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This study aimed to verify the efficiency of an electrocoagulation reactor to generate low carbon hydrogen and treat textile effluent simultaneously. The electrolytic cell comprised a hermetically sealed polypropylene container containing 800 mL of effluent and a pair of immersed stainless steel 304 L electrodes powered by a photovoltaic solar panel (540 W). A gas chromatograph with a dielectric-barrier discharge ionization detector (GC-BID) measured the hydrogen gas produced. The efficiency of the textile effluent treatment was evaluated using the parameters of dissolved organic carbon, turbidity, pH, conductivity, and color. The electrical energy consumed by hydrogen generation and effluent treatment was also measured. The maximum concentration of hydrogen produced was 89.87% (v/v) with 898676.9 ppm. The process removed 100% of color, 92% of dissolved organic carbon, and 99.53% of turbidity. The electrical energy consumed for hydrogen generation ranged from 19.02 to 55.74 KW h/m3H 2. • Simultaneous electrolytic process of low carbon hydrogen generation and textile effluent treatment. • Hydrogen concentration values were obtained in the 475773.3 ppm (47.57 %) to 898676.9 ppm (89.87 %) range. • The process removed 100%, 99.53%, and 92% of color, turbidity, and dissolved organic carbon, respectively. • The energy per volume of hydrogen produced was 19.02–55.74 KW h/m3H 2. [ABSTRACT FROM AUTHOR]

Pollution of water bodies from improper disposal of toxic metal contaminated effluents causes several problems for the environment. Several processes can be used to remove these metal ions from aqueous media, and the adsorption being the most efficient technique. In this process, a diversity of adsorbent materials is used, with the use of zeolite 4A emphasized in this study. This study aimed to evaluate the efficiency of zeolite 4A as an adsorbent material for the removal of Cu2+, Cd2+, Pb2+, and Zn2+ from aqueous media. For this, zeolite 4A was synthesized by the hydrothermal route starting from two sources of precursors, one from standard reagents (ZA-P) and the other from coal fly ash (ZA), a residue from a thermoelectric industry plant in the state of Ceará (Brazil). Both materials were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and cation exchange capacity techniques. The materials were subjected to batch adsorption tests with multi-element synthetic solutions of Pb2+, Cu2+, Zn2+, and Cd2+. The parameters investigated in the adsorption experiments were the dosage effect, contact time, and adsorption equilibrium. Flame atomic absorption spectroscopy was used for metal ion quantitation. The characterization results showed that both ZA-P and ZA yielded mainly the crystalline phase of zeolite 4A. In the dosage test, a weight of 100 mg promoted the best results for both ZA-P and ZA, with ZA achieving superior removal results. Pb2+ was more efficiently removed at 95% for ZA and 93% for ZA-P. In addition, at the time of contact, it was observed that ZA reached equilibrium faster (10 min) than ZA-P (50 min). In the adsorption equilibrium, the Langmuir model was able to describe almost all results, only the Zn2+ for ZA was modeled by the Freundlich isotherm. The affinity of metal ions for materials followed the order (Pb2+ > Cd2+ > Zn2 > Cu2+) for ZA-P and (Pb2+ > Cd2+ > Cu2+ > Zn2+) for ZA. Finally, it is concluded that both products have potential for application as metal adsorbents of Cu2+, Cd2+, Pb2+, and Zn2+ in aqueous solutions and that coal fly ash can be recycled to obtain zeolite. [ABSTRACT FROM AUTHOR]

Textile effluents are known to be complex matrices, requiring a combination of treatment techniques to achieve conditions that allow effluent to be discarded into environment. The electrocoagulation technique manages to remove most of the pollutants present in textile effluents, but generally does not achieve complete removal. This work studied the efficiency of combined electrochemical oxidation and ozonation techniques in the post-treatment of a real textile effluent after electrocoagulation and decantation processes. The experiments were carried out in batch mode using Ti/RuO2 electrodes (2 plates) and an ozone generator (0.875 g·h-1·L-1). Three current densities were studied, 33.3, 66.6, and 133.3 A·m-2. The turbidity, color, dissolved organic carbon, and pH were analyzed to evaluate the treatment process. The results showed higher efficiency for removing color and dissolved organic carbon with increasing current density. Applying the ozonation process alone had the lowest color and dissolved organic carbon removal efficiencies. The best experiment was with the current density of 66.6 A·m-2 integrated with O3 promoted removal percentages of 91.77%, 33.02%, and 91.09% for turbidity, dissolved organic carbon, and color, respectively. [ABSTRACT FROM AUTHOR]

Raw water was submitted to a treatment process using electro-oxidation and ozonation, evaluating the parameters color, dissolved organic carbon (DOC), turbidity, UV-Vis adsorption spectrum, SUVA, and energy consumption. In the electro-oxidation process were used two current densities (22 and 44 A m–2) ruthenium electrodes and two types of current, (direct and pulsed). The percentages of removal of apparent and true color varied from 40.84 to 70.17% and from 47.09 to 80.06%, respectively. The electro-oxidation by direct current in the presence of ozone had the best removal efficiencies. DOC removal reached levels of 1.55–15.69%. The use of the electro-oxidation by pulsed current has obtained lower values of energy consumption. [ABSTRACT FROM AUTHOR]