Enhanced solar light photocatalytic performance of Fe-ZnO in the presence of H2O2, S2O82−, and HSO5− for degradation of chlorpyrifos from agricultural wastes: Toxicities investigation

This study reported Fe doped zinc oxide (Fe-ZnO) synthesis to degrade chlorpyrifos (CPY), a highly toxic organophosphate pesticide and important sources of agricultural wastes. Fourier transform infrared, X-ray diffraction, scanning electron microscope, and energy-dispersive X-ray spectroscopic analyses showed successful formation of the Fe-ZnO with highly crystalline and amorphous nature. Water collected from agricultural wastes were treated with Fe-ZnO and the results showed 67% degradation of CPY by Fe-ZnO versus 39% by ZnO at 140 min treatment time. Detail mechanism involving reactive oxygen species production from solar light activated Fe-ZnO and their role in degradation of CPY was assessed. Use of H2O2, peroxydisulfate (S2O82−) and peroxymonosulfate (HSO5−) with Fe-ZnO under solar irradiation promoted removal of CPY. The peroxides yielded hydroxyl ([rad]OH) and sulfate radical ([Formula presented]) under solar irradiation mediated by Fe-ZnO. Effects of several parameters including concentration of pollutant and oxidants, pH, co-existing ions, and presence of natural organic matter on CPY degradation were studied. Among peroxides, HSO5− revealed to provide better performance. The prepared Fe-ZnO showed high reusability and greater mineralization of CPY. The GC-MS analysis showed degradation of CPY resulted into several transformation products (TPs). Toxicity analysis of CPY as well as its TPs was performed and the formation of non-toxic acetate imply greater capability of the treatment technology

Zeolite-Assisted Immobilization and Health Risks of Potentially Toxic Elements in Wastewater-Irrigated Soil under Brinjal (Solanum melongena) Cultivation

Application of wastewater to agricultural soils not only enhances economic benefits but is also considered as a safe disposal option by the administrators. Worldwide, peri-urban horticulture is a common practice for growing vegetables. When agricultural soils are irrigated with wastewater, numerous potentially toxic elements (PTEs) contained therein are bioaccumulated and pose health risks. The presented study aimed to reveal the PTEs, i.e., copper (Cu), cadmium (Cd), nickel (Ni) and lead (Pb) concentration in the agricultural soils irrigated with wastewater for longer times. Zeolite, a natural mineral was used to immobilize these in contaminated soils to reduce its availability to brinjal (Solanum melongena L.). During a pot study, zeolite was applied at four different levels, i.e., 0.25, 0.50, 1.00 and 2.00% in contaminated soil, keeping one control. The results revealed that growth as well as biochemical and physiological characters were found best with treatment receiving zeolite at 2.00%. In edible parts (fruit), PTE contents were found lowest in the same treatment. Relative to the control, ~121, 87, 120 and 140% less DTPA-extracted Cu, Cd, Ni and Pb in soil was found with this treatment. Based on the results, it was revealed that zeolite effectively immobilized Cu, Cd, Ni and Pb in the soil. Although all the applied levels of zeolite had positive potential to immobilize PTEs in wastewater-contaminated soil, zeolite applied at 2.00% proved most effective.11s

Visible light driven doped CeO2 for the treatment of pharmaceuticals in wastewater: A review

The high-level contamination of pharmaceuticals in aquatic environment, and their toxicities is a serious issue. This review highlights the use of ceria photocatalyst for treatment of pharmaceuticals. Cerium oxide (CeO2) with high oxygen storage, ecofriendly properties, reusability, and photostability contrary to other metal oxides photocatalysts is reportedly a better choice. However, ceria with high band gap energy show photoactivity mainly under UV light. This review highlights pharmaceuticals contamination in water, their contamination level, and toxicities and properties of CeO2 and different approaches used for extending photoactivity of CeO2 under visible irradiation. Metals and non-metals doping is found to promote greatly photoactivity of CeO2 under visible irradiation by narrowing band gap, shift in absorption edge to visible region, crystal defects and yield of oxygen vacancy, lower recombination of conduction band electrons and valence band holes and increasing surface area. The visible irradiation of CeO2 is found to produce hydroxyl radical (OH) and superoxide radical (O2 –) which contribute in pharmaceuticals degradation. The electron paramagnetic resonance spectroscopy and radical scavenger studies confirmed the formation of reactive oxygen species from CeO2 photoactivation. Doping was found to incorporate into the lattice of CeO2 and improve reusability and stability of CeO2 photocatalyst. The suggested mechanisms involved in the treatment of pharmaceuticals through OH and O2 – is discussed. Furthermore, the outlook and future challenges in the use CeO2 for photocatalytic degradation of pharmaceuticals and other organic pollutants are evaluated

Toxicities, kinetics and degradation pathways investigation of ciprofloxacin degradation using iron-mediated H\u3csub\u3e2\u3c/sub\u3eO\u3csub\u3e2\u3c/sub\u3e based advanced oxidation processes

© 2018 Institution of Chemical Engineers Ciprofloxacin (CIP) is a widespread emerging water pollutant and thus its removal from aquatic environment is vital. The use of Fe3+/H2O2 and Fe2+/H2O2 resulted in 38 and 64% removal of CIP (8.0 ppm), respectively, within 80 min reaction time (pH 5.8, [H2O2]0 = 80 ppm, and [iron]0 = 20 ppm). Low pH, high temperature, high dose of H2O2 and Fe2+, and low CIP concentration facilitated removal of CIP. The radical scavenger studies proved in situ generated [rad]OH to be involved primarily in the removal of CIP. The effect of temperature was used to estimate enthalpy and activation energies of the removal of CIP. At 800 min reaction time, the Fe2+/H2O2 resulted in 54% mineralization of CIP using 16.0 ppm [CIP]0, 320.0 ppm [H2O2]0, and 40.0 ppm [Fe2+]0. The potential degradation pathways of CIP established from the degradation of CIP by [rad]OH and products evolved was found to be initiated at C6 through the loss of fluoride ion. The acute and chronic toxicities of CIP and its degradation products were estimated with the final product found to be non-toxic. The results suggest that Fe2+/H2O2-mediated AOPs have high potential for degradation as well as toxicity elimination of CIP and its degradation products

Chromium removal from aqueous solution using bimetallic Bi\u3csup\u3e0\u3c/sup\u3e/Cu\u3csup\u3e0\u3c/sup\u3e-based nanocomposite biochar

Chromium (Cr), due to its greater contamination in aquifers and distinct eco-toxic impacts, is of greater environmental concern. This study aimed to synthesize nanocomposites of almond shells biochar (BC) with zerovalent bismuth and/or copper (Bi0/BC, Cu0/BC, and Bi0–Cu0/BC) for the removal of Cr from aqueous solution. The synthesized nanocomposites were investigated using various characterization techniques such as XRD, FTIR spectroscopy, SEM, and EDX. The Cr removal potential by the nanocomposites was explored under different Cr concentrations (25–100 mg/L), adsorbent doses (0.5–2.0 g/L), solution pH (2–8), and contact time (10–160 min). The above-mentioned advanced techniques verified successful formation of Bi0/Cu0 and their composite with BC. The synthesized nanocomposites were highly effective in the removal of Cr. The Bi0–Cu0/BC nano-biocomposites showed higher Cr removal efficiency (92%) compared to Cu0/BC (85%), Bi0/BC (76%), and BC (67%). The prepared nanocomposites led to effective Cr removal at lower Cr concentrations (25 mg/L) and acidic pH (4.0). The Cr solubility changes with pH, resulting in different degrees of Cr removal by Bi0–Cu0/BC, with Cr(VI) being more soluble and easier to adsorb at low pH levels and Cr(III) being less soluble and more difficult to adsorb at high pH levels. The experimental Cr adsorption well fitted with the Freundlich adsorption isotherm model (R 2 \u3e 0.99) and pseudo-second-order kinetic model. Among the prepared nanocomposites, the Bi0–Cu0/BC showed greater stability and reusability. It was established that the as-synthesized Bi0–Cu0/BC nano-biocomposite showed excellent adsorption potential for practical Cr removal from contaminated water

The study of removal chromium (VI) ions from aqueous solution by bimetallic ZnO/FeO nanocomposite with Siltstone: Isotherm, kinetics and reusability

In this study, nanocomposites of Baghanwala Siltstone (BSS) with ZnO (BSS/ZnO), FeO (BSS/FeO), and BSS/ZnO/FeO were successfully prepared for the removal of hexavalent chromium [(Cr (VI)] from aqueous solutions via a batch adsorption process. The characterization studies by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX) found successful synthesis of the composites and demonstrated the occurrence of different active functional groups that played an active role in Cr ion adsorption. The effect of Cr initial concentrations (25–100 mg/L), adsorbent dose (0.5–2 g/L), pH (2–8), and contact time (0–160 min) on Cr remediation from contaminated water was examined. The order of Cr ion removal was BSS/ZnO/FeO (77–87%) \u3e BSS/ZnO (74–83%) \u3e BSS/FeO (71–77%) \u3e BSS (68–74%). The as-synthesized BSS/ZnO/FeO led to successful Cr removal (87%) at a 25 mg/L Cr concentration at pH 4.0. The Cr ion adsorption by the BSS/ZnO/FeO nanocomposite was well explained by the Langmuir adsorption isotherm model (R2 \u3e 0.99), while the kinetic experimental data was well fitted with the pseudo-second-order model (R2 \u3e 0.99). Among the as-synthesized adsorbents, the BSS/ZnO/FeO nanocomposite showed excellent stability and reusability in seven sorption cycles. The results showed that the as-synthesized BSS/ZnO/FeO nanocomposite had the greatest adsorption potential for removing Cr ions from contaminated water

Potential of siltstone and its composites with biochar and magnetite nanoparticles for the removal of cadmium from contaminated aqueous solutions: Batch and column scale studies

© 2020 Elsevier Ltd The present study is the first attempt to evaluate the pilot and batch scale adsorption potential of siltstone (SS) and its nanocomposites with biochar (EDB/SS), magnetite nanoparticles (MNPs/SS) and MNPs/EDB/SS for Cd removal from contaminated water. The SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were characterized with FTIR, XRD, BET, SEM, TEM, TGA and point of zero charge (PZC). The effects of adsorbent dosage, contact time, initial Cd concentration, pH and presence of competing ions were evaluated on the Cd removal and its adsorption. The order for Cd removal was: MNPs/EDB/SS \u3e MNPs/SS \u3e EDB/SS \u3e SS (95.86–99.72% \u3e 93.10–98.5% \u3e 89.66.98–98.40% \u3e 74.90–90%). Column scale experiments yielded maximum retention (95%) of Cd even after 2 h of injection at 100 mg Cd/L. The exhausted SS, EDB/SS, MNPs/SS and MNPs/EDB/SS were reused without losing significant adsorption potential. Similarly, maximum Cd adsorption (117.38 mg/g) was obtained with MNPs/EDB/SS at dose 1.0 g/L. The results revealed that coexisting cations reduced the Cd removal due to competition with Cd ions. The experimental results were better explained with Freundlich isotherm model and pseudo 2nd order kinetic models. The results revealed that SS and its composites can be used efficiently for the removal of Cd from contaminated water

Effect of biochar modified with magnetite nanoparticles and HNO\u3csub\u3e3\u3c/sub\u3e for efficient removal of Cr(VI) from contaminated water: A batch and column scale study

© 2020 Elsevier Ltd Chromium (Cr) poses serious consequences on human and animal health due to its potential carcinogenicity. The present study aims at preparing a novel biochar derived from Chenopodium quinoa crop residues (QBC), its activation with magnetite nanoparticles (QBC/MNPs) and strong acid HNO3 (QBC/Acid) to evaluate their batch and column scale potential to remove Cr (VI) from polluted water. The QBC, QBC/MNPs and QBC/Acid were characterized with SEM, FTIR, EDX, XRD as well as point of zero charge (PZC) to get an insight into their adsorption mechanism. The impact of different process parameters including dose of the adsorbent (1–4 g/L), contact time (0–180 min), initial concentration of Cr (25–200 mg/L) as well as solution pH (2–8) was evaluated on the Cr (VI) removal from contaminated water. The results revealed that QBC/MNPs proved more effective (73.35–93.62-%) for the Cr (VI) removal with 77.35 mg/g adsorption capacity as compared with QBC/Acid (55.85–79.8%) and QBC (48.85–75.28-%) when Cr concentration was changed from 200 to 25 mg/L. The isothermal experimental results follow the Freundlich adsorption model rather than Langmuir, Temkin and Dubinin-Radushkevich adsorption isotherm models. While kinetic adsorption results were well demonstrated by pseudo second order kinetic model. Column scale experiments conducted at steady state exhibited excellent retention of Cr (VI) by QBC, QBC/MNPs and QBC/Acid at 50 and 100 mg Cr/L. The results showed that this novel biochar (QBC) and its modified forms (QBC/Acid and QBC/MNPs) are applicable with excellent reusability and stability under acidic conditions for the practical treatment of Cr (VI) contaminated water

Synthesis, characterization and application of novel MnO and CuO impregnated biochar composites to sequester arsenic (As) from water: Modeling, thermodynamics and reusability

© 2020 Elsevier B.V. The present study aimed at enhancing the adsorption potential of novel nanocomposites of Sesbania bispinosa biochar (SBC) with copper oxide (SBC/CuO) and manganese oxide nanoparticles (SBC/MnO) for the efficient and inexpensive removal of environmentally concerned contaminant arsenic (As) from contaminated water at batch scale. The scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, energy dispersive X-ray (EDX), X-ray diffraction (XRD) and point of zero charge (PZC) analyses proved successful impregnation of the metallic nanoparticles on SBC surface. The results revealed the maximum As removal (96 %) and adsorption (12.47 mg/g) by SBC/CuO composite at 10 mg As/L, optimum pH-4, dose 1.0 g/L and ambient temperature (25 ± 1.5 °C) as compared with SBC (7.33 mg/g) and SBC/MnO (7.34 mg/g). Among four types of adsorption isotherms, Freundlich isotherm demonstrated best fit with R2 \u3e 0.997. While pseudo second-order kinetic model revealed better agreement with kinetic experimental data as matched with other kinetic models. The thermodynamic results depicted that As adsorption on the as-synthesized adsorbents was endothermic and spontaneous in nature with increased randomness. The SBC/CuO displayed excellent reusability and stability over four adsorption/desorption cycles and proved that the as-synthesized SBC/CuO composite may be the efficient adsorbent for practical removal of As from contaminated water

Reclamation of salt-affected soils using amendments and growing wheat crop

With more pressing demands for non-agricultural sectors, availability of good-quality water is falling short of the crop water requirement, particularly in arid and semi-arid regions of the world, like Pakistan. Studies were conducted at three sites following randomized complete block design (RCBD) with three replications. The treatments employed were: Tube well water (TW) alone; TW + Gypsum @ 50% soil gypsum requirement (TW + G50); TW–Canal water (CW) + G50; TW–CW + farm manure (FM) @ 25 Mg ha-1 (TW-CW + FM) before sowing wheat. After the harvest of wheat 2008-09, non-significant decrease in bulk density was recorded with applied treatments while infiltration rate remained unchanged. There was maximum and significant decrease in ECe and SAR with TW–CW + FM at all the three sites. Maximum decrease in ECe (72.65%) at 0-15 cm soil depth was at site 2, while maximum decrease in ECe (77.62%) at 15-30 cm soil depth was at site 1. Maximum percent decrease in SAR was 75.76% at 0-15 cm followed by 63.93% at15-30 cm at sites 2 and 3, respectively, with TW–CW + FM. Maximum wheat grain yields (3656, 3531 and 3826 kg ha-1) and straw yields (4826, 4624 and 4707 kg ha-1) were recorded at sites 1, 2 and 3, respectively, with TW–CW + FM. The net benefit was maximum with TW–CW + FM at all the three sites