Leaching Index Research Articles

Immobilization of radioactive sulphate waste simulate in polymer–cement composite based on recycled expanded polystyrene foam: evaluation of the final waste form resistance for Cs-134 and Co-60 leachability

The present study investigates to incorporate spiked sulfate solution simulate into polymer–cement composite (PCC) based on recycled expanded polystyrene foam. The main aim is to convert the waste stream into leach resistance solid forms able to slow down or even to retard the back release of hazardous radionuclides to the surrounding. Effective parameters e.g. leachant medium, temperature, radioactivity contents, leachant volumes and radionuclides speciation versus the leaching time were studied. The incremental leach rate (Rn, cm/day) and the leach index (Lx) were evaluated for the final waste form after 145 days. The experimental results revealed that the Lx for the all variances can fulfil the waste acceptance criteria for the disposal facility and are above the threshold value of 6. Moreover, leach rate percentages for Cs-134 and Co-60 were not exceeding 2%. The acquired data, based on lab leaching experiments, can recommend the developed PCC under consideration for solidification of radioactive sulphate waste stream safely.

Chemical and physical identification and classification of an artificial soil (circular economy)

The perception and explanation of changes in the mechanical behaviour of contaminated soils are associated with physical classification and chemical composition. Elements are evolutionary in this type of soil and in the context of a contaminated environment. Let’s start by evaluating a group of artificial soils. The matrix is a granitic residual soil with a mixture (M) of hydraulic lime with used lubricating oil. The samples used have proportions of 5, 10, 15 and 20% of M in the residual granitic soil. A soil sample with 5% oil (OS5) was also made, which constitutes the optimal oil content in the soil. Afterwards, the alteration of the physical-chemical identification and the evolutionary classifications of these artificial soils were studied. The structure of the soil is altered, and this is associated with the flocculation of fine particles by the effect of lime and oil and will probably influence the mechanical behaviour of the soils. In chemical terms, it is assumed an increase in the leaching index, a decrease in the chemical mobility index and an increase in losses when it comes to artificial samples. These indices show some potential in the assessment of pollution, but eventually need adjustments, mainly in the scales.

Study on semi-dynamic leaching and microstructure characteristics of MSWI fly ash solidified sediment

municipal solid waste incineration (MSWI) fly ash partially replaces cement to solidify sediment, and then can be used as intermediate cover materials in landfill as one of the resources utilization ways of MSWI fly ash and sediment. The strength and the semi-dynamic leaching characteristics of MSWI fly ash solidified sediment under hydrochloric acid attack at different pH were studied by means of unconfined compressive strength (UCS), semi-dynamic leaching, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Thermogravimetric analysis (TGA). Results revealed that the UCS strength increased as the curing age and cement content increased. When the curing content is 50% and the replacement ratio of MSWI fly ash is 75% and 80%, the UCS of 7 d can be greater than 50 kPa. The primary contribution to the strength development was from silicic acid gels such as calcium silicate hydrate (C–S–H) and carbonates. Notably, the leaching behavior of Zn and Cu within the solidified sediment underwent substantial alterations. The leaching amount of heavy metals in a strong acidic environment (pH = 2) is significantly greater than that in a weak acidic (pH = 4) and neutral (pH = 7) environment. Conversely, minimal disparities were observed in the leaching characteristics of Zn and Cu between the weakly acidic and neutral environments. Ca(OH)2, C–S–H and carbonate exhibits a remarkable acid-resistant buffering capacity in the solidified sediment. The obvious diffusion coefficient (Dobs) was less than 10−9 m2/s in semi-dynamic leaching tests. Moreover, the mobility of Zn and Cu surpassing 12.5, coupled with a leaching index exceeding 8, further attests to the favorable S/S outcome achieved. Based on these findings, the solidified material is confidently recommended to be used as suitable landfill middle soil cover material.

Epoxy resin for solidification/stabilization of soil contaminated with copper (II): Leaching, mechanical, and microstructural characterization

Among different types of heavy metal-contaminated soil, copper (Cu)-contaminated soil is very serious, and the Cu concentration in it is usually very high. It is common to solidify/stabilize Cu-contaminated soil using alkaline cementitious material. However, the remediated Cu-contaminated soil fails to meet the requirements of environmental safety and load-bearing capacity. This dilemma in the remediation of Cu-contaminated soil hinders the effective utilization of land resources. In this study, epoxy resin (EP) was utilized to solidify/stabilize Cu-contaminated soil due to its stable and rapid curing performance and excellent resistance to acid, alkali, and salt erosion. The mechanical properties, environmental effects, and curing mechanism of EP-cured Cu-contaminated soil were investigated. The results showed that the application of EP significantly enhanced the unconfined compressive strength (UCS), cohesion and internal friction angle of Cu-contaminated soil. All specimens met the UCS criterion specified by the United States Environmental Protection Agency (USPEA), namely no less than 0.35 MPa, which indicated that those EP-cured Cu-contaminated soil were qualified for practical engineering applications. According to the toxicity characteristic leaching procedure (TCLP), the application of EP enhanced the stability of Cu in Cu-contaminated soil. The leaching index of Cu ranged from 11 to 14. A high leaching index showed that the S/S treatment was safe and effective and the remediated Cu-contaminated soil satisfied the environmental requirement for heavy metals. This study confirmed the feasibility of utilizing EP in the solidification/stabilization (S/S) technology to convert high-concentration Cu-contaminated soil into secure and stable engineering materials. The remediation of Cu-contaminated soil by EP lays a solid foundation for the safe treatment and reuse of heavy metal-contaminated land resources.

BEHAVIOUR OF MAGNESIUM POTASSIUM PHOSPHATE CEMENT UNDER LEACHING

The effectiveness of the use of magnesium potassium phosphate cements (MKPC) as protective matrices for radioactive waste was investigated in this work from the point of view of the main elements leaching. Fly ash and blast-furnace slag were used as MKPC fillers. Leaching tests were performed on monolithic MKPC samples according to ANSI/ANS 16.1 test. Based on the obtained data, the cumulative leaching fractions, leaching mechanisms, effective diffusion coefficients and leaching indices K, Mg, P, B, Si, Al, and Ca were determined. The values of the calculated leaching indices (>10) of the constituent elements indicate that the characteristics of the studied MKPC matrix are acceptable for radioactive waste immobilization.

Derivation of operating conditions for the Jordan cement solidification process and evaluation of disposability of the cement waste form produced in the process

The purpose of this study is to develop a process control program for the cement solidification process of the Jordan Research and Training Reactor (JRTR). The optimal operating conditions of the cement solidification process were found to be a concentrate/cement ratio of 0.65 (water/cement ratio of 0.45) and a salt content of 20 wt%. The compressive strength of the cement solidified material was 17.8–23.8 MPa, which is much higher than the 3.44 MPa specified in the waste acceptance criteria (WAC) for a disposal facility in South Korea, as developed by the Korea radioactive waste agency. In addition, through evaluation of the leaching stability for Cs, Sr, and Co, the leaching index of the samples was confirmed to be >10, 10.8, and 8.05 for Co, Sr, and Cs, respectively; all of these values exceed the WAC leaching index standard of 6.

Process mineralogy approach to optimize curing-leaching in vanadium-bearing stone coal processing plants

The purpose of this study is to apply process mineralogy as a practical tool to further understand and analyze the reasons for low leaching rates in the curing-leaching process of vanadium-bearing stone coal and to find a solution or improvement to optimize the leaching index. Using vanadium-bearing stone coal with the V2O5 mass fraction of 0.88% as the research object, the effects of particle size, mineral composition, and sulfuric acid curing on the feed, intermediate, and final products of curing-leaching were analyzed. The main vanadium-bearing minerals in the feed samples included sericite/illite, montmorillonite, kaolinite, limonite, and schreyerite. Through the penetration depth analysis of sulfuric acid, the reason for the high vanadium content in the coarse leaching residue (0.205% V2O5) was found, mainly due to the poor curing effect and incomplete washing after screening. Therefore, thorough washing after sieving and further optimizing the curing process are necessary. The vanadium content of the fine leaching residue (0.078%) was low and the curing-leaching effect was good. However, the vanadium content in the thickened residue (0.296%) exceeded that in the fine leaching residue, which was attributed to the neutralization reaction in the #1 thickener. To solve this problem, the neutralization and thickening processes should be performed in separate equipment. The analysis and detection of key products is helpful for identifying problems and improving the curing-leaching circuit process.

Influence of pyrolysis temperature on rice straw biochar properties and corresponding effects on dynamic changes in bispyribac-sodium adsorption and leaching behavior in soil

Bispyribac-sodium is a weakly acidic herbicide with high water solubility and is thus a potential source of groundwater contamination. Considering the risk inherent to the use of this herbicide, this study assessed the impacts of rice straw (RS) and biochar amendments on the adsorption and leaching behavior of bispyribac-sodium in soil. Biochars were produced from RS at different pyrolysis temperatures and characterized using various spectral techniques. Rice straw had a surface area of 3.996 × 104 m2 kg–1, which increased under pyrolysis; biochars prepared at 350 and 550 °C (RS350 and RS550) in a closed furnace with limited oxygen supply had a surface area of 5.763 × 104 and 6.890 × 104 m2 kg–1, respectively, and biochar prepared by purging the pyroformer with N2 (RSC) had the highest surface area of 12.173 × 104 m2 kg–1. After amendment with RS and biochar, soil Freundlich adsorption capacity (KFads) increased to varying extents in the order RSC > RS350 > RS550, from 2.89 × 103 to 29.57 × 103 mg1–1/n kg–1 L1/n, compared to 1.55 × 103 mg1–1/n kg–1 L1/n in unamended soil. The variability in KFads of bispyribac-sodium amongst the RS- and biochar-amended soils was dependent on the surface area of the amendments. The desorption of bispyribac-sodium decreased in the RS- and biochar-amended soils and varied from 90.45% to 95.20% in unamended soils and from 60.95% to 89.50% in amended soils. The adsorption and desorption of bispyribac-sodium varied significantly depending on its concentration and the type and application rate of soil amendment. Different leaching risk evaluation indices, viz., modified leach index (M.LEACH), leach index (LEACH), groundwater ubiquity score (GUS), Hornsby index (HI), leaching index (LIN), and pesticide leaching potential (PLP) index, were used to assess the susceptibility of groundwater to herbicide leaching. To reduce the repetitive effects of common parameters in each index, a new index was developed by employing principal component analysis (PCA) to condense their information into a single ranking. The results of the PCA indicated that RS and biochar amendments could be an effective management practice for controlling the leaching potential of bispyribac-sodium in soil.

Potential Risk of Agrochemical Leaching in Areas of Edaphoclimatic Suitability for Coffee Cultivation

Studies show that agricultural activities around the world still present a strong dependence on agrochemicals that can leach into the soil profile, causing its contamination, as well as that of water resources. In this context, the present study evaluates the potential risk of pesticide leaching in areas of edaphoclimatic suitability for coffee cultivation in Espírito Santo state, Brazil. As a methodology, the areas of edaphoclimatic suitability for conilon and arabica coffee were defined, and subsequently, the risk of leaching of active agrochemical ingredients in these areas was evaluated using the Groundwater Ubiquity Score (GUS), Leaching Index (LIX) and Attenuation Factor/Retardation Factor (AF/RF) methods. Of the ten active ingredients evaluated, sulfentrazone and thiamethoxam present a potential risk of leaching into the groundwater level. The study allowed us to evaluate the potential risk of agrochemical leaching in tropical soils cultivated with coffee using geographic information system (GIS) techniques. The methodological proposal can be adapted for other agricultural areas and crops.

Experimental Investigation of Vitrification Process for the Disposal of Hazardous Solid Waste Containing Chlorides

Vitrification has attracted much attention as an efficient method for solidifying heavy metals in hazardous solid wastes, but its effect is limited when hazardous solid wastes contain chlorides. Aiming at fly ash, a normal chlorine-containing solid waste, a novel process of chlorination melting and glass curing was developed to completely realize the harmlessness of heavy metals. Melting temperature, time, and auxiliary agent were adequate to realize the harmlessness, and their influence on the migration and transformation of Cl, Na, Pb, and Zn and the leaching of slag were studied. The results showed that the majority of Cl, Na, Pb, and Zn in the fly ash had been transferred to the soot, and the residual part in the slag had been solidified in glass by controlling the process conditions. Under the optimized conditions (12 wt.% CaO and 5 wt.% SiO2 was added, the N2 flow ratio was at 1 L/min, and the melting temperature was 1300 °C for 2 h), the leaching index was determined, including the acid dissolution ratio, the Pb and Zn content of the water leaching solution, and the acid leaching solution, which all met the requirements of the relevant standards. Furthermore, the novel process provided a simple and efficient approach for the disposal of other similar solid wastes containing chlorides and heavy metals.

Evaluation of Utility of the Cement Solidification Process of Waste Ion Exchange Resin.

The present study aimed to evaluate the utility of the cement solidification process for stably disposing of waste ion exchange resin generated during the treatment of radioactive wastewater. The cement solidification process using the in-drum mixing system was selected to be used for the solidification process of waste ion exchange resins. The disposal safety of waste forms was evaluated according to the waste acceptance criteria (WAC) applicable to domestic waste disposal sites, and the tests were conducted for six test items provided in the WAC. A total of 15 representative samples were collected from the waste-form drums produced using the optimum operating conditions, and their structural stability for disposal considerations was evaluated. In addition, the leaching index of the samples was 11.05, 10.12, 8.39 for Co, Sr, and Cs, respectively, and it was found to exceed 6, the leaching index standard of WAC. The results confirmed that cement waste forms including waste ion exchange resins produced through this process were considered to be conforming to the requirements for disposal safety.

Preparation of solid-waste-based pervious concrete for pavement: A two-stage utilization approach of coal gangue

As the most discharged solid waste in China; coal gangue (CG) occupies a considerable amount of land and severely pollutes the environment. Large-scale production, low added value of products, and lack of innovative disposal methods have lead to the difficult situation of effective utilization of CG. Therefore, it is very important to develop new ways to utilize CG on a large scale and with high-valued. This paper proposes a new method for reducing the environmental burden and realizing a high-value utilization of CG. The study was based on a two-stage utilization approach. Raw CG was first used to prepare solid-waste-based sulfoaluminate cement (WSAC). Then the prepared WSAC combined with self-ignited coal gangue (SCG) was used to prepare a high-strength pervious concrete (HSPC). The mechanical properties, mineral composition, and microstructure of the prepared WSAC clinker were analyzed. The results show that mortar from the prepared WSAC clinker had a reasonable mineral composition, well-developed crystals, and a compressive strength of 55.2 MPa at three days, which meets the standard for 52.5 N ordinary Portland cement. Furthermore, the influence of the water-binder (W/B) ratio, a ggregate-binder (A/B) ratio, and different SCG content on the performance of HSPC was studied. It was observed that the optimal HSPC was prepared when the W/B ratio and the A/B ratio were 0.22 and 4.0, respectively. Compared with traditional pervious concrete, the prepared HSPC has both high strength and high water permeability, and the obtained compressive strength is 34.8 MPa, a connected porosity of 19.80%, a water permeability of 7.95 mm/s, and a hardening density of 1930.8 kg/m3. An SCG content of 10%–20% was considered to the best dosage range for the preparation of HSPC. Furthermore, the freeze–thaw cycle analysis and abrasion resistance test indicated that HSPC with 10% SCG content has acceptable durability. Finally, the environmental impact of HSPC was evaluated through heavy-metal leaching tests, revealing that HSPC has a good curing ability on heavy metals and the leaching index was lower than the limit specified by the regulations, which reflects the environmental friendliness. Thus, this paper presents a low-cost and promising method for the resourceful utilization of CG and production of a sustainable pavement material. In addition, further research is needed before the application of this material to explore its durability and practicality in a specific environment.

Bio-weathering of granites from Eastern Dharwar Craton (India): a tango of bacterial metabolism and mineral chemistry

The bio-weathering process contributes majorly in the physical shaping of earth’s surface. The weathering of mineral is coupled to the formation of new minerals and release of bio-available nutrients for flora as well as microbial communities. Granites from the Eastern Dharwar Craton (EDC) India are felsic plutonic igneous rock composed of nutritive minerals. The major elemental composition of granite is such that, it forms an ancient ecological niche for diverse microbial communities. Interdisciplinary approaches were taken to construct a more comprehensive understanding of potential functional attributes of Actinobacteria in bio-weathering of granite. This work includes molecular characterization of the isolated strains, detecting their granite bioweathering potentials through leaching experiments where Nocardioides showed highest mineral leaching indices with iron (Fe) being the most leached element (~ 6372 ppm). Scanning electron microscopic imaging indicated biofilm formation and Actinobacterial hyphae colonization. Petrographic, XRD and FTIR based study shows formation of secondary minerals (kaolinite, vermiculite and smectite). To further establish the hypothesis of soil formation and nutrition transport, long-term (360 days) microcosm was developed. Deterioration and grain size alternations with increase in clay based minerals (kaolinite, vermiculite) and total protein content was observed. A bioinformatics based functional biodiversity approach in link to global bio-weathering of rocks by the genus Actinobacteria was adopted to understand their distribution patterns and contribution to alterations of rock minerals.

Forecasting of Dangerous Influence of Avermectin Insecticides to Human Organism Using Surface and Groundwater for Drinking

More than 400 types of harmful organisms cause damage to agricultural crops. Insecticides occupy one of the last places in the structure of the pesticides assortment among formulations authorized for application in the world. However, they occupy the first place according to their toxicity and the hazard effect to the human body. The purpose of our study was comparative hygienic assessment of soil stability, surface and groundwater migration potential, prediction of dangerous effects of insecticides-avermectins on the human body after using surface and groundwater for drinking needs. For an integral assessment of the potential danger of pesticide exposure to the human body after consumption of water from surface and groundwater supply sources, a scale of four gradations was used. It includes the LEACH (index of potential contamination of groundwater and river waters), half-life period (DT50) in water and an allowable daily dose (ADD) or acceptable daily intake (ADI). It has been established that in different soil and climatic conditions, according to the LEACH index, there is a very low risk of groundwater and surface water contamination. This is due to their relatively high solubility in water, low soil persistence and very high values of the organic carbon sorption coefficient. According to the IIWH index (integral index of water hazard), abamectin and emamectin benzoate in different soil and climatic conditions are moderately hazardous for a person after consumption of contaminated drinking water (class 3); emamectin benzoate in the soil and climatic conditions of Ukraine is hazardous (class 2). It is necessary to monitor carefully the boundaries of sanitary-protective areas from treated areas to water bodies, and control the process of exploitation of water supply sources, especially decentralized in rural areas. In regions with intensive agricultural production, it is recommended to use the IIWH index to make a decision about the necessity of monitoring research on insecticides in water.

Experimental study on thiosulfate leaching of gold from a high copper gold concentrate

The conventional cyanide leaching process is used to extract gold from a high copper gold concentrate. Because the copper associated minerals consume sodium cyanide in large quantities, the cost of the reagents is high and the economic benefit is not ideal. At the same time, a large number of cyanide tail slag are produced, which brings a series of environmental problems. In order to solve the environmental problems caused by excessive sodium cyanide consumption and cyanogen slag, the feasibility of leaching gold by thiosulfate in copper ammonia system was studied. The gold leaching rate of thiosulfate was increased to more than 90% by using the direct thiosulfate leaching process and pretreatment thiosulfate leaching process, which was close to the gold leaching index of sodium cyanide at the production site.

Leaching characteristic of potentially toxic metals of artificial soil made from municipal sludge compost

Landscaping of municipal sludge is a good choice to solve the sludge disposal problem, and EDTA treatment can effectively promote the uptake of heavy metals (HMs) by plants, but the heavy metal leaching process and its main control factors are still poorly understood during the sludge landscaping disposal. In this study, the migration behavior of HMs in artificial soil made from municipal sludge compost (MSC) were investigated using soil column experiments. After six leaching events for a total of one year’s rainfall, the average reduction percentage of total phosphorus, total nitrogen, organic matter in the MSC artificial soil were 13.4%, 10.1%, and 7.8%, respectively, while those of copper, lead, zinc, cadmium, nickel were 12.9%, 8.37%, 11.5%, 5.94%, and 10.7%, respectively. Treating ethylenediaminetetraacetic acid (EDTA) to the MSC artificial soil further enhanced the leach index of HMs to different degrees. HM concentration in leachate were increased with peak times postponed. Though EDTA treatment increased HM concentrations in subsoil, it did not change their water washing efficiency. The retention of HMs in subsoil was related to properties of local soil and its interaction with leachate. The potential ecological risk was of quite strong risk category in the MSC artificial soil and rapidly decreased from moderate to slight risk in subsoil. Cadmium was the main contribution accounting for 46%–93% of ecological risk. For landscaping applications, the composition of MSC artificial soil and local soil, as well as the capacity of the surrounding water, needs to be considered.

Leaching behaviour appraisal of eight persistent herbicides on a loam soil amended with different composted organic wastes using screening indices

The addition of organic wastes is a common agronomic practice in some Mediterranean regions to increase soil organic matter. In addition, they consume high amounts of agrochemicals. Hand-packed soil columns were used to evaluate the effect of three different composted organic soil amendments (agro-forestry, agro-industrial and animal manure) on the leachability of eight persistent herbicides. A new leaching index based on the amounts recovered from leachates and referred as Experimental Leaching Index (ELI) is proposed according to the mean annual precipitation in a specific place. This index is compared with others such as Groundwater Ubiquity Score (GUS), Relative Leaching Potential Index (RLPI) and Leachability Index (LIX), which only include degradation (DT50) and sorption (KOC) parameters. According to ELI, metribuzin is very mobile in all cases, while terbuthylazine, chlorotoluron and isoproturon present high leachability only in unamended soil reducing their leaching potential in amended soils. Aclonifen, oxyfluorfen, trifluralin and pendimethalin behave in all cases as immobile (non-leacher) compounds.

Exogenous organic matter as strategy to reduce pesticide leaching through the soil

ABSTRACT This research was to assess the effect of exogenous organic matter (composted sheep manure, CSM) on the sorption, disappearance and leaching of four pesticides (boscalid, flonicamide, myclobutanil and penconazole) using an agricultural soil from a semiarid area (SE Spain) to determine their potential for groundwater pollution. Results of batch equilibrium experiments show that the sorption capacity of amended soil was significantly increased in all cases. In both, unamended and amended soils, a rapid degradation of flonicamide was observed, while boscalid, myclobutanil and penconazole had high persistence (t½ >110 d) although half-lives were higher in amended soil due to the increased adsorption. Leaching experiment indicated that the addition of CSM significantly limited the downward movement of the pesticides through the soil columns especially for boscalid and penconazole, considerably decreasing the amounts recovered of both in leachates. A new leaching index referred as Experimental Leaching Index (ELI) is compared with others such as GUS, RLPI and LIX, based on degradation (DT50) and sorption (K OC) parameters. According to ELI, all pesticides were very mobile (1.5 > ELI ≤ 2) in unamended soil, decreasing their mobility in the amended soil, especially boscalid and penconazole (0.6 > ELI ≤ 1.5).

Use of Index-Based Screening Models to Evaluate the Leaching of Triclopyr and Fluroxypyr Through a Loam Soil Amended with Vermicompost.

The effect of vermicompost added to a loam soil on the leaching behaviour of two herbicides (triclopyr and fluroxypyr) was examined. Mobility of the herbicides was assessed using disturbed soil columns under laboratory conditions. In both cases, the addition of vermicompost significantly increased the sorption of the compounds. For both, DT50 values were slightly higher in the amended soil, due to the increased adsorption. Rate constants (k) calculated according to pseudo-first order model were significantly lower in the case of triclopyr (very persistent), which led to a much lower degradation rate compared to fluroxypyr (persistent) in both unamended and amended soils. Values calculated for the experimental leaching index (ELI) in unamended and amended soils showed medium and high leachability for fluroxypyr (0.31 and 0.29) and triclopyr (0.72 and 0.70), respectively. Other index-based screening models (GUS, RLPI, LIX) also catalogue both herbicides as potential leachers. Results confirm that triclopyr and fluroxypyr may contaminate groundwater resources.

Immobilization of radioactive corrosion products by cold sintering of pure hydroxyapatite.

An efficient method for the consolidation of cobalt (Co(II)) adsorbed calcium hydroxyapatite was investigated to develop a simplified route for decontamination of the coolant system of nuclear power plants and direct immobilization of as-spent adsorbent. Calcium hydroxyapatite nano-powder synthesized by a wet precipitation method was used as an adsorbent and 94% Co(II) surrogate removal from simulated water was measured. The as-spent adsorbent was sintered at 200 °C, a temperature significantly lower than conventional sintering temperatures (900-1300 °C) for hydroxyapatite, under a uniaxial pressure of 500 MPa for 10 min. The relative density after the cold sintering was >97% and sintered samples displayed good compressive strength (175 MPa). The normalized leaching rate of the Co(II) was measured as per ASTM-C1285 standard and found to be 2.5 × 10-5 g/m2/day. ANSI/ANS-16.1 test procedure was used to analyze the leachability of the sintered matrices and the measured leaching index value was 6.5. Thus, the use of pure calcium hydroxyapatite nano-powder as adsorbent and its cold sintering offers a mean by which radioactive waste form can be processed in an environment friendly manner.