A method of determining the cation exchange capacity of a sample material

Abstract

A method for determining the cation exchange capacity of a sample material, including: preparing a Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to a measured concentration; establishing one or more Cu-Trien calibration curves; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after the addition of the Cu-Trien stock solution; homogenizing the sample material after the addition of the Cu-Trien stock solution; passing the sample material through a filter to form a filtrate after homogenizing the sample material; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material.

Description

[0001]A METHOD OF DETERMINING THE CATION EXCHANGE CAPACITY OF A SAMPLE MATERIAL BACKGROUND OF THE INVENTION 1. Field of Invention This invention relates to methods of detecting and quantifying clays or other materials in slurries or dry solid samples and, in particular, to a method of determining the cation exchange capacity (CEC) of clay or other sample materials using copper (II) triethylenetetramine and spectrophotometry. 2. Description of Related Art Clay minerals are small (< 2 µm) particles that have large surface areas. Even a small fraction present in a mineral mixture can have a significant impact on the mixture properties. Clay minerals have a layered structure, with negatively charged sites on their plate surfaces, edges and interlayers. These negatively charged sites absorb and hold positively charged ions (cations) by electrostatic force. Active clays are typically defined as smectite or swelling clays that have an average basal surface charge of 0.2-0.6 per formula unit leading to large cation exchange capacities (60-200 meq / 100 g). Active clays can cause significant challenges for water-based separation and sorting operations (extraction, flotation) due to their small size, high negative charge, and ability to form gels increasing the viscosity of fluids. This requires extra resources for treatment. The presence of active clays also complicates the rheological properties of slurries, pipe flow pumping requirements, hydro transport, and significantly slows the settling rate of tailings causing difficulties in many mineral processing operations often requiring thickening and flocculation to settle. While active clays present challenges for many mineral industries including oil sands, potash, kimberlite, and uranium, they are, however, used as an input for many other industries. For example, smectite clay is used as a clarifying agent in the fining process in the wine industry, as an absorbent in cat litter, and as an adhesive for green sand molds in metal casting for foundries. In either scenario, quantifying the active clay content in near real-time is important for process control. One effective way to detect and quantify active clays is to measure the cation exchange capacity (“CEC”) of the solids. The CEC is the measure of the particle’s ability to adsorb and exchange cations with the surrounding environment. The CEC can then be correlated to the clay activity and clay content, where higher CEC values are indicative of active clays. The cationic complex copper (II)-triethylenetetramine (“Cu-Trien”) can be used to measure the CEC of clays and thus to identify and quantify clays and active clays, by adsorbing to the negatively charged exchange sites on the clay’s surfaces via electrostatic attraction. While Cu-Trien has been used to determine the CEC of clays, it is generally a time intensive and not easily scalable process requiring experimentation to determine the exact amount of Cu-Trien to use to effectively and accurately determine the CEC of the sample slurry in a single exchange reaction. An object of the invention is to address the above shortcomings. SUMMARY The above shortcomings may be addressed by providing, in accordance with one aspect of the invention, a method for determining the cation exchange capacity of a sample material. The method includes: preparing a Cu- Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to a measured concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each of the calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after the addition of the Cu-Trien stock solution; homogenizing the sample material after the addition of the Cu-Trien stock solution; passing the sample material through a filter to form a filtrate after homogenizing the sample material; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ](Formula 1)(Formula 2) The method may include: adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; and homogenizing the sample material after adding the buffer solution to the sample material; before the step of adding an amount of the Cu-Trien stock solution to the sample material. The method may further include wherein the step of homogenizing the sample material is conducted at a rate of 10,000 – 17,000 revolutions per minute. The method may further include wherein the step of homogenizing the sample material is conducted with a high intensity homogenizer. The high intensity homogenizer may be a high shear homogenizer. The method may further include wherein the step of homogenizing the sample material is conducted for a duration of 3 – 10 minutes. In accordance with another aspect of the invention, there is provided a method for determining the cation exchange capacity of a sample material. The method includes: calculating a determined volume and concentration of a Cu-Trien stock solution required for the sample material using the following formulas: (Formula 9) preparing the Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to the determined volume and concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each of the calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after adding the Cu- Trien stock solution to the sample material; homogenizing the sample material after adding the Cu-Trien stock solution to the sample material; passing the sample material through a filter to form a filtrate after homogenizing the sample material with the Cu-Trien stock solution; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ](Formula 1)(Formula 2) The method may include use of the following formulas: The method may further include wherein the step of homogenizing the sample material is conducted at a rate of 10,000 – 17,000 revolutions per minute. The method may further include wherein the step of homogenizing the sample material is conducted with a high intensity homogenizer. The high intensity homogenizer may be a high shear homogenizer. The method may further include wherein the step of homogenizing the sample material is conducted for a duration of 3 – 10 minutes. The foregoing summary is illustrative only and is not intended to be in any way limiting. Other aspects and features of the present invention will become apparent to those of ordinary skill in the art upon review of the following description of embodiments of the invention in conjunction with the accompanying figures and claims. BRIEF DESCRIPTION OF THE DRAWINGS In drawings which illustrate by way of example only embodiments of the invention: Figure 1 is a graphical representation of absorbance of a sample material vs. three Cu-Trien standards at between 550-600 nm according to the method of the invention; Figure 2 is a graphical representation of determined by a Cu- Trien calibration curve according to the method of the invention; Figure 3 is a chart and graphical representation of the example results obtained according to the method of the invention; and Figure 4 is a graphical representation of data displaying target ratio of available Cu-Trien to required Cu-Trien. DETAILED DESCRIPTION In the following detailed description, reference is made to the accompanying figures, which form a part hereof. In the figures, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, figures, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, separated, and designed in a wide variety of different configurations, all of which are explicitly contemplated herein. A method for determining the cation exchange capacity of a sample material includes: preparing a Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to a measured concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after adding the Cu- Trien stock solution to the sample material; homogenizing the sample material after adding the Cu-Trien stock solution to the sample material; passing the sample material through a filter to form a filtrate after homogenizing the sample material with the Cu-Trien stock solution; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ] The step of preparing a Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to a measured concentration includes use of the cationic complex of copper (II) triethylenetetramine, which is composed of copper (II) sulfate (Cu2+) and triethylenetetramine (Trien) according to Formula 1: (Formula 1) In some embodiments, the Cu-Trien stock solution is prepared by adding a controlled amount of dissolved copper (II) sulfate and triethylenetetramine in reverse osmosis (RO) water and mixed well to reach the target Cu-Trien2+concentration (mol / L) and stock solution volume (L) based on Formula 2: (Formula 2) Where: is the molar mass of Triethylenetetramine, . The Cu-Trien stock solution concentration will preferably be in a range of 0.0085~0.03 mol / L, however other concentrations of the Cu-Trien stock solution can be used depending on the application. As an example, to prepare 0.030 mol / L Cu-Trien stock solution: (1) in a 250 mL volumetric flask, using a plastic dropper, transfer 1.83 g Trien (60% w / w) to the volumetric flask, record the mass of the empty flask and the increment mass increase measured by an analytical balance to 0.0001 g; (2) in a 50 mL beaker, transfer 1.89 g copper (II) sulfate pentahydrate powder into the beaker (the mass of copper (II) is controlled in a range between 1.71 to 1.74 times of the mass of Trien), record the mass measured by an analytical balance to 0.0001 g; (3) add reverse osmosis water to the 50 mL beaker containing copper (II) powder and swirl the liquid until the copper (II) powder is fully dissolved; (4) transfer the copper (II) solution into the Trien volumetric flask, add reverse osmosis water to rinse the copper (II) beaker 10 times until the beaker is clean, then add reverse osmosis water to bring the Cu-Trien stock solution in flask to the volume mark; (5) seal the Cu-Trien stock solution flask with parafilm, invert the Cu-Trien stock solution flask end-over-end to mix a minimum 15 times before using the Cu-Trien stock solution; (6) seal the Cu-Trien stock solution flask with parafilm, cover with aluminum foil when not in use and store it at room temperature, preferably out of the sunlight; and (7) use the Cu-Trien stock solution within one week after preparation. In some embodiments, a 0.01 ~ 0.02 mol / L sodium bicarbonate solution is prepared and utilized as a buffer solution for specific applications such as oil sands samples. A sodium bicarbonate buffer solution is preferred for oil sands application. Different buffer solutions or concentrations or no buffer solution may be required for a different application. Other applications may use other sodium bicarbonate dosages, reverse osmosis water, other buffer solutions, or not use any buffer solutions. As an example, to prepare a 0.015 mol / L sodium bicarbonate buffer solution with pH adjusted to 9.6 ± 0.1: (1) in a 1000 mL volumetric flask, transfer 1.26 g sodium bicarbonate powder and add reverse osmosis water to the volume mark; (2) invert the sodium bicarbonate solution flask end-over-end to mix a minimum 10 times; (3) transfer the 0.015 mol / L sodium bicarbonate solution to a 1000 mL beaker and add a magnetic bar; (4) use a magnetic stirrer to mix the solution; and (5) using a pH probe, pre-calibrated by using buffers at pH 4, 7 and 10, adjust the pH of the 0.015 mol / L sodium bicarbonate buffer solution to pH 9.6 ± 0.1 by slowly adding drop by drop by either 10% w / w NaOH or 10% v / v H2SO4 solution while stirring. The step of establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each calibration solutions through a filter and a spectrophotometer includes mixing a controlled amount of the Cu-Trien stock solution with a controlled amount of the buffer solution (formed of sodium bicarbonate) to form multiple calibration solutions of varying Cu-Trien2+concentrations that cover the Cu-Trien concentration range to be measured in the clay analysis. For example, as illustrated in Figure 1 and Figure 2, a three-point calibration is performed by correlating the Cu-Trien2+concentration of the sample material against the respective calibration solutions’ peak spectral absorbance between 550-600 nm based on Formula 3: (Formula 3)The slope (Slope) and intercept ( ) of the Cu-Trien calibration curve(s) will beused to calculate the final concentration of Cu-Trien2+([Cu-Trien2+]final) after reacting with the sample material (see Formula 5). As an example, and referring to Figure 1 and Figure 2, to obtain a calibration curve from the Cu-Trien stock solution: (1) a three point calibration curve is required to determine the final concentration of Cu-Trien2+after reaction with the sample material; (2) label three 4-oz jars as Std 1, Std 2 and Std 3; (3) weigh each jar with lid, record the mass of empty jar with lid to 0.01 g; (4) add 30 mL, 80 mL and 50 mL of a prepared 0.015 mol / L sodium bicarbonate buffer solution into the jars labelled as Std 1, Std 2 and Std 3 respectively, record increment mass increase to 0.01 g; (5) add 10 mL of prepared Cu-Trien stock solution into the jars labelled Std 1 and Std 2 (but not Std 3 which is used as blank for sodium bicarbonate), record increment mass increase to 0.01 g; (6) rinse a 20 mL syringe once with the solution being filtered (from each of the jars labelled Std 1, Std 2 and Std 3), then filter the solution (from each of the jars labelled Std 1, Std 2 and Std 3) through a 0.45 µm pore size nylon filter to obtain the filtrate, put the filtrate into individual cuvettes (it is preferred to use 0.45 µm pore size nylon syringe filters but other type / pore size syringe filters can be used for a specific application); (7) rinse the empty cuvettes once with the filtrate being analyzed before placing the filtrate into the cuvette; (8) before putting the cuvette back into the spectrophotometer holder, dry off cuvette with a cleansing wipe and inspect for bubbles, if bubbles are present, gently tap the cuvette to get the bubbles to the top and out of the filtrate; (9) measure the peak spectral absorbance between 550-600 nm of each cuvette, record the absorbance data. The step of measuring and recording the mass of the sample material after adding the buffer solution to the sample material may be conducted by any appropriate means such as use of a scale or use of a strain gauge. The step of homogenizing the sample material after adding the buffer solution to the sample material includes homogenizing the sample material at a specific rate of between 10,000 - 17,000 revolutions per minute (RPM) for an optimized duration of between 3-10 min. Homogenizing the sample material with the buffer solution facilitates dispersion of the solids. In some embodiments, a high intensity homogenizer may be used to homogenize the sample material with the buffer solution. In some embodiments, the high intensity homogenizer may be a high shear homogenizer. The step of adding an amount of the Cu-Trien stock solution to the sample material includes adding a controlled amount of Cu-Trien solution between 0.0085-0.03 mol / L to the sample material. The step of measuring and recording the mass of the sample material after adding the Cu-Trien stock solution to the sample material may be conducted by any appropriate means such as use of a scale or use of a strain gauge. The initial Cu-Trien2+concentration before reacting with the solids can be calculated with Formula 4: (Formula 4) Where: is the mass of liquid into which the sample material is prepared and dispersed in, including but not limited to the buffer solution and the Cu-Trien stock solution, in grams. is the moisture content associated with the sample material, in grams. It is very important to include the moisture content of the sample material( ). The moisture content of the sample material can be measuredseparately before or after the analysis. The step of homogenizing the sample material after the addition of the Cu- Trien stock solution includes homogenizing the sample material at a specific rate of between 10,000 - 17,000 revolutions per minute (RPM) for an optimized duration of between 3-10 min. Homogenizing the sample material with the Cu- Trien stock solution facilitates the cation exchange reaction. In some embodiments, a high intensity homogenizer may be used to homogenize the sample material with the Cu-Trien stock solution. In some embodiments, the high intensity homogenizer may be a high shear homogenizer. The step of passing the sample material through a filter to form a filtrate after homogenizing the sample material with the Cu-Trien stock solution includes extracting an aliquot of the sample material and passing the aliquot through a filter with a 0.45 µm pore size, forming a filtrate. The step of scanning and measuring the filtrate with a spectrophotometer includes transferring the filtrate to an optical flow cell, and scanning the filtrate in the optical flow cell with a spectrophotometer. The filtrate is scanned and measured with a spectrophotometer against the buffer solution in the reference optical cell. The peak spectral absorbance of the filtrate is then measured between 550 - 600 nm by the spectrophotometer and recorded. The step of calculating the cation exchange capacity of the sample material includes calculating the final Cu-Trien2+concentration after reacting with the sample material according to Formula 5: (Formula 5) Where: abs refers to the peak spectral absorbance of the filtrate between 550-600 nm. Slope refers to the slope of the Cu-Trien calibration curve. refers to the intercept of the Cu-Trien calibration curve. The peak spectral absorbance of the filtrate measured between 550-600 nm (abs), along with the slope and determined from the Cu-Trien calibration curve (using Formula 3), are used to calculate the final Cu-Trien2+concentration with Formula 5. The step of calculating the cation exchange capacity of the sample material further includes use of Formula 6: Where: is the cation exchange capacity of the sample, in meq / 100 g. is the concentration of the Cu-Trien calibration solution, in mol / L. is the concentration of the Cu-Trien stock solution, in mol / L. is the initial Cu-Trien2+concentration before adding to and reacting with the sample material, in mol / L. is the final Cu-Trien2+concentration after homogenizing and reacting with the sample material, in mol / L. is the mass of liquid into which the sample material is prepared and dispersed in, including but not limited to the buffer solution and the Cu-Trien stock solution, in grams. is the moisture content associated with the sample material, in grams. is the mass of the sample material being analyzed, on a dry basis in grams. is the average density of all liquid associated in the method, including the buffer solution, which is the main component of liquid, in g / mL. Cu-Trien refers to Copper (II) -Triethylenetetramine. As an example, to measure spectral absorbance for quality control (QC) samples and sample materials: (1) two QC samples are required for quality control (this is done by determining the final concentrations of Cu-Trien2+after reacting the Cu- Trien stock solution with 2 g of kaolinite clay standard samples, and the steps are the same as for the sample materials); (2) label two 100 mL tubes as QC 1 and QC 2; (3) add 2 g of kaolinite clay into the tubes labelled as QC 1 and QC 2 respectively, record kaolinite clay mass to 0.01 g; (4) label a series of tubes in sequence (e.g., #1, #2, #3, etc., or as sample ID); (5) add 2 g of dry solids, or a slurry sample containing 1~2 g solids dry basis into each sample tube, record each sample mass to 0.01 g; (6) for sample materials having solids concentration higher than 60 wt.% or lower than 1 wt.%, it is recommended to adjust the concentration of the Cu-Trien stock solution accordingly, otherwise it may generate inaccurate CEC results for these sample materials; (7) add 40 mL of 0.015 mol / L sodium bicarbonate buffer solution into each QC or sample tube, record each sodium bicarbonate mass to 0.01 g; (8) swirl the liquid mixture until sample solids are well mixed with sodium bicarbonate solution in the tube; (9) set the homogenizer on a lab stand and the homogenizer’s head should be fully submerged in the liquid mixture and its tip is ~1 cm from the bottom of the tube; (10) homogenize the sample material and sodium bicarbonate mixture at the specified RPM for the specified amount of time; (11) add 10 mL Cu-Trien stock solution into each QC or sample tube, record Cu-Trien mass to 0.01 g; (12) homogenize the sample material with Cu-Trien solution at the specified RPM for the specified amount of time; (13) allow the solids in tube to settle for 1-30 min (sample dependent) until a sufficient layer of blue supernatant is separated, then use the 20 mL syringe to remove about 15 mL of the supernatant from the sample tube; (14) filter the supernatant through a 0.45 µm pore size nylon filter to obtain a filtrate; (15) rinse a cuvette with the filtrate 1-2 times then place the filtrate in the cuvette; (16) before putting the cuvette back into the spectrophotometer, dry off the cuvette with a cleansing wipe (for example a KimwipeTM) and inspect for bubbles (f bubbles are present gently tap the cuvette to get the bubbles to the top and out of the filtrate); (17) measure the liquid peak absorbance between 550-600 nm of each filtrate on the cuvettes, record the absorbance to 0.0001 AU; (18) rinse the homogenizer mixing head and its shaft with reverse osmosis water until clean then dry it with paper towel, before homogenizing the next sample; (19) use VarsolTMor another degreaser to clean the homogenizer head and sample test tube if oily samples are analyzed, collect the spent material and dispose it into designated waste disposal containers; and (20) calculate the CEC results of each sample material based on Formulas 1-6. Referring to Figure 3, as another example of the method for determining the cation exchange capacity of a sample material: 500 ml of 0.03 mol / L Cu-Trien stock solution is prepared by mixing 3.655 g of tri-ethylene tetramine (60% w / w concentration) and 3.784 g of copper (II) sulfate pentahydrate. Three kaolinite clays (2 ~ 4 g) and three bentonite clays (0.2 ~ 0.4 g) were tested using the manual Cu-Trien method. The CEC result of each clay sample is shown in Figure 3. The above examples, including but not limited the homogenizer speed and mixing duration, is for illustration purposes. It will be understood by a person skilled in the art that the type and size of the equipment will vary depending on operational factors, including but not limited to the particular protocol for the method being used. Accordingly, in some aspects, the present invention provides a method for determining the cation exchange capacity of a sample material (of solids from slurries or dry samples). The method (and Formulas 1-6) can be adjusted to a different Cu-Trien stock solution concentrations for different types of clay minerals and / or different sample materials (such as potash, kimberlite, gold, uranium, oil sands, metal casting, wine, and cat litter) and to accommodate a range of CEC values, and / or can be scaled up to a larger reagent volume required for an automated process in which industrial size equipment can be utilized. In another embodiment, a method for determining the cation exchange capacity of a sample material includes: calculating a determined volume and concentration of a Cu-Trien stock solution required for the sample material using the following formulas: (Formula 7) preparing the Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to the determined volume and concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each of the calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after adding the Cu- Trien stock solution to the sample material; homogenizing the sample material after adding the Cu-Trien stock solution to the sample material; passing the sample material through a filter to form a filtrate after homogenizing the sample material with the Cu-Trien stock solution; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ](Formula 1)(Formula 2) (Formula 3) ) The step of calculating a determined volume and concentration of a Cu- Trien stock solution required for the sample material includes calculating themoles of Cu-Trien2+ required per gram of dry sample ( in mol / g)with Formula 7: (Formula 5) and are determined from Formulas 4 and 5 from a small scale lab experiment. Calculating the volume and concentration of the Cu-Trien stock solution required for the sample material includes an optimal ratio of vs. to between 2-15x for an effective method of determining a carbon exchange capacity of a sample material. Referring to Figure 4, data relating to the target ratio of available Cu-Trien to the required Cu-Trien is plotted on a graph. Below 2x, insufficient Cu-Trien is available to drive reaction while above 15x the Cu-Trien concentration saturates the detector resulting in negative CEC values. The minimum moles of per gram of dry sample can be determined by Formula 8: (Formula 8) Where: refers to the optimal ratio of vs. , which should be kept at 2-15x. is the moles of Cu-Trien2+available per gram of dry sample, in mol / g. is the moles of Cu-Trien2+required per gram of dry sample, in mol / g. After (mol / g) is determined, one or all of the parameters (in Formula 9), including new sample mass in grams, or amount of Cu- Trien stock solution to be added , in grams, or the concentration of Cu-Trien stock solution ( in mol / L, can be adjusted based onFormula 9: (Formula 9) Where: is the density of the Cu-Trien stock solution, in g / mL. Accordingly, the initial and final concentrations of Cu-Trien2+may be predicted using Formulas 10 and 11: (Formula 10) (Formula 11) Where: is the mass of the Cu-Trien stock solution to be added, in grams. is the mass of liquid into which the sample material is prepared and conditioned, including but not limited to the buffer solution and Cu-Trien stock solution, in grams. is the moisture content associated with the sample material, in grams. is the mass of the sample material, in grams. Accordingly, in some aspects, the CEC value of the sample material may be predicted by Formula 12: Where: is the predicted CEC value of the sample material, in meq / 100 g. Finally, the percentage of Cu-Trien2+remaining ] after reacting with the sample material may be calculated by using Formula 13, which is preferably kept between 5% to 50%: (Formula 13) Where: is the percentage of the concentration of Cu-Trien2+reacted with the sample material. is the predicted initial Cu-Trien2+concentration before reacting with the sample material, in mol / L. is the predicted final Cu-Trien2+concentration after reacting with the sample material, in mol / L. In some embodiments, the method can be used for potash, kimberlite, gold, uranium, oil sands, soils, metal casting, wine, and cat litter, and any application where the sample cation exchange capacity value and clay activity needs to be determined, and the active clay content needs to be quantified. Accordingly, in some aspects, the present invention provides near real- time detection of clays and active clays in sample material (e.g., slurries or dry samples) to enable accurate process control for many aspects of industrial operations, for example: to analyze active clays in mineral ores and achieve optimal ore blending ratios based on clay content in each ore fraction to minimize the impact of active clays on subsequent processes; to provide the active clay content in samples for chemical and coagulant / flocculant dosing to control for tailings process and improve slurry dewatering and solids-liquid separation; or to control the active clay fraction in the green sand to achieve an optimal molding strength in metal casting for foundries to save production cost and improve product quality; as well as other benefits to persons skilled in the art. The present invention improves the precision and sample throughput, resulting in operational cost savings. While embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only. The invention may include variants not described or illustrated herein in detail. For example, different sample materials other than clay may be analyzed with the method, and different buffer solutions or no buffer solutions may be used. Thus, the embodiments described and illustrated herein should not be considered to limit the invention as construed in accordance with the accompanying claims.

Claims

What is claimed is:

1. A method for determining the cation exchange capacity of a sample material, comprising: preparing a Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to a measured concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each of the calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material after adding the Cu-Trien stock solution to the sample material; homogenizing the sample material after adding the Cu-Trien stock solution to the sample material; passing the sample material through a filter to form a filtrate after homogenizing the sample material with the Cu-Trien stock solution; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ](Formula 1)(Formula 2) (Formula 3)2. The method of claim 1, wherein the step of homogenizing the sample material is conducted at a rate of 10,000 – 17,000 revolutions per minute.

3. The method of claim 1, wherein the step of homogenizing the sample material is conducted with a high intensity homogenizer.

4. The method of claim 3, wherein the high intensity homogenizer is a high shear homogenizer.

5. The method of claim 1, wherein the step of homogenizing the sample material is conducted for a duration of 3 – 10 minutes.

6. A method for determining the cation exchange capacity of a samplematerial, comprising: calculating a determined volume and concentration of a Cu-Trien stock solution required for the sample material using the following formulas:preparing the Cu-Trien stock solution by adding an amount of copper (II) sulfate and triethylenetetramine to water to the determined volume and concentration; establishing one or more Cu-Trien calibration curves by mixing a controlled amount of the Cu-Trien stock solution and a controlled amount of a buffer solution to form one or more calibration solutions and running each of the calibration solutions through a filter and a spectrophotometer; adding an amount of the buffer solution to the sample material; measuring and recording the mass of the sample material after adding the buffer solution to the sample material; homogenizing the sample material after adding the buffer solution to the sample material; adding an amount of the Cu-Trien stock solution to the sample material; measuring and recording the mass of the sample material adding the Cu- Trien stock solution to the sample material; homogenizing the sample material after adding the Cu-Trien stock solution to the sample material; passing the sample material through a filter to form a filtrate afterhomogenizing the sample material; scanning and measuring the filtrate with a spectrophotometer; and calculating the cation exchange capacity of the sample material using the following formulas: ](Formula 1)(Formula 2)(Formula 3)7. The method of claim 6, further comprising use of the following formulas: (Formula 10)(Formula 11)2) 8. The method of claim 6, wherein the step of homogenizing the sample material is conducted at a rate of 10,000 – 17,000 revolutions per minute.

9. The method of claim 6, wherein the step of homogenizing the sample material is conducted with a high intensity homogenizer.

10. The method of claim 6, wherein the high intensity homogenizer is a high shear homogenizer.

11. The method of claim 6, wherein the step of homogenizing the sample material is conducted for a duration of 3 – 10 minutes.

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