Exchange Capacity
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Author(s):  
D. Vidhyeswari ◽  
A. Surendhar ◽  
S. Bhuvaneshwari

Abstract The aim of this study is to synthesis SPEEK composite proton exchange membrane with the addition of TiO2 nanofillers for microbial fuel cell application. SPEEK composite membrane with varying weight percentage of TiO2 (2.5, 5, 7.5 and 10%) was prepared to study the effect of TiO2 concentration on membrane performance. Synthesized composite membranes were subjected to various characterization studies such as FT-IR, XRD, Raman spectroscopy; TGA, UTM and SEM. Physico-chemical properties of membrane such as water uptake capacity, ion exchange capacity and thickness were also analyzed. 5% TiO2 – SPEEK composite membrane exhibited the higher water uptake capacity value and Ion exchange capacity value of 31% and 1.71 meq/g respectively. Performance of the MFC system with TiO2 – SPEEK membranes were evaluated and compared with the pristine SPEEK and Nafion membrane. 5% TiO2 – SPEEK membrane produced the higher power density (1.22 W/m2) and voltage (0.635 V) than the other membranes investigated. Efficacy of MFC in wastewater treatment was evaluated based on the chemical oxygen demand (COD), total organic carbon content and turbidity. Biofilm growth over the surface of the electrodes was also analyzed using scanning electron microscopy.


2021 ◽  
Vol 13 (21) ◽  
pp. 11739
Author(s):  
Carlos Manuel Hernández ◽  
Aliou Faye ◽  
Mamadou Ousseynou Ly ◽  
Zachary P. Stewart ◽  
P. V. Vara Prasad ◽  
...  

Investigating soil and climate variability is critical to defining environments for field crops, understanding yield-limiting factors, and contributing to the sustainability and resilience of agro-ecosystems. Following this rationale, the aim of this study was to develop a soil–climate characterization to describe environmental constraints in the Senegal summer-crops region. For the soil database, 825 soil samples were collected characterizing pH, electrical conductivity (EC), phosphorus (P), potassium (K), cation exchange capacity (CEC), and total carbon (C) and nitrogen (N). For the climate, monthly temperature, precipitation, and evapotranspiration layers were retrieved from WorldClim 2.1, CHIRPS and TERRACLIMATE. The same analysis was applied individually to both databases. Briefly, a principal component analysis (PCA) was executed to summarize the spatial variability. The outcomes from the PCA were subjected to a spatial fuzzy c-means algorithm, delineating five soil and three climate homogeneous areas, accounting for 73% of the soil and 88% of the climate variation. To our knowledge, no previous studies were done with large soil databases since availability field data is often limited. The use of soil and climate data allowed the characterization of different areas and their main drivers. The use of this classification will assist in developing strategic planning for future land use and capability classifications.


Geosciences ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 434
Author(s):  
Melissa Magno ◽  
Ingrid Luffman ◽  
Arpita Nandi

Inorganic contaminants, including potentially toxic metals (PTMs), originating from un-reclaimed abandoned mine areas may accumulate in soils and present significant distress to environmental and public health. The ability to generate realistic spatial distribution models of such contamination is important for risk assessment and remedial planning of sites where this has occurred. This study evaluated the prediction accuracy of optimized ordinary kriging compared to spatial regression-informed cokriging for PTMs (Zn, Mn, Cu, Pb, and Cd) in soils near abandoned mines in Bumpus Cove, Tennessee, USA. Cokriging variables and neighborhood sizes were systematically selected from prior statistical analyses based on the association with PTM transport and soil physico-chemical properties (soil texture, moisture content, bulk density, pH, cation exchange capacity (CEC), and total organic carbon (TOC)). A log transform was applied to fit the frequency histograms to a normal distribution. Superior models were chosen based on six diagnostics (ME, RMS, MES, RMSS, ASE, and ASE-RMS), which produced mixed results. Cokriging models were preferred for Mn, Zn, Cu, and Cd, whereas ordinary kriging yielded better model results for Pb. This study determined that the preliminary process of developing spatial regression models, thus enabling the selection of contributing soil properties, can improve the interpolation accuracy of PTMs in abandoned mine sites.


2021 ◽  
Author(s):  
Fatemeh Amir Aslanzadeh Mamaghani ◽  
Amin Salem ◽  
Shiva Salem

Abstract The efficient management of solid waste deposited in the landfill of used motor oil recovery units is an important environmental challenge which is originated from the regeneration by bentonite as an effective adsorbent. The current study was attempted to convert the black waste into zeolite based compounds through fusion technique. The collected waste powder were mixed with sodium hydroxide, and boehmite followed by treatment at different temperatures, 600-800 °C. Then, the obtained precursors were hydrothermally converted to zeolite A or hydroxysodalite. The effect of parameters like alkalinity, boehmite, and sodium aluminate ratios, fusion temperature, and aging time on structural characteristics, and cation exchange capacity (CEC) were studied in details. The potential of solid waste in the production of zeolite A is significantly affected by mentioned factors which govern on purity, crystallinity, morphology, and CEC. The cation exchange capacity about 190 mg g-1 can be achieved by alkali, and boehmite ratios of 2.00, and 0.53, respectively. The microstructural analyses showed the morphological evolution from rounded shape to sharp edges by fusion at 800 °C due to appropriate recrystallization. Besides, hydrosodalite powder with extended surface area, 77 m2 g-1, could be produced by limited content of boehmite in the presence of NaAlO2.


2021 ◽  
pp. 104-136
Author(s):  
. Nurdin ◽  
Mochtar Lutfi Rayes ◽  
. Soemarno ◽  
. Sudarto ◽  
Endang Listyarini ◽  
...  

Ten representative pedons from the Bulia micro watershed of Gorontalo Province, Indonesia, were characterized and classified to determine its land quality (LQ) class. Angular blocky, sticky, plastic consistencies and a hard consistency prevailed in the soil structure. In the alluvial plains the soil texture is dominated by the clay fraction, while in the hills and volcanic mountains the sand fraction is dominated. The soils in the Bulia micro watershed also have acid to neutral reaction, with the range of very low to high OC (organic carbon) levels, the reserve of exchangeable bases was dominated by Ca2+ in two series patterns, namely: Ca2+ > Mg+ > Na+ > K+ and Ca2+ > Na+ > Mg+ > K+, cation exchange capacity (CEC) ranged from low to very high, and the base saturation varied from moderate to very high. The alluvial plain is represented by Inceptisol in P1 and Typic Humustepts (P7), also by Oxic Humustepts (P3), then Mollisol on P4 (Typic Argiudolls) and Typic Haplustolls (P6), Alfisol on P5 (Typic Paleustalfs). Entisol on P2 (Typic Ustipsamments) was found in volcanic mountains and P9 (Typic Paleustolls) P8 (Ultic Paleustalfs), P10 (Inceptic Haplustalfs) are typical of volcanic hills. On the alluvial plains the land was categorized as the LQ class II, III and IV, the volcanic mountains were the LQ class IV, while the land on the volcanic hills was categorized as the LQ class VI. River bank erosion on the land river terraces can be held by the manufacture of gabions, talud, cliff reinforcement plants and terraces. The soil temperatures and high clay content can be regulated by mulching and organic materials.


Toxics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 268
Author(s):  
Andrea Vannini ◽  
Elisabetta Bianchi ◽  
Diego Avi ◽  
Nicole Damaggio ◽  
Luigi Di Lella ◽  
...  

The aim of this study was to investigate the ability of biochar amendment to reduce the availability of Pb in the soil and its uptake in lettuce (Lactuca sativa L. var. adela). Seedlings of lettuce were cultivated in Pb-contaminated soils, both with and without 5% biochar (w/w), as well as in a simplified soilless system (hydroponics) at the ecologically relevant Pb concentration of 100 µM, both with and without 1% biochar. Soils amended with biochar resulted in a ca. 50% reduction of the extractable (bioavailable) fraction of Pb, limiting the accumulation of this toxic element in the leaves of lettuce by ca. 50%. A similar behavior was observed for lettuce plants grown hydroponically, even with a much higher reduction of Pb uptake (ca. 80%). Increased cation exchange capacity and pH were likely the main factors limiting the bioavailability of Pb in the soil. Complexation with functional groups and precipitation/co-precipitation both on the biochar surface and in soil aggregates were likely the main mechanisms immobilizing this element.


Agronomy ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 2052
Author(s):  
Karolina Villagra-Mendoza ◽  
Federico Masís-Meléndez ◽  
Jaime Quesada-Kimsey ◽  
Carlos A. García-González ◽  
Rainer Horn

Soil degradation and water stress in Costa Rica challenge the production of highly sensitive crops. This work is aimed at evaluating the physical and chemical changes in sandy loam (SL) and a silt loam (SiL) soil when amended with bamboo biochar while estimating the enhancement of tomato productivity. Biochar, obtained from Guadua Angustifolia bamboo feedstock, was mixed into sieved bulk soil substrate from the topsoil, from Andosol and Umbrisol groups, at application rates of 1, 2.5, and 5% (dry mass). Physicochemical and morphological properties of biochar such as pH, hydrophobicity, scanning electron microscopy images, helium picnometry, specific surface area by the Brunauer–Emmett–Teller (BET) method, CHNS, and ash content were determined. Soil hydrophobicity, acidity, electrical conductivity, cation exchange capacity and water retention, available water content, and air capacity were analyzed for the amended soils. Tomato yield was quantified after a harvest period of two months. The admixture of biochar did not significantly increase soil cation exchange capacity but increased water retention in the range of available water content. Class A (>200 g) tomato yield increased 350% in the SL and 151% in the SiL. Class B (100–200 g) tomato yields increased 27% in the SL but decreased about 30% in the SiL. Tomato yield response seems attributable to variation of water retention capacity, available water content, and air capacity. These results support the use of adapted water management strategies for tomato production based on soil physical changes of biochar.


2021 ◽  
Author(s):  
Wenwen Zhou ◽  
Haoran Jia ◽  
Lang Liu ◽  
Baotong Li ◽  
Yuqi Li ◽  
...  

Abstract. (E)-Pyriminobac-methyl (EPM), a pyrimidine benzoic acid esters herbicide, has a high potential as weedicide; nevertheless, its environmental behaviors are still not well understood. In this study, we systematically investigated for the first time the adsorption–desorption, degradation, and leaching behaviors of EPM in agricultural soils from five exemplar sites in China (characterized by different physicochemical properties) through laboratory simulation experiments. The EPM adsorption–desorption results were well fitted by the Freundlich model (R2 > 0.9999). In the analyzed soils, the Freundlich adsorption (i.e., Kf-ads) and desorption (i.e., Kf-des) coefficients of EPM varied between 0.85–32.22 mg1−1/n L1/n kg−1 and between 0.78–5.02 mg1−1/n L1/n kg−1, respectively. Moreover, the degradation of EPM reflected first-order kinetics: its half-life ranged between 37.46–66.00 d depending on the environmental conditions, and abiotic degradation was predominant in the degradation of this compound. The mobility of EPM in the five soils varied from immobile to highly mobile. The groundwater ubiquity score ranged between 0.9765–2.7160, indicating that EPM posed threat to groundwater quality. Overall, the results of this study demonstrate the easy degradability of EPM, as well as its high adsorption affinity and low mobility in soils with abundant organic matter content and high cation exchange capacity. Under such conditions, there is a relatively low contamination risk for groundwater systems in relation to this compound. At the same time, due to its slow degradation, EPM has a low adsorption affinity and tends to be highly mobile in soils poor in organic matter content and with low cation exchange capacity. Under such conditions, there is a relatively high contamination risk for groundwater systems in relation to this compound. Overall, our findings provide a solid basis for predicting the environmental impacts of EPM.


Author(s):  
Victor Casimiro Piscoya ◽  
Cristiane Maria Gonçalves Crespo ◽  
Renisson Neponuceno de Araújo Filho ◽  
Julyane Silva Mendes Policarpo ◽  
Nayane Laisa de Lima Cavalcanti ◽  
...  

Through sustainable agriculture it is possible to explore the coffee culture in consortium with native forests in more rugged reliefs, as coffee is a permanent crop in addition to the climatic conditions offered by the swamps that favor its development. Given the above, the present work proposes, based on the acidity results, to quantify  the need for correctives in the soil to obtain a better nutritional use offered by agroforestry cultivation of organic coffee in the shade with favorable results to increase productivity and, consequently, the farmer's profit. The research was carried out at the Várzea da Onça farm, in the Yaguara Ecological Complex, located in the municipality of Taquaritinga do Norte, Borborema plateau, in the Agreste Pernambuco mesoregion. Altitude, it is necessary to adopt appropriate management techniques that guarantee production, soil conservation and biodiversity, proposing soil correction to guarantee the ideal nutritional conditions for coffee growth. For this purpose, soil samples were collected in the Top (T), Hillside (E) and Pedimento (P) ranges at depths of 0-20, 20-40 and 40-60 cm when planting shaded coffee and soil samples from Native Forest (MN) preserved and legally protected from the Brejo de Taquaritinga. Active, exchangeable and potential acidity were analyzed, as well as the sum of bases, the potential and effective cation exchange capacity, base saturation and aluminum saturation. The results obtained were subjected to analysis of variance and the means were tested at 5% by the Tukey test. A potential of the system was found with low to very low natural fertility, with a strongly acidic reaction. Thus, adequate soil management and correction techniques are necessary for the crop to absorb all the nutrients made available by the organic matter present on the surface, concluding that all slopes require liming, the slope of Hillside and Mata Nativa they also need plastering for the culture to develop properly.


Agriculture ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 985
Author(s):  
Frédéric Feder

Sugarcane cultivation is suitable for the exploitation of organic waste products. However, minimum complementary mineral input is necessary for optimal fertilisation. Control mineral fertilisation treatments with mulch (MCM) or without mulch (MC) were compared with two organic waste treatments, a pig slurry with mulch (PSM) and without mulch (PS), and a sugarcane vinasse with mulch (SVM) and without mulch (SV) on a Nitisol in French Reunion Island. The sugarcane yields obtained with the different treatments differed each year. However, no trend was observed and no significant and recurrent effect of the presence of mulch or of the different treatments was identified over the course of the 4 year experiment. Soil pHw and pH KCl measured in the different treatments increased from year 3 in with the treatments including organic waste products (PS, PSM, SV and SVM) but remained constant with the treatments including only mineral fertilisation (MC and MCM). With the exception of PS and PSM, which were significantly higher in year 4, soil organic carbon content was not modified by the treatments. Soil cation exchange capacity increased only slightly with the PS and PSM treatments from year 3 on. The differences in yields and soil properties can be explained by the nature of the organic waste products, the accumulation of nutrients after several applications, and the specific characteristics of the sugarcane crop. The improvement in soil properties from the third year on was not reflected in the yield of sugarcane because it was too weak, and the crop explores a much larger volume of soil.


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