Decolorization of reactive dye using a photo-ferrioxalate system with brick grain-supported iron oxide

Waste Bricks Applied as Removal Agent of Basic Blue 41 from Aqueous Solutions: Base Treatment and Their Regeneration Efficiency

Waste brick materials were applied as removal materials of basic blue 41 (BB-41) from artificially contaminated water. They were characterized by different techniques prior their use. A series of removal tests were carried out at different conditions, such as a dosage effect, pH value, initial concentrations, and chemical treatment. The removal results indicated that the two untreated waste bricks had limited removal capacities of basic blue 41, ranging from 19 to 30 mg/g. However, these values were improved upon treatment with NaOH solution or by increasing the removal temperature. Waste brick collected from the Medina area (Med-WB) exhibited higher removal capacity compared to the one collected from the Jeddah area (Jed-WB), with a maximum removal capacity of 60 mg/g at 60 °C. The pH of the BB-41 solution also played an important factor, as it improved the removal amounts from 25 mg/g to 45 mg/g at initial concentration of 200 mg/L. The regenerative process was studied using oxidative reaction of the removed basic blue 41 with a solution of oxone and cobalt nitrate. The efficiency was maintained after 5 runs for Med-WB, with a slight variation of 25%, while it felt to 50% for Jed-WB material after three runs. These data indicate that the waste brick materials present as potential candidates for the dye removal and their origin has to be identified.

Photo-Fenton oxidation of 3-amino-5-methylisoxazole: a by-product from biological breakdown of some pharmaceutical compounds

The present study aims to assess the removal of 3-amino-5-methylisoxazole (AMI), a recalcitrant by-product resulting from the biological breakdown of some pharmaceuticals, applying a solar photo-Fenton process assisted by ferrioxalate complexes (SPFF) (Fe³⁺/H₂O₂/oxalic acid/UVA-Vis) and classical solar photo-Fenton process (SPF) (Fe²⁺/H₂O₂/UVA-Vis). The oxidation ability of SPFF was evaluated at different iron/oxalate molar ratios (1:3, 1:6, and 1:9, with [total iron] = 3.58 × 10^-2 mM and [oxalic acid] = 1.07 × 10^-1, 2.14 × 10^-1 and 3.22 × 10^-1 mM, respectively) and pH values (3.5-6.5), using low iron contents (2.0 mg Fe³⁺ L^-1). Additionally, the use of other organic ligands such as citrate and ethylenediamine-N,N'-disuccinic acid (EDDS) was tested. The oxidation power of the classical SPF was assessed at different pH values (2.8-4.0) using 2.0 mg Fe²⁺ per liter. Furthermore, the effect of AMI concentration (2-20 mg L^-1), presence of inorganic ions (Cl^-, SO₄^2-, NO₃^-, HCO₃^-, NH₄⁺), and radical scavengers (sodium azide and D-mannitol) on the SPF method at pH 3.5 was also assessed. Experiments were done using a lab-scale photoreactor with a compound parabolic collector (CPC) under simulated solar radiation. A pilot-scale assay was conducted using the best operation conditions. While at near neutral pH, an iron/oxalate molar ratio of 1:9 led to the removal of 72 % of AMI after 90 min of SPFF, at pH 3.5, an iron/oxalate molar ratio of 1:3 was enough to achieve complete AMI degradation (below the detection limit) after 30 min of reaction. The SPF process at pH 3.5 underwent a slower AMI degradation, reaching total AMI degradation after 40 min of reaction. The scale up of SPF process showed a good reproducibility. Oxalic and oxamic acids were identified as the main low-molecular-weight carboxylic acids detected during the pilot-scale SPF reaction. Graphical abstract ᅟ.

A Simple Two-Step Cloud Point Extraction Process for Removing Fluorescent Whitening Agents VBL in Industrial Wastewater and Recycling of Surfactant

  With the enhancement of people's environmental consciousness, the treatment of wastewater was studied as the focus of this paper. Here we present a simple two-step extraction to realize efficient separation of fluorescent whitening agents VBL and cyclic utilization of surfactant to reduce the cost of wastewater treatment and environmental pollution. Firstly, the removal of VBL has been achieved by CPE using TX-114 as nonionic surfactant. The results showed that complete extraction was possible using 1% (w/w) TX-114 for VBL concentration not exceeding 17.5 mg/L, otherwise using a higher concentration of 1.5% (w/w) TX-114. Then the surfactant from the coacervate phase was recycled by changing the potential difference between phases. The morphology of micelles and solubilization mechanism of VBL were demonstrated through the observation of a fluorescent microscope. This method was successfully used to remove the VBL from wastewater sample and the surfactant could be reused several times.

Homogeneous photocatalytic oxidation of UV filter para-aminobenzoic acid in aqueous solutions

The presence of personal care product (PCP) residues in the aquatic environment is an emerging issue due to their uncontrolled release through graywater; for this reason, efforts are being made to develop methods to inactivate or eliminate this class of substances in the environment. In this work, homogeneous photocatalysis has been applied for the degradation of UV filter para-aminobenzoic acid (PABA), which exists in several types of PCPs, in order to identify the optimum degradation conditions. The oxidation of PABA by photo-Fenton and oxalate-induced photo-Fenton (ferrioxalate) processes was investigated, and the effect of various operating variables has been assessed, i.e., Fe³⁺ (0.0035-0.014 g L^-1), H₂O₂ (0.025-0.2 g L^-1), T (280-323 K), and type of radiation (UV-A, visible). Furthermore, experiments under optimal conditions have been performed in order to evaluate the transformation pathways and phytotoxicity of the treated PABA solution.

Applicability of fluidized bed reactor in recalcitrant compound degradation through advanced oxidation processes: a review

Treatment of industrial waste water (e.g. textile waste water, phenol waste water, pharmaceutical etc) faces limitation in conventional treatment procedures. Advanced oxidation processes (AOPs) do not suffer from the limits of conventional treatment processes and consequently degrade toxic pollutants more efficiently. Complexity is faced in eradicating the restrictions of AOPs such as sludge formation, toxic intermediates formation and high requirement for oxidants. Increased mass-transfer in AOPs is an alternate solution to this problem. AOPs combined with Fluidized bed reactor (FBR) can be a potential choice compared to fixed bed or moving bed reactor, as AOP catalysts life-span last for only maximum of 5-10 cycles. Hence, FBR-AOPs require lesser operational and maintenance cost by reducing material resources. The time required for AOP can be minimized using FBR and also treatable working volume can be increased. FBR-AOP can process from 1 to 10 L of volume which is 10 times more than simple batch reaction. The mass transfer is higher thus the reaction time is lesser. For having increased mass transfer sludge production can be successfully avoided. The review study suggests that, optimum particle size, catalyst to reactor volume ratio, catalyst diameter and liquid or gas velocity is required for efficient FBR-AOP systems. However, FBR-AOPs are still under lab-scale investigation and for industrial application cost study is needed. Cost of FBR-AOPs highly depends on energy density needed and the mechanism of degradation of the pollutant. The cost of waste water treatment containing azo dyes was found to be US$ 50 to US$ 500 per 1000 gallons where, the cost for treating phenol water was US$ 50 to US$ 800 per 1000 gallons. The analysis for FBR-AOP costs has been found to depend on the targeted pollutant, degradation mechanism (zero order, 1st order and 2nd order) and energy consumptions by the AOPs.