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The precipitation process was successfully employed to prepare ZnFe2O4 and ZnFe2O4@SiO2 nanoparticles. The synthesized nanoadsorbents were characterized employing transmission electron microscopy (TEM), X-ray diffraction (XRD), and Brauner-Emmett and Teller (BET) methods. The potential adsorption capacities of the generated nanoparticles were assessed under various conditions, including pH, starting dye concentration, contact time, and temperature. The adsorption efficiency of ZnFe2O4@SiO2 nanoparticles (95%) was higher than ZnFe2O4 (93%). The adsorption data were described using Langmuir, Freundlich, Temkin, and Dubinin-Kaganer-Radushkevich (DKR) isotherm models. The methylene blue (MB) removal kinetics by ZnFe2O4 and ZnFe2O4@Silica nanoparticles were evaluated using linear pseudo-first-order (PFO) and pseudo-second-order (PSO) models. The removal fitted to pseudo-second-order (PSO) models as the correlation coefficient (R2) value was (0.9994). The Boyd model may be used to validate the kinetics data, and it can be deduced that the rate-determining phase was not intra-particle diffusion, but rather the hypothesized adsorption process was endothermic and spontaneous in nature. Based on the findings, ZnFe2O4@silica is an adsorbent material that may be useful in removing methylene blue from aqueous solutions. [ABSTRACT FROM AUTHOR]

Prolonged use of the chromate [Cr(VI)]-contaminated water originates severe health problems for the public. Thus, the societal urgency is a reusable and cost-effective material for efficient scavenging of Cr(VI) from contaminated industrial wastewater. Aiming this, we had targeted to prepare some cheap and effective materials for scavenging Cr(VI) from the contaminated water. Herein, we report the preparation of hydrous cerium-copper oxide (HCCO) with some tailored compositions and employed toward the abstraction of chromate from water solution. The HCCO (Ce: Cu = 1:4, mole/mole) has shown the highest Cr(VI) scavenging capacity. Experimentally, highest Cr(VI) abstraction efficiency is recorded at pH ~ 3.0 (508.853 mg. g−1 at 303 K). Kinetically, the Cr(VI) scavenging reaction with HCCO surfaces agrees better with the pseudo second-order model (R2 = 0.987) equation and the equilibrium Cr(VI) distribution data explain the Freundlich isotherm model (R2 = 0.998) equation, which anticipates the multi-layered adsorption on heterogeneous sites of the adsorbent. A negative value of the Gibbs free energy change indicates that the Cr(VI) adsorption over HCCO surfaces is spontaneous. The positive enthalpy change indicates the endothermic nature of the said reaction. HIGHLIGHTS: One-pot synthesis of hydrous Ce(IV)-Cu(II) oxide (HCCO) and characterizations. Systematic Cr(VI) scavenging from modeled ground water with HCCO. Best fit pseudo-second-order kinetic model, implying the chemisorption mechanism. Very high amount of Cr(VI) scavenging at ambient condition reported to be 508.85 mg.g−1. Coulombic interaction between HCCO and Cr(VI) is responsible for scavenging Cr(VI). [ABSTRACT FROM AUTHOR]

This study explores the adsorption of Pb(II) from aqueous solutions using glutathione-modified carbon powder at room temperature. The graphite powder was modified through oxidation followed by surface immobilization of glutathione. The Pb(II) concentration was measured using square wave anodic stripping voltammetry (SWASV). Experiments were conducted with the following varying initial Pb(II) ion concentrations: 20.72 mg L−1, 41.44 mg L−1, 62.16 mg L−1, 82.88 mg L−1, 103.60 mg L−1, and 124.32 mg L−1. The effect of varying the glutathione-modified carbon powder dosage (12.5 mg, 25.0 mg, 50.0 mg, 75.0 mg, and 100.0 mg) on Pb(II) uptake was studied. The adsorption data were modeled using the Freundlich isotherm, resulting in a regression coefficient (R2) of 0.96, which signifies a good fit. The Freundlich constants obtained were KF = 3.54 × 10−5 (adsorption capacity) and n = 1.56 (adsorption intensity). At optimal conditions (10.0 mL of 20.72 mg L−1 Pb(II) solution with 100.0 mg of glutathione-modified carbon powder), the adsorption efficiency was 96.3%. The glutathione-modified carbon powder exhibits a high capacity for adsorbing Pb(II) from aqueous solutions. [ABSTRACT FROM AUTHOR]

The traditional craft villages in Vietnam in general and in Bac Ninh province in particular have been exposing many negative impacts on the environment. The heavy metal-rich wastes from the metal recycling casting craft villages in the field of metal recycling and metal casting are causing severe heavy metal pollution not only to the air, soils, and sediments but also to the groundwater resources. In Da Hoi iron recycling craft village in Chau Khe ward, Tu Son town, Bac Ninh province, Vietnam, the Holocene aquifer is exposed to the Ngu Huyen Khe River's sediments contaminated with heavy metals Lead, Cadmium, Nickel, and Zinc. Freundlich isotherm parameters of the Holocene aquifer have been selected for finite element modeling of heavy metal transport with high temporal and spatial varying retardation factors to get reliable quantitative heavy metals' distribution in depth and time. Initial and boundary conditions have been augmented to be established. The retardation factors of the advection and dispersion transport in the Holocene aquifer for heavy metals Pb, Zn, Cd, and Ni are very highly none-linear and very much varying in time and space: 8.7–66.4 for Pb, 2.0–12 for Zn, 1.7–4.8 for Cd and 1.1–5.9 for Ni. The results of the numerical modeling show that heavy metal transport in the Holocene aquifer is very fast and the entire aquifer thickness has equilibrium aquifer formation and aquifer water heavy concentrations after around 2–2.5 years for Cd and Ni, around 4 years for Zn and around 27 years for Pb. The heavy metals' fluxes from the Holocene aquifer to the Pleistocene aquifer are maximal and more or less constant from the equilibrium time and would cause severe contamination of the Pleistocene aquifer. [ABSTRACT FROM AUTHOR]

Use of nitrogen (N) fertilizers is gaining popularity to meet crop nutrient requirement for sustaining the food security of the increasing global population. However, improper management of N fertilizers in acid soils causes leaching and surface runoff because of excessive rainfalls and poor N retention in the tropics in particular. This results in N pollution in water bodies (also known as eutrophication), which degrades water quality to the detriment of aquatic ecosystems near farms. Thus, there is a need for using inorganic soil amendments such as Calciprill and sodium silicate to improve soil N adsorption because of the alkalinity and ability of these amendments to retain N for mitigating excessive N contamination in water bodies. To this end, this N sorption study was conducted to determine the effects of Calciprill and sodium silicate on ammonium (NH4+) adsorption and desorption in an acid soil (Bekenu series, Typic Paleudults). The soil was co-applied with different rates of Calciprill (80 %, 90 %, and 100 % Ca saturations) and sodium silicate (90, 105, 120, 135, and 150 kg ha-1), followed by the NH4+ adsorption capacity determination through the additions of NH4+ isonormal solutions at the five concentrations (0, 25, 50, 75, and 100 mg L-1) to establish a linear relationship between the amount of NH4+ absorbed (qe) and the amount of NH4+ left in the solution (Ce) after 24 h of equilibration. Apart from the soil only without any amendment (C0S0), there were another two additional treatments where the soil was added with Calciprill (100 % Ca saturation) (C3) and sodium silicate only (150 kg ha-1) (S5) to determine their respectively effects on N sorption. The collected data were fitted to the Langmuir and Freundlich isotherms. Thereafter, NH4+ desorption was determined using the same soil samples added with 2 mol dm-3. Compared with the soil without any amendment (C0S0), the Calcirpill alone (C3) and the combined use of Calciprill and sodium silicate significantly increased NH4+ adsorption at the NH4+ addition of 250 mg L-1, suggesting that Calciprill is the amendment which dominantly increases NH4+ adsorption and the effects of amendments are more pronounced at the lower soil NH4+ concentration. The results also revealed that the NH4+ adsorption in the soils following the co-application of Calciprill and sodium silicate followed the assumption of Freundlich isotherm. Regardless of the NH4+ concentration used, the effects of Calciprill and sodium silicate on the NH4+ desorption remain unclear, which could be because of the ability of sodium silicate to stabilize the soil structure. This stabilization reaction might have impeded the dissolution of Calciprill and temporarily fixed the absorbed NH4+. These findings suggest that it is possible to use the amendments to amend NH4+ sorption in Bekenu series for mitigating NH4+ leaching and runoff to prevent eutrophication. [ABSTRACT FROM AUTHOR]

Immobilizing microalgae cells in a hyphal matrix can simplify harvest while producing novel mycoalgae products with potential food, feed, biomaterial, and renewable energy applications; however, limited quantitative information to describe the process and its applicability under various conditions leads to difficulties in comparing across studies and scaling-up. Here, we demonstrate the immobilization of both active and heat-deactivated marine diatom Phaeodactylum tricornutum (UTEX 466) using different loadings of fungal pellets (Aspergillus sp.) and model the process through kinetics and equilibrium models. Active P. tricornutum cells were not required for the fungal-assisted immobilization process and the fungal isolate was able to immobilize more than its original mass of microalgae. The Freundlich isotherm model adequately described the equilibrium immobilization characteristics and indicated increased normalized algae immobilization (g algae removed/g fungi loaded) under low fungal pellet loadings. The kinetics of algae immobilization by the fungal pellets were found to be adequately modeled using both a pseudo-second order model and a model previously developed for fungal-assisted algae immobilization. These results provide new insights into the behavior and potential applications of fungal-assisted algae immobilization.

In the current investigation, the utilization of sawdust was modified through chemical means employing diethylenetriamine. This modified form of sawdust served as an effective adsorbent for the purpose of adsorbing Eosin Y dye from aqueous samples. The chemical modification procedure was thoroughly examined, comparing the fourier transform of infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) before and after the modification. Various factors including solution pH (ranging from 2 to 6), adsorbent dosage (ranging from 0.2 to 2.0 g L-1 ), contact time (ranging from 5 to 35 min), agitation rate, and initial dye concentration (ranging from 20 to 1000 mg L-1 ) were investigated. Remarkably, the modified sawdust exhibited a notable uptake capacity at ambient temperature and successfully removed approximately 96% of the Eosin Y dye with a mere 1.2 g L-1 of adsorbent in just 5 minutes. Moreover, it was discovered that the adsorbent maintained its promising adsorption ability even after undergoing ten cycles of adsorption and desorption. The Freundlich isotherm model was employed to determine the adsorption parameters. This methodology was also implemented to eliminate dye from authentic samples of diverse water sources. [ABSTRACT FROM AUTHOR]

Abstract Heavy metals like Cadmium, Lead, and Chromium are the pollutants emitted into the environment through industrial development. In this work, a new diphenylamine coordinated cobalt complex (Co-DPA) has been synthesized and tested for its efficiency in removing heavy metals from wastewater, and its adsorption capacity was investigated. The effectiveness of heavy metals removal by Co-DPA was evaluated by adjusting the adsorption parameters, such as adsorbent dose, pH, initial metals concentration, and adsorption period. Heavy metal concentrations in real sample were 0.267, 0.075, and 0.125 mg/L for Cd2+, Pb2+, and Cr3+ before using as-synthesized Co-DPA to treat wastewater. After being treated with synthesized Co-DPA the concentration of heavy metals was reduced to 0.0129, 0.00028, 0.00054 mg/L for Cd2+, Pb2+, and Cr3+, respectively, in 80 min. The removal efficiency was 95.6%, 99.5%, and 99.5% for the respective metals. The adsorption process fitted satisfactorily with Freundlich isotherm with R2(0.999, 0.997, 0.995) for Cd2+, Pb2+, and Cr3+, respectively. The kinetic data obeyed the pseudo-second order for Cd2+ and Cr2+ and the pseudo-first order for Pb2+. Based on the results obtained within the framework of this study, it is concluded that the as-synthesized Co-DPA is a good adsorbent to eliminate heavy metal ions like Cd2+, Pb2+, and Cr3+from wastewater solution. In general, Co-DPA is a promising new material for the removal of heavy metal ions from water. Graphical Abstract

Chitosan (CTS) and polyvinyl alcohol (PVA) are two environmentally friend polymers. In this research, methacrylate‐modified FDU‐12 (FDU‐12‐NH2) nanoparticle was synthesized. It was used in the preparation of CTS/PVA/FDU‐12‐NH2 (2%, 5% w) composites. Fourier transfer infrared spectroscopy, nitrogen adsorption/desorption, and transmission electron microscopy techniques were applied for the characteristics of the composites. Then, the produced composites were used as the adsorbents to remove cadmium (II) from the aqueous solutions. The optimal conditions of the Cd (II) adsorption factors were achieved. The different isotherms and kinetic models were applied to obtain the equilibrium adsorption information. The results indicated that Freundlich isotherm was the best isotherm model. Also, the kinetic model followed the pseudo‐second‐order. The maximum adsorption capacities were found 125 and 200 mgg−1 of the adsorbents by the Langmuir model. The results showed that the synthesized nanocomposite exhibited a good adsorbent for cadmium metal in the aqueous solution. [ABSTRACT FROM AUTHOR]

Heavy metals like Cadmium, Lead, and Chromium are the pollutants emitted into the environment through industrial development. In this work, a new diphenylamine coordinated cobalt complex (Co-DPA) has been synthesized and tested for its efficiency in removing heavy metals from wastewater, and its adsorption capacity was investigated. The effectiveness of heavy metals removal by Co-DPA was evaluated by adjusting the adsorption parameters, such as adsorbent dose, pH, initial metals concentration, and adsorption period. Heavy metal concentrations in real sample were 0.267, 0.075, and 0.125 mg/L for Cd2+, Pb2+, and Cr3+ before using as-synthesized Co-DPA to treat wastewater. After being treated with synthesized Co-DPA the concentration of heavy metals was reduced to 0.0129, 0.00028, 0.00054 mg/L for Cd2+, Pb2+, and Cr3+, respectively, in 80 min. The removal efficiency was 95.6%, 99.5%, and 99.5% for the respective metals. The adsorption process fitted satisfactorily with Freundlich isotherm with R2(0.999, 0.997, 0.995) for Cd2+, Pb2+, and Cr3+, respectively. The kinetic data obeyed the pseudo-second order for Cd2+ and Cr2+ and the pseudo-first order for Pb2+. Based on the results obtained within the framework of this study, it is concluded that the as-synthesized Co-DPA is a good adsorbent to eliminate heavy metal ions like Cd2+, Pb2+, and Cr3+from wastewater solution. In general, Co-DPA is a promising new material for the removal of heavy metal ions from water. [ABSTRACT FROM AUTHOR]

Silica gel nanoparticles (SGNPs) have been successfully prepared and utilized for capturing aqueous uranyl ions (VI) by batch sorption. The IR, SEM, PXRD, TGA, and DSC characterize and study the nanoparticles. The maximum efficiency of SGNPs toward capturing UO22+ ions is found at pHi = 7, Ci = 1.0 mg L−1, T = 25 °C, 80 rpm, and dosage = 2 g L−1 achieving 99% within 40 min of equilibrium sorption's. U(VI) ion sorption follows the Freundlich isotherm model (R2 > 0.999) and the pseudo-second-order kinetic model (R2 > 0.999). Based on these promising results, we candidate silica gel nanoparticles (SGNPs) as an effective filter for capturing low concentrations of uranium (VI) ions from the water. [ABSTRACT FROM AUTHOR]

Eliminating synthetic dyes and organic contaminants from water is crucial for safeguarding human health and preserving the environment. In this study, we explored the effectiveness of Ag–Cu–CeO2 nanocomposites as adsorbents to remove Congo Red dye from water. Three compositions of Ag–Cu–CeO2 nanocomposites (10:20:70, 15:15:70, and 20:10:70) have been synthesized by the aqueous coprecipitation method. A comprehensive analysis was performed by different techniques including X-ray diffraction, Fourier transform infrared spectroscopy, BET surface area determination, Thermogravimetric analysis, Scanning electron microscopy, and TEM. The synthesized nanocomposites have a dimension of 5 ± 1 nm and a high surface area (51.832–78.361 m2g-1).Among these, the nanocomposite with composition 15:15:70 showed the highest adsorption capacity of 4.71 mg/g adsorption (96.83 % removal) from the 0.8 × 10−4 M (55.6 mg/l) Congo Red solution at pH values of 2 at 20 °C with contact time of 3h. The adsorption data is best fitted in the Freundlich adsorption isotherm and pseudo-second-order kinetic model. The negative values of enthalpy variation (−27.57, −26.43, and −16.73 kJ/mol) demonstrated that the adsorption was spontaneous and exothermic. The cycling run showed a mere 12 % deactivation after five cycles of use thus indicating that Ag–Cu–CeO2 nanocomposites hold great potential as effective and eco-friendly adsorbents to remove Congo Red from water.

The sorption behavior of potentially toxic metals in soils influences their spread to other environmental compartments and their bioavailability to life forms. The present study evaluated the sorption of Cu(II) ions in two representative soils from Yala and Tindinyo regions along River Yala in Lake Victoria basin, Kenya. The sorption experiments were carried out in single component solution systems using the batch technique. The equilibrium data was modeled using Henry’s isotherm model and four two-parameter isotherm models. Freundlich and bi-phasic Henry’s isotherm models best described the data, while both negative constants for Langmuir and Elovich necessitated rejection of the models. The y-intercept values for Henry’s monophasic fitting were negative, but the corresponding soil solution values of 0.43 μg/mL and 0.45 μg/mL for the Yala and Tindinyo soils, respectively, were taken as the background Cu(II) solution levels. We propose that in cases where the y-intercepts are negative, the bi-phasic Henry’s model can be used to predict a soil’s critical retention limit for a given pollutant, while the corresponding soil solution amount gives the permissible level in the soil solution. Using bi-phasic Henry’s model, the critical Cu(II) retention limits were determined as 300.11 μg/g and 301.48 μg/g for Yala and Tindinyo soils, respectively. The corresponding soil solution amounts were 3.47 μg/mL and 3.36 μg/mL for Yala and Tindinyo soils, respectively. The background and equilibrium soil solutions were below and above the WHO limit of 2 μg/mL for drinking water, respectively, while the sorbed amount was above the WHO limit of 36 μg/g soil. These findings indicate that a contaminant in soil may not pose any toxicity risk unless its concentration exceeds the critical retention limit, and that a pollutant’s toxicity is dependent on the soil solution amount rather than the total amount in soil. Dissolved organic carbon was more dominant than clay fractions in influencing the degree of sorption in both soils. Surface complexation between Cu(II) ions and carboxylic functional groups is hypothesized as a plausible sorption mechanism. Immobilization of Cu(II) in soil was significantly increased by amendment with fish-scales-derived biochar which, therefore, has promising potential application in mitigating environmental contamination by metals.

The adsorption of a cationic dye, Methylene blue (MB), and a zwitterionic dye, 8-Hydroxyquinoline (8-HQ), onto zeolites synthesized from different clays has been investigated. The presence of certain metals and the Si/Al ratio of the parent clay has an overall effect on the type of zeolites produced. Zeolites LTA and FAU Y were obtained using the hydrothermal method. X-ray diffraction and Fourier transform infrared spectroscopy (FTIR) spectral analysis was used to study the adsorption phenomena of the adsorbates on the adsorbents. The adsorption profile of MB (Topological Polar Surface Area (TPSA) 43.9 Å2 and 8-HQ (TPSA 33.1 Å2) compared favourably with a Freundlich isotherm with R2 > 0.9 for all the zeolitic materials synthesized. Adsorption capacities of zeolite FAU was significantly different from zeolite LTA for MB removal. The higher adsorption capacity of zeolite FAU was attributed to geometric effects resulting in greater shrinkage in the inter lattice spacing of zeolite LTA leading to a reduction in surface area. Adsorption of the relatively smaller 8-HQ however, did not show significant difference in the two zeolite types. Surface and structural characterization showed that adsorbates/adsorbents interactions were driven by both geometric (inter lattice spacing which imparts higher surface area of the adsorbent) and electronic (electrostatic repulsions through electron back donation from metals in the zeolitic structure) considerations.

Anion exchange membranes have received great deal of attention for their ability to remove harmful dye contamination from industrial wastewater while also ensuring profitable and fuel-efficient commercialization. The ability of anion exchange membrane BIII to eradicate acid orange 7 dye from aquatic environment is demonstrated here. SEM and FTIR analyses revealed the surface properties and existence of distinct operational groups on the sorbent. Numerous constraints on AO7exclusion in an aquatic environment, such as contact duration, temperature, sorbent dose, and starting dye concentration were also scrutinized. For the purpose of assessing kinetics, Liquid film diffusion, Elovich, Lagergren first-order, Bangham, pseudo-second-order, and modified Freundlich models, were employed. These findings imply that the AO7 dye sorption onto the BIII membrane is well controlled by the liquid-film diffusion process and that the sorption comprehends pseudo-second-order kinetics with an utmost value of R2(0.99). To evaluate tentative data, multiple linear and nonlinear isotherm models were utilized. Freundlich isotherm was found to be in excellent agreement with sorption data. Thermodynamic specifications, such as a change in Gibb's free energy, enthalpy, and entropy, for dye sorption on the anion exchange BIII membrane were optimized between 308 and 338 K to maximize AO7 dye removal. Since ΔGo is negative and, ΔHo and ΔSo are positive, inferred that the sorption is spontaneous and endothermic. Anion exchange membrane BIII was effective for up to four successive cycles without losing its competence.

The widespread use of clothianidin as a pest control agent has led to its contamination in soil and water environments. We conducted an adsorption–desorption study of clothianidin in two different agricultural soils, namely Delhi and Manipur soils, with and without rice straw-based FYM amendments at 0.1, 0.2, 0.5, 1, and 2 μg/ml by using the batch equilibrium method. The results demonstrated that the equilibrium adsorption data conformed well to the Freundlich isotherm model (1/n < 1), with R2 values above 0.98 and standard error of estimation (SEE) below 0.60. Additionally, the pseudo-first-order kinetics model provided the best fit for the adsorption of rice straw-based FYM, exhibiting correlation coefficients (R2) greater than or equal to 0.986 and SEE values of 0.41 or higher. Among the tested soils, Manipur soil amended with rice straw-based FYM (59.38–60.55%) exhibited the highest clothianidin adsorption capacity, followed by Delhi soil with rice straw-based FYM (54.75–55.28%), Manipur soil (52.53–53.26%), and Delhi soil (46.26–49.37%). Moreover, artificial neural networks (ANNs) also confirmed the importance of organic carbon and clay content through the adsorption coefficient (Kd) model. Characterization of the FYM using Fourier-transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS) revealed N-H stretching of aliphatic primary amine and heterogenous surface properties with calcium abundance. The findings indicate that the addition of farmyard manure (FYM) enhanced the adsorption capacity of the soil containing higher organic carbon and clay content, with significant influence of primary amine and heterogeneous surface interactions. [ABSTRACT FROM AUTHOR]

Traditional freshwater sources have been over-abstracted in the worldwide crisis of water scarcity. Effluents have extremely high amounts of Zn2+ and Pb2+, according to an investigation of wastewater samples taken from several industrial zones. However, these heavy metals are among the most harmful to both humans and wildlife that are currently known. Streptomyces sp. is utilized in this study as a biosorbent to biosorb Zn2+ and Pb2+ from single and binary aqueous solutions. Several factors, such as biomass concentration (0.25–4 g), metal solution concentration (5–50 mg L−1), solution pH (2–5), and contact time were standardized. Streptomyces sp. biomass was able to extract 93% Pb2+ and 91% Zn2+ from a single and 95% Pb2+ and 97% Zn2+ from a binary metal aqueous solution containing 25 mg L−1 and pH 4. The highest adsorption capacity in both single and binary sorption experiments was determined to be shared by Zn2+ and Pb2+. The biosorbent's metal adsorption increased from 0.48 to 4.56 mg g−1 for Pb2+ and from 0.21 mg g−1 to 4.65 mg g−1 for Zn2+ when the metals were present singly, and from 0.44 to 4.18 mg g−1 for Pb2+ and from 0.41 mg g−1 to 5.67 mg g−1 for Zn2+ when the metals were present in binary form. The amount of metal ions was raised from 5 to 50 mg L−1. Correlation coefficient (R2) values indicate that the adsorption pattern for Zn2+ and Pb2+ followed Freundlich isotherm R2 > 0.9543 for single and 0.9582 for binary sorption system. In order to remove Zn2+ and Pb2+ from an aqueous solution, Streptomyces sp. is a potential and different source of adsorbents. [ABSTRACT FROM AUTHOR]

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Hydroxyapatite nanoparticles (HAp NPs) were synthesized with Muntingia calabura leaf extract as solvent and eggshell waste as a calcium source. The synthesized nanoparticles were irregular rod-like, as visualized by FESEM, while EDX and XPS studies confirmed the formation of hydroxyapatite. The synthesized HAp NPs were polycrystalline and highly thermostable as per XRD and TGA studies respectively. FTIR confirmed the stable coating of plant phytochemicals onto the HAp NPs. Congo red adsorption using HAp NPs nanoadsorbent was optimized by central composite design, wherein 89.96% of 33.18 mg/L dye was adsorbed in 137 min at 180 RPM. The adsorption process was in line with pseudo-second-order model and the Freundlich isotherm indicated chemical adsorption. The adsorption process was feasible, exothermic, and spontaneous as indicated by the thermodynamic studies. The adsorption capacity of HAp NPs stood at a maximum of 217 mg/g, indicating its superiority among other adsorbents reported earlier. It is evident from the convincing results that the HAp NPs synthesized in the present investigation may have a major role in developing novel adsorbents for dye removal out of wastewater streams.

Copyright of Baghdad Science Journal is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study demonstrated that Moringa oleifera seed biomass (MOSB) has the potential to be used as a natural alternative in the removal of lead (Pd), cadmium (Cd), and copper (Cu) from water which was justified by the level of toxicity, environmental unfriendliness, and costly nature of chemical coagulants presently used. The Fourier Transform Infrared (FTIR) analysis was used to identify the MOSB and functional groups present in the adsorption of metal ions. The maximum removal at pH 5, room temperature, and 0.8 g dosage was 90, 81.77, and 70% for Pb(II), Cd(II), and Cu(II), respectively. The order of biosorption preference was Pb(II)>Cd(II)>Cu(II) in single sorption and is in a consistent correlation between physiochemical properties of metal ions and selective biosorption of MOSB functional groups. The adsorption data fitted better to the Langmuir than the Freundlich models as the sorption capacities (qm) of MOSB for Pb(II), Cd(II), and Cu(II) were 6.19, 5.03, and 3.64 mg/g, respectively. The separation factor (RL) was within the range of 0–1 which showed that the Pb(II), Cd(II), and Cu(II) adsorption processes were favourable for M. oleifera adsorbent. The results showed that MOSB is an effective adsorbent in the removal of the studied heavy metals from contaminated water. In all these water-purifying properties of the moringa seed biomass, no deliberate attempt has been made to study the use of a ternary system of very toxic metals like Pb, Cd, and Cu knowing the anti-bacterial properties of the metal system. Similarly, the reproducibility, low cost, and no requirement of a power source make this an efficient process for obtaining potable water even in homes in rural settings. HIGHLIGHTS To evaluate the efficiency of Moringa oleifera seeds.; Process for producing defatted M. oleifera seeds.; It will guide researchers in examining the best techniques in water treatment.; It will allow young scientists to have an understanding of the alternative process of water treatment instead of the conventional process.;

Due to the use of non-recyclable materials and the high costs of the technologies, removal of dyes from wastewater is becoming more and more pricey. This paper presents the capacity of Ficus Benjamina (FB) leaf powder to eradicate methyl violet dye 10 B (MV) in an aqueous fluid. The surface characteristics and presence of various functional groups on the surface of sorbent were revealed by SEM and FTIR studies. Diverse constraints on the elimination of methyl violet 10 B in an aqueous environment were also studied, including starting dye concentration, temperature, and contact duration. The Elovich & liquid film diffusion models, along with Lagergren first-order, pseudo-second-order, Bangham, and modified Freundlich modeling operated to assess kinetics. Experiments confirmed the pseudo-second-order concept. To investigate tentative data, multiple linear Langmuir, Freundlich, Temkin, as well as two parameters nonlinear isotherm models were applied, with findings indicating that sorption data were like both linear and non-linear isotherms. Sorption data were found to be in excellent agreement with the Freundlich isotherm with R2 value (0.99). The sorption capacity of the sorbent was computed i.e. 312.2 mg/g. Thermodynamic characteristics were also computed. It was concluded that the sorption of methyl violet 10 B sorption on FB leaf powder is exothermic. Hence, it is a potentially cost-effective bio sorbent for exclusion of dye from wastewater.

Biosorption was carried out using Fraxinus excelsior L. (Oleaceae) (FEO) as a natural waste to remove methylene blue from aqueous solutions. Based on the results of the study carried out under optimum conditions (pH: 6, initial dye concentration: 5 mg/L, biosorbent dose: 1 g, contact time: 30 min, stirring speed: 150 rpm, and temperature: 298 K), the FEO biosorbent removed 89% of methylene blue from aqueous solutions. In addition, parameters affecting biosorption (pH, initial dye concentration, biosorbent dose, temperature, and stirring speed) were examined, and isotherm, kinetic, and thermodynamic studies were performed. Freundlich, Langmuir, Elovich, Temkin, and Dubinin–Radushkevich isotherms were calculated in the isotherm studies, and the Freundlich isotherm was higher than the others. The correlation coefficient of pseudo-second-order kinetic model was higher than for the pseudo-first-order kinetic model. The ΔG values from the thermodynamic studies showed that the process occurred spontaneously. Consequently, the FEO biosorbent is suitable in removing synthetic dyes from aqueous solutions due to its effectiveness, low cost, and eco-friendly characteristics. [ABSTRACT FROM AUTHOR]

This work shows the efficiency of wash waters from lipopeptide production as a remediation strategy to treat urban water samples contaminated with p-cresol. The harvesting step in surfactin production involved a centrifugation step, generating a major soluble fraction and a fraction that is adsorbed to the biomass. The adsorbed fraction was recovered by washing steps. These wash waters containing lipopeptides (mostly surfactins), were successfully used to adsorb and solubilize p-cresol. The method of decontamination applied to an artificially contaminated natural water was monitored using a biosensor based on laccase/magnetic nanoparticles. Given the amount of surfactin within the wash water, the removal of p-cresol from artificially contaminated water was approximately 46.0%. This result confirms the successful and sustainable application of surfactin-rich wash waters to remove p-cresol from artificially contaminated natural water. The adsorption mechanism is potentially based on a multi-layer adsorption process, considering Langmuir and Freundlich adsorption isotherms. [ABSTRACT FROM AUTHOR]

Waste from electrical and electronic equipment (WEEE) is constantly increasing in quantity and becoming more and more heterogeneous as technology is rapidly advancing. The negative impacts it has on human and environment safety, and its richness in valuable rare earth elements (REEs), are accelerating the necessity of innovative methods for recycling and recovery processes. The aim of this work is to comprehend the adsorption and release mechanisms of two different solid sorbents, activated carbon (AC) and its pentaethylenehexamine (PEHA)-modified derivative (MAC), which were deemed adequate for the treatment of REEs deriving from WEEE. Experimental data from adsorption and release tests, performed on synthetic mono-ionic solutions of yttrium, neodymium, and lanthanum, were modelled via linear regression to understand the better prediction between the Langmuir and the Freundlich isotherms for each REE-sorbent couple. The parameters extrapolated from the mathematical modelling were useful to gain an a priori knowledge of the REEs–sorbents interactions. Intraparticle diffusion was the main adsorption mechanism for AC. PEHA contributed to adsorption by means of coordination on amino groups. Release was based on protons fostering both a cation exchange mechanism and protonation. The investigated materials confirmed their potential suitability to be employed in real processes on WEEE at the industrial level. [ABSTRACT FROM AUTHOR]

Granular activated carbon (GAC) and ion exchange resin (IXR) are widely used as adsorbents to remove PFAS from drinking water sources and effluent waste streams. However, the high cost associated with GAC and IXR generation has motivated the development of less expensive adsorbents for treatment of PFAS-impacted water. Thus, the objective of this research was to create an economically viable and sustainable PFAS adsorbent from sewage sludge. Stepwise pyrolysis at temperatures from 300 °C to 1000 °C yielded biochars whose specific surface area (SSA) and porosity increased from 41 to 148 m2/g, and from 0.062 to 0.193 cm3/g, respectively. On a per organic char basis, the SSA of the biochar was as high as 1183 m2/g, which is comparable to commercially-available activated carbons. The adsorption of perfluorooctane sulfonic acid (PFOS) on sludge biochar increased with increasing pyrolysis temperature, which was positively correlated with increasing porosity and SSA. When 1000 °C processed biochar was tested with a mixture of eight PFAS, preferential adsorption of longer carbon chain-length species was observed, indicating the importance of PFAS hydrophobic interactions with the biochar and the availability of a wide range of mesopores. The adsorption of each PFAS was dependent upon both chain length and head group, with longer chain-length species exhibiting greater adsorption than shorter chain-length species, along with greater adsorption of species with sulfonic acid head groups compared to their chain length counterparts with carboxylic acid head groups. These findings demonstrate that biochar derived from municipal solid waste can serve as a cost-effective and sustainable adsorbent for the removal of PFOS and PFAS mixtures from source waters. The circular economy benefits and waste reduction potential associated with the use of sewage sludge-derived biochar supports the development of a viable sludge-derived biochar for the removal of PFAS from water. [Display omitted] • Biochars were derived from sewage sludge by pyrolysis at 300–1000 °C. • Adsorption isotherms were measured for eight PFAS on four biochars. • Biochar surface area and mesoporosity were key factors for PFAS adsorption. • Adsorption on biochar was dependent on PFAS chain-length and head group. • Repurposing of sludge into adsorptive biochar offers circular economy benefits. Synopsis : Biochar produced from a municipal solid waste is a potentially cost-effective and sustainable adsorbent for treatment of PFAS-impacted water. [ABSTRACT FROM AUTHOR]

The study focuses on the adsorption of caffeine (CAF) from aqueous solutions onto sawdust (SD), a naturally available, eco-friendly, and low-cost adsorbent. The influence of various operating parameters such as; CAF initial concentration (5–20 mg/L), SD dosage (0.5–3.0 g/L), and pH (3.0–9.0) was investigated in detail. The experimental results of the adsorption process showed the maximum CAF removal efficiency of 94.5% at optimized conditions (CAF initial concentration 5 mg/L, SD dosage 2.0 g/L, and pH 7.0). The applicability of adsorption isotherm models for CAF removal by SD has also been revealed. The R2 values obtained for Langmuir and Freundlich isotherms (0.9371 and 0.9966) showed that the Freundlich isotherm model with the higher R2 value of 0.9966 had better suitability than the Langmuir isotherm model. The suitability of experimental data was analyzed with response surface methodology using Design-Expert software. The obtained analysis of variance results with a coefficient of determination; R2 = 0.9643 and adjusted R2 value = 0.9516 demonstrated good agreement between experimental and predicted data. The 3D surface plots confirm the significance of all the three parameters investigated. [ABSTRACT FROM AUTHOR]

Due to the prevailing treacherous impacts of dyes on aquatic as well as terrestrial ecosystems, the designing of cost effective and facile removal methods are utmost need of time. The current research encompasses the study of modified rice husk (MRH) as an efficient adsorbent for the abatement of Congo red (CR), an anionic dye from an aqueous solution. Fourier transform infrared (FTIR) confirmed adsorption of CR onto MRH. Morphology of rice husk before and after modification was investigated by using scanning electron microscopy (SEM). Moreover, a prominent increase in surface area and porosity occurred through chemical treatment of rice husk. The effect of various factors including contact time, mass of MRH (dosage), initial concentration of CR in an aqueous solution, temperature and pH on CR adsorption was explored. Adsorption of CR was studied by using several isotherm models including Langmuir, Freundlich, Temkin and Dubinin–Radushkevich (D–R). Results showed that CR adsorption onto MRH fitted well to Freundlich isotherm. Adsorption kinetics for CR adsorption was revealed by applying many models such as pseudo-first-order, pseudosecond-order, Elovich model, modified Freundlich equation, and Bangham equation. Obtained results showed that CR adsorption from an aqueous solution onto MRH obeyed pseudo-secondorder model. Adsorption thermodynamics result showed that CR adsorption onto MRH was exothermic process (ΔH° = –4.75 kJ/mol). The maximum adsorption capacity of 10.13 mg/g was found. [ABSTRACT FROM AUTHOR]

As adsorption-desorption behaviour of herbicide plays an important role in determining leachability, release rate and availability to target species, the present study aims to evaluate the influence of soil properties, temperature and ionic state of imazamox on its adsorption-desorption behaviour. The sorption was significantly influenced by above evaluated parameters and Freundlich adsorption coefficient varied from 0.24 × 103 to 7.60 × 103 mg1−1/n kg−1 L1/n. In soils with pH in the range of 6.4–9.5, sorption of imazamox decreased with increase in solution pH while in acidic soil (pH 2.3 to 5.9), adsorption increased with increase in solution pH. At low solution pH adsorption occurs mainly through cationic form while at high solution pH adsorption was predominantly through anionic form. The presence of electrostatic attractive and repulsive forces, ∏→∏ charge transfer, hydrogen bonding and van der waals forces was key mechanism affecting the adsorption of imazamox. Greater adsorption hysteresis was observed in soils having pH in the range of 6.2–9.5 suggesting relatively less adsorption and difficult desorption of imazamox in these soils. Due to irreversible binding in high pH soil, it can be speculated that it may enhance the chances of crop injury in these soils. [ABSTRACT FROM AUTHOR]

Traditional freshwater sources have been over-abstracted in the worldwide crisis of water scarcity. Effluents have extremely high amounts of Zn2+ and Pb2+, according to an investigation of wastewater samples taken from several industrial zones. However, these heavy metals are among the most harmful to both humans and wildlife that are currently known. Streptomyces sp. is utilized in this study as a biosorbent to biosorb Zn2+ and Pb2+ from single and binary aqueous solutions. Several factors, such as biomass concentration (0.25–4 g), metal solution concentration (5–50 mg L−1), solution pH (2–5), and contact time were standardized. Streptomyces sp. biomass was able to extract 93% Pb2+ and 91% Zn2+ from a single and 95% Pb2+ and 97% Zn2+ from a binary metal aqueous solution containing 25 mg L−1 and pH 4. The highest adsorption capacity in both single and binary sorption experiments was determined to be shared by Zn2+ and Pb2+. The biosorbent’s metal adsorption increased from 0.48 to 4.56 mg g−1 for Pb2+ and from 0.21 mg g−1 to 4.65 mg g−1 for Zn2+ when the metals were present singly, and from 0.44 to 4.18 mg g−1 for Pb2+ and from 0.41 mg g−1 to 5.67 mg g−1 for Zn2+ when the metals were present in binary form. The amount of metal ions was raised from 5 to 50 mg L−1. Correlation coefficient (R2) values indicate that the adsorption pattern for Zn2+ and Pb2+ followed Freundlich isotherm R2 > 0.9543 for single and 0.9582 for binary sorption system. In order to remove Zn2+ and Pb2+ from an aqueous solution, Streptomyces sp. is a potential and different source of adsorbents.

A citric-acid-modified Moringa peregrina leaf substrate was prepared and studied as an effective adsorbent for the adsorptive removal of citalopram HBr (CTM). FTIR spectra were utilized to characterize the prepared solid. The effects of experimental variables on the percentage removal of citalopram HBr were investigated using response surface methodology. The optimum conditions selected for removal of CTM were 7 and 4 min, 0.17 g per 50 mL and 35 mg·L−1 for pH, contact time, adsorbent dose and initial concentration of CTM, respectively. Under the optimized experimental conditions, 82.59% CTM (35 mg·L−1) was removed. The Langmuir isotherm, Freundlich isotherm, pseudo second-order kinetic model and diffusion-chemisorption model explained the adsorption data successfully. The maximum adsorption capacity at 298 K was 8.58 mg·g−1. A thermodynamic study illustrated that CTM adsorption was spontaneous and endothermic in nature. [ABSTRACT FROM AUTHOR]

Phenol constitutes one of the main pollutants in wastewater. In the present study, adsorption with the use of a cheap alternative bio-filtration medium (activated ceramic, AC) was carried out to remove organic (phenol) and inorganic metals, such as zinc (Zn+2), copper (Cu+2), and lead (Pb+2). Activated ceramic was modified by ozonation with a mixture of crushed coal, Kaolin, and Bentonite, which were thermally treated in a vacuum furnace at temperatures ranging between 300 °C and 600 °C. The volume ratio of crushed coal to Kaolin to Bentonite was 4:6:1. This mixture was mixed with water by the volume ratio of 1:1. The mixture had been exposed to ozone before being used for activation. The pH measurements, chemical analysis, and FT-IR spectra were performed, and textural characterization was obtained. The influence of different parameters including different doses and contact times were investigated. For contact times of between 20 and 120 min, the removal efficiencies of phenol were 23% to 61%, and 56% to 79% with AC amounts of 5 g and 40 g, respectively. The Freundlich and Langmuir isotherm equations were used to explore the adsorption kinetics. The equilibrium data was found to best fit with both models. The use of AC for the removal of phenol showed a high removal efficiency of 85%, whereas the AC removes 67%, 59%, and 41% of Pb+2, Cu+2, and Zn+2, respectively.

[Display omitted] • Innovative Nanocomposite : Introduced g-C3N4-modified ZnO for efficient pollutant removal. • Comprehensive Characterization : Detailed SEM, BET, XPS, FTIR, and XRD analysis of nanosorbent. • Efficient Dye Removal : Adsorption capacity soared from 42.03 to 478.14 mg/g for Basic Fuchsin. • Adsorption Mechanism Insights : Explored hydrogen bonding and π-π interactions in detail. • Robust Reusability : Showcased multiple-cycle robustness, cost-effective wastewater solution. Organic dye pollution poses a critical environmental challenge, necessitating sustainable solutions for effective removal. This study presents a g-C 3 N 4 -modified ZnO nanosorbent to remove Basic Fuchsin dye from aqueous solutions efficiently. Synthesis and comprehensive characterization (SEM, BET, XPS, FTIR, XRD) elucidated the nanosorbent's properties and adsorption performance and mechanisms. Experimental results demonstrate optimal performance under alkaline conditions, with significant adsorption capacity (up to 478.14 mg/g at 300 ppm dye concentration). Adsorption behavior is well-described by the Freundlich isotherm and pseudo-first-order kinetic models. The nanosorbent demonstrates reusability and cost-effectiveness and exploits hydrogen bonding and π-π interactions for adsorption. This work highlights the potential of g-C 3 N 4 @ZnO as a promising solution for mitigating dye pollution and promoting sustainable water treatment technologies. [ABSTRACT FROM AUTHOR]

The bio-inspired synthesis of Fe3O4 nanoparticles using a common kitchen waste, Bengal gram bean (Cicer arietinum L.) extract (BGBE) for enhanced adsorption of toxic indigo carmine dye is reported. Synthesised adsorbent was characterised by FTIR, FE-SEM, XRD, BET and XPS to understand its meticulous properties. The Fe3O4 adsorbent shows fascinating surface area of 78.61 m2 g−1 with a pore volume of 0.25 cc g−1 at P/P0 = 0.98 and displayed nanograin like morphology. The efficiency towards adsorption of toxic IC dye was found up to 99.71 ± 0.35% within 40 min at pH 7 with 0.25 g of Fe3O4 nanomaterials having the 299 ± 2 K surrounding temperature. The Langmuir monolayer adsorption capacity was found to 393.7 mg g−1 at the stroke speed 150 rpm. The experimental data follows the Freundlich adsorption isotherm. Kinetically the uptake rate of IC dye follows pseudo-second-order kinetic model. The thermodynamic study reveals that IC dye adsorption process is spontaneous and endothermic in nature. [ABSTRACT FROM AUTHOR]

The groundwater quality has undergone a change to such an extent that the use of it could be risky and hazardous due to arsenic contamination. The presence of excess arsenic (> 0.01 mg/L) is area-specific, and the sources of contamination are mostly natural and geogenic. Arsenic-free safe drinking water can be supplied in affected areas by applying the appropriate arsenic removal technologies to groundwater or by the conventional surface water treatment process. Arsenic removal from groundwater is commonly accomplished through co-precipitation and adsorption processes. However, the application of the electrocoagulation method for the removal of arsenic has emerged as an efficient and appropriate technology. In the present study, electrocoagulation experiments were performed in batch mode using three different electrode combinations, viz. mild steel (MS)–stainless steel (SS), MS-MS, and MS–aluminum (Al) electrodes (anode–cathode) of locally available materials with arsenic-contaminated natural groundwater. The arsenic removal efficiency is significantly higher than 99% for MS–SS, MS-MS, and about 67% for MS–Al, and the pH, total dissolved solids (TDS), and iron levels in effluent water are within desirable limits. The value of empirical constants and correlation coefficient (R2) have been estimated for the Langmuir and Freundlich adsorption isotherm models. The R2 value of the Langmuir isotherm fits well for MS–SS, and MS-MS, but MS–Al fitted with the Freundlich isotherm. The kinetic study has been described using pseudo-first-order, pseudo-second-order, and intraparticle diffusion models. The pseudo-first-order rate of expression has been observed for MS-SS and MS-MS, whereas MS-Al has been followed the pseudo-second-order model. Finally, the intraparticle diffusion model confirms the equilibrium stage. [ABSTRACT FROM AUTHOR]

Batch adsorption experiments at pH 4 were conducted to estimate the Pb (II) removal abilities of adsorbents prepared from Acacia pennata pods, Artocarpus heterophyllus seeds, Colocasia esculenta tubers, and Ziziphus mauritiana seed stones at different initial Pb concentrations. The results obtained were analyzed using the Langmuir, the Freundlich, and the Dubinin–Radushkevich isotherms. Acacia pennata, A. heterophyllus, C. esculenta, and Z. mauritiana could remove 79–93, 66–85, 42–71, and 22–81% of Pb (II), respectively, from aqueous solutions. The Langmuir and Freundlich isotherm analysis revealed that A. pennata pods had the highest qmax (maximum adsorption capacity) and KF values, respectively. Artocarpus heterophyllus and A. pennata had the highest R2 values for the Langmuir and Freundlich isotherms, respectively. Among the different linear forms of Langmuir isotherm, Langmuir I showed the highest R2 value for A. pennata, C. esculenta, and Z. mauritiana, while R2 for A. heterophyllus did not show any difference among Langmuir I, II, and III. When compared with some other bioadsorbents, the qmax values for A. pennata and A. heterophyllus could be considered moderately high. Kinetic analysis showed that the pseudo-second-order kinetic model best explained the adsorption of Pb (II) on all the four adsorbents. The Dubinin–Radushkevich isotherm analysis indicated that adsorption mainly occurred through physical adsorption in the case of A. pennata, A. heterophyllus, and Z. mauritiana, while it was through chemisorption in C. esculenta. The findings suggest that A. pennata and A. heterophyllus could be further explored for their possible utilization in Pb removal from water. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are the dominant energy storage tools for electric vehicles and portable devices. Their prospects depend on the development of new electrode materials. The electrode properties are highly affected by phenomena on the electrode's surfaces. Besides experimental means, there are various simulation ways to investigate these phenomena where experiments have difficulty analyzing. However, simulating some of these events is challenging for existing simulation methods, and researchers are looking for new simulation tools to fill this gap. Here, we focus on developing and evaluating a new method for studying the key surface phenomenon inside a battery electrode in nanoscale, i.e., adsorption. In particular, we are interested in the adsorption behavior of ions on the surface of a nanosized electrode. We developed a general cellular automata model for studying the adsorption behavior of various materials, where desorption and intercalation happen during an adsorption process. The model results are compared with Freundlich isotherm and show a high resemblance. Also, an experiment concerning the lithium-ion adsorption on Titania nanotube is modeled with our C.A. model. The model is highly time-efficient and exhibits spectacular performance for simulating relatively complex systems as the results are quite close to the experimental results. As this model is general, its local rules and parameters can be modified and calibrated easily with either experiment or simulation, enabling one to study various sorption behaviors. [ABSTRACT FROM AUTHOR]

Coke wastewater is one of the most problematic industrial wastewaters, due to its large volume and complex pollutant load. In this study, ion exchange technology was investigated with the objective of reducing the fluoride content of the effluent from a coke wastewater treatment plant (26.7 mg F-/L). Two Al-doped exchange resins with chelating aminomethyl-phosphonic acid and iminodiacetic groups were assessed: Al-doped TP260 and TP207 resins, respectively. The effect of resin dosage, varying from 5 to 25 g/L, was evaluated. F- removal was within the range 57.8–89.3% and 72.0–92.1% for Al-doped TP260 and TP207, respectively. A kinetic study based on a generalized integrated Langmuir kinetic equation fitted the experimental data (R2 > 0.98). The parameters of the said kinetics met the optimal conditions for the ion exchange process, which seemed to be more favorable with Al-doped TP260 resin than with Al-doped TP207 resin, using the same resin dosage. Furthermore, the experimental data were well described (R2 > 0.98) by Langmuir and Freundlich isotherm models, in agreement with the findings of the kinetic study: the maximum sorption capacity was obtained for the Al-doped TP260 resin. [ABSTRACT FROM AUTHOR]

In this work, the stability of imidacloprid in fresh water and sludge was studied. The results revealed that the pesticide is unstable in both media. In fresh water, it underwent hydrolysis whereas a degradation to several metabolites has been observed in sludge. The rate constants for the hydrolysis and degradation at 25°C were 0.0.0067 and 0.0.0099 d–1, respectively. Monitoring the degradation of imidacloprid in sludge by high-pressure liquid chromatography-mass spectrometry (HPLC-MS) revealed that five metabolites have emerged during the study. These metabolites include imidacloprid urea, imidacloprid-guanidine, 6-hydroxynicotinic acid, an olefin, and 5-hydroxy, 1-(6-chloro-3-pyridylmethyl)-2-(nitroimino)-imidazolidin-5-ol. The efficiency of Al-Quds University Wastewater Treatment Plant towards the removal of imidacloprid indicates that the ultrafiltration-hollow fiber unit was insufficient, whereas the ultrafiltration-spiral wound, activated carbon, and reverse osmosis units were efficient for complete removal of the pesticide. Adsorption experiments of imidacloprid using either activated charcoal or micelle-clay complex were found to fit Langmuir isotherms better than Freundlich isotherm. The data demonstrate a higher Langmuir Qmax value for the activated charcoal (126.6 mg g–1) when compared to the micelle-clay complex (11.76 mg g–1). Filtration column experiments conducted with mixed micelle-clay complex and sand (using a ratio of 1/50 by mass) at a flow rate of 2 mL min–1 and influent concentration of 50 mg L–1 revealed that a sufficient removal of imidacloprid was achieved in the first fraction of 100 mL elution. These findings indicate that the adsorption technology using the micelle-clay complex provides efficient removal of imidacloprid in continuous flow mode. [ABSTRACT FROM AUTHOR]

In this study, activated carbon derived from Monotheca buxifolia waste seeds was used for the adsorptive removal of a number of selected azo dyes such as Eriochrome Black T (EBT), Remazol brilliant blue (RBB), Remazol yellow (RY) and Remazol brilliant orange (RBO) from an aqueous solution by changing the initial dye concentration, adsorbent dosage, solution pH, contact time and temperature. A Fourier transform infrared spectroscopic analysis of the activated carbon showed the existence of hydroxyls, methyl, methylene, carbonyls, alkane and alkenes groups while the scanning electron microscopic image displayed the gradual formation of cavities and open pores on the surface. The results showed that as the amount of the adsorbent and the shaking time were increased, the removal percentage of the dye increased accordingly. Higher adsorption percentages were observed at a lower dye concentration and temperature in an acidic media at a pH range (1-5). The investigated data were evaluated with the Langmuir and Freundlich adsorption models. The maximum adsorption capacities obtained from the Langmuir model were 112.36, 96.34, 97.65 and 90.91 mg/g for EBT, RBB, RY and RBO, respectively. The results indicated that the electrostatic interaction was the main cause of the adsorption of these anionic azo dyes on the surface of the activated carbon.