Removal of phosphates from aqueous solution by sepiolite-nano zero valent iron composite optimization with response surface methodology

In this study, sepiolite-nano zero valent iron composite was synthesized and applied for its potential adsorption to remove phosphates from aqueous solution. This composite was characterized by different techniques. For optimization of independent parameters (pH = 3–9; initial phosphate concentration = 5–100 mg/L; adsorbent dosage = 0.2–1 g/L; and contact time = 5–100 min), response surface methodology based on central composite design was used. Adsorption isotherms and kinetic models were done under optimum conditions. The results indicated that maximum adsorption efficiency of 99.43 and 92% for synthetic solution and real surface water sample, respectively, were achieved at optimum conditions of pH 4.5, initial phosphate concentration of 25 mg/L, adsorbent dosage of 0.8 g/L, and 46.26 min contact time. The interaction between adsorbent and adsorbate is better described with the Freundlich isotherm (R ² = 0.9537), and the kinetic of adsorption process followed pseudo-second-order model. Electrostatic interaction was the major mechanisms of the removal of phosphates from aqueous solution. The findings of this study showed that there is an effective adsorbent for removal of phosphates from aqueous solutions.     

TiO<Subscript>2</Subscript>-based shaped catalyst for the recovery of elemental sulfur from H<Subscript>2</Subscript>S and SO<Subscript>2</Subscript> gas streams

The Claus process has been used for the conversion of H₂S and SO₂ to elemental sulfur. These two sulfur compounds need special attention because they are very poisonous with negative impact on both the environment and human health. Here, highly active Fe–Ni/TiO₂ catalyst has been prepared and shaped by three different binders (bentonite, polyethylene glycol and carboxymethyl cellulose) into extrudes. Comparing the mechanical strength and surface area of prepared extrudes, the optimal shaped catalyst was selected with 20% of bentonite, 2% of PEG and 2% of CMC. The optimal catalyst was characterized by X-ray powder diffraction, temperature-programmed reduction, Brunauer–Emmett–Teller specific surface area, Barrett–Joyner–Halenda, scanning electron microscopy and energy-dispersive X-ray techniques and used for sulfur recovery process. The performance of this product for sulfur recovery via Claus process was excellent with the conversion of hydrogen sulfide of 76.77% and sulfur dioxide of 97.83%. The catalyst also provides high hydrolysis activity of CS₂ (83.06%). Therefore, a highly active TiO₂-supported shaped catalyst with 85.62% of conversion efficiency has been prepared successfully to convert the small amounts of H₂S, SO₂ and CS₂ to elemental sulfur.     

Investigation of heavy metal uptake by three types of ornamental plants as affected by application of organic and chemical fertilizers in contaminated soils

Accumulation of heavy metals in soil media is considered as a serious environmental problem, which is hazardous to human and animal health. There have been several methods for the removal of these toxic metals. One of the commonly used methods is the use of plants, especially ornamental plants to remove heavy metals from soils. In this regard, the study has been conducted on the soils contaminated with Mn, Pb, Ni, and Cd using factorial experiment in a completely randomized design with two factors including three types of soil (soil A for the highest level of contamination, B for the lowest level of pollution, and C for the non-contaminated soil) with different contamination levels as well as three types of ornamental plants, gladiolus, daffodils, and narcissus with four replications. In another part of the study, soil A and gladiolus were used in a completely randomized design with three replications, and also three types of fertilizers, such as municipal solid waste compost, triple superphosphate and diammonium phosphate, were added to this soil. In addition, the availability of heavy metal was studied in gladiolus as influenced by the application of organic and chemical fertilizers. The results showed that heavy metal pollution caused reduction in the dry weight of gladiolus and tulips compared to the control sample, while there was no significant effect of pollution on the dry weight of narcissus. The uptake of Mn, Pb, Ni, and Cd by all three plants has been increased with enhancing the pollution levels of heavy metals. The highest concentration of Pb in the shoots of plants was observed in soil A with an average amount of 61.16 (mg kg^?1), which revealed a substantial difference relative to the treatment of soil B and C. The most and least amount of Ni in the plants shoots were related to soil A and soil C with an average of 2.35 and 0.89 mg kg^?1, respectively. The uptake of Pb by shoots of all three plants was nearly similar to each other, while more Pb was absorbed by the bulbs of gladiolus compared to the bulbs of other plants. Increment in the pollution levels led to the decrement in enrichment factor (EF); however, there was no effect of pollution levels on EF of Mn and Pb. Moreover, there was no effect of increasing pollution levels on translocation factor of these elements. In gladiolus, after application of organic and chemical fertilizers, it was observed that the concentration of heavy metals was far more in the bulbs compared to the shoots. In conclusion, the cultivation of these ornamental plants is highly recommended due to not only their decorative aspect but also their ability for bioremediation as well as being economical.     

Comparing grain size distribution of sediment and original soil under raindrop detachment and raindrop-induced and flow transport mechanism

The grain size distribution (GSD) of sediment in comparison with the original soil GSD is discussed under different slopes (5, 15 and 25%) and rainfall intensities (30, 60 and 90 mm h^–1 with respective duration of 30, 15 and 10 min) but identical runoff (15 mm). The sediment quantification was carried out by raindrop-induced flow transport (RIFT) or/and transport by flow (FT) using a rainfall simulator and a 6 × 1 m² erosion plot and a silt loam. The results show a high degree of enrichment for size classes of 2–4 and 4–8 μm and a high degree of depletion for size classes of >63 μm under different slopes and rainfall intensities. In addition, the results show that the experimental enrichment ratio (ER) for particle size <16 μm under different slopes and rainfall intensities was greater than 1, while the ER for particle size >32 μm was less than 1.     

Evaluation of two satellite-based products against ground-based observation for drought analysis in the southern part of Iran

Natural Hazards - Water stress or more specifically drought assessment plays a key role in water management, especially in extreme climate conditions. Basically, globally gridded satellite-based...     

Characteristics of Mineralizing Fluids of the Darreh‐Zerreshk and Ali‐Abad Porphyry Copper Deposits,Central Iran,Determined by Fluid Inclusion Microthermometry

The Darreh‐Zereshk (DZ) and Ali‐Abad (AB) porphyry copper deposits are located in southwest of the Yazd city, central Iran. These deposits occur in granitoid intrusions, ranging in composition from quartz monzodiorite through granodiorite to granite. The ore‐hosting intrusions exhibit intense hydrofracturing that lead to the formation of quartz‐sulfide veinlets. Fluid inclusions in hydrothermal quartz in these deposits are classified as a mono‐phase vapor type (Type I), liquid‐rich two phase (liquid + vapor) type (Type IIA), vapor‐rich two phase (vapor + liquid) type (Type IIB), and multi‐phase (liquid + vapor + halite + sylvite + hematite + chalcopyrite and pyrite) type (Types III). Homogenization temperatures (Th) and salinity data are presented for fluid inclusions from hydrothermal quartz veinlets associated with potassic alteration and other varieties of hypogene mineralization. Ore precipitation occurred between 150° to >600°C from low to very high salinity (1.1–73.9 wt% NaCl equivalent) aqueous fluids. Two stages of hydrothermal activity characterized are recognized; one which shows relatively high Th and lower salinity fluid (Type IIIa; Th_(L‐V) > Tm_(NaCl)); and one which shows lower Th and higher salinity (Type IIIb; Th_(L‐V) < Tm_(NaCl)). The high Th_(L‐V) and salinities of Type IIIa inclusions are interpreted to represent the initial existence of a dense fluid of magmatic origin. The coexistence of Type IIIb, Type I and Type IIB fluid inclusions suggest that these inclusions resulted either from trapping of boiling fluids and/or represent two immiscible fluids. These processes probably occurred as the result of pressure fluctuations from lithostatic to hydrostatic conditions under a pressure of 200 to 300 bar. Dilution of these early fluids by meteoritic water resulted in lower temperatures and low to moderate salinity (<20 wt% NaCl equiv.) fluids (Type IIA). Fluid inclusion analysis reveals that the hydrothermal fluid, which formed mineralized quartz veinlets in the rocks with potassic alteration, had temperatures of ～500°C and salinity ～50 wt% NaCl equiv. Cryogenic SEM‐EDS analyses of frozen and decrepitated ore‐bearing fluids trapped in the inclusions indicate the fluids were dominated with NaCl, and KCl with minor CaCl₂.     

Removal of heavy metals from paint industry’s wastewater using Leca as an available adsorbent

The ability of light expanded clay aggregate to remove lead and cadmium from paint industry’s effluents was studied at different levels of adsorbent, contact time and pH in April 2008. For this purpose, lead and cadmium removal from paint industry effluents were studied in batch reactors. lead and cadmium measurements have been taken with non-flame atomic absorption techniques and test methods were adapted from 19^th. Ed. of standard methods for the examination of water and wastewater. In this study, different amounts of Leca (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 g/L) were investigated. The amount of adsorbed lead and cadmium exposure to Leca increased from 1.41 to 3 mg/g and 0.22 to 0.75 mg/g, respectively. The maximum removal efficiency for Pb was 93.75 % at pH = 7 and exposure to 10 g/L of Leca, while for cadmium, it was nearly 89.7 % at the same condition. In this study, adsorption process of lead and cadmium was fitted with Freundlich adsorption isotherm (R² _Pb = 0.97 and R² _Cd = 0.98). The sufficient contact time was deemed 1–2 h for lead and cadmium. According to the results, Leca is recommended as a low cost and available adsorbent to remove lead and cadmium from industrial wastewater.     

Biostratigraphy and Sequence Stratigraphy of the Gurpi Formation at Deh Dasht Area,Zagros Basin,SW Iran

Abstract: A rich assemblage of planktonic foraminifera has been studied from an outcrop of the Gurpi Formation, the hydrocarbon source rock in the southwest Iran, Deh Dasht area (Kuh-e Siah anticline). Based on the distribution of the planktonic foraminifera, eight biozones have been recognized that included: Dicarinella concavata Interval Zone (Earliest Santonian), Dicarinella asymetrica Total Range Zone (Santonian to Earliest Campanian), Globotruncanita elevata Partial Range Zone (Early Campanian), Globotruncana ventricosa Interval Zone (Middle to Late Campanian), Radotruncana calcarata Total Range Zone (Late Campanian), Globotruncanella havanensis Partial Range Zone (Late Campanian), Globotruncana aegyptiaca Interval Zone (Late to latest Campanian), Gansserina gansseri Interval Zone (Latest Campanian to Early Maastrichtian). These biozones indicates that the Gurpi Formation deposited during the Early Santonian- Early Maastrichtian. These biozones are compared to the most standard biozones defined in Tethysian domain. Based on distribution of morphotype groups of planktonic foraminifera, planktonic to benthic ratio (P/B) and content of carbonate, nine third-order sequences are recognized.     

Comparing different statistical models for assessing Fe-contaminated soils based on VNIR/SWIR spectral data

Two statistical models including partial least squares regression (PLSR) and principal component regression were comparatively utilized to determine the predictive accuracy of visible–near-infrared and short-wave infrared reflectance spectroscopy in quantifying the Fe concentration in contaminated soils. Two scenarios were applied to select the best model: Scenario I included all wavelengths (400–2450 nm) and Scenario II encompassed characteristic bands of Fe. Pre-processing techniques used to select the best model included: first and second derivatives (FD and SD), multiplicative scatter correction (MSC) and standard normal variate. The abilities of the predictive models were evaluated by splitting soil samples into two random groups (80 and 20%). The first group (80%) was used to evaluate calibration and validation sets by employing the cross‐validation method, and the second group (20%) was applied to test the models. The coefficient of determination (R ²), root mean square error and residual prediction deviation were calculated to evaluate the models. Applying Scenario I indicated that the PLSR model with SD pre-processing was a more accurate technique for predicting the Fe concentration, whereas in the Scenario II, the PLSR model with MSC pre-processing had a better performance. Comparing Scenarios I and II indicated that the more reliable models for predicting the soil Fe content could be constructed by the PLSR model with the SD pre-processing techniques and all wavelengths. The modeling results produced by the PLSR model with the SD pre-processing could be used to detect, map and monitor Fe-contaminated soils by proximal and remote sensing in the mining areas.