Chloroacetic Acid Research Articles

Increased degradation of PLA/PBAT blends with organic acids and derivatives in outdoor weathering and marine environment

Bio-Flex® is a commercial blend of poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) used in several industrial and daily applications. To understand the degradation behavior of this mixture, two laboratory tests were conducted, one simulating outdoor accelerated weathering (OAW) and the other mimicking degradation in marine environments in seawater (MES). To increase its degradability, Bio-Flex was mixed with various additives such as chloroacetic acids - trichloroacetic acid (TCA) and dichloroacetic acid (DCA) - and esters of the latter. The samples were characterized before and after the degradation tests by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and mechanical properties. Size exclusion chromatography (SEC) and contact angle were also evaluated. The acids were found to be very effective in degrading PLA/PBAT blends, even during the blending process. It follows that the esters of DCA are suitable as good additives to increase the degradation ratio of the PLA/PBAT blend when an enhanced degradation process is required.

A Comparative Study of Different Methods for Cellulose Extraction from Lignocellulosic Wastes and Conversion into Carboxymethyl Cellulose

AbstractCarboxymethyl cellulose (CMC) is an appealing industrial chemical obtained by modification of cellulose with redundant applications in food, pharmaceuticals, paints, detergents and others. This report demonstrates the comparative study of potential of different lignocellulosic biomass by using five traditional methods to get white, pristine cellulose with higher percentage yield from waste, later, conversion of cellulose into its derivative i. e., carboxymethyl cellulose (CMC). Four raw materials comprising of wheat straw, sugarcane bagasse, rice straw and banana leaves were employed as an alternating source of cellulose. Sulfide method came out as a most viable delignification method, used to degrade all dewaxed wastes, efficiently. After cellulose extraction, substitution of hydroxyl groups of cellulose was executed by infusing cellulose with sodium hydroxide (NaOH) and monochloroacetic acid (MCA) in the presence of isopropanol as supporting medium. In this way, a variety of cellulose and CMC were obtained and verified with commercial samples of both products. Furthermore, characteristics of different CMC were checked including degree of substitution (DS), CMC content, moisture content, solubility and purity. The CMC from wheat straw showed the highest DS (2.1), solubility and yield. FTIR spectra confirmed the replacement of hydroxyl group with carboxymethyl group by indicating characteristic peak of carbonyl group (‐CO) at 1588 cm−1. In 1H NMR spectrum, plethora of peaks in the region 3–5 ppm indicated the derivatization of cellulose and 13C NMR confirmed the peaks of carbonyl carbons at 180 and 182 ppm. X‐ray diffraction (XRD) shows that the crystallinity of CMC has been reduced, significantly.

Precursor characteristics of mono-HAAs during chlorination and cytotoxicity of mono-HAAs on HEK-293T cells.

Monohaloacetic acids (mono-HAAs), a class of disinfection by-products widely occurred in drinking water, receives significant attention due to their extremely high toxicity. Many studies on the biological toxicity of mono-HAAs have been reported, yet the toxic effects of mono-HAAs on human renal cells (kidney is one of the target organs for disinfection by-products) has not been involved. Studies on organic precursors for mono-HAAs formation were also very limited due to their lower levels as compared to di-HAAs and tri-HAAs. Based on this, the formation of mono-HAAs after chlorination of some typical source water samples and their relationship with water quality parameters were investigated. Meanwhile, the cytotoxicity of monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), and monoiodoacetic acid (MIAA) were tested using human embryonic kidney cells (HEK-293T cells). The results showed that the levels of mono-HAAs formed during chlorination of source water samples were between 0.44 and 0.87μg/L. Formation of MBAA positively (p<0.05) correlated with bromide ion and dissolved organic carbon, but negatively (p<0.01) correlated with SUVA254 (specific UV absorbance at 254nm), while formation of MCAA was only positively (p<0.05) related with SUVA254. These results suggested that although MCAA and MBAA both belong to the mono-HAAs, the characteristics of their organic precursors differ significantly. MCAA precursors have high aromaticity and are more hydrophobic, yet MBAA precursors have low aromaticity and are more hydrophilic. The half-lethal concentrations (LC50) of MCAA, MBAA, and MIAA on HEK293T cells were 1196-1211μM, 16.07-18.96μM, and 6.08-6.17μM, respectively. An in-depth analysis showed that the cytotoxicity of mono-HAAs on HEK 293T cells could not be explained by the parameters concerning cellular uptake (e.g., logP and pKa), but the SN2 reaction of C-X bond with cellular molecules (e.g., glyceraldehyde-3-phosphate dehydrogenase, etc) may be the relevant cause for the cytotoxicity of mono-HAAs on HEK 293T cells.

Six-Step Continuous Flow Synthesis of Diclofenac Sodium via Cascade Etherification/Smiles Rearrangement Strategy: Tackling the Issues of Batch Processing.

Invited for the cover of this issue are Dang Cheng, Fener Chen and co-workers at Fudan University. The image depicts six-step continuous-flow synthesis of diclofenac sodium from commercially available aniline and chloroacetic acid in a desktop microchemical plant. Read the full text of the article at 10.1002/chem.202201420.

Characterization and Antibacterial Activities of Carboxymethylated Paramylon from Euglena gracilis.

Paramylon from Euglena gracilis (EGP) is a polymeric polysaccharide composed of linear β-1,3 glucan. EGP has been proved to have antibacterial activity, but its effect is weak due to its water insolubility and high crystallinity. In order to change this deficiency, this experiment carried out carboxymethylated modification of EGP. Three carboxymethylated derivatives, C-EGP1, C-EGP2, and C-EGP3, with a degree of substitution (DS) of 0.14, 0.55, and 0.78, respectively, were synthesized by varying reaction conditions, such as the mass of chloroacetic acid and temperature. Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), and nuclear magnetic resonance (NMR) analysis confirmed the success of the carboxymethylated modification. The Congo red (CR) experiment, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetry (TG) were used to study the conformation, surface morphology, crystalline nature, and thermostability of the carboxymethylated EGP. The results showed that carboxymethylation did not change the triple helix structure of the EGP, but that the fundamental particles’ surface morphology was destroyed, and the crystallization area and thermal stability decreased obviously. In addition, the water solubility test and antibacterial experiment showed that the water solubility and antibacterial activity of the EGP after carboxymethylation were obviously improved, and that the water solubility of C-EGP1, C-EGP2, and C-EGP3 increased by 53.31%, 75.52%, and 80.96% respectively. The antibacterial test indicated that C-EGP3 had the best effect on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with minimum inhibitory concentration (MIC) values of 12.50 mg/mL and 6.25 mg/mL. The diameters of the inhibition zone of C-EGP3 on E. coli and S. aureus were 11.24 ± 0.15 mm and 12.05 ± 0.09 mm, and the antibacterial rate increased by 41.33% and 43.67%.

Six-Step Continuous Flow Synthesis of Diclofenac Sodium via Cascade Etherification/Smiles Rearrangement Strategy: Tackling the Issues of Batch Processing.

Diclofenac sodium is a widely used nonsteroidal anti-inflammatory drug (NSAID) as over-the-counter (OTC) medication for the treatment of inflammatory diseases. Herein, the development of an intensified six-step continuous flow synthesis of diclofenac sodium from commercially available aniline and chloroacetic acid is described. A challenging and unprecedented etherification/Smiles rearrangement cascade of 2-chloro-N-phenylacetamide and 2,6-dichlorophenol into hydroxyacetyldiphenylamine operated with the precise control of reaction conditions in continuous flow was realized as the key step in this multistep synthetic chemistry. The undesired amide hydrolysis in Smiles rearrangement was addressed and the extra installation of N-chloroacetyl group in current industrial batch mode was avoided. Diclofenac sodium was obtained in 63 % isolated yield with an average yield of above 90 % for each step in a total residence time of 205 min.

Enhanced Photocatalytic Removal of Hexavalent Chromium over Bi12TiO20/RGO Polyhedral Microstructure Photocatalysts.

A Bi12TiO20/RGO photocatalyst with polyhedron microstructure was fabricated via the template-free hydrothermal method, and the visible-light-induced photocatalytic activity of the prepared Bi12TiO20 was also evaluated by the photocatalytic reduction of heavy metal pollutants. The structures and optical properties of the prepared Bi12TiO20/RGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The effects of the reaction time and mineralizer concentration on the formation of the Bi12TiO20 polyhedral microstructure were analyzed. The enhanced photocatalytic performances of Bi12TiO20/RGO were observed which were ascribed to the combination of the Bi12TiO20 microstructure induced photogenerated charges and the RGO nanostructure as a photogenerated charges carrier. The effect of organic acids, p-hydroxybenzoic acid (PHBA), chloroacetic acid, and citric acid on the Cr(VI) photocatalytic reduction was also discussed. This work provides an insight into the design of the bismuth-based microstructure photocatalyst towards the application for environment purification of heavy metals.

SYNTHESIS AND PROPERTIES OF CARBOXYMETHYL CELLULOSE FROM AGRICULTURAL WASTE – SUGARCANE LEAVES

"Sugarcane leaves are an abundant agricultural waste with the potential for use as a source of cellulose. Cellulose from sugarcane leaves was converted to carboxymethyl cellulose (CMC) by carboxymethylation using sodium hydroxide and monochloroacetic acid in isopropyl alcohol. The yield of CMC was 212.16%. A degree of substitution (DS) equivalent to 0.79 was obtained during the conversion, indicating that the product was water-soluble. Fourier transform infrared (FT-IR) spectroscopy confirmed the presence of major peaks expected for carboxymethyl substitution, compared to commercial CMC. Thermal properties were studied using simultaneous thermal analysis (STA). Melting temperature (Tm) and degradation temperature (Td) of the sample were 116.6 °C and 270.4 °C, respectively, while the residual mass of 36.49% at 800 °C indicated the presence of a non-volatile component fraction. CMC morphology showed a non-circular form with small particles. Results indicated the potential of sugarcane leaves for production of commercial grade CMC."

Biofriendly chitosan-based high-efficiency dialysis membrane

Chitosan, a biofriendly material, has a wide range of applications owing to its biocompatibility and biodegradability. We successfully prepared super-adsorbent membranes by dip-coating filter paper in chemically and physically modified chitosan solutions, and compared the urea adsorption performances of the different chitosan membranes. Chemical modification was achieved by successfully introducing carboxyl and amine groups into chitosan by carboxylation and amination using chloroacetic acid (ClCH₂CO₂H) and ethylenediamine (C2H4(NH2)2), respectively. Physical modification was performed by attempting different crosslinking reactions using sodium tripolyphosphate and copper ions (Cu2+). The effects of the various physical and chemical modifications was determined on the urea reduction ratio (URR). At a urea concentration of 500 ppm, the modified chitosan membranes exhibited URRs of >80 % within 2 h, a 38 % decrease in the equilibrium swelling ratio, and a 600 % increase in the bursting strength. These results demonstrate the immense potential of these membranes for hemodialysis in biomedical research. Lastly, model fitting revealed that the mechanisms of urea adsorption onto chitosan were best described using the Freundlich adsorption isotherm and the pseudo-second-order kinetic model.

Fabrication and Characterization of Orodispersible Composite Film from Hydroxypropylmethyl Cellulose-Crosslinked Carboxymethyl Rice Starch.

Crosslinked carboxymethyl rice starch (CLCMRS), prepared via dual modifications of native rice starch (NRS) with chloroacetic acid and sodium trimetaphosphate, was employed to facilitate the disintegration of hydroxypropylmethylcellulose (HPMC) orodispersible films (ODFs), with or without the addition of glycerol. Fabricated by using the solvent casting method, the composite films, with the HPMC--LCMRS ratios of 9:1, 7:1, 5:1 and 4:1, were then subjected to physicochemical and mechanical evaluations, including weight, thickness, moisture content and moisture absorption, swelling index, transparency, folding endurance, scanning electron microscopy, Fourier transform infrared spectroscopy, tensile strength, elongation at break, and Young’s modulus, as well as the determination of disintegration time by using the Petri dish method (PDM) and slide frame and bead method (SFM). The results showed that HPMC-CLCMRS composite films exhibited good film integrity, uniformity, and transparency with up to 20% CLCMRS incorporation (4:1 ratio). Non-plasticized composite films showed no significant changes in the average weight, thickness, density, folding endurance (96–122), tensile strength (2.01–2.13 MPa) and Young’s modulus (10.28–11.59 MPa) compared to HPMC film (135, 2.24 MPa, 10.67 MPa, respectively). On the other hand, the moisture content and moisture absorption were slightly higher, whereas the elongation at break (EAB; 4.31–5.09%) and the transparency (4.73–6.18) were slightly lowered from that of the HPMC film (6.03% and 7.03%, respectively). With the addition of glycerol as a plasticizer, the average weight and film thickness increased, and the density decreased. The folding endurance was improved (to >300), while the transparency remained in the acceptable range. Although the tensile strength of most composite films decreased (0.66–1.75 MPa), they all exhibited improved flexibility (EAB 7.27–11.07%) while retaining structural integrity. The disintegration times of most composite films (PDM 109–331, SFM 70–214 s) were lower than those of HPMC film (PDM 345, SFM 229 s). In conclusion, the incorporation of CLCMRS significantly improved the disintegration time of the composite films whereas it did not affect or only slightly affected the physicochemical and mechanical characteristics of the films. The 5:1 and 4:1 HPMC:CLCMRS composite films, in particular, showed promising potential application as a film base for the manufacturing of orodispersible film dosage forms.

Preparation and properties of monomethoxyl polyethylene glycol grafted O-carboxymethyl chitosan for edible, fresh-keeping packaging materials

The main target of the current exploration is to represent a novel type of edible biomaterial composed of monomethoxyl polyethylene glycol-modified O-carboxymethyl chitosan (MPEG-O-CMC) for fresh-keeping food packaging materials. MPEG-O-CMCs were prepared by a facile method that consists of three steps: the C6-hydroxyl group of chitin (CH) was first substituted by chloroacetic acid; O-carboxymethyl chitosan (O-CMC) was subsequently obtained via a deacetylation reaction; and finally, the NH2 groups of O-CMC were reacted with isocyanate-terminated methoxypolyethylene glycol (MPEG-NCO) to yield MPEG-O-CMC. The chemical structures of O-CMC, MPEG-NCO, and MPEG-O-CMC were scrutinized through nuclear magnetic resonance spectroscopy (NMR) and Fourier transform–infrared spectroscopy (FT-IR), and the influences of the MPEG content on the physicochemical features of the solution-cast MPEG-O-CMC films was extensively researched. The results showed that the introduction of polyethylene glycol (PEG) could ameliorate the hydrophilicity, thermal stability, flexibility, and tensile features of the film. When the grafting degree of MPEG was approximately 25% (the MPEG content in MPEG-O-CMC was 18.5 wt%), the film possessed a lower Tg of −30 °C and higher tensile features (strain at break: 221%; ultimate stress: 4.4 MPa). The water vapor transmission rates (WVTR) of the MPEG-O-CMC films was evaluated by osmosis tests at different humidity, and the results showed that films possessed good WVTR of 25–200 g·mm/(m2∙24 h) at 50% humidity. The WVTR decreased gradually with the increase of MPEG content in the material, which was mainly attributed to the flexible MPEG segments acting as a plasticizer and reducing the dimension of the transient interspaces. Furthermore, the preliminary evaluation of bacteriostatic activity indicated that the films possess a certain bacteriostatic activity against Escherichia coli. Due to its good tensile properties, acceptable WVTR and potential bacteriostatic activity, this nontoxic and even edible biomaterials hold significant promise for application in fresh-keeping food packing materials.

Synthesis of Mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-4-ones and Study of their Monoamine Oxidase, Succinate Dehydrogenase Inhibitory, Anti-convulsant, and Antibacterial Activity

1-Aryl-2-mercapto-4-(phenyl/p-chlorophenyl)imidazoles (Ia-j) were condensed with monochloroacetic acid to give 1-aryl-4-(phenyl/p-chlorophenyl)imidazo-2-mercaptoacetic acid (IIa-j). These acids were subsequently cyclized with an acetic anhydride-pyridine mixture to give a new fused ring mesoionic 1-aryl-4-(phenyl/p-chlorophenyl)imidazo[2,1-b]thiazol-1-3-ones (IIIa-j). These compounds possess AID50 values ranging from 500 to 1000 mg kg-1, inhibit monoamineoxidase (32-68%), and succinate dehydrogenase (28-55%) in vitro at a concentration of 2×10-4 M, and provide 20-60% protection against pentylenetetrazole induced convulsions in mice.

Disinfection byproducts in chlorinated or brominated swimming pools and spas: Role of brominated DBPs and association with mutagenicity

Although the health benefits of swimming are well-documented, health effects such as asthma and bladder cancer are linked to disinfection by-products (DBPs) in pool water. DBPs are formed from the reaction of disinfectants such as chlorine (Cl) or bromine (Br) with organics in the water. Our previous study (Daiber et al., Environ. Sci. Technol. 50, 6652; 2016) found correlations between the concentrations of classes of DBPs and the mutagenic potencies of waters from chlorinated or brominated swimming pools and spas. We extended this study by identifying significantly different concentrations of 21 individual DBPs in brominated or chlorinated pool and spa waters as well as identifying which DBPs and additional DBP classes were most associated with the mutagenicity of these waters. Using data from our previous study, we found that among 21 DBPs analyzed in 21 pool and spa waters, the concentration of bromoacetic acid was significantly higher in Br-waters versus Cl-waters, whereas the concentration of trichloroacetic acid was significantly higher in Cl-waters. Five Br-DBPs (tribromomethane, dibromochloroacetic acid, dibromoacetonitrile, bromoacetic acid, and tribromoacetic acid) had significantly higher concentrations in Br-spa versus Cl-spa waters. Cl-pools had significantly higher concentrations of Cl-DBPs (trichloroacetaldehyde, trichloromethane, dichloroacetic acid, and chloroacetic acid), whereas Br-pools had significantly higher concentrations of Br-DBPs (tribromomethane, dibromoacetic acid, dibromoacetonitrile, and tribromoacetic acid). The concentrations of the sum of all 4 trihalomethanes, all 11 Br-DBPs, and all 5 nitrogen-containing DBPs were each significantly higher in brominated than in chlorinated pools and spas. The 8 Br-DBPs were the only DBPs whose individual concentrations were significantly correlated with the mutagenic potencies of the pool and spa waters. These results, along with those from our earlier study, highlight the importance of Br-DBPs in the mutagenicity of these recreational waters.

Green synthesis of carboxymethyl cellulose from agricultural waste its characterization

In the present study, corncob (an agricultural waste) has been explored as a source of cellulose. Cellulose was extracted from corncob through removal of hemicellulose and lignin. The carboxymethyl cellulose (CMC) was then synthesized from extracted cellulose by alkalization and etherification with 30% NaOH and 120% monochloro acetic acid (MCA) in ethanol medium respectively. Characterization of prepared CMC was carried out by various techniques like Fourier Transform Infra-Red (FTIR) spectroscopy, X-Ray Diffraction (XRD) and Scanning Electron Microscpoe (SEM). Back titration method was used to determine the Degree of Substitution (DS). The synthesized CMC obtained has a large DS value of 2.27. The purity of CMC was high at 91.65% and showed a yield of 1.20g/g, intrinsic viscosity of 1.02, water holding capacity 3.81g/g and oil holding capacity 1.66g/g. Higher degree of substitution is achieved in this work. The synthesized product is effective suitable additive for food and various pharmaceuticals industries.

Determination of Haloacetic Acids, Disinfection Byproducts, in Tap Water with Reversed-Phase Ultra-Performance Liquid Chromatography-High Resolution Mass Spectrometry

To establish a method for quantitative analysis of haloacetic acids (HAAs), disinfection byproducts, in tap water with reversed-phase ultra-performance liquid chromatography-quadrupole-orbitrap high resolution mass spectrometry. Tap water samples were collected and 0.70 g/L ascorbic acid was added to eliminate residual chlorine. Then, the water samples were directly injected into the instrument for analysis after filtration. After separation on a pentafluorobenzene (PFP) column with an inner diameter of 1.0 mm at a higher linear velocity and a lower volume flow rate compared with those of a narrow-bore column, nine HAAs, namely, monochloroacetic acid (MCAA), monobromoacetic acid (MBAA), dichloroacetic acid (DCAA), bromochloroacetic acid (BCAA), dibromoacetic acid (DBAA), trichloroacetic acid (TCAA), bromodichloroacetic acid（BDCAA), chlorodibromoacetic acid (CDBAA) and tribromoacetic acid (TBAA), were examined by negative electrospray ionization and full MS/dd-MS 2 acquisition mode. In order to adjust for the matrix effect, matrix matching calibration curves were used to quantitate the nine HAAs. Good linearity was obtained for each of the nine HAAs within their respective linear ranges. The detection limits and quantification limits of the method were 0.020-1.0 μg/L and 0.060-3.0 μg/L. The recoveries were 69.8%-119%. The proposed method showed strengths in separation speed and qualitative accuracy. It did not require for complicated pretreatment procedures and can meet the need of tap water sample analysis.

Microextraction Preconcentration of Chloroacetic Acids with the Flotation Separation of the Extract

Microextraction Preconcentration of Chloroacetic Acids with the Flotation Separation of the Extract

Enhancing esterification of small molecular acids with alcohols by molten salt hydrates

A novel approach is reported for efficient esterifying low molecular acids with alcohols in molten salt hydrate (MSH) without additional catalyst. A series of MSHs (LiCl, CaCl2, ZnCl2 and ZnBr2) were evaluated for catalytic esterification of chloroacetic acid (CA) with methanol to methyl chloroacetate (MC). The effects of coordination water number also examined. It was found that appropriate coordination water number not only can promote the protonation of the reactant acids, but also enhance the activity of the protons as well as esterification equilibrium towards ester formation. A MC yield of 98.1% with concentration of 92.1% in the organic-phase could be readily achieved after reacting at 80 °C for 2.0 h in CaCl2·4H2O. MSH also demonstrated excellent performance in esterification of other acids (acetic, mercaptoacetic, propionic, n-butyric and levulinic acids) with alcohols (ethanol, n-propanol and n-butanol). After removing portion of the water from MSH, it can be reused without any difficulty. The promotion effects of MSH on the esterification reaction can be categorized to three aspects: (1) accelerating the reaction rate due to the enhanced protonation of the reactant acids and reduction in the hydration degree of the protons; (2) facilitating phase-splitting by virtue of the poor solubility in MSH and thus expelling the formed esters into organic-phase, as a result, boosting up esterification conversions; and (3) promoting the esterification reaction equilibrium owing to the strong hygroscopicity of MSH.Economic analysis shows, compared with the conventional esterification of CA with ethanol, in which organic solvents is used as the water-carrying agent, that esterification in MSH could not only accelerate the reaction rate and strengthen the equilibrium conversion, but also save energy input.

An efficient biosynthesis of palladium nanoparticles using Bael gum and evaluation of their catalytic and antibacterial activity

We report a facile microwave-assisted synthesis of palladium nanoparticles (PdNPs) using Bael gum (BG) and it's carboxymethylated (CMBG) derivative. The prepared nanoparticles (BG@PdNPs and CMBG@PdNPs) were evaluated for antibacterial and catalytic activity in the reduction of organic dye pollutants. The developed synthetic method is simple, low cost and eco-friendly, wherein the process requires no additional reducing or capping agents. The CMBG was prepared via etherification reaction between BG and monochloroacetic acid using Williamson synthesis method. The PdNPs were synthesized using BG and CMBG as stabilizers and reducing agents. The PdNPs were found to be well dispersed spherical, with the crystalline size of the order of 7–21 nm. The results showed that the CMBG@PdNPs were smaller in size (7 ± 2 nm) than those capped with BG@PdNPs (10 ± 2 nm). The catalytic ability of CMBG@PdNPs was examined for the reduction of Methyl Orange (MO), Methyl Red(MR), and Rhodamine-B (RhB) in the presence of NaBH4. The results showed that CMBG@PdNPs exhibited a higher catalytic ability than BG@PdNPs. Moreover, it was found that CMBG@PdNPs served several times as a retrievable and reusable catalyst which is stable even after six cycles of reaction. The CMBG@PdNPs and BG@PdNPs showed excellent antibacterial activity. The results indicate that CMBG@PdNPs have greater potential application as a catalyst in the reduction of organic pollutants and antibacterial activity.

Performance Evaluation of Composite Antisalt Agents and the Antisalt Dynamics Simulation Mechanism.

The conventional ferrocyanide complex ([Fe(CN)6]4–) has been widely used as a scale inhibitor under mild conditions, but its oxidation at high temperature compromises the subsequent wastewater treatment processes. To conquer the inadequacies of Fe(CN)6]4–, aminotriacetamide (NTA) was synthesized using chloroacetic acid as an initial material and its molecular structure was characterized using FT-IR spectroscopy, H-NMR, and TGA. NTA was exploited in combination with polyaspartic acid (PASP) and sodium dodecyl benzene sulfonate (SDBS) to prepare a high-performance antisalt composite, and the scaling inhibitor performance was evaluated. The results revealed that as the concentration of the antisalt composite increased from 0.5 to 1.2 wt %, the solubility and inhibition rate increased by 95.6 and 12.33%, respectively, at 100 °C. The results from molecular simulation evidenced that the order of binding energy between a unit mass of the salt inhibitor and sodium chloride crystal increased in the following order; SDBS > NTA > PASP. The deformation strength between the salt inhibitor and sodium chloride crystal increased as follows: NTA > PASP > SDBS. In addition, the antisalt composite mainly hampered salt precipitation through strong adsorptions arising from both the nitrogen atom of NTA and oxygen atom of SDBS with the sodium atom of sodium chloride crystals, and as a result, it not only altered the crystalline form of sodium chloride but also reduced the adsorption of sodium atoms and eventually improved the salt solubility.

Advanced oxidation of dodecyl dimethyl benzyl ammonium chloride by VUV/UV/chlorine: Synergistic effect, radicals, and degradation pathway

Quaternary ammonium compounds (QACs) are crucial ingredients in many cleaning agents, disinfectants and personal care products. They are widely detected in aquatic environments. In this study, vacuum ultraviolet (VUV)/UV/chlorine was used to degrade dodecyl dimethyl benzyl ammonium chloride (DDBAC, a typical QAC). The degradation efficiency of VUV/UV/chlorine on DDBAC was the highest among chlorine, UV, VUV/UV, UV/chlorine and VUV/UV/chlorine. During the VUV/UV/chlorine process, with chlorine concentration increasing from 0 to 700 μM, the degradation rate constant of DDBAC increased from 0.16 to 0.22 min−1 then decreased to 0.17 min−1. When the chloride concentration was 10 mM and 50 mM, the degradation rate constant of DDBAC decreased by 31% and 55%, respectively. Inorganic anions and organic compounds in the reverse osmosis concentrate inhibited the degradation of DDBAC by quenching radicals. The degradation mechanisms of DDBAC degradation during the VUV/UV/chlorine process include UV photolysis and oxidation by OH, Cl and other reactive species. With the increase in pH from 5 to 10, the OH concentration decreased from 18.7 × 10−14 M to 7.5 × 10−14 M, and the Cl concentration decreased from 8.8 × 10−14 M to 2.1 × 10−14 M. At pH 5–10, contributions of OH and Cl to DDBAC degradation were 30%−44% and 18%−37%, respectively. Degradation mechanisms of DDBAC mainly include hydrogen abstraction, hydroxylation, and cleavage of the C-N bond. The concentrations of four chlorinated products (trichloromethane, monochloroacetic acid, dichloroacetic acid, and trichloroacetic acid) mostly initially increased and then decreased.