Study on the Removal of Fluorescent Whitening Agent from Paper-Mill Wastewater Using the Submerged Membrane Bioreactor (SMBR) with Ozone Oxidation Process

In this study, paper-mill wastewater was treated using the Submerged Membrane Bioreactor (SMBR) process. In particular, the ozone oxidation treatment process is applied after SMBR to remove the fluorescent whitening agent, which is a trace pollutant and non-biodegradable. Fluorescent whitening agent concentration was indirectly measured by UV scanning and COD concentration. The concentration of COD before SMBR and ozone oxidation was 449.3 mg/L, and the concentration of treated water was 100.3 mg/ℓ. The COD removal efficiency of paper-mill wastewater through SMBR and the ozone oxidation process was about 77.68%. The optimized amount of ozone was required for the removal of the fluorescent whitening agent after SMBR was 95 mg·O3/ℓ calculated by UV scan results. Additionally, the optimized amount of required ozone to remove COD was calculated to 0.126 mg·COD/mg·O3.

A Ground-State Complex Between Methyl Viologen and the Fluorescent Whitening Agent 4, 4’–bis (2-sulfostyryl)-biphenyl disodium salt: A Fluorescence Spectroscopy Study

This study explores the quenching of the dianionic fluorescent whitening agent, NFW, by various substances, including methyl viologen (MV), in water and in the presence of Beta-cyclodextrin (β-CD). Results of a fluorescence spectroscopic examination of the β-CD-NFW system are presented. It was found that NFW forms a 1:1 inclusion complex with β-CD with an association constant of 2540 ± 380 M^-1. The included NFW fluorescent state is protected by the β-CD cavity from a range of water-based quenchers (neutral, anionic and cationic). Quenching proceeds near the diffusion-controlled limit in water for the quenchers tested with the exception of the dicationic MV. MV is an extremely efficient quencher of NFW fluorescence with a nominal K_SV ~ 5.0x10³ M^-1 in water alone, corresponding to a nominal k_q of ~ 4x10¹² M^-1s^-1, which exceeds the diffusion-controlled limit in this solvent. The quenching efficiency of MV is strongly suppressed in the presence of 10 mM β-CD (K_SV = 105 ± 12 M^-1) and in the presence of NaCl (K_SV = 106 ± 9 M^-1 at 0.5 M salt). In the absence of CD or salt, there is a strong contribution from static quenching in the MV system; the presence of these additives suppresses the static quenching. Various results suggest the static quenching is due to formation of a ground-state complex between the dianion NFW and the dication MV.

The influence of FWA chemical constitution to the whiteness and UV protection of cotton and cotton/polyester blend

It is well known that the optimal concentration of fluorescent whitening agent (FWA) in the bath results in high whiteness of single component textiles. At the same time, due to fluorescence of FWA, the higher UV protection is achieved as well. However, for the textile blends it is not so easy to achieve. Depending on the fabric chemical composition, different FWAs must be applied. Therefore, the influence of FWA chemical constitution to the whiteness and UV protection of cotton and cotton/polyester blend were researched in this paper. For that purpose, cotton and cotton/polyester blended (50%/50%) fabrics was treated with four different FWAs by Huntsman, Uvitex® brand: BHT, RSB, NFW and EBF. Spectral remission before and after FWA treatment was measured on a remission spectrophotometer Spectraflash SF 300, Datacolor. Whiteness degree was calculated according to ISO 105-J02:1997, and the Tint Deviations and its coloristic meanings were determined according to Griesser. The UV protection of cotton and cotton/polyester fabrics treated with FWA was determined according to AS/NZS 4399:2017 using transmission spectrophotometer Cary 50/Solascreen, Varian. Based on the results obtained,the stilbene disulphonic acid triazine derivative (Uvitex® RSB) can be recommended for use on a cotton/polyester blend.

A Study on the Removal of Fluorescent Whitening Agent by Pretreatment Ozone Oxidation for MBR Process Application

In this study, ozone oxidation experiment was carried out for the removal of fluorescent whitening agent which is widely used in textile dyeing and paper industry. The stilbene fluorescent whitening agent has been industrialized since the earliest, and the amount of current production is the highest. Due to the characteristics of the fluorescent whitening agent that cannot be removed by conventional wastewater treatment methods, the fluorescent whitening agent in wastewater treatment has difficulty in using as recycled water in the process. Pre-treatment ozone oxidation experiment was conducted prior to the introduction of Membrane Bio Reactor (MBR) treatment process by converting biodegradable materials into biodegradable materials. The removal efficiencies of fluorescent whitening agents, a diaminostilbene disulfonic acid derivative by ozone oxidation were evaluated by UV254 Scan, COD, T-N and color using a synthetic wastewater sample (COD=433.0 mg/ℓ) and paper and paper mill wastewater (COD=157.2 mg/ℓ).

Study on the Removal of Fluorescent Whitening Agent for Paper-mill Wastewater Reuse using the Submerged Membrane Bioreactor (SMBR) with Ozone Oxidation Process

In this study, effluent water was produced through Submerged Membrane Bio-Reactor (SMBR) process, which is a simple system and decomposes organic matter contained in wastewater with biological treatment process and performs solid-liquid separation, Especially, ozone oxidation treatment process is applied to effluent water containing fluorescent whitening agent, which is a trace pollutant which is not removed by biological treatment, and influences the quality of reused water. The concentration of COD in the SMBR was 449.3 mg/ℓ-COD, and the concentration of permeate water was 100.3 mg/ℓ-COD. The removal efficiency was about 70.1%. The amount of ozone re- quired for the removal of the fluorescent whitening agent in the permeated water in SMBR was 6.67 g-O3/min, and the amount of ozone required to remove COD relative to the permeate water was calculated to remove 0.997 mg-COD for 1 mg of O3.

Synthesis of novel 4,4'-bis(2,4-pyrimidinyl)-diaminostilbene-2,2'-disulfonic acid derivatives and their whitening effect on cotton fiber as fluorescent whitening agents

Some novel 4,4'-bis(2,4-pyrimidinyl)-diamino stilbene-2,2'-disulfonic acid derivatives 4a-d were designed and synthesized. Their structures were confirmed by proton nuclear magnetic resonance, elemental analysis and ultraviolet absorption spectra. All newly synthesized compounds were interrogated on their whitening effect on cotton fiber as fluorescent whitening agents. Their optical properties were evaluated by the degree of whiteness, color index, light fastness, wet rubbing fastness and dry rubbing fastness. The results indicated that compounds 4a-d showed an obvious whitening effect on cotton fiber and higher fastness than that of C186. The reflectivity of cotton fiber treated with compounds 4a-d at the critical concentration was up to 120.76%. In contrast, the reflectivity of untreated cotton fiber was only 87.23%. The ultraviolet absorption properties of compound 4d were tested under diverse pH values. The results showed that the ultraviolet absorption intensity of compound 4d decreased significantly and the absorption curve had blue shift under acidic conditions. Compound 4d was found to be the most effective molecule as a fluorescent whitening agent with a higher degree of whiteness (CIE Whiteness 135.04) compared to untreated cotton fiber (CIE Whiteness 73.02) at the critical concentration (0.1%).

Improvement of color value of bio-based polyamide 56 fibers

This paper introduces a feasible method to improve the color value of bio-based polyamide 56 (PA56) fiber. Three types of whitening modifiers were introduced into the bio-based PA56 fibers by the in-situ polymerization method and melt blending method in order to improve the fiber color. The color values and mechanical properties of PA56 fibers were tested and analyzed and the optimum additive ratio and process conditions were discussed. The results show that the improved color value of bio-based PA56 fibers can be achieved by the melt blending method of fluorescent whitening masterbatch and reasonable spinning condition control. When the additive amount of fluorescent whitening agent is 0.3%, the index of lightness (L) increased from 84 to 90, while the yellow index (YI) reduced from 16.8 to 12.6. Moreover, PA56 fibers show high breaking strength about 4.27 cN/dtex and good yellowing resistance and durability.