scholarly journals Removal of Chromium from a Contaminated Soil Using Oxalic Acid, Citric Acid, and Hydrochloric Acid: Dynamics, Mechanisms, and Concomitant Removal of Non-Targeted Metals

2019 ◽  
Vol 16 (15) ◽  
pp. 2771 ◽  
Author(s):  
Sun ◽  
Guan ◽  
Yang ◽  
Wang
Keyword(s):  
Citric Acid ◽  
Hydrochloric Acid ◽  
Oxalic Acid ◽  
Contaminated Soil ◽  
Photoelectron Spectroscopy ◽  
Contaminated Soils ◽  
Acid Leaching ◽  
Morphological Properties ◽  
X Ray ◽  
Fe And Mn

Soil leaching is an effective remediation technique using agents to leach the target pollutants from the soil. However, the dynamics and mechanisms for leaching of Cr and other non-pollutant metals from Cr-contaminated soils are not yet well understood. Here, column leaching experiments were conducted to determine the effect of hydrochloric acid (HCl), citric acid (CA), and oxalic acid (OX) on the leaching of Cr, as well as of Ca, Mg, Fe, and Mn, from a soil contaminated by a Cr slag heap. Acid leaching decreased soil pH and enhanced the mobility of all the surveyed metals. Leaching dynamics varied with both metals and acids. OX had the highest removal rates for Cr, Fe, Mn, and Mg, but had the poorest ability to leach Ca. HCl leached the largest amount of Ca, while CA leached similar amounts of Mg and Mn to OX, and similar amounts of Fe and Cr to HCl. Cr in the leachates was correlated with Ca, Mg, Fe, and Mn. Cr mainly interacted with soil mineral components and showed a punctate distribution in soil particles. The X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS) analyses showed soil mineralogical and morphological properties were differently altered after leaching by different acids. Complexation of Cr(III), competitive desorption, and reduction of Cr(VI) make significant contribution to Cr leaching by organic acids. In conclusion, OX can be applied in leaching remediation of Cr-contaminated soil, but the concomitant removal of other non-targeted metals should be taken into account because of the loss of soil minerals and fertility.

scholarly journals The Effect of Citric Acid Concentration on the Properties of LaMnO3 as a Catalyst for Hydrocarbon Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 226 ◽  
Author(s):  
Zakaria Sihaib ◽  
Fabrizio Puleo ◽  
Giuseppe Pantaleo ◽  
Valeria La Parola ◽  
José Luis Valverde ◽  
...  
Keyword(s):  
Citric Acid ◽  
Physicochemical Properties ◽  
Photoelectron Spectroscopy ◽  
Catalytic Performance ◽  
Morphological Properties ◽  
Molar Ratio ◽  
Hydrocarbon Oxidation ◽  
Total Oxidation ◽  
Propene Oxidation ◽  
X Ray

LaMnO3 (LM) catalysts with a molar ratio of citric acid (CA) to metal (La3+ + Mn2+) nitrates ranging from 0.5 to 2 (LM0.5 to LM2) were synthesized by the citrate sol–gel method with the aim of studying the effect of the citric acid ratio on the physicochemical properties and the catalytic performance in hydrocarbon oxidation. Structural and morphological properties of these catalysts were characterized by X-ray diffraction (XRD) and specific surface area (N2 adsorption) measurements, while the chemical composition was determined by inductively coupled plasma atomic emission spectroscopy (ICP-OES). In the selected samples, additional characterizations were carried out by thermogravimetric and differential thermal analysis (TGA/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), temperature-programmed reduction by hydrogen (H2-TPR), and X-ray photoelectron spectroscopy (XPS). The results showed that the amount of citric acid used significantly influenced the TGA/DTA profile of gels along with the physicochemical properties of the catalysts. The XRD patterns are consistent with the perovskite formation as the main phase. The segregation of a small amount of Mn3O4, detected for molar ratios ranging between 0.5 and 1.5, suggested the formation of a slightly nonstoichiometric LaMn1−xO3 phase with a relatively high content of Mn4+. The catalytic performance was evaluated in the total oxidation of two selected hydrocarbons, toluene and propene, which represent typical volatile organic compounds (VOCs). Typically, three consecutive catalytic cycles were performed in order to reach steady-state performance in toluene and propene oxidation. Moreover, the stability of the catalysts under reaction conditions was investigated through 24-h experiments at 17% of toluene conversion. The catalysts LM1.2, LM1.3, and LM1.5 showed the best catalytic performance in both hydrocarbon oxidations, well comparing with the Pd/Al2O3 used as a reference.

Remediation of Arsenic Contaminated Soils and Treatment of Washing Effluent Using Calcined Mn-Fe Layered Double Hydroxide

2014 ◽  
Vol 955-959 ◽  
pp. 2014-2021 ◽  
Author(s):  
Pei Ya Liu ◽  
Huan Liu ◽  
Yu Jiao Li ◽  
Chang Xun Dong
Keyword(s):  
Citric Acid ◽  
Oxalic Acid ◽  
Layered Double Hydroxide ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Pure Water ◽  
Soil Washing ◽  
Extraction Rate ◽  
Effective Capacity ◽  
Double Hydroxide

Arsenic contaminated soil is a serious worldwide problem nowadays, and soil washing technique is one of hottest topics in the area of remediating arsenic contaminated soils, while treatment of the washing effluent is still an urgent problem. In this study, in order to select the best washing extractants for arsenic contaminated soil of the Xiangxi Autonomous Prefecture, nine kinds of extractants (citric acid, oxalic acid, malic acid, tartaric acid, H3PO4, KH2PO4, KOH, NH4Ac and ultra-pure water) were studied. Innovatively, a new material (calcined Mn-Fe Layered double hydroxide) was firstly introduced and fully applied to the adsorption of arsenic washing effluents. Results showed citric acid, oxalic acid and KH2PO4 were the optimal extractants for arsenic contaminated soil, considering the extraction rate and environmental perspective. When the concentrations were 200, 300, 300 mmol/ L , solution soil ratios were 10, 10, 20 mL/g , extraction times were 12,12,12 h, the citric acid, oxalic acid and KH2PO4, respectively, achieved the maximum extraction rate of 39%, 65% and 29%. Calcined Mn-Fe LDH used in this work was characterized by SEM and FT-IR, indicating the unique structure and high phase purity of the synthetic samples. For the 28mg/L arsenic effluent washing by citric acid, calcined Mn-Fe LDH showed the most effective capacity as adsorbent under neutral or weak base condition as well as 2 h absorption time.

scholarly journals Characterization of MgO:Cd thin films grown by SILAR method

2018 ◽  
Vol 96 (7) ◽  
pp. 804-809 ◽  
Author(s):  
Harun Güney ◽  
Demet İskenderoğlu
Keyword(s):  
Thin Films ◽  
Photoelectron Spectroscopy ◽  
Soda Lime ◽  
Morphological Properties ◽  
Emission Region ◽  
Soda Lime Glass ◽  
Silar Method ◽  
Soda Lime Glass Substrate ◽  
X Ray ◽  
Cd Doping

The undoped and 1%, 2%, and 3% Cd-doped MgO nanostructures were grown by SILAR method on the soda lime glass substrate. X-ray diffractometer (XRD), ultraviolet–visible spectrometer, scanning electron microscope, photoluminescence (PL), and X-ray photoelectron spectroscopy measurements were taken to investigate Cd doping effects on the structural, optical, and morphological properties of MgO nanostructures. XRD measurements show that the samples have cubic structure and planes of (200), (220) of MgO and (111), (200), and (220) of CdO. It was observed that band gaps increase with rising Cd doping rate in MgO thin film. The surface morphology of samples demonstrates that MgO nanostructures have been affected by the Cd doping. PL measurements show that undoped and Cd-doped MgO thin films can radiate in the visible emission region.

scholarly journals Preparation of pod-shaped TiO 2 and Ag@TiO 2 nano burst tubes and their photocatalytic activity

2019 ◽  
Vol 6 (9) ◽  
pp. 191019 ◽  
Author(s):  
Shang Wang ◽  
Zhaolian Han ◽  
Tingting Di ◽  
Rui Li ◽  
Siyuan Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photocatalytic Activity ◽  
Oxalic Acid ◽  
Ultraviolet Light ◽  
Photoelectron Spectroscopy ◽  
Degradation Process ◽  
Catalytic Performance ◽  
Tetrabutyl Titanate ◽  
Order Kinetic ◽  
X Ray

The pod-shaped TiO 2 nano burst tubes (TiO 2 NBTs) were prepared by the combination of electrospinning and impregnation calcination with oxalic acid (H 2 C 2 O 4 ), polystyrene (PS) and tetrabutyl titanate. The silver nanoparticles (AgNPs) were loaded onto the surface of TiO 2 NBTs by ultraviolet light reduction method to prepare pod-shaped Ag@TiO 2 NBTs. In this work, we analysed the effect of the amount of oxalic acid on the cracking degree of TiO 2 NBTs; the effect of the concentration of AgNO 3 solution on the particle size and loading of AgNPs on the surface of TiO 2 NBTs. Scanning electron microscopy and transmission electron microscopy investigated the surface morphology of samples. X-ray diffraction and X-ray photoelectron spectroscopy characterized the structure and composition of samples. Rhodamine B (RhB) solution was used to evaluate the photocatalytic activity of pod-shaped TiO 2 NBTs and Ag@TiO 2 NBTs. The results showed that TiO 2 NBTs degraded 91.0% of RhB under ultraviolet light, Ag@TiO 2 NBTs degraded 95.5% under visible light for 75 and 60 min, respectively. The degradation process of both samples was consistent with the Langmuir–Hinshelwood first-order kinetic equation. Therefore, the catalytic performance of the sample is: Ag@TiO 2 NBTs > TiO 2 NBTs > TiO 2 nanotubes.

scholarly journals Stabilization Study of a Contaminated Soil with Metal(loid)s Adding Different Low-Grade MgO Degrees

2020 ◽  
Vol 12 (18) ◽  
pp. 7340
Author(s):  
Jessica Giro-Paloma ◽  
Joan Formosa ◽  
Josep M Chimenos
Keyword(s):  
Contaminated Soil ◽  
Contaminated Soils ◽  
Low Grade ◽  
X Ray Diffraction ◽  
Optimal Stabilization ◽  
X Ray ◽  
Neutralization Capacity ◽  
Stabilizing Agents ◽  
Acid Test ◽  
By Products

Low-grade magnesium oxide (LG-MgO) was proposed as ordinary Portland cement (OPC) or lime substitute (CaO) for metal(loid)s remediation in contaminated soils. Some metal(loid)s precipitate at pH ≈ 9 in insoluble hydroxide form thus avoiding their leaching. LG-MgO avoids the re-dissolution of certain metal(loid)s at 9.0 < pH < 11.0 (pH-dependents), whose solubility depends on the pH. A highly contaminated soil with heavy metal(loid)s was stabilized using different LG-MgO by-products sources as stabilizing agents. Two of the three studied LG-MgOs were selected for the stabilization, by mixing 5, 10, and 15 wt.%. The effect of using LG-MgO not only depends on the size of the particles, but also on those impurities that are present in the LG-MgO samples. Particle size distribution, X-ray fluorescence (XRF), X-ray diffraction (XRD), thermogravimetric analysis, citric acid test, specific surface, bulk density, acid neutralization capacity, batch leaching tests (BLTs), and percolation column tests (PCTs) were techniques used to deeply characterize the different LG-MgO and the contaminated and remediated soils. The remediation’s results efficacy indicated that when the medium pH was between 9.0 and 11.0, the concentration of pH-dependent metal(loid)s decreases significantly. Although around 15 wt.% of a stabilizing agent was appropriate for the soil remediation to ensure an alkali reservoir that maintains optimal stabilization conditions for a long period, 5 wt.% of LG-MgO was enough to remedy the contaminated soil. When evaluating a polluted and decontaminated soil, both BLTs and PCTs should be complementary procedures.

scholarly journals Uranium Leaching from Contaminated Soil Utilizing Rhamnolipid, EDTA, and Citric Acid

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Sara Asselin ◽  
Jani C. Ingram
Keyword(s):  
Citric Acid ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Metal Removal ◽  
Uranium Content ◽  
Open Pit ◽  
Open Pit Mining ◽  
Water Control ◽  
Soil Matrix ◽  
Northern Arizona

Biosurfactants have recently gained attention as “green” agents that can be used to enhance the remediation of heavy metals and some organic matter in contaminated soils. The overall objective of this paper was to investigate rhamnolipid, a microbial produced biosurfactant, and its ability to leach uranium present in contaminated soil from an abandoned mine site. Soil samples were collected from two locations in northern Arizona: Cameron (site of open pit mining) and Leupp (control—no mining). The approach taken was to first determine the total uranium content in each soil using a hydrofluoric acid digestion, then comparing the amount of metal removed by rhamnolipid to other chelating agents EDTA and citric acid, and finally determining the amount of soluble metal in the soil matrix using a sequential extraction. Results suggested a complex system for metal removal from soil utilizing rhamnolipid. It was determined that rhamnolipid at a concentration of 150 μM was as effective as EDTA but not as effective as citric acid for the removal of soluble uranium. However, the rhamnolipid was only slightly better at removing uranium from the mining soil compared to a purified water control. Overall, this study demonstrated that rhamnolipid ability to remove uranium from contaminated soil is comparable to EDTA and to a lesser extent citric acid, but, for the soils investigated, it is not significantly better than a simple water wash.

Removal of Bound PAH Residues in Contaminated Soils by Fenton Oxidation

Catalysts ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 619 ◽  
Author(s):  
Xuqiang Zhao ◽  
Li Qin ◽  
Michael Gatheru Waigi ◽  
Pengfei Cheng ◽  
Bing Yang ◽  
...  
Keyword(s):  
Citric Acid ◽  
Oxalic Acid ◽  
Contaminated Soils ◽  
Chelating Agent ◽  
Fenton Oxidation ◽  
Valuable Insight ◽  
First Order Kinetics ◽  
Bound Residues ◽  
Polycyclic Aromatic ◽  
Insight Into

The availability of bound residues of polycyclic aromatic hydrocarbons (PAHs), in reference to their parent compounds, can be enhanced by microbial activity and chemical reactions, which pose severe risks for the ecosystems encompassing contaminated soils. Considerable attention has been raised on how to remove these bound residues from PAH-contaminated soils. This paper provides a novel application of Fenton oxidation in the removal of bound residues of model PAHs, such as naphthalene (NAP), acenaphthene (ACP), fluorene (FLU) and anthracene (ANT), from naturally contaminated soils. The citric acid-enhanced Fenton treatment resulted in the degradation of bound PAH residues that followed pseudo-first-order kinetics, with rate constants within 4.22 × 10−2, 1.25 × 10−1 and 2.72 × 10−1 h−1 for NAP, FLU, and ANT, respectively. The reactivity of bound PAH residues showed a correlation with their ionization potential (IP) values. Moreover, the degradation rate of bound PAH residues was significantly correlated with H2O2-Fe2+ ratio (m/m) and H2O2 concentrations. The highest removal efficiencies of bound PAH residues was up to 89.5% with the treatment of chelating agent oxalic acid, which was demonstrated to be superior to other acids, such as citric acid and hydrochloric acid. This study provides valuable insight into the feasibility of citric acid-Fenton and oxalic acid-Fenton treatments in rehabilitating bound PAH residues in contaminated soils.

Preparation of LiFePO4/C Composite Powders

2011 ◽  
Vol 391-392 ◽  
pp. 377-380
Author(s):  
Guo Jun Li ◽  
Ming Yang ◽  
Hai Li Jing ◽  
Rui Ming Ren
Keyword(s):  
Citric Acid ◽  
Oxalic Acid ◽  
Specific Capacity ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
Charge Capacity ◽  
X Ray ◽  
Initial Charge

LiFePO4/C composite powders were prepared by a simple reaction of as-synthesized FePO4•2H2O, LiOH•H2O, oxalic acid and citric acid. The influence of oxalic acid and citric acid in different ratios was investigated on morphology and electrochemical performance of LiFePO4/C composite powders. The characterization of the composites included X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis indicates that the material is well crystallized without impurities. The obtained LiFePO4/C composite powders with well dispersion at CA/OA ratio of 1:1.50 and the initial charge capacity reached 159.3 mAhg-1 at 0.1C rate, meanwhile, the particles prepared at 1:0.75 were close to spherical in shape and the specific capacity value was 149.8 mAhg-1 at 0.1C rate, with a slight decrease on greater C-rates reaching 141.3 mAhg-1 at 1C.

scholarly journals Evaluation of Acid Leaching on the Removal of Heavy Metals and Soil Fertility in Contaminated Soil

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Chen-Yao Chu ◽  
Tzu-Hsing Ko
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Seed Germination ◽  
Soil Fertility ◽  
Sequential Extraction ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Germination Rate ◽  
Extraction Procedure ◽  
Acid Leaching

Heavy metal-contaminated soils were leached with various acid reagents, and a series of treatments was assessed to understand soil fertility after acid leaching. Aqua regia digestion and a five-step sequential extraction procedure were applied to determine heavy metal distribution. The average total concentrations of Zn, Cd, Cu, and Pb for contaminated soil were 1334, 25, 263, and 525 mg·kg−1 based on the ICP/AES quantitative analysis. Other than Pb extracted by H2SO4, over 50% removal efficiency of other heavy metals was achieved. A five-step sequential extraction revealed that the bound-to-carbonate and bound-to-Fe-Mn oxides were the major forms of the heavy metals in the soil. The addition of organic manure considerably promoted soil fertility and increased soil pH after acid leaching. Seed germination experiments demonstrated that after acid leaching, the soil distinctly inhibited plant growth and the addition of manure enhanced seed germination rate from 35% to 84%. Furthermore, the procedure of soil turnover after acid leaching and manure addition greatly increased seed germination rate by 61% and shortened the initial germination time. Seed germination in untreated soil was superior to that in acid-leached soil, illustrating that the phytotoxic effect of acid leaching is more serious than that of heavy metals.

Sign in / Sign up

Export Citation Format

Share Document