DL-Malic acid

Recycling of LiCoO2 cathode material from spent lithium ion batteries by ultrasonic enhanced leaching and one-step regeneration.[Pubmed:33032002]

J Environ Manage. 2021 Jan 1;277:111426.

A novel process for recycling of spent LiCoO2 cathode materials has been developed. The novel process comprises an ultrasonic enhanced leaching and one-step regeneration of LiCoO2 materials with spray drying method. The ultrasonic is novelly applied for effectively improving leaching process of spent LiCoO2 materials in the system of DL-Malic acid and H2O2. The leaching efficiencies of 98.13% for Li and 98.86% for Co were presented under the optimal condition of 1.5 mol/L DL-Malic acid with 3 vol% H2O2, the solid/liquid ratio of 4 g/L, ultrasonic power of 95 W, temperature of 80 degrees C and leaching time of 25 min. Based on kinetic analysis, the ultrasonic enhanced leaching process is mainly controlled by the diffusion control model. Meanwhile, the product of Co(C4O5O5)2 formed on particles surface of spent LiCoO2 materials during ultrasonic enhanced leaching process, which is provided from reaction mechanism analysis of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). Finally, the regenerated LiCoO2 materials are regenerated in one step by spray drying from leaching solution, which present good electrochemical performance.

New bioanalytical method for the quantification of (-) - hydroxycitric acid in human plasma using UPLC-MS/MS and its application in a Garcinia cambogia pharmacokinetic study.[Pubmed:32505893]

J Pharm Biomed Anal. 2020 Sep 5;188:113385.

A new, rapid, selective and sensitive UPLC-MS/MS method was developed and validated for the quantification of (-) - hydroxycitric acid (HCA) in human plasma, using DL-Malic acid-2,3,3-d3 as internal standard (IS) and simple protein precipitation for the sample preparations. HCA is a highly polar compound make challenging its determination in biological fluids. A specific chromatography column Acquity UPLC HSS T3 (100 x 2.1 mm, 1.8 mum), eluted with mobile phase composed of acetonitrile/ammonium hydroxide 0,1 % (15:85, v/v) were applied for the HCA quantification. The bioanalytical method showed high-throughput achieving as fast chromatographic run as 1 min per sample. No matrix effect was observed with excellent mean chromatographic peak areas ratio of 0.98 +/- 0.07 and CV% of 7.17 from normal, lipemic and hemolyzed plasma lots. Calibration curves range was linear at 0.05-10 mug/mL, presenting adequate mean correlation coefficient great than 0.99. Excellent intra-assay and inter-assay precision were achieved, ranging from 5.02-12.01 % (CV%) as well as great intra- and inter-assay accuracy from 0.29-9.20 % (RE%). UPLC-MS/MS bioanalytical method was efficiently applied to the HCA pharmacokinetic study analyzing more than 670 plasma samples.

Distinct gene expression and secondary metabolite profiles in suppressor of prosystemin-mediated responses2 (spr2) tomato mutants having impaired mycorrhizal colonization.[Pubmed:32337100]

PeerJ. 2020 Apr 16;8:e8888.

Arbuscular mycorrhizal fungi (AMF) colonization, sampled at 32-50 days post-inoculation (dpi), was significantly reduced in suppressor of prosystemin-mediated responses2 (spr2) mutant tomato plants impaired in the omega-3 FATTY ACID DESATURASE7 (FAD7) gene that limits the generation of linolenic acid and, consequently, the wound-responsive jasmonic acid (JA) burst. Contrary to wild-type (WT) plants, JA levels in root and leaves of spr2 mutants remained unchanged in response to AMF colonization, further supporting its regulatory role in the AM symbiosis. Decreased AMF colonization in spr2 plants was also linked to alterations associated with a disrupted FAD7 function, such as enhanced salicylic acid (SA) levels and SA-related defense gene expression and a reduction in fatty acid content in both mycorrhizal spr2 roots and leaves. Transcriptomic data revealed that lower mycorrhizal colonization efficiency in spr2 mutants coincided with the modified expression of key genes controlling gibberellin and ethylene signaling, brassinosteroid, ethylene, apocarotenoid and phenylpropanoid synthesis, and the wound response. Targeted metabolomic analysis, performed at 45 dpi, revealed augmented contents of L-threonic acid and DL-Malic acid in colonized spr2 roots which suggested unfavorable conditions for AMF colonization. Additionally, time- and genotype-dependent changes in root steroid glycoalkaloid levels, including tomatine, suggested that these metabolites might positively regulate the AM symbiosis in tomato. Untargeted metabolomic analysis demonstrated that the tomato root metabolomes were distinctly affected by genotype, mycorrhizal colonization and colonization time. In conclusion, reduced AMF colonization efficiency in spr2 mutants is probably caused by multiple and interconnected JA-dependent and independent gene expression and metabolomic alterations.

Recycling of cathode material from spent lithium ion batteries using an ultrasound-assisted DL-malic acid leaching system.[Pubmed:31865035]

Waste Manag. 2020 Feb 15;103:52-60.

Herein, a novel process involving ultrasound-assisted leaching developed for recovering Ni, Li, Co, and Mn from spent lithium-ion batteries (LIBs) is reported. Carbonate coprecipitation was utilized to regenerate LiNi0.6Co0.2Mn0.2O2 from the leachate. Spent cathode materials were leached in DL-Malic acid and hydrogen peroxide (H2O2). The leaching efficiency was investigated by determining the contents of metal elements such as Li, Ni, Co, and Mn in the leachate using atomic absorption spectrometry (AAS). The filter residue and the spent cathode materials were examined using Fourier transform infrared (FTIR) and scanning electronic microscopy. The leaching efficiencies were 97.8% for Ni, 97.6% for Co, 97.3% for Mn, and 98% for Li under the optimized conditions (90 W ultrasound power, 1.0 mol/L DL-Malic acid, 5 g/L pulp density, 80 degrees C, 4 vol% H2O2, and 30 min). The leaching kinetics of the cathode in DL-Malic acid are in accordance with the log rate law model. The electrochemical analysis indicates that the LiNi0.6Co0.2Mn0.2O2 regenerated at pH 8.5 has good electrochemical performance. The specific capacity of the first discharge at 0.1 C is 168.32 mA h g(-1) at 1 C after 50 cycles with a capacity retention of 85.0%. A novel closed-loop process to recycle spent cathode materials was developed, and it has potential value for practical application and for contributing to resource recycling and environmental protection.

Simultaneous separation and determination of seven chelating agents using high-performance liquid chromatography based on statistics design.[Pubmed:31773826]

J Sep Sci. 2020 Feb;43(4):719-726.

We describe an optimization approach to determine simultaneously occurring chelating agents (glycine, malonic acid, citric acid, glycolic acid, lactic acid, DL-Malic acid, and ethylenediaminetetraacetic acid) in an electroplating effluent using high-performance liquid chromatography. With chromatography signal area and overall resolution considered as responses, detection conditions were optimized via multiple functions combined with response surface methodology and Plackett-Burman design. Optimized detection conditions were as follows: 15 mmol/L ammonium phosphate buffer (pH 2.5), a 94:6 v/v ratio of ammonium phosphate buffer/acetonitrile, a column temperature of 23.3 degrees C, and a mobile phase flow rate of 1 mL/min. The experimental values conformed to the predicted values and were repeatable (relative standard deviation < 6.4%) and linear (r(2 ) > 0.991) over concentration ranges of 1-100 micromol/L. Moreover, the quantification limit (signal-to-noise ratio = 10) and the detection limit (signal-to-noise ratio = 3) ranged from 0.03 to 0.15 micromol/L and from 0.01 to 0.04 micromol/L, respectively. These results indicate that high-performance liquid chromatography coupled with statistical design may be a simple and rapid method for simultaneously determining multiple chelating agents in electroplating wastewater effectively.

High-efficiency inorganic nitrogen removal by newly isolated Pannonibacter phragmitetus B1.[Pubmed:30265957]

Bioresour Technol. 2019 Jan;271:91-99.

An aerobic heterotrophic nitrogen removal bacterium strain, B1, was isolated from aquaculture water and identified as Pannonibacter phragmitetus (99% similarity) by 16S rRNA sequencing analysis. When ammonium, nitrite or nitrate was the sole nitrogen source, with an initial nitrogen concentration of 14mg/L, the nitrogen removal efficiencies were 98.66%, 99.96% and 98.73%, respectively, and the corresponding maximum removal rates reached as high as 1.16, 0.77 and 0.81mg/L/h, respectively. In the presence of NH4(+)-N, the removal efficiency of 56mg/L NO2(-)-N within 27h increased by 83.50%, and the corresponding removal rate reached as high as 1.72mg/L/h. Additionally, different carbon sources (DL-Malic acid, sucrose, sodium citrate, and glucose) could be utilized in nitrogen removal. Sequence amplification indicates that the denitrification genes nirK, norB and narG are present in strain B1. All results demonstrate that strain B1 has high promise for future applications of removing inorganic nitrogen from wastewater.

The Recognition of Sweat Latent Fingerprints with Green-Emitting Carbon Dots.[Pubmed:30103556]

Nanomaterials (Basel). 2018 Aug 12;8(8). pii: nano8080612.

The recognition of fingerprints has played an extremely important role in criminal investigations, due to its uniqueness. This paper reports on the recognition of sweat latent fingerprints using green-emitting, environment-friendly carbon dots prepared with DL-Malic acid and ethylenediamine, and the exploration of impacting factors in the development process of fingerprints. The experiments showed that better fingerprint images could be obtained when the latent fingerprints are developed in green-emitting carbon dots with pH 9 for 30 min, at room temperature. The reported method was also effective for latent fingerprints on a variety of substrates, as well as for those water-immersed ones, where the developed fingerprint remained stable after long-term preservation. Furthermore, the fluorescent three-dimensional fingerprint image could provide direct and simple evidence on pressing habits. The objective of this paper was to present this method. The method may help to narrow the range of suspects during criminal investigations and in forensic science.

Sustainable recovery of valuable metals from spent lithium-ion batteries using DL-malic acid: Leaching and kinetics aspect.[Pubmed:29212425]

Waste Manag Res. 2018 Feb;36(2):113-120.

An eco-friendly and benign process has been investigated for the dissolution of Li, Co, Ni, and Mn from the cathode materials of spent LiNi1/3Co1/3Mn1/3O2 batteries, using DL-Malic acid as the leaching agent in this study. The leaching efficiencies of Li, Co, Ni, and Mn can reach about 98.9%, 94.3%, 95.1%, and 96.4%, respectively, under the leaching conditions of DL-Malic acid concentration of 1.2 M, hydrogen peroxide content of 1.5 vol.%, solid-to-liquid ratio of 40 g l(-1), leaching temperature of 80 degrees C, and leaching time of 30 min. In addition, the leaching kinetic was investigated based on the shrinking model and the results reveal that the leaching reaction is controlled by chemical reactions within 10 min with activation energies (Ea) of 21.3 kJ.mol(-1), 30.4 kJ.mol(-1), 27.9 kJ.mol(-1), and 26.2 kJ.mol(-1) for Li, Co, Ni, and Mn, respectively. Diffusion process becomes the controlled step with a prolonged leaching time from 15 to 30 min, and the activation energies (Ea) are 20.2 kJ.mol(-1), 28.9 kJ.mol(-1), 26.3 kJ.mol(-1), and 25.0 kJ.mol(-1) for Li, Co, Ni, and Mn, respectively. This hydrometallurgical route was found to be effective and environmentally friendly for leaching metals from spent lithium batteries.

Recovery of lithium and cobalt from spent lithium-ion batteries using organic acids: Process optimization and kinetic aspects.[Pubmed:28365275]

Waste Manag. 2017 Jun;64:244-254.

An environmentally-friendly route based on hydrometallurgy was investigated for the recovery of cobalt and lithium from spent lithium ion batteries (LIBs) using different organic acids (citric acid, DL-Malic acid, oxalic acid and acetic acid). In this investigation, response surface methodology (RSM) was utilized to optimize leaching parameters including solid to liquid ratio (S/L), temperature, acid concentration, type of organic acid and hydrogen peroxide concentration. Based on the results obtained from optimizing procedure, temperature was recognized as the most influential parameter. In addition, while 81% of cobalt was recovered, the maximum lithium recovery of 92% was achieved at the optimum leaching condition of 60 degrees C, S/L: 30gL(-1), citric acid concentration: 2M, hydrogen peroxide concentration: 1.25Vol.% and leaching time: 2h. Furthermore, results displayed that ultrasonic agitation will enhance the recovery of lithium and cobalt. It was found that the kinetics of cobalt leaching is controlled by surface chemical reaction at temperatures lower than 45 degrees C. However, diffusion through the product layer at temperatures higher than 45 degrees C controls the rate of cobalt leaching. Rate of lithium reaction is controlled by diffusion through the product layer at all the temperatures studied.

Facile Synthesis of N-Doped Carbon Dots as a New Matrix for Detection of Hydroxy-Polycyclic Aromatic Hydrocarbons by Negative-Ion Matrix-Assisted Laser Desorption/Ionization Time-of-Flight Mass Spectrometry.[Pubmed:27180617]

ACS Appl Mater Interfaces. 2016 May 25;8(20):12976-84.

N-doping carbon dots (N-CDs) were prepared by microwave-assisted pyrolysis of DL-Malic acid and ethanolamine as precursors. The material served as an excellent matrix for the detection of the environmental pollutants hydroxy-polycyclic aromatic hydrocarbons (OH-PAHs) by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) in negative ion mode. The obtained N-CDs exhibited good UV absorption capacity and favorable solubility. The use of the N-CDs matrix exhibited low matrix background interference and was beneficial to improve the signal response due to the specific pi-conjugated polyaromatic structure and the doping of nitrogen atoms. The developed method was found to have good reproducibility and sensitivity. The N-CDs as a new matrix also were employed for the detection of OH-PAHs in real PM2.5 samples. The mass concentrations of Sigma-hydroxy-pyrene, Sigma-dihydroxy-anthraquinone, and Sigma-dihydroxy-benzo(a)pyrene on the collected PM2.5 samples ranged from 0.125 to 0.136 ng/m(3), 0.039 to 0.052 ng/m(3), and 0.053 to 0.072 ng/m(3), respectively. This work extends the application field of N-CDs and provides a good candidate of matrix for MALDI-TOF MS detection of environmental pollutants.

Comparative study for N and S doped carbon dots: Synthesis, characterization and applications for Fe(3+) probe and cellular imaging.[Pubmed:26526917]

Anal Chim Acta. 2015 Oct 22;898:116-27.

A facile and eco-friendly approach to prepare nitrogen(N)- and sulfur(S)-doped carbon dots (CDs) by one step microwave-assisted pyrolysis of the precursors with DL-Malic acid as carbon source, ethanolamine and ethane-sulfonic acid as N and S dopants, respectively, was reported. Through the extensive investigation on morphology, chemical structures and optical properties of the carbon dots, it was found that the obtained CDs exhibited good luminescence stability, high resistance to photo bleaching and favorite solubility. Compared with undoped CDs, adding the N or S dopant could give rise to a slightly smaller particle size and a long fluorescence lifetime of CDs. Moreover, the optimal N-CDs was successfully employed as good multicolor cell imaging probes due to its fine dispersion in water, excitation-dependent emission, excellent biocompatibility and low toxicity. Besides, such N-CDs showed a wide detection range and excellent accuracy as fluorescent probe for Fe(3+) ions. This probe enabled the selective detection of Fe(3+) ions with a linear range of 6.0-200 muM and a limit of detection of 0.80 muM.