High Cation Exchange Capacity Research Articles

Biochar Production, Modification, and Its Uses in Soil Remediation: A Review

Soil remediation is the act of removing or reducing the availability of contaminants from soil. In the case of agriculture, soil remediation targets the removal of pollutants, including residual pesticides/herbicides, hydrocarbons, and toxic heavy metals. This is often done by chemical treatments with multiple washes or excavation of soils, which are costly and time-consuming. Therefore, finding cheaper, less time-consuming remediation methods is highly desirable. In this review, we will examine the addition of biochar as an effective method of soil remediation. Biochar is a carbon-rich material derived from burning biomass in an oxygen-limited environment with benefits such as high cation exchange capacity, large surface area, neutral to alkaline pH, and some nutritional content. Biochar can also be a sanctuary for naturally occurring microbes and can be inoculated with specific microbes for contaminant breakdown. The physical and chemical characteristics of biochar combined with biological activity can help bind and promote the degradation process of these contaminants without the need to use hazardous chemicals or remove a large amount of soil. Biochar, and the microbes they house, can bind these contaminants through electrostatic attraction, sorption, precipitation, and bioaccumulation, reducing their availability to the surrounding environment. However, the characteristics of biochar and its biological activity can vary depending on the feedstock, pyrolysis temperature, and time the mass is heated. Therefore, some of these traits can be modified through pre or post-treatments to suit their intended use, allowing for biochar to be made for specific contaminants. This review hopes to increase interest in biochar research to fill in missing gaps of information that could make biochar production cheaper and more consistent, as it offers a greener way to clean up contaminants in soil.

Kinetics of native and added carbon mineralization on incubating at different soil and moisture conditions in Typic Ustochrepts and Typic Halustalf

The carbon dynamics in soils is of great importance due to its links to the global carbon cycle. The prediction of the behavior of native soil organic carbon (SOC) and organic amendments via incubation studies and mathematical modeling may bridge the knowledge gap in understanding complex soil ecosystems. Three alkaline Typic Ustochrepts and one Typic Halustalf with sandy, loamy sand, and clay loam texture, varying in percent SOC of 0.2; S1, 0.42; S2, 0.67; S3 and 0.82; S4 soils, were amended with wheat straw (WS), WS + P, sesbania green manure (GM), and poultry manure (PM) on 0.5% C rate at field capacity (FC) and ponding (P) moisture levels and incubated at 35 °C for 1, 15, 30 and 45 d. Carbon mineralization was determined via the alkali titration method after 1, 5, 7 14, 21, and 28 d. The SOC and inorganic carbon contents were determined from dried up (50 °C) soil samples after 1, 15, 30, and 45 d of incubation. Carbon from residue mineralization was determined by subtracting the amount of CO2-C evolved from control soils. The kinetic models; monocomponent first order, two-component first order, and modified Gompertz equations were fitted to the carbon mineralization data from native and added carbon. The SOC decomposition was dependent upon soil properties, and moisture, however, added C was relatively independent. The carbon from PM was immobilized in S4. All the models fitted to the data predicted carbon mineralization in a similar range with few exceptions. The residues lead to the OC build-up in fine-textured soils having relatively high OC and cation exchange capacities. Whereas, fast degradation of applied OC in coarse-textured soils leads to faster mineralization and lower build-up from residues. The decline in CaCO3 after incubation was higher at FC than in the P moisture regime.

Quantifying Coupling Effects Between Soil Matric Potential and Osmotic Potential

AbstractSoil matric potential and osmotic potential are widely accepted as two independent components of total soil water potential. However, laboratory observations repeatedly demonstrated that matric potential can vary with salt concentration, implying a potential coupling between matric potential and osmotic potential. To date, it remains elusive whether matric potential and osmotic potential are independent or not and why so, and a theoretical theory for quantifying the coupling between them is still missing. Herein, a theoretical model is developed to quantitatively explain this problem via a lens provided by a recent concept of soil sorptive potential (SSP). The proposed model substantiates that matric potential and osmotic potential are not independent. The increasing salt concentration can notably depress two variables underpinning SSP, namely relative permittivity and electrical double layer thickness, leading to non‐negligible decreasing (more negative) of matric potential in the high suction range, and increasing (less negative) of it in the low suction range. In turn, the soil‐water interactions redistribute ions in soil water, raising osmotic potential especially for clay with high cation exchange capacity. The proposed model shows excellent performance in capturing experimental data, validating its accuracy. A parametric study implies that the neglection of coupling effects can lead to a significant underestimation of soil hydraulic conductivity in the film flow regime.

Fine Particle Adsorption Capacity of Volcanic Soil from Southern Kyushu, Japan.

"Akahoya" is a volcanic soil classified as a special soil deposited in Kyushu, Japan. Many of its properties are not yet clearly understood. We found that Akahoya had the potential to adsorb bacteria in cattle feces, which prompted us to investigate its material properties and perform experiments to comprehensively evaluate its adsorption performance for various fine particles such as acidic and basic dyes, NOx/SOx gas, and phosphoric acid ions, in addition to bacteria. Akahoya had a very high specific surface area owing to the large number of nanometer-sized pores in its structure; it exhibited a high adsorption capacity for both NO2 and SO2. Regarding the zeta potential of Akahoya, the point of zero charge was approximately pH 7.0. The surface potential had a significant effect on the adsorption of acidic and basic dyes. Akahoya had a very high cation exchange capacity when the sample surface was negatively charged and a high anion exchange capacity when the sample surface was positively charged. Akahoya also exhibited a relatively high adsorption capacity for phosphoric acid because of its high level of Al2O3, and the immersion liquid had a very high Al ion concentration. Finally, filtration tests were performed on Escherichia coli suspension using a column filled with Akahoya or another volcanic soil sample. The results confirmed that the Escherichia coli adhered on the Akahoya sample. The results of the Escherichia coli release test, after the filtration test, suggested that this adhesion to Akahoya could be phosphorus-mediated.

Soil-Available Nutrients Associated with Soil Chemical and Aggregate Properties following Vegetation Restoration in Western Sichuan, China

The status and drivers of soil-available nutrients in plant-recovered soils are not fully understood, limiting our ability to explore the role of soil-available nutrients in soil geochemical cycling and ecosystem sustainability. Here, we combined the spatial distribution of soil-available nutrients and chemical and aggregate properties from six soil types (subalpine meadow soil, meadow soil, dark brown soil, brown soil, yellow-brown soil, and cinnamon soil) and three horizons (a leaching horizon, sediment horizon, and parent material horizon) to study the status and drivers of soil-available nutrients. Our findings reveal that the soil-available nitrogen (AN) ranged from 72.33 to 169.67 mg/kg, the soil-available phosphorus (AP) ranged from 1.77 to 75.90 mg/kg, and the soil-available potassium (AK) ranged from 46.43 to 88.55 mg/kg in the six soil types. The subalpine meadow soil and the dark brown soil had the highest soil AN, with means of 169.67 and 139.35 mg/kg, respectively. The brown soil had the highest soil AP, with a mean of 75.9 mg/kg, and the dark brown soil and the brown soil had the highest soil AK, with means of 83.49 and 88.55 mg/kg, respectively. The results show that the soil types and soil depths had a significant impact on the status of AN, AP, and AK (p < 0.05). Moreover, a higher cation exchange capacity (CEC), the macro-aggregate contents (with 2–1 mm and 1–0.5 mm particle sizes) of the non-water-stable aggregates, and the macro-aggregate content and stability (2–1 mm particle size and geometric mean diameter (GMD) of the water-stable aggregates were deemed to facilitate soil-available nitrogen because of the positive correlations (p < 0.05). Lower exchangeable cations (ECs) and the micro-aggregate content (≤0.1 mm particle size) of the water-stable aggregates and higher soil cations helped in the accumulation of soil-available phosphorus and soil-available potassium, respectively. Moreover, the regulation of the soil chemical and aggregate properties was found to vary with soil type and horizon in a correlation analysis. Together, our results provide insights into the importance of chemical and aggregate properties in regulating soil nutrient availability across soil types, as well as providing strong support for the inclusion of soil resource utilization in regional forest restoration and management.

Low levels of arsenic and cadmium in rice grown in southern Florida Histosols - Impacts of water management and soil thickness

Rice is planted as a rotation crop in the sugarcane-dominant Everglades Agricultural Area (EAA) in southern Florida. The Histosols in this area are unlike other mineral soils used to grow rice due to the high organic content and land subsidence caused by rapid oxidation of organic matter upon drainage. It remains unknown if such soils pose a risk of arsenic (As) or cadmium (Cd) mobilization and uptake into rice grain. Both As and Cd are carcinogenic trace elements of concern in rice, and it is important to understand their soil-plant transfer into rice, a staple food of global importance. Here, a mesocosm pot study was conducted using two thicknesses of local soil, deep (D, 50 cm) and shallow (S, 25 cm), under three water managements, conventional flooding (FL), low water table (LWT), and alternating wetting and drying (AWD). Rice was grown to maturity and plant levels of As and Cd were determined. Regardless of treatments, rice grown in these Florida Histolsols has very low Cd concentrations in polished grain (1.5–5.6 μg kg−1) and relatively low total As (35–150 μg kg−1) and inorganic As (35–87 μg kg−1) concentrations in polished grain, which are below regulatory limits. This may be due to the low soil As and Cd levels, high soil cation exchange capacity due to high soil organic matter content, and slightly alkaline soil pH. Grain As was significantly affected by water management (AWD < FL = LWT) and its interaction effect with soil thickness (AWD-D ≤ AWD-S ≤ FL-D = LWT-S = LWT-D ≤ FL-S), resulting in as much as 62 % difference among treatments. Grain Cd was significantly affected by water management (AWD > FL > LWT) without any soil thickness impact. In conclusion, even though water management has more of an impact on rice As and Cd than soil thickness, the low concentrations of As and Cd in rice pose little health risk for consumers.

Are anthropogenic soils from dumpsites suitable for arable fields? Evaluation of soil fertility and transfer of potentially toxic elements to plants

Background and purposeThe fertility of anthropogenic soils developed from dumpsites used for arable fields is not well-studied. The study aimed to evaluate the fertility of anthropogenic soils from an abandoned dumpsite in Awotan, Nigeria, by measurable indicators and the bioaccessibility of elements of selected plant species.MethodsThe study adopted multi-analytical approaches to determine the signatures of the soils and further parameterized the bioaccessibility of elements to plants.ResultsThe comparatively high content of Ca and Na in the anthropogenic soil contributed to the slightly alkaline soil reaction against the slightly acidic control. The high amount of organic matter is well-indicated by the enrichment of organic C and N in the anthropogenic soil. Waste deposition significantly contributed to the high accumulation of macronutrients (P, Ca, K, S) and micronutrients (Mn, Na, Fe) sufficient for maximum plant growth and yields, with an adequate C/N ratio supporting effective mineralization. The high cation exchange capacity of the anthropogenic soil contributed to cations binding. Indiscriminate waste deposition resulted in a high accumulation of potentially toxic elements (PTEs; Cu, Zn, As, Cd, Pb) above permissible limits in agricultural soils following WHO limits. Potential effects on lives are evident in the high PTEs accumulation in roots and leaves of Chromolaenaodorata, Saccopetalumtectonum, Passiflorafoetida, and Sennasiamea. These plant species exhibited various PTEs accumulation, especially for Cd and Pb.ConclusionAlthough anthropogenic soils remained fertile, the bioaccessibility of PTEs by plants indicates potential threats to consumers of crops and herbs produced from such sites.

Agronomic Potential of Avocado-Seed Biochar in Comparison with Other Locally Available Biochar Types: A First-Hand Report from Ethiopia

Biochar is a promising option for improving soil fertility and agricultural productivity. The potential of biochar for specific purposes depends on its physical and chemical characteristics. The avocado seed is widely available as a leftover after the fleshy part is used for food and as a byproduct of avocado-oil producing agro-industries in Ethiopia. Its potential as a biochar for an agronomic purpose has not been studied. The objective of this study was to compare the agronomic potential of avocado-seed biochar (ASB) type in comparison to other biochar types produced from locally available feedstocks at two selected pyrolysis temperatures (450 and 550°C). It was identified that on a mass-base, the produced biochar yields were in a range of 29.68 to 47.45%, higher for ASB pyrolyzed at 450°C. The scanned images of the biochar types showed a remarkable surface morphology for bamboo biochar (BB) and ASB. The bulk density of the biochars were in the range of 0.21 to 0.49 g/mL. The highest volatile matter was measured for BB-450°C, fixed carbon for BB-550°C, and ash content for BB-450°C. The mean pH values were in the range of 9.1 to 11.3. The ASB-450 and 550°C exhibited higher nutrient content. The highest cation exchange capacity (CEC) was recorded for ASB-450°C; organic carbon (OC) for corncob biochar (CCB) was followed by ASB-450 and 550°C. The calcium carbonate (CaCO3) content of ASB-550°C was the second-highest value next to coffee husk biochar (CHB). In this study, ASB and BB were found to have important qualities for improving degraded agricultural soils in terms of soil acidity, nutrient content, and soil fertility. Therefore, ASB-450°C and BB-450°C can be suggested to be promising candidates for reclaiming acid-soils and for improving nutrient-depleted infertile soils into agriculturally productive soils.

Composition of Chemical Elements and Ion Exchange Complex of Acid- and Alkali-Modified Natural Zeolites From the Sokyrnytsky Deposit

Natural zeolites are abundant and inexpensive resources. They are crystalline hydrated aluminosilicates with a framework structure that has pores and channels occupied by water, alkali, and alkaline earth cations. Having high cation exchange capacity, acting as a molecular sieve, natural zeolites have been widely utilized in recent decades as adsorbents in separation and purification processes. Modification of natural zeolite increases its adsorption capacity of environmental pollutants, in particular, radionuclides from low-level liquid radioactive waste. The article presents results obtained from a study of the chemical composition of the structural elements and ion exchange complexes of natural, acid-modified and alkali-modified zeolites from the Sokyrnytske deposit. The main rock-forming mineral of the Sokyrnytske zeolite is clinoptilolite. The zeolite was modified by a 5.5 M HCl solution for 2 hours at 100 oC using a backflow condenser. The ratio of solid to liquid phases was 1:2. For alkaline modification, 1.4 M NaOH solution was used. The exposure time was 2.75 hours. The conditions and phase ratio were similar to those in acidity modification. By composition of the ion exchange complex, natural zeolite belongs to potassium-calcium-sodium (K &gt; Ca &gt; Na) clinoptilolites. In the process of acidity and alkaline modification of the natural zeolite, redistribution of the exchangeable cations is observed and the content of structural cations in the clinoptilolite lattice changes. In alkali-modified zeolite, the content of exchangeable Na and Ca cations increases, and the content of K and structural Al cations decreases. In the acid-modified zeolite, the number of exchangeable Na, Mg, Ca, K cations decreases. At the same time, the content of Fe and Al decreases and the relative amount of Si in the lattice increases. The Si/Al ratio increases in the following succession: natural zeolite → alkali-modified zeolite → acid-modified zeolite. The specific surface area of the modified zeolites increases compared to the natural ones. The largest increase is observed for the acid-modified zeolite. The textural characteristics and mineral composition of the studied samples indicate that the natural, acid-modified and alkali-modified zeolites from the Sokyrnytske deposit may be used for removal of radionuclides from low-level liquid radioactive waste.

Chemical and physical properties of zeoponic and their influence on growth of forestry plant seedling and horticultural crops

Zeolite is a hydrated microporous mineral of the aluminosilicate group, and the cation exchange capacity (CEC) of zeolite is high. Based on porous properties and high CEC, zeolite has the potential to be used as plant growth media (PGM). Zeoponic is a PGM made from zeolite mixed with compost and cocopeat added with macro and micro fertilizers suitable for plant growth. The goal of this research is to characterize the chemical and physical properties of zeoponic and several other PGM obtained from the market and to compare them for the growth of forestry plant seedlings and horticultural crops. This study was carried out from October 2021 to March 2022 in the greenhouse of the Department of Soil Science and Land Resources, Faculty of Agriculture, IPB University. The analysis of PGM was pH, electrical conductivity (EC), CEC, NO3-N, NH4-N, and bulk density. Parameters of plant growth were the height of plant, the leaves number, the leaf width and length, and the diameter of stem. The findings revealed that zeoponic has high CEC value than the other PGM, causing zeoponic to have low EC even though it contains high nutrients. With the chemical and physical properties mentioned above, the growth of mahogany plant seedlings in zeoponic is better than in other PGM. Likewise, the growth of horticultural crops grown in zeoponic is better than that of commercial media. This shows that zeoponic is a PGM suitable for growing forestry plant seedlings and horticultural crops.

Prilog poznavanju nekih fizičkih i hemijskih osobina krečnjačkih zemljišta planinskog masiva Ozren

Soils formed on limestones occupy large area in Serbia, but there is not a lot of information about their properties. This paper presents physical and chemical properties of the Brownized Calcomelanosols and Moderately-deep Calcocambisols of the Ozren Mountain. Brownized Calcomelanosols under natural grassy vegetation were investigated at the Vlasina pass, whereas Calcocambisols under mixed forests were investigated near the site "Ozrenske livade". Soil profiles were excavated up to the parent material, and disturbed and undisturbed soil samples were collected from soil genetic horizons. Following soil characteristics were determined: particle size distribution, soil structure and water resistance of structural aggregates, bulk density, total porosity, air capacity, water-holding capacity, water conductivity, pH, content of humus, available phosphorus (P2O5) and potassium (K2O), hydrolytic acidity, cation exchange capacity (CEC), sum of exchangeable base cations, and base saturation. Humus-accumulative horizon (Amo) of the Brownized Calcomelanosols has silty clay texture, whereas the cambic (B)rz horizon of both soils has a clay texture. The Amo horizon of Calcomelanosols is characterized by fine to medium granular structure (0.5-5 mm) of very high water resistance. The total porosity, air capacity and water permeability of both soils is high. Their water-holding capacity is high. Amo horizon of Calcomelanosols is characterized by a high humus content (&gt;10%). Soil reaction in water of Amo horizon is neutral, whereas in (B)rz horizons both soils are moderately acid. Both soils have high CEC (&gt;58 cmol kg-1 ) and base saturatation (&gt;95%). Brownized Calcomelanosol is moderately to highly supplied with available K2O, whereas Calcocambisol is moderately supplied; while both soils are very poor in available P2O5. Since this study presents quite favorable physical and chemical properties of the investigated soils due to the conservation of natural forests and grasslands, the results can help in a deeper understanding of soil ecology and the preservation of natural plant cover.

The Impact of the Sowing Time on Peanuts Yield`s Components in Marginal Sandy Soils in Southern Oltenia, Romania

Marginal sandy soils are frequently characterized by low fertility, low organic matter, moderate to high acidity and low cationic exchange capacity, limiting the options of smallholding farmers for various crops. To investigate the impact of the sowing time on grain yield, yield components, protein and oil content of peanuts cultivated in marginal sandy soils in Southern Oltenia, Romania, a bifactorial experiment in a randomized complete block design with three replications was conducted during 2015-2017 at the Research Development Station for Plant Culture on Sands Dăbuleni. The first factor was sowing time (the 25th April as early sowing and the 5th May as late sowing) and the second factor was peanut cultivar (Dăbuleni, Viorica, Viviana). According to the results of the experiment the sowing time had significant impact on the pods number per plant, the production of pods and the grain oil content. Analyzing the interaction between the sowing time and the cultivar there were significant differences only in the pod number per plant in 2015 and the production of pods in 2016. In all peanut’s genotypes studied, early sowing led to higher yields of pods compared to late sowing, probably due to the shortening of the vegetation period of the crop by late sowing on the 5th May, which led also to less dry matter and lower oil content accumulated in peanut grains. Therefore, the results suggested that early sowing time is the most recommended for peanuts growth and quality yield in sandy marginal areas.

Textural, mineralogical and physico-chemical characterization of red clay of Tanout (Zinder-Niger) with a view to its valorization in water treatment

This study aims to determine the textural (specific surface, pore volume and pore size) and mineralogical characteristics of Tanout red clay of Zinder region (Niger) in order to have textural data allowing its use as an adsorbent. The methodology is based on textural analyzes (adsorption of N2 at 77 K by the Brunauer-Emmett-Teller method), mineralogical (X-ray fluorescence, X-ray diffraction, thermo-gravimetric analysis, scanning electron microscopy) and physicochemical (preliminary analyses). The results obtained show that the red clay has a specific surface of 418.4 m2.g-1 and 967.7 m2.g-1 calculated according to the BET and Langmuir methods respectively and a microporous surface of 540 m2.g- 1, with pore volume varying from 0.0389 to 0.2535 cm3.g-1 and pore size varying from 0.3675 to 5.423 nm calculated according to the methods (Barrett-Joyner-Halenda, Dubinin-Radushkevich, Dubinin -A, Horvath-Kawazoe and Saito-Foley). It has slit and cylindrical micro- pores. It has a slightly neutral pH in an aqueous medium and a high cation exchange capacity with low humidity and density, and is mainly composed of SiO2 (83.2%), Al2O3 (7.04%) and Fe2O3 (3.35%) with trace elements, the main ones being: Zr (2490 ppm), Sr (310.21 ppm), Cu (310.1 ppm), V (290.1 ppm) and Zn (140ppm). It consists essentially of Montmorillonite, illite and Kaolinite with impurities such as quartz and rutile. This clay has a high degree of crystallinity. These characteristics make it a promoter material that can be used as an adsorbent.

Lead Ion Sorption Capacity and the Structural Properties of the Humic Acid Extracts from Evergreen Forests of Different Agro-ecological Zones of Kerala Western Ghats

Forest soils are enriched with soil carbon content. The vegetation and precipitation influences it’s chemical structure. The chemical structure directly contributed to its entire properties. Physico-chemical properties play vital role in its soil functioning. The sorption capacity of the humic acid can be applied in the nutrient uptake enhancement and waste water treatment. The study was conducted in the humic acid extract of evergreen forest of different agro-ecological zones of Kerala. Extraction was done by the acidic precipitation method recommended by International Humic Substance Society (IHSS). Determine the chemical structural variations and properties of the humic acid extracts followed by determining the sorption capacity of the material with lead ion. The study revealed the higher percentage of adsorption of lead ion with humic acid extract from evergreen forest of northern high hills –charnockite zone of western ghats of Kerala. This was the combined effect of enhanced cation exchange capacity and –COOH acidity of the material. These chemical structure and the functional properties to the sorption capacity of the humic acid extract to chelate the lead ion was evaluated .The higher cation exchange capacity and the –COOH acidity favoured the lead ion adsorption. Adsorption isotherm modeling was revealed the multilayer and monolayer adsorption of lead ion on humic acid depends with the heterogeneity of the HA surfaces. Maximum amount of lead ion molecule adsorbed on the HA surface was observed for humic acid from SHH-K agro-ecological zone. This method can be considered as economically viable green method for looking forward technology for waste water treatment.

Effect of amendments on bioavailability of cadmium in soil-rice system: a field experiment study.

The field experiment study investigated the effect of lime (L), manure compost (M), combination of lime and manure (LM), and combinations of lime with four kinds of passivators (LP1, LP2, LP3, and LP4) on the bioavailability of cadmium (Cd) in soil and Cd accumulation in rice plants. These four passivating products were composed of organic and inorganic compounds such as silicon-sulfhydryl group, CaO, SiO2, and so on. The results indicated that the application of these amendments improved soil pH, organic matter content, and cation exchange capacity (CEC) by 0.19-0.73 unit, 0.6-8.2%, and 5.7-38.9%, respectively; meanwhile, decreased soil acid-extractable Cd by 4.0-13.9% compared with before remediation. Alleviating Cd stress to rice also resulted in a significant increase in rice grains yield, whereas the LP4 showed an increment of 15.8-27.6%. Among these amendments, LP4 had a relatively high effectiveness, it promoted the decrease of extractable Cd by 13.9% and the increase of residual Cd by 8.1%; meanwhile, the bioconcentration factor of rice grain in LP4 decreased by 71.3%. The high pH, CEC, and rich functional groups in amendments might cause soil Cd transform from mobile fraction to residual fraction, and the cation ions in amendments also competed with Cd ions due to the antagonism. Taken all of these effects, the amendments alleviated Cd pollution in soil-rice system, decreasing Cd migration from soil to grain. In future, the long-term field experiment will need to be done for verify the long-term effect of soil amendments.

Potentiality of Pressmud as an Additional Material in Soil Amendments to Enhance Soil Fertility and Strength Ability

In Malaysia, there are some accumulation of sugar refinery byproducts with a lot of this material not being utilized in a productive manner, while, these byproducts had the great potential when mixed into agricultural soils as organic fertilizer with many of benefits that can improve soil health, and sustainable agronomic productivity. Pressmud or known as filter cake is a by-product of sugar industry and for every 100 tons of sugarcane crushed about 3 tons of pressmud cake is left behind as by-product. This studies carried out on this material have not properly summarized their characteristics properties that they can be used as aid for future works. Data from tests involving pressmud samples from Malayan Sugar Manufacturing (MSM) Prai Berhad, Penang which was part of a larger collection was analyzed. The physicochemical properties of pressmud characterization as well as leaching test were carried out. The physicochemical and engineering properties involved compaction behavior, permeability, cation exchange capacity (CEC), compressive stress test and its surface functional groups. The leaching test method included batch equilibrium test and column test. The optimum value of water content in pressmud was determined in the compaction test. It was found out that pressmud has higher optimum water content value was observed. The permeability test of pressmud gave value in ranges of 1.84 x 10-5 cm/s. The Cation Exchange Capacity (CEC) of pressmud indicated value in the range of 99 to 101 meq/100 g. The high cation exchange capacity indicated that pressmud was believed to be primarily responsible for sorption of metal ions. It can be concluded that pressmud having the capability to remove heavy metals through CEC process. Pressmud also showed higher compressive strength value. Batch equilibrium test glaringly showed that pressmud have the capability to remove from 53.6%-93.8% metal removed from metal solutions for Chromium (Cr), Copper (Cu), Manganese (Mn), Nickle (Ni), Lead (Pb) and Zinc (Zn). From the result of column test, pressmud alone was able to retain efficiently all the heavy metals as these metals did not reach 1 (relative concentration) until 10 pore volume (PV.) indicating that pressmud was a good mixture material as it can assist in adsorption of heavy metals. Based on the characterization study, removal efficiency and column test, pressmud has great potentiality to be used as an additional material in soil amendments to enhance soil fertility and strength ability.

Montmorillonite for Adsorption and Catalytic Elimination of Pollutants from Wastewater: A State-of-the-Arts Review

Clay minerals have been recognized as one of the cheap and effective materials for wastewater remediation. Among the various clay minerals, montmorillonite (MMT) has received much attention due to its wide availability, low-cost and promising properties such as high porosity, mechanical strength, and cation exchange capacity. Additionally, MMT has high swelling properties. These features make it an ideal material for wastewater remediation applications. In addition, it possessed good cationic exchange capacity, making it easier to interact with various molecules. MMT and its composites exhibited good selectivity and catalytic activity for contaminants elimination from wastewater. Surface modification and functionalization have been identified as a way to improve the MMT’s adsorptive performance and endow it with light and light-harnessing properties. Thus, MMT composites, especially metal and metal-oxide nanoparticles, have shown good adsorption and photocatalytic activity toward the elimination/mineralization of various contaminants such as dyes, pharmaceuticals, heavy metals, and other organic and inorganic species. As such, MMT and its composites can be adopted as potential materials for wastewater remediation.

Characterization of bentonite, vermiculite and soil as potential materials to compose the natural barriers in a near-surface repository

The use of nuclear technology is growing in Brazil, where it is possible to carry out the entire nuclear fuel cycle. This technology generates radioactive waste that must be treated before being released into the environment or stored in suitable facilities. Then, the first national repository - CENTENA - will be implemented, where all low and intermediate level radioactive waste generated in Brazilian territory will be safely stored. One of the barriers that will compose the repository will be composed of natural materials such as soils and clays, the latter for having a high adsorption and cation exchange capacities and swelling potential. The purpose of the article is to show the research carried out in Centro de Desenvolvimento da Tecnologia Nuclear (CDTN) with natural materials aiming their use in natural barriers. Four materials were characterized: CDTN soil, this soil with bentonite, expanded vermiculite and bentonite, using the clay characterization protocol. Primary mineralogical, physical and chemical analyzes were performed, such as X-ray diffraction, scanning electron microscopy, particle size distribution, specific surface area and cation exchange capacity. The results showed that these clays are potentially candidates for composing CENTENA's natural barriers.

Low-cost zeolite-based sorbents prepared from industrial perlite by-product material for Zn2+ and Ni2+ removal from aqueous solutions: synthesis, properties and sorption efficiency

The conversion of waste/by-product materials into efficient sorbents is at the forefront of innovative remediation techniques. In the present study, the relationships among the synthesis conditions, physicochemical properties of synthesized sorbents and Zn2+ and Ni2+ removal efficiencies were studied in detail. Zeolite X, zeolite P, phillipsite, analcime, sodalite and cancrinite were synthesized from industrial perlite by-product material. The zeolite content in the synthesized sorbents and zeolite framework topology (dimensions, numbers and spatial configuration of channels) were the key factors affecting the removal of Zn2+ and Ni2+ from aqueous solutions. Zeolite X-based sorbent exhibited the best sorption performance mainly due to the large zeolite channel dimensions, low Si/Al ratio, high cation exchange capacity and high specific surface area. Nevertheless, the efficiency and stability of this sorbent need to be tested under field conditions prior to its application for remediation technologies.

Evaluation of Crosslinked Sulfonated Polymers Derived from Different Resins for Removal of Ammonium Ions

AbstractAmmoniacal nitrogen is an environmental pollutant present in various effluents, such as landfill leachate. It is possible to use ion‐exchange resins in systems for tertiary treatment of effluents containing NH4+ ions and as support for NH3 recovery after treatment of these effluents by employing air stripping. This article presents an exploratory study of sorption of NH4+ ions by sulfonic resins prepared from styrene‐divinylbenzene (Sty‐DVB) copolymers with varied morphological structures: hypercrosslinked resin, a macroporous copolymer prepared by conventional aqueous suspension polymerization, and a polyHIPE copolymer. These three resins are sulfonated by employing concentrated sulfuric acid. The sulfonic resin derived from hypercrosslinked resin has the highest cation exchange capacity (5.06 meq g−1) and is selected for batch studies and column tests. The best result (removal rate of 87%) is achieved with 20 g of resin, time of 20 min, and concentration of 100 ppm. Kinetic behavior and sorption processes are best described by the pseudo‐second‐order, Weber–Morris intraparticle diffusion, and Langmuir models. The saturation point occurs when 900 mL of the NH4+ solution at 2500 ppm (15 mL min−1) is percolated through the column. The working capacity of this resin is 14.06 g cm−3. The resin can be reused during five cycles with removal efficiency between 71% and 82%.