DSD Acid Research Articles

Customized carbon dots as a fluorescent sensor for detecting paraquat through enhanced excited state binding energy

A novel fluorescent sensor utilizing customized carbon dots (CDs) has been developed for the rapid and efficient detection of the herbicide paraquat. The 4,4′-diamino-2,2′-stilbenedisulfonic acid (DSD acid) functionalized CDs (DSD-CDs) were synthesized by a hydrothermal method using citric acid and L-cysteine as precursors, followed by amidation with DSD acid. The resultant DSD-CDs exhibited bright blue fluorescence upon UV excitation. The fluorescence of the functionalized carbon dots was effectively quenched by paraquat, following a static quenching mechanism as confirmed by fluorescence lifetime measurements. Interestingly, the mechanism study revealed that the excited-state of the DSD-CDs could interact effectively with paraquat, resulting in stronger fluorescence quenching compared to the ground-state. The sensor showed high sensitivity, selectivity, and stability, with a wide linear range of 0.01 ∼ 2 mg/L (R2 = 0.997) and a low detection limit of 0.003 mg/L. The developed fluorescent sensor demonstrated exceptional potential for paraquat detection in actual samples, encompassing blood, urine, soybean, and river water, with recovery rates exceeding 83 % and relative standard deviations (RSD) below 10 %. This underscores its practical utility in environmental protection and clinical testing applications.

Nitrogen doped carbon supported iron catalysts for highly selective production of 4,4′-diamino-2,2′-stilbenedisulfonic acid

Nitrogen doped carbon supported iron catalysts were prepared from pyrolysis of a multidentate nitrogen ligand iron complex supported on chitosan at different temperature, and showed good performances in the reduction of 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNS acid) to 4,4′-diamino-2,2′-stilbenedisulfonic acid (DSD acid) with hydrazine hydrate (N2H4·H2O) as reductant. Characterization results revealed that the iron is mainly present in the form of Fe2O3 and metallic iron nanoparticles. The doped N atoms functionalized as anchoring sites to stabilize iron nanoparticles, which endows the catalysts with excellent activity and superior reusability.

Multifunctional water-soluble polymeric fluorescent whitening agents based on 4,4'-bis (1,3,5-triazinyl)- diamino stilbene-2,2'-disulfonic acid structure

A series of multifunctional water-soluble polymeric fluorescent whitening agents (PFWAs, 5a-f) based on 4,4′-diamino-stilbene-2,2′-disulfonic acid (DSD acid)-triazine structure were successfully synthesized using a nucleophilic substitution reaction with cyanuric chloride, DSD acid, amino compounds, polyethylene glycol (PEG), and/or polyvinyl alcohol (PVA) as raw materials. The structure of the PFWAs was characterized by FT-IR, and the substitution degree was calculated from the results of an elemental analysis. The optical properties of the PFWAs were measured by the UV-vis spectra and fluorescence spectra when the PFWAs were applied to paper fiber to serve the roles of light stabilizer, fluorescent whitener, and surface-sizing agent. Then the performance of the PFWAs on paper was evaluated by measuring the surface strength and smoothness of paper, brightness degree of paper, and the yellowness value (value of PC) of paper. The results indicated that the PFWAs had better light stability in water solution than that of a conventional fluorescent whitening agent (FWA) as a light stabilizer. According to the surface-sizing experiment and UV aging experiment, it was concluded that not only could the PFWAs enhance the surface strength and smoothness of paper, but also have a better effect on anti-UV aging than that of FWA as a light stabilizer and fluorescent whitener agent.

Pre-treatment of pyridine wastewater by new cathodic–anodic-electrolysis packing

A novel cathodic–anodic-electrolysis packing (CAEP) used in the treatment of pyridine wastewater was researched, which mainly consisted of 4,4′-diamino-2,2′-disulfonic acid (DSD acid) industrial iron sludge. The physical properties and morphology of the packing were studied. The CAEP was used in a column reactor during the pretreatment of pyridine wastewater. The influence of pH, hydraulic retention time (HRT), the air–liquid ratio (A/L) and the initial concentration of pyridine were investigated by measuring the removal of total organic carbon (TOC) and pyridine. The characterization results showed that the bulk density, grain density, water absorption percentage and specific surface area were 921kg/m3, 1086kg/m3, 25% and 29.89m2/g, respectively; the removal of TOC and pyridine could reach 50% and 58% at the optimal experimental conditions (pH=3, HRT=8hr, A/L=2). Notably, the surface of the packing was renewed constantly during the running of the filter, and the handling capacity was stable after running for three months.

Solubility of disodium 4,4′-dinitrobibenzyl-2,2′-disulfonate in aqueous organic solutions and its effects on the oxidation reaction of DSD acid synthesis

The solubility of disodium 4,4′-dinitrobibenzyl-2,2′-disulfonate (DNDNa) in aqueous ethylene glycol monoethyl ether solution and aqueous ethylene glycol monobutyl ether solution was measured over the temperature range from 278 to 334 K at atmospheric pressure by a dynamic method. The solubility of DNDNa in aqueous ethylene glycol monoethyl ether solution and aqueous ethylene glycol monobutyl ether solution increased with temperature over all solvent mixture compositions investigated. A synergistic effect on DNDNa solubility was observed with the maximum solubility at solute-free mass fraction of ethylene glycol monoethyl ether w30=0.6003 and solute-free mass fraction of ethylene glycol monobutyl ether w40=0.4054 , respectively. The solubility data were correlated using the electrolyte non-random two-liquid model and model parameters were determined simultaneously. It was found that around 0.4 (solute-free mass ratio) ethylene glycol monobutyl ether solution is suitable as the reaction medium in oxidation 4-nitrotoluene-2-sulfonic acid to 4,4′-dinitrostilbene-2,2′-disulfonic acid. The effect of different aqueous organic solutions on the oxidation reaction was discussed.

Synthesis of a novel tetrakisazo navy-blue reactive dye based on DSD acid and its synergistic blackening property

Purpose – The purpose of this paper is to synthesise a tetrakisazo reactive dye and to characterise its dyeing property to meet the demand for better black reactive dyes. Design/methodology/approach – The novel tetrakisazo navy-blue reactive dye based on 4,4′-diaminostilbene-2,2′-disulphonic acid was designed and synthesized. The dyeing behaviour of it on cotton fabric was discussed. The synergistic blackening effect and absorbance spectra were investigated by absorbance and reflectance spectra, K/S and colorimetric data. Findings – The exhaustion and fixation of the designed reactive dye were higher than 20 per cent than those of the commercial reactive dye, CI Reactive Black 5. The novel reactive dye has complementary with Reactive Red SPB and Reactive Yellow C-5R in absorbance spectra from 360 to 700 nm. Three reactive dyes had synergistic effect in colour deepening properties. The dyed cotton fabric possessed high K/S value and low reflectance in the whole visual spectrum range from 360 to 700 nm. Practical implications – Comparison with the commercial Reactive Black DN-RN, the blackness of the dyed fabrics with the mixture dyes was greatly improved and the fastness properties on cotton fabrics were also good. Originality/value – The paper is an original research work. Because the mixture dyes had better blackness and good fastness properties, it would have wide application in the dyeing of cotton fabric.

Preparation and characteristics of lightweight sludge ceramics by dehydrated sludge from dye intermediate processing wastewater treatment

Lightweight sludge ceramics (LSC) manufactured by two kinds of clay and dehydrated sludge from 4,4′-diaminostilbene-2,2′-disulfonic acid (DSD acid) processing wastewater treatment (DSD sludge) were studied for the sludge treatment. The raw pellets were preheated at 400°C for 15.0 min and sintered at 1,150°C for 8.0 min, which was beneficial to produce LSC. The optimum DSD sludge addition rate was determined by the physical properties (bulk density, water absorption, grain density, and expansion ratio), and then toxic metal leaching properties and microstructure properties were characterized. The results indicated that clay with high content of Fe2O3 might be more suitable for ceramics preparation, lower bulk (627.00 kg m−3), and grain density (1,280.00 kg m−3), and higher expansion ratio (18.80 v/v%) could be obtained with the optimum DSD sludge addition rate of approximately 50.0 wt%. Toxic metal leaching test showed that LSC was nontoxic and would not cause secondary pollution to water environment when applied as fillers, and the sintered ceramics had rough surface and porous interior according to microstructure analysis. Therefore, LSC prepared in this study might be utilized as biological media in wastewater treatment, which could turn hazardous solid waste (DSD sludge) into useful materials.

Solubility of disodium 4,4′-dinitrostilbene-2,2′-disulfonate and sodium 4-nitrotoluene-2-sulfonate in aqueous organic solutions and its application feasibility in oxidation stage of DSD acid synthesis

Solid–liquid equilibrium (SLE) measurements for disodium 4,4′-dinitrostilbene-2,2′-disulfonate (DNSNa) and sodium 4-nitrotoluene-2-sulfonate (NTSNa) in aqueous ethylene glycol monoethyl ether solution and aqueous ethylene glycol monobutyl ether solution were conducted using a dynamic method over the temperature range from (280 to 335)K. A synergistic effect on DNSNa solubility was observed with the maximum solubility at solute-free mass fraction of ethylene glycol monoethyl ether w30=0.4000 and solute-free mass fraction of ethylene glycol monobutyl ether w40=0.5999, respectively. The solubility data were correlated using the thermodynamic electrolyte non-random two-liquid (E-NRTL) model and model parameters were determined simultaneously. Aqueous ethylene glycol monobutyl ether solution at solute-free mass fraction of ethylene glycol monobutyl ether w40=0.2000 was found to be suitable solvent medium for the oxidation of 4-nitrotoluene-2-sulfonic acid (NTS) to 4,4′-dinitrostilbene-2,2′-disulfonic acid (DNS) and the conclusion was confirmed using the static analytical method combined with UV–VIS spectrophotometer.

Synthesis and Properties of the Composite DSD Acid-Triazine Structure Containing Long-Chain Quaternary Ammonium Fluorescent Brighteners

The cetyl \ octadecyl dimethyl tertiary amine（percentage composition 7:3）is a very common and inexpensive chemical raw material in the chemical market. In this paper, a series of the new chemical composite DSD acid-triazine structure containing long chain quaternary ammonium salt fluorescent brighteners (FBs) were synthesized through a three-step condensation reaction of cyanuric chloride, DSD acid, cetyl \ octadecyl dimethyl tertiary amine and amino compound. The obtained compounds were characterized by the analysis of the IR spectrum, UV spectrum and fluorescence excitation and emission spectrum, and whiteness were tested through dyeing filter paper. The results show that compounds 7a-j have the obvious UV absorption, fluorescence emission and dyeing properties, with a wider absorption, emission wavelength range and enhancing fluorescence quantum yield, achieving the synergetic enhancement effect by compounding.

Synthesis, Optical and Surface Properties of the New Gemini Quaternary Ammonium Surfactants Containing DSD Acid-triazine Structure

Four novel gemini quaternary ammonium surfactants containing DSD acid-triazine structure were synthesized using a facile three-step synthetic route , from 4,4'-diamino-2,2'-disulfonic-stilbene (DSD acid), cyanuric chloride and dimethyl dodecylamine. The structures and optical properties of compounds (6a-d) were characterized by Fourier-Transform infrared (FT-IR) spectroscopy, UV-visible absorption spectra and fluorescence emission spectrum. The surface tension and the Critical Micelle Concentration (CMC) were evaluated. The result shows that the four compounds at lower concentrations can greatly reduce the surface tension of aqueous solutions. The spectroscopic properties of these quaternary ammonium salts are assessed for their effectiveness and potential as fluorescent brightening agents.

Integration of a coagulation step in a cometabolism sequencing batch reactor for the treatment of DSD acid wastewater from a reduction process

4,4-Diaminostilbene-2,2′disulfonic acid (DSD acid) wastewater from a reduction process is characterized by slow biodegradation. With a coagulation step as pretreatment, the contaminant can be efficiently removed by a cometabolism sequencing batch reactor (SBR) in the presence of glucose. Since a part of COD from DSD acid wastewater was colloidal and refractory, coagulation was applied as the pretreatment process, which demonstrated that the optimal concentration of aluminum sulfate was 90mg/L. In the biological section, reduction efficiencies for COD, chromaticity and NH4+–N were 84%, 93% and 92%, respectively, when working with 10h and pH 7.0. In addition, dehydrogenase activity was proven to be a good parameter which can characterize the microorganism activity in this study.

Integration of coagulation step in cometabolism sequencing batch reactor for the treatment of DSD acid wastewater from reduction process

Integration of coagulation step in cometabolism sequencing batch reactor for the treatment of DSD acid wastewater from reduction process

Treatment of DSD acid wastewater using a weak basic resin

The D301R resin was screened to separate DSD acid from DSD acid wastewater. The effect of pH, temperature and time on adsorption behavior was investigated. Batch experiments indicated that the COD removal ratio of DSD acid wastewater was over 86%, and the COD of treated wastewater was under 100 mg/L at appropriate operating conditions. The results of column dynamic adsorption and regeneration showed that COD could be efficiently removed by the D301R resin from DSD acid wastewater, and the resin was easily regenerated by NaOH stripping.

Pretreatment and biodegradability enhancement of DSD acid manufacturing wastewater

Two advanced oxidation processes, Fenton's reagent oxidation and ozonation, were used for pretreatment of a 4,4′-diaminostilbene-2,2′-disulfonic acid (DSD-acid) manufacturing wastewater on a laboratory scale. The results showed that both methods are suitable for partial removal of chemical oxygen demand (COD) and color as well as the enhancement of biodegradability of DSD-acid manufacturing wastewater before the conventional biological treatment. Fenton's reagent oxidation by 9.0 g/L H 2O 2 and 150 mg/L Fe 2+ and ozonation by 7.5 g/L O 3 led to an improved biodegradability (BOD 5/COD = 0.3). Fenton's reagent oxidation in combination with Fe 3+ coagulation has shown to effectively remove COD and color. About 90% of COD and 95% of color removals were obtained at the optimum condition, oxidation by 150 mg/L Fe 2+ and 2 g/L H 2O 2, followed by two-stage coagulation with 5 g/L and 2 g/L FeCl 3, respectively.