyrolysis as it uses lower temperatures and hence less energy. The main objective of this study was to produce liquid fuel from plastic waste using indigenous clay as a catalyst through catalytic pyrolysis. The clay from Kisumu County was characterized through an X-ray fluorescence spectrometer (XRFS) and an X-ray diffractometer (XRD). The reaction setup consisted of a round-bottom flask reactor through which plastic feed and catalyst were heated in a temperature-controlled furnace. Vapor product was condensed using a Liebig type water condenser to give pyrolysis liquid product. Solid char was recovered from the flask at the end of the reaction. Optimization studies using central composite design (CCD) and response surface methodology (RSM) were performed in design expert software to predict optimal conditions of the operating variables for maximum yield of the liquid fuel. Results show that clay has a composition of silica and alumina at 64.5 wt% and 16.3 wt%, respectively, indicating high acidity of the clay, being a requirement for a good pyrolysis catalyst. For high-density polyethylene and polypropylene, the highest liquid yield of 87.23 wt% and 60.36 wt%, respectively, was at 300°C and a catalyst concentration of 10 wt%. Indigenous clay was established to be a suitable catalyst for catalytic pyrolysis of plastic waste, with the potential to replace imported catalysts since high yields of liquid fuel were obtained at lower reaction temperatures of 300-450°C, as compared to the 600°C required for thermal pyrolysis. In conclusion, waste plastics can be used to generate alternative fuel for industrial use. The liquid fuel can be used in diesel engines as a transport fuel, in turbines for electricity generation, and as a heating source in boilers and furnaces. Further studies on the modification of the surface and structure of clay are suggested to enhance its catalytic performance in the pyrolysis process for a better fuel yield.

Temperature and concentration dependence of ammonium migration in bentonite-clay mixtures: A case study in Hanoi, Vietnam

Groundwater in southern Hanoi, Vietnam has been recently detected to possess high concentration of ammonium ion (NH4+). Otherwise, one of the abundant sources of NH4+ comes from municipal solid waste landfills. Bentonite-clay mixtures (BCMs) widely utilized as landfill bottom barriers in various countries, but limited in Vietnam should perform well to isolate NH4+ from groundwater. This study is to evaluate combined effects of temperature and initial ammonium concentration on adsorption, diffusion, and permeability through mixtures of indigenous clay with 0 %, 5 %, 10 %, 15 % bentonite. The results indicated more effective NH4+ adsorption capacity for low initial concentration than high initial concentration in all temperatures (20, 35, and 50 °C). The temperature dependency showed an increase in adsorption coefficient from 20 °C to 35 °C and a decrease in the range of 35 °C and 50 °C. Whereas diffusion coefficient and hydraulic conductivity for all cases keep increasing gradually in both temperature ranges. The reasonable mass of bentonite content of 15 % should be added into local clay for landfill bottom liners in such conditions of elevated temperature at 50 °C and interaction of ammonium solution 1000 mg/L. The micro-structures via SEM images of these materials provided the proofs of both improvement of hydraulic barrier properties for indigenous clay owing to bentonite presence and NH4+ effects on their micro-structures.

Formulation of an Optimal Mix of Indigenous Clay in Water Well Drilling

Formulation of an Optimal Mix of Indigenous Clay in Water Well Drilling

Evaluation of Bentonite Mixed Indigenous Clays for Development of Clay Liners

This study presents experimental investigation of indigenous clays mixed with Bentonite to assess their suitability in potential use as clay liners. Soil samples with 0, 4, 8, and 12% Bentonite content from three different sites in Peshawar region were tested for various geotechnical properties. Grain size distribution, specific gravity, Atterberg limits and free swell were found through laboratory tests using appropriate ASTM procedures. Maximum dry density and optimum moisture content were calculated using Atterberg limits in available relationships. Finally, one dimensional consolidation tests were conducted to find relevant parameters for calculating hydraulic conductivity. A decrease in specific gravity, increase in free swell, and in optimum moisture content, decline in maximum dry density and hydraulic conductivity was observed with increase in Bentonite content across all three soil samples. During free swell, the soil clusters become larger leading to formation of floccules resulting in the narrowing of inter-particle space and thus blocking of permeable paths. It is concluded that 8% Bentonite content by weight yields a suitable mixture for a clay liner that has hydraulic conductivity in the range of recommended limits.

Characterization of Agar-CMC/Ag-MMT nanocomposite and evaluation of antibacterial and mechanical properties for packaging applications

The effect of silver modified montmorillonite (Ag-MMT) on the physical, mechanical and antimicrobial properties of agar-carboxymethyl cellulose (agar-CMC) bionanocomposites film, prepared by a solution intercalation method were investigated. The nanocomposite of agar and carboxymethyl cellulose (CMC) with Ag-MMT (based on Indigenous clay) has a promise in designing eco-friendly antibacterial packaging. The films were tested for transmittance, tensile and X-ray diffraction patterns which indicated that Ag-MMT the most compatible with Agar-CMC matrix. The Agar-CMC/Ag-MMT bio-nanocomposite films exhibited a great antibacterial activity against both Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria. Overall, it is seen that the Agar-CMC/Ag-MMT bionanocomposite films could be used as packaging material for food preservation by controlling foodborne pathogens and spoilage bacteria.

Synthesis and characterization of local clay–titanium dioxide core–shell extender pigments

A simple chemical technique has been used to prepare core–shell extender pigments based on Nigerian indigenous clays as core and titanium dioxide as shell. The prepared core–shell extender pigments were characterized using X-ray fluorescence and scanning electron microscopy. The physico-chemical properties of these extender pigments were also evaluated according to ASTM measurements. The study showed that the prepared core–shell pigments were nontoxic and environmentally friendly. They are of low cost and can be incorporated in semi-gloss paints, paper, rubber, and plastic composites without much effect on the volume. The characteristics of these pigments showed that they combine the properties of both their precursors, and have the potential to overcome their disadvantages, e.g., low hiding power of clays and photochemical activity of titanium dioxide.

Effect of intensity of compaction on crushing strength of indigenous baked clay

Compressive strength can be modified and improved by applying compaction through compression. This study is a part of an ongoing study relating to the study of baked clay reinforced beams, in terms of flexural stresses. This paper presents the relation of cube crushing strength of baked clay and the intensity of compaction during casting. Laboratory size clay beams were cast from a moist mixture of indigenous clay and pit sand. These beams were compacted in filter press condition at various intensities of compaction. After drying, these beams were baked and cubes were cut. The results show that with increasing rate of compaction, density of the beams also increased, which resulted in relative increase in the cube crushing strength of baked clay. The compressive strength of baked clay cubes obtained is 50% more than design cube crushing strength of concrete.

The efficiency of inorganic immobilization agents to stabilize tailings from the mine

Toxic metals, which are found in waste sludge from mine tailings of lead and zinc Sase, were immobilized with different compaction imobilazacionim agents (indigenous clay, red mud ) in the monoliths of different proportions. The efficiency of immobilization procedures was monitored using diffusion leaching tests (ANS 16.1). Also, certain parameters (coefficients of diffusion, leachability index) were determined to be used for evaluating the efficiency of immobilization techniques previously applied. In the treatment of tailings with clay and red mud can be observed decrease in mobility of metals (Cr, Ni, As, Pb and Zn) with an increase in the percentage of added red mud, while the Cu and Cd comes to deviations. A mixture of clay tailings and red mud proved to be a very good immobilization agent for all treated metals.

Sonication mediated hydrothermal process – an efficient method for the rapid synthesis of DDR zeolite membranes

The formation and growth of a DDR zeolite membrane was developed on the low cost indigenous clay–alumina substrate for separation of H2 from H2–CO2 mixture by selective deposition of oriented seed crystals, followed by secondary growth method with sonication mediated hydrothermal technique. The formation of free radicals by ultrasonic irradiation in the sonochemical method enhances the rate of nucleation which ultimately reduces the DDR zeolite crystallization time. Surface seeding not only accelerates the zeolite crystallization on the support surface but also enhances the formation of an homogenous zeolite membrane layer. The DDR seeds were synthesized by a sonication mediated hydrothermal technique within a short crystallization time i.e. 2 days and used to provide nucleation for the membrane growth. Accordingly DDR zeolite membranes were synthesized on seeded substrate within 5 days. The membrane thickness was found to be ∼26 μm. The synthesized membranes along with seed crystals were characterized by XRD, FTIR, FESEM and EDAX analysis. The performance of the membrane formed was evaluated by single gas as well as mixture gas permeation measurement for H2 and CO2. The H2–CO2 separation selectivity of the membrane increased up to 3.7 at room temperature which is more than the reported values. To the best of our knowledge, there is no report on the synthesis of a DDR zeolite membrane within 7 (2 days for seed crystal and 5 days for membrane synthesis) days by a secondary growth technique.

Highly selective SAPO 34 membrane on surface modified clay–alumina tubular support for H2/CO2 separation

The formation and growth of Silicoaluminophosphate (SAPO 34) zeolite membrane was developed on the low cost indigenous clay–alumina tubular substrate modified by cationic polymer as an intermediate layer. The amino (–NH2) and hydroxyl (–OH) groups on the backbone of polymer are responsible for hydrogen bonding between zeolite surface and support surface. Seeding of the support surface accelerates the zeolite crystallization and enhances the formation of homogenous SAPO 34 membrane layer. The seeds were synthesized by hydrothermal process and used to provide nucleation for the membrane growth. The synthesized membranes along with seed crystals were characterized by XRD, FTIR, FESEM, TEM and EDAX analysis. The performance of the membrane formed was evaluated by single gas as well as mixture gas permeation measurement for H2 and CO2. The H2/CO2 separation selectivity of the membrane increased upto 5.88 at room temperature which is more than reported values and the reproducibility towards gas permeation and selectivity of SAPO 34 membrane shows excellent result.

Thermodynamics of removal of cadmium by adsorption on an indigenous clay

Abstract Equilibrium and thermodynamic studies of the removal of cadmium by adsorption on an indigenous adsorbent, china clay, have been investigated. The results of effect of temperature and thermodynamic parameters confirm the process of removal to be exothermic in nature. The removal decreased from 80.3% to 51.3% by increasing the temperature from 30 to 50 °C at 5.10 × 10−5 M initial concentration of cadmium, 1.0 × 10−2 M NaClO4 ionic strength, 6.5 pH, 100 μm particle size and 100 rpm. Rate was found in decreasing pattern with increasing temperature and value of rate constant of the reaction, kad, was found to be 5.10 × 10−2 min−1 at 30 °C. Values of Langmuir's constants, ‘Qo’ and ‘b’ were also determined. Thermodynamic parameters namely enthalpy of adsorption, isosteric heat of adsorption, change in standard free energy, ΔG°, standard enthalpy, ΔH°, and standard entropy, ΔS° were determined.

The Effect of Firing on Berea Sandstone

Summary The petroleum industry uses Berea sandstone as a standard testing material. It is often fired to desensitize indigenous clays. Here, we study the effect of firing by comparing unfired Berea to samples fired at 1000°C for 5 hours. The observed changes in the petrographic and petrophysical parameters are then related to single- and two-phase coreflood data.

Glass Melting Pots and Indigenous Clays: Characteristics and Processing

The essential requirements of refractory clays for satisfactory application in pot making are considered to be bonding characteristics and Wide vitrification range apart from adequate refractoriness. In the absence of a comprehensive information on the availability of typical pot clays in India, and in view of the need for improving upon the performance of ceramic pots wherever these are deployed for glass melting, some of the clays from different sources in the country have been investigated for relevant physico-chemical characteristics and With respect to attainment of suitable properties vis-a-vis optimisation of variables in processing and fabrication. The results have been tabulated for comparison. Several compositions of pot mixes through adjustment of proportion of grog and gradings thereof have been evaluated for characteristics With a view to ascertaining the most appropriate requirement. Minor additions were tried to adjudge their role thereof towards improvement. A blend of clays that may provide satisfactory performance, if processed with care in different modes of fabrication, has been indicated. © 1979 Taylor & Francis Group, LLC.

Analytical Techniques for Recognizing Water- Sensitive Reservoir Rocks

Abstract The permeability damage that certain reservoir rocks undergo when infiltrated by fresh water is well recognized in the petroleum industry. Two causes of damage, swelling of clays and plugging by rearrangement of indigenous particles, result from inherent properties of some rocks and can be determined by laboratory analysis. The presence, cause and magnitude of water sensitivity in most reservoir rocks can be recognized by a combination of the following techniques: - Single phase permeability measurements with gas and a series of brine of decreasing salinity on extracted core plugs to determine if permeability varies with salinity. - X-ray diffraction analysis to detect swelling clays (montmorillonite, mixed-layer clays and certain types of illite). - Physical swelling tests to determine the actual swelling capacity of indigenous clay minerals. - Microscopic examination of rock thin sections to determine the distribution of clay minerals relative to the pore system. Typical analyses are given for reservoir rocks than are - not sensitive, - water sensitive from swelling clays and - water sensitive from particle plugging. Introduction Reservoir rocks that are susceptible to permeability damage during drilling, completion, stimulation and workover operations are well known in the petroleum industry. Permeability damage around a well bore can prevent the detection of oil zones in a wildcat well or lower productivity of completed wells. In secondary recovery operations, a damaged reservoir may mean the difference between economic success or failure. Research and development work on secondary and tertiary oil recovery processes must consider the susceptibility of a reservoir rock to permeability damage in evaluating the recovery process. A whole host of physical and chemical processes are responsible for reservoir damage. Some types of damage occur because of the particular mineralogical and textural properties of the reservoir rock; other types of damage occur as a result of a particular production operation. The causes of damage that are related to rock properties are:1. swelling of indigenous clays that constrict the pores;2. dispersion of indigenous, non- swelling particles, rearrangement of the particles during fluid flow, and plugging of the pore system; and 3. a combination of swelling and dispersion; slight swelling promotes loosening and mobility of fine particles. Causes of damage that originate from a specific production operation are:1. invasion of solid particles from drilling mud or injected fluids; 2. invasion of solid particles from oil well cementing operations; 3. precipitation of salts from the reservoir brine in the zone of relatively lower pressure around the well bore; 4. water block or emulsion block; 5. direct or indirect effects of bacteria; and6. completion practices not suitable for a specific reservoir. Any porous medium, regardless of its inherent properties, could undergo permeability damage by conditions in the second category. The first category of reservoir damage, however, is possible only in rocks that are inherently water sensitive as a result of their mineralogy and texture. In either case, reservoir damage produces the same symptom: reduced well productivity. Before the damage can be repaired, or before damage to a similar reservoir can be prevented, the cause must be determined. The analytical methods presented in this paper were developed to recognize water sensitive reservoir rocks. The philosophy of developing this type of analysis is as follows. If damage is suspected in a reservoir, core samples can be analyzed for water sensitivity. If the analysis indicates sensitivity, then production operations can perhaps be modified to prevent additional damage. If the results of the analysis indicate no sensitivity, attention can then be focused on the production operations rather than on the reservoir rock.