High Cation Exchange Capacity Research Articles

Migration of two antibiotics during resuspension under simulated wind–wave disturbances in a water–sediment system

In this study, the migration of antibiotics (norfloxacin, NOR; and sulfamethoxazole, SMX) under simulated resuspension conditions across the sediment-water interface were quantified for two locations in China: point A, located in Meiliang Bay of Lake Taihu, and point B, located in Dapukou of Lake Taihu. The concentrations of suspended solids (SS) in the overlying water amounted to 100, 500, and 1000 mg/L during background, moderate, and strong simulated wind–wave disturbances, respectively. At each SS level, the initial concentrations of the two antibiotics were set to 1, 5, and 10 mg/L. The results showed that both resuspended SS and the initial concentration of antibiotics could influence the migration of NOR in the water–sediment system. Specifically, both higher SS and initial antibiotic concentrations were associated with higher rates of migration and accumulation of NOR from water to sediment. In contrast, the migration of SMX in the water–sediment system was not impacted by SS or initial antibiotic concentration. The adsorption capacities of sediments for NOR and SMX were significantly different at both locations, possibly reflecting differences in cation exchange capacity (CEC) and organic material (OM) contents. In general, higher CEC and OM values were found in sediments with a higher adsorption capacity for the antibiotics. When CEC and OM values of sediments were higher, the adsorption capacity reached up to 51.73 mg/kg. Large differences in the migration from water to sediment were observed for the two antibiotics, with NOR migration rates higher than those of SMX. The accumulation of NOR in surface sediment during resuspension was about 14 times higher than that of SMX. The main reason for this is that the chemical adsorption of NOR is seldom reversible. Overall, this study demonstrates that resuspension of NOR and SMX attached to sediments under simulated wind–wave disturbances can promote the migration of the antibiotics from water to sediment; these results could be useful for assessing the migration and fate of commonly used antibiotics in water–sediment systems.

Comportamento de Cs e Co em Sedimentos Marinhos da Enseada de Piraquara de Fora - Angra dos Reis

As a result of discharging of liquid effluents of the Angra dos Reis power plants, 137 Cs and 60 Co radionuclides are the greatest contributors to increasing of radioactivity level in the sediments of the Saco de Piraquara de Fora (SPF) inlet. The thermodynamic and kinetic of sorption of the two radionuclides in sediments of the impact area from the effluent liquid discharge were study to investigate their role in the radionuclide distribution patterns and trends. Cobalt sorption is slightly higher than the cesium one, but mostly both distribution coefficient values were lower than the literature data, which could be ascribed to the predominance of the kaolinite clay in the sediments. For both metals the sorption was higher onto the sediment with the highest cation exchange capacity. Although the velocities of sorption are slow for both metals, both may accumulate in considerable amount in sediments and their sorption is irreversible: 60 Co and 137 Cs accumulate in orders of magnitude of 10 10 and 10 9 Bq g -1 sediment , respectively, which shows the ability of the sediments to adsorb much of the radionuclides released by the power plants. In the range of SPF water temperature, as much the sorption as the desorption of the two metals increase with temperature; however, in general, the retention rate of the metals in the sediments remain constant. The sorption sites are heterogeneous as the sorption data could be fitted by the Langmuir and Freundlich isotherms. The process of sorption of Co and Cs is endothermic, which is spontaneous at low temperature.

Optimization of the synthesis process of zeolites with high cation exchange capacity using copper mine tailings as raw material

This study presents the optimization of the synthesis process of zeolites with high cation exchange capacity using copper mine tailings as raw materials by means of a Central Composite Design. The method consists of two steps: a fusion process with NaOH and the hydrothermal treatment. The results show the formation of zeolite P and cancrinite. Optimal conditions to synthesize zeolite P (94%) are tailings/NaOH weight ratio 1:1.2 (g/g), at 900°C and 2 h (fusion process); 90°C, 102 h and solid/liquid ratio = 0.25 g/mL (hydrothermal treatment). The use of copper mine tailings in the synthesis of zeolites represents benefits to the environmental by the reduction of the amount of tailings to be disposed off. This mitigates the contamination caused by this residue. The product obtained can be used on‐site or off‐site in the remediation of water resources contaminated with metals. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 996–1002, 2018

Thermodynamics and sorption characteristics of Zn(II) onto natural and chemically modified zeolites for agricultural and environmental using

Zeolites with high porous and cation exchange capacity have been widely used for agricultural and environmental purposes. This study was conducted to assess the thermodynamics and sorption characteristics of chemically modified zeolite (CMZ) from obtained natural zeolite (NZ), and to compare its properties. At first step of the sorption experiment, effects of pH, slurry concentration, stirring time, and heat on Zn removal were determined. Linear Langmuir isotherm was well fitted to data, and maximum sorption capacities (q max) were calculated as 20.87 and 33.44 mg/g for NZ and CMZ, respectively. Dubinin-Redushkevich (D-R) isotherm showed that the adsorption process was probably controlled by chemical ion-exchange mechanism. The solubility of zinc DTPA should be so directly related to the model of D-R model. Therefore, zeolites can be used as carrier Zn in soils with insufficient zinc arid and semiarid regions. Enthalpy (ΔH°) and entropy (ΔS°) values were positive. The change values of Gibbs free energy (ΔG°) illustrated that the sorption of Zn ions onto zeolites was feasible and spontaneous. From the obtained results, it could be concluded that chemical modification increased q max value of NZ, and the findings indicate clearly the possibility of using NZ and CMZ as Zn carrier in agricultural and also environmental treatments.

Enhanced Sweep Efficiency by Use of Smart Water in Tight Oil Reservoirs

This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 185032, “Enhance Microscopic Sweep Efficiency by Use of Smart Water in Tight and Very Tight Oil Reservoirs,” by T. Kadeethum, H.K. Sarma, and B.B. Maini, University of Calgary, prepared for the 2017 SPE Canada Unconventional Resources Conference, Calgary, 15–16 February. The paper has not been peer reviewed. In the literature, improvement of oil recovery in smart-water-injection schemes has been shown to be mediated by wettability alteration. This process reduces residual oil saturation, which, in turn, affects microscopic sweep efficiency and leads to subsequent enhancement of overall waterflood performance. Currently, there are few studies on smart waterflooding in tight and very tight oil reservoirs. This work examines smart-waterflood opportunities in such reservoirs. Introduction Residual-oil-saturation reduction improves microscopic sweep efficiency and, therefore, overall waterflood performance. Furthermore, decreasing endpoint water relative permeability diminishes mobility of the water phase such that water production is similarly reduced. Though these circumstances improve oil-production behavior, the primary parameters that lead to this improvement are still not well-understood. Among the statistically significant parameters that can influence smart-waterflood performance is clay content. One plausible explanation for the strong correlation between clay content and oil recovery is the positive correlation between cation-exchange capacity (CEC) and clay content. With higher CEC values, more rock surface may be charged. This results in either the expansion or compression of the double layer, which also induces a wettability alteration. Although tight oil reservoirs have limited flow capability, high CEC values in these reservoirs facilitate the wettability-alteration process. The objectives of the complete paper are to ex-amine the smart-waterflood potential in tight and very tight oil reservoirs, and to identify the CEC effect on smart-water-injection performance. The complete paper provides a discussion of the methodology (procedures and strategies) of the study. Discussion The literature contains evidence of smart-waterflood performance, with some works demonstrating that smart water improves oil recovery by reducing residual oil saturation. Furthermore, it decreases the endpoint water relative permeability. Smart water also improves microscopic sweep efficiency, leading to overall waterflooding efficiency. There is a distinct effect of porosity mean and porosity variance on CEC; there is furthermore a profound effect of CEC upon smart-water performance. Simulation properties relevant to the CEC effect are shown in Table 3 of the complete paper. There are two main types of fluid composition: in-situ fluid composition, which is the initial fluid in the reservoir at timestep zero, and the injected-fluid composition, which is the fluid that is forced into the reservoir at timestep greater than zero. Three homogeneous-reservoir cases with varying CEC values are considered.

Recycling of rice straw through pyrolysis and its adsorption behaviors for Cu and Zn ions in aqueous solution

Biochar has been suggested as new adsorbent for removing heavy metals from aqueous solutions. However, adsorption nature of biochar is influenced by feedstock-specific properties. In this study, experiments were performed to characterize the effect of cation exchange on adsorption behavior of Cu and Zn in single- and binary-metal systems by rice straw biochar (RSB) made by pyrolysis at 600°C. Result of kinetic experiment showed that the Cu and Zn in aqueous solution were rapidly adsorbed from the RSB in the first 2h and then reached the equilibrium after 4h. The fitting of intraparticale diffusion model showed fast Cu diffusion into boundary layer and pores of biochar than Zn. In parallel with 2.65meqL−1 Cu and 1.79meqL−1 Zn being adsorbed by RSB, up to 1.65 and 0.76meqL−1 exchangeable cations were released into the solution, indicating that cation exchange could contribute 62.3 and 42.5% to Cu and Zn sorption by RSB. Langmuir maximum adsorption capacities (a) of RSB for Cu and Zn were 56.5 and 38.6mgg−1 in single-metal system and 40.2 and 7.9mgg−1 in binary-metal system, respectively. Overall, the results demonstrate that the Cu and Zn adsorption by RSB was closely related to the exchangeable cation. The application of RSB could be especially attractive when considering biochar with high cation exchange capacities.

MUNICIPAL WASTEWATER TREATMENT WITH BENTONITE FROM MILOS ISLAND, GREECE

Bentonite clay minerals belonging to the smectite group have a wide range of chemical and industrial uses. The structure and chemical composition, exchangeable ion type and small crystal size of smectite are responsible for several properties, including a large chemically active surface area and a high cation exchange capacity. A wastewater treatment using bentonite from Milos island, Greece, was investigated. Raw wastewater sample (influent) from the wastewater treatment plant (WTP) of the city of Kilkis, Northern Greece was treated using bentonite in conjunction with chemical coagulants (polyaluminium chloride-PAC and cationic polyelectrolyte), in batch type experiments. Theremoval of suspended solids (SS), chemical oxygen demand (COD), nitrate ion, ammonium ion, phosphate ion, and toxic metals were evaluated. The treatment gave overflowed clear water improved concerning the quality parameters. The bentonite adding prior to flocculation resulted in effective removal of heavy metals such as chromium and copper. Additionally, the bentonite removed nitrogen compounds with relatively high efficiency, while the clay presence highly improved the COD removal. The quality parameters after treatment were improved fulfilling the requirements for disposition as downstream, irrigation, swimming and fish waters.

Enhancing nitrogen availability from urea using clinoptilolite zeolite

The high costs of nitrogen fertilizers have necessitated best-developed practices to optimize nitrogen fertilizers use whilst minimizing nitrate losses. Ammonium adsorption inhibits loss of nitrogen in the form of nitrate thereby increasing nitrogen availability for crops. Due to the negatively charged properties of nitrate, it moves freely in the soil solution and not adsorbed onto soil particle surfaces. In this study, clinoptilolite zeolite was used in soil leaching and ammonium adsorption and desorption studies to determine: (i) soil total nitrogen availability, exchangeable ammonium, and available nitrate, and (ii) the capacity of clinoptilolite zeolite to adsorb and desorb ammonium from different rates of urea. Different rates of urea amended with clinoptilolite zeolite significantly reduced ammonium and nitrate release from urea compared with urea alone. Clinoptilolite zeolite enhanced retention of soil total nitrogen, exchangeable ammonium, and available nitrate due to the high cation exchange capacity of the mineral to adsorb ammonium, thus, improving nitrogen availability through temporary retention on the exchange sites of the clinoptilolite zeolite. The availability of nitrogen can be enhanced if urea is amended with clinoptilolite zeolite.

Properties of soils in the marginal upland of Sta. Rita, Samar, Philippines

The widespread occurrence of marginal uplands is a serious agricultural and ecological problem in the Philippines. The study evaluated the morphological and physico-chemical properties of soils in the marginal upland of Sta. Rita, Samar. Three soil profiles located at different physiographic positions were examined and sampled. Findings revealed that the marginal upland soils were derived from mudstone. They were characterized by an Ap-Bt-BC horizon sequence and they were clayey with moderate to high porosity and water holding capacity values. The soils were friable in their surface horizons when moist, but plastic and sticky when wet. The soils had pH(water) values ranging from 5.20 to 6.86, indicating that soil acidity was not yet a serious problem in these soils. The soils had moderate soil organic matter contents in their surface horizons but low amounts in subsurface horizons. Total N and available P of the soils were low and a problem for crop production. However, the soils had moderate to high exchangeable bases and cation exchange capacity values. In terms of degree of soil development, the marginal upland soils was observed to be mature as reflected by their horizonation, particularly by the presence of an argillic horizon (B horizon with high clay accumulation). But they still had high base saturation, suggesting that they were not yet highly leached and thus, were classified as Typic Hapludalfs or Haplic Luvisols.

Novel magnetic carboxyl modified hypercrosslinked resins for effective removal of typical PPCPs

A series of novel magnetic carboxyl modified hypercrosslinked resins were successfully prepared via a sequence of suspension polymerization, hydrolysis and post-crosslinking reactions. The serial resins possessed both high cation exchange capacity and high specific surface area with MA-10 having the supreme specific surface area of 1238.65 m2/g and MA-70 having the largest exchange capacity of 6.45 mmol/g. The serial resins exhibited excellent adsorption capacity of typical PPCPs including chloramphenicol, atenolol, ibuprofen and tetracycline, which were neutral, cationic, anionic and zwitterionic respectively in natural water. The adsorption of chloramphenicol and ibuprofen was dominated by the hydrophobic and π–π Electron-Donor-Acceptor (EDA) interactions, while as to atenolol, the electrostatic interaction dominated the adsorption process. Especially, MA-50 was found to have the largest adsorption amount and the longest equilibrium time of zwitterionic tetracycline compared with other resins, the mechanism of which needed further investigation. Breakthrough tests showed that the serial resins had significant advantages over granular activated carbon F400D in contaminants removal for all of the four target pharmaceuticals. Batch experiments proved that the serial resins possessed strong anti-pollution ability and excellent regeneration property, which made it possible for the practical application in future water treatment.

Waterleaf (Talinum triangulare) response to biochar application in a humid-tropical forest soil

Waterleaf (Talinum triangulare), like many other leafy vegetable is cultivated in home gardens to improve nutritional quality for the family and may provide additional income for female farmers. However, the role of Talinum cultivation is often counteracted by declining soil fertility. In recent years, biochar (pyrolysed biomass) has gained importance as a soil amendment tool. However, not much attention has been focused on the influence of biochar on soil quality and plant growth in the humid tropics. This study was conducted to assess different locally available crop waste residues as possible sources of biochar for home garden or small-scale production units of leafy vegetable using Talinum as proxy on highly weathered acid soils in the humid tropics. The experimental set-up was a pot experiment in a complete randomized design in five replicates using biochar sources from cassava stems, rice husk, corncob and sawdust. The results obtained showed that biochar samples had a high cation exchange capacity (CEC), total nitrogen, total carbon and pH (7.8 to 10.8), as compared to the no-input soil (pH 5.7). It is evident that adding biochar to poor and acidic soils could possibly increase the pH and reduce lime requirements. Positive and significant response of biochar (P<0.05) application were also observed with the growth, nutrient uptake, and yield of waterleaf. Biochar produced from rice husks obtained the best response followed by sawdust, cassava and corncob. Similarly, the C and N uptake of waterleaf was generally higher with rice husk biochar use as compared to the other treatments. This study has demonstrated that biochar production could be useful in valorizing crop waste residues and biochar use is likely to enhance the productivity of leafy vegetables. More research on possible combination of biochar and other farming strategies such as the application of animal manure and mineral fertilizer to maximize Talinum production should be encouraged. Key words: Biochar, cassava stems, crop waste, residues, nitrogen, soil pH, Talinum.

Modeling CO2–Water–Mineral Wettability and Mineralization for Carbon Geosequestration

Carbon dioxide (CO2) capture and storage (CCS) is an important climate change mitigation option along with improved energy efficiency, renewable energy, and nuclear energy. CO2 geosequestration, that is, to store CO2 under the subsurface of Earth, is feasible because the world's sedimentary basins have high capacity and are often located in the same region of the world as emission sources. How CO2 interacts with the connate water and minerals is the focus of this Account. There are four trapping mechanisms that keep CO2 in the pores of subsurface rocks: (1) structural trapping, (2) residual trapping, (3) dissolution trapping, and (4) mineral trapping. The first two are dominated by capillary action, where wettability controls CO2 and water two-phase flow in porous media. We review state-of-the-art studies on CO2/water/mineral wettability, which was found to depend on pressure and temperature conditions, salt concentration in aqueous solutions, mineral surface chemistry, and geometry. We then review some recent advances in mineral trapping. First, we show that it is possible to reproduce the CO2/water/mineral wettability at a wide range of pressures using molecular dynamics (MD) simulations. As the pressure increases, CO2 gas transforms into a supercritical fluid or liquid at ∼7.4 MPa depending on the environmental temperature. This transition leads to a substantial decrease of the interfacial tension between CO2 and reservoir brine (or pure water). However, the wettability of CO2/water/rock systems depends on the type of rock surface. Recently, we investigated the contact angle of CO2/water/silica systems with two different silica surfaces using MD simulations. We found that contact angle increased with pressure for the hydrophobic (siloxane) surface while it was almost constant for the hydrophilic (silanol) surface, in excellent agreement with experimental observations. Furthermore, we found that the CO2 thin films at the CO2-hydrophilic silica and CO2-H2O interfaces displayed a linear correlation, which can in turn explain the constant contact angle on the hydrophilic silica surface. In view of the literature and our study results, a few recommendations seem necessary to construct a molecular system suitable to study wettability with MD simulations. Future work should be conducted to determine the influence of brine salinity on the wettability of minerals with high cation exchange capacity. Mineral trapping is believed to be an extremely slow process, likely taking thousands of years. However, a recent pilot study demonstrated that CO2 mineralization occurs within 2 years in highly reactive basalt reservoirs. A first-principles MD study has also shown that carbonation reactions occur rapidly at the surface oxygen sites of a reactive mineral. We observed carbonate ions on both a newly cleaved quartz surface (without hydrolysis), and a basalt andesine surface after hydrolysis in a CO2-rich environment. Future work should consider the influence of water, gas impurities, and mineral cation type on carbonation.

The role of tailored biochar in increasing plant growth, and reducing bioavailability, phytotoxicity, and uptake of heavy metals in contaminated soil

Microwave-assisted catalytic pyrolysis was investigated using K3PO4 and clinoptilolite to enhance biochar sorption affinity for heavy metals. The performance of resulting biochar samples was characterized through their effects on plant growth, bioavailability, phytotoxicity, and uptake of heavy metals in a sandy soil contaminated with Pb, Ni, and Co. The produced biochars have high cation-exchange capacity (CEC) and surface area, and rich in plant nutrients, which not only reduced heavy metals (Pb, Ni, and Co), bioavailability and phytotoxicity, but also increased plant growth rate by up to 145%. The effectiveness of biochar in terms of reduced phytotoxicity and plant uptake of heavy metals was further improved by mixing K3PO4 and clinoptilolite with biomass through microwave pyrolysis. This may be due to the predominance of different mechanisms as 10KP/10Clino biochar has the highest micropore surface area (405 m2/g), high concentrations of K (206 g/kg), Ca (26.5 g/kg), Mg (6.2 g/kg) and Fe (11.9 g/kg) for ion-exchange and high phosphorus content (79.8 g/kg) for forming insoluble compounds with heavy metals. The largest wheat shoot length (143 mm) and lowest extracted amounts of Pb (107 mg/kg), Ni (2.4 mg/kg) and Co (63.9 mg/kg) were also obtained by using 10KP/10Clino biochar at 2 wt% load; while the smallest shoot length (68 mm) and highest extracted amounts of heavy metals (Pb 408 mg/kg, Ni 15 mg/kg and Co 148 mg/kg) for the samples treated with biochars were observed for soils mixed with 1 wt% 10Clino biochar. Strong negative correlations were also observed between biochar micropore surface area, CEC and the extracted amounts of heavy metals. Microwave-assisted catalytic pyrolysis of biomass has a great potential for producing biochar with high sorption affinity for heavy metals and rich nutrient contents using properly selected catalysts/additives that can increase microwave heating rate and improve biochar and bio-oil properties.

Role of clays in fouling-resistant clay-embedded polyelectrolyte multilayer membranes for wastewater effluent treatment

ABSTRACTThis study aimed to investigate the effects of cation exchange capacity (CEC) and location of clay nanoplatelets on the structure and performance of clay-embedded polyelectrolyte multilayer (c-PEM) membranes for wastewater effluent treatment. Two kinds of clay nanoplatelets, montmorillonite and kaolin, were deposited on the ultrafiltration membrane by employing layer-by-layer (LbL) assembly with poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). Negatively charged clay platelets or PAA interacted with positively charged PAH to form a bilayer in the c-PEM membrane. The filtration effect of clay platelets was successively distinguished from PEM by reducing the number of (PAH/PAA) bilayers from four to one, while keeping the clay layer at the outermost layer of assembly. When the clay platelets were deposited only as the outermost layer of the LbL multilayers, the c-PEM membrane with one clay layer and one bilayer assembly showed significant flux barrier and fouling resistance. Clay platelets as the outermost layer physically increased the flow path length and decreased the number of pores, as well as effectively blocked the organic contaminants in the wastewater. Meanwhile, when the clay layer was embedded in the middle of the PEM, the synergistic effect of clay platelets and PEM for wastewater treatment was difficult to obtain because the presence of clay platelets defected the buildup of fully interdigitated c-PEM and the adsorption of clay platelets was decreased. For the clays having low CEC, a higher number of LbL multilayers were required to deposit the clay platelets and to improve the performance of membrane. The high CEC clays (montmorillonite) turned out to be better than the low CEC clays (kaolin) in the structure and performance of the c-PEM membrane for wastewater effluent treatment.

Sorption properties optimization of agricultural wastes-derived biochars using response surface methodology

Abstract Pyrolysis of biomass into biochar and application of a carbon-rich product to water and soil media have been demonstrated to be effective in sequestering of contaminants. Fundamentally, biochar characteristics are controlled by feedstock and pyrolysis variables. The present study investigated the effects of synthesis variables (highest treatment temperature, heating rate and residence time) on biochar sorption properties. Oil palm empty fruit bunch (EFB) and rice husk (RH) biomasses were compared as initial feedstock. The variables were optimized using response surface methodology (RSM) to optimize the values of responses including biochars organic carbon content, cation exchange capacity (CEC), surface area and pores volume. Sorption performances of the optimized biochars were further investigated in removal of a polar imidazolinone herbicide from soil. Based on the results, pyrolysis temperature was the most effective variable on the responses followed by residence time and heating rate. Optimum conditions to maximize the biochars sorption properties were pyrolysis temperature of 493.44 °C and 700 °C and residence time of 1 h and 3 h for EFB and RH biochars, respectively. The best heating rate was 3 °C/min for both biochars. Optimized EFB biochar showed higher affinity for the herbicide due to its higher CEC and functionality, effective in sorption of polar compounds.

Organic matter and clay interaction in a meromictic lake: Implications for source rock OM preservation (Lac Pavin, Puy-de-Dôme, France)

Investigation of organic matter (OM) preservation mechanisms is crucial for understanding organic accumulation in sedimentary environments. We focus here on the contribution of organo-clay interaction in such preservation. Most studies addressing this issue deal with organo-mineral complexes which have settled, omitting consideration of early aggregation within the water column. We therefore investigated the sorption of OM on montmorillonite (Na MMt) and kaolinite (Kaol) immersed in a permanently stratified water column (Lake Pavin, France). The two types of clay samples were kept immersed for different lengths of time and characterized via analytical methods suited for the organic phase [pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS), GC-MS, Fourier transform infrared spectroscopy (FT-IR) and dissolved organic carbon (DOC) analysis], as well as for the mineral phase [X ray diffraction (XRD) and microprobe elementary cartography]. Results suggest that strong organo-clay interaction occurred within the water column to a varying extent depending on water physicochemical conditions and the mineral phase typology. A higher concentration of DOC was observed in the proximal environment of the clay traps, suggesting an attractive effect induced by the clay minerals. Lipid compounds sorbed during the immersion were essentially fatty acids and aromatic compounds. Their distributions were closer to a phytoplankton signature than allochtonous pedogenetic OM.The sorption was particularly efficient in the O2 transition zone, with a greater amount of OM on Na-MMt than Kaol. This was principally due to the high specific surface area and cationic exchange capacity (CEC) of the 2/1 clay mineral. Besides, XRD characterization revealed an increase in Na MMt interlayer spacing, which did not necessarily correspond to organic intercalation.The study confirms that the sorption of dissolved OM cannot alone explain the preservation of hydrocarbon-rich OM in such a lacustrine environment. Indeed, the sorbed OC was very low compared with the amount proposed by several authors as an expression of the monolayer equivalent principle.

Impact of organic fertilization on soil properties, plant physiology and yield in two newly planted olive (Olea europaea L.) cultivars under Mediterranean conditions

The aim of the present research was to investigate the effect of two commercial organic fertilizers (Activit and Agrobiosol) on two newly planted olive cultivars for two successive years. Two cultivars were used, ‘Koroneiki’ an olive oil cultivar and “Konservolia” a table olive one. The organic fertilizers were combined with inorganic fertilizers which when used alone served as control. Organic fertilizer application resulted in lower soil pH values (8.0–8.15 compared to 8.46 in control) and higher cation exchange capacity (up to 19.6meq 100g−1 compared to 17.1meq 100g−1 in control). Soil N, K, Mn and Zn concentration were higher under the combined application of Activit plus inorganic fertilizer. A significant increase of leaf area index was observed when organic fertilizers were used. Nutrient concentrations of the leaves were in all treatments within the adequacy range. Carbon assimilation rate also increased under organic fertilization in ‘Koroneiki’ in summer (17.4–18.7μmolm−2s−1) compared to control (14.9μmolm−2s−1). Yield of ‘Koroneiki’ trees during the second year (the only cultivar bearing fruits) was higher under both organic fertilizers application, reaching almost 55% increase compared to the use of only inorganic fertilizer.

Use of Surfactant-Modified Zeolites and Clays for the Removal of Heavy Metals from Water

The presence of heavy metals in water for human use or consumption represents a major risk to human health. It is therefore important to find materials to remove or minimise the concentration of these pollutants. The adsorption process for the removal of heavy metals is favoured by the use of low-cost materials that exhibit a porous structure and a high cation exchange capacity, such as zeolites and clays. On the other hand, chemical treatments, e.g., using acids and bases, can modify the properties of these materials, but more recently the application of surfactants has also shown to be successful for broadening their metal affinity and allowing the removal of diverse organic and inorganic pollutants from water. This paper reviews the application of modified zeolites and clays for the removal of heavy metals from water.

Synthesis optimization of oil palm empty fruit bunch and rice husk biochars for removal of imazapic and imazapyr herbicides

Imidazolinones are a family of herbicides that are used to control a broad range of weeds. Their high persistence and leaching potential make them probable risk to the ecosystems. In this study, biochar, the biomass-derived solid material, was produced from oil palm empty fruit bunches (EFB) and rice husk (RH) through pyrolysis process. Feedstock and pyrolysis variables can control biochar sorption capacity. Therefore, the present study attempts to evaluate effects of three pyrolysis variables (temperature, heating rate and retention time) on abilities of biochars for removal of imazapic and imazapyr herbicides from soil. Response surface methodology (RSM) was used for optimizing the variables to achieve maximum sorption performance of the biochars. Experimental data were interpreted accurately by quadratic models. Based on the results, sorption capacities of both biochars raised when temperature decreased to 300 °C, mainly because of increased biochars effective functionality in sorption of polar molecules. Heating rate of 3°C/min provided optimum conditions to maximize the sorption capacities of both biochars. Retention time of about 1 h and 3 h were found to be the best for EFB and RH biochars, respectively. EFB biochar was more efficient in removal of the herbicides, especially imazapyr due to its chemical composition and higher polarity index (0.42) rather than RH biochar (0.39). Besides, higher cation exchange capacity (CEC) values of EFB biochar (83.90 cmolc/kg) in comparison with RH biochar (70.73 cmolc/kg) represented its higher surface polarity effective in sorption of the polar herbicides.

Geospatial modelling for optimum management of fertilizer application and environment protection

Soil as an important source, guaranties the plant growth and supplies more than 97% of food need of world. Knowledge of soil spatial variability is important in natural and environment resource management, interpolation and soil sampling design, but requires a considerable amount of geo-referenced data. Soil cation exchange capacity (CEC) is a vital indicator of soil fertility quality and pollutant sequestration capacity. Plants such as rice need to provide their nutrient elements by using fertilizers for much more production in surface unit. For this purpose, it is essential to recognize macro-elements amount in soils and prepare their ideal maps. 247 soil samples were collected from depth 0–30 cm with distance minimum 250 m and maximum 1500 m using a stratified random sampling scheme on central areas of Guilan province located in north of Iran. CEC, total nitrogen, available potassium and phosphorus maps prepared using kriging geostatistical method. Evaluation criteria values of root mean square error (RMSE) and mean absolute error (MAE) derived for potassium 27.84 and 0.106, phosphorus 8.17 and 4.63, total nitrogen 0.059 and 0.025 and CEC 4.06 and 3.09, respectively. Criteria value of RMSE and MAE showed that accuracy of prepared maps was ideal. The fit of the experimental semivariograms to the theoretical models indicated that kriging could successfully interpolate soil variables. Thus, the kriging geostatistical method used on a large scale could accurately evaluate the spatial variability of soil nutrient properties. With regard to soil nitrogen and phosphorus maps, application of more amounts of nitrate and phosphorus fertilizers than their optimum level cause ground waters pollution and environment damages therefore their application must be carried out with high consideration. Potash fertilizers consumption in land with high CEC results its fixation, too. Precise attention to CEC map and on-time fertilizer application can solve this problem. Therefore, accurate notice to different amounts of these parameters in prediction maps, critical and optimum levels can well manage fertilizers application, prevents additional costs to farmer, pollution of ground waters and environment resources.