s. m. etezad

The treatment of textile dyeing wastewater represents a remarkable environmental challenge, particularly with the use of natural dyes. Despite their more eco-friendly profile compared to synthetic counterparts, natural dyes contribute to pollution when not fully removed from effluents. Among various remediation techniques, adsorption stands out for its effectiveness, with metal-organic frameworks (MOFs) emerging as promising adsorbents due to their high adsorption capacities and structural stability. This study focuses on the application of a synthesized and characterized MIL-53 (Al) MOF for the adsorption of cochineal extract, a widely used natural red dye in the textile industry, especially handmade carpets. Employing Response Surface Methodology (RSM), we optimized dye removal under varying conditions such as adsorbent amount, temperature, contact time, and pH. Our findings revealed that adsorbent quantity notably influenced the adsorption efficiency, whereas temperature had the least impact, with the highest adsorption capacity observed at 60 °C being 178.57 mg/g. Kinetic analyses indicated that the adsorption process conformed to the pseudo-second-order model, suggesting a physical adsorption mechanism, as further evidenced by an activation energy of 4.914 KJ/mol. Thermodynamic parameters, including changes in enthalpy (∆H°), entropy (∆S°), and Gibbs free energy (∆G°), were determined, revealing an endothermic reaction consistent with physical adsorption. The positive enthalpy change and the spontaneous nature of the process, inferred from a negative Gibbs free energy, underscore the potential of MIL-53 (Al) in efficiently removing cochineal dye from wastewater, contributing to the development of sustainable wastewater treatment strategies in the textile industry.

Deinking waste paper is done in various ways, and research on newer methods is also being done. Traditional deinking methods to remove ink from waste printing papers have a relatively high efficiency compared to contact methods, but in non-contact printing such as electrophotographic printing (LaserJet printers and photocopiers) due to Mixing of the ink with the paper texture during the stabilization of the ink with the help of high heat, the traditional deinking methods are less efficient and it is necessary to use newer methods. In this research, enzymatic deinking of office waste paper was done by a commercial cellulase enzyme in a neutral environment. 15 tests were conducted, and optical and printing properties including the paper were investigated. By measuring the reflection before and after printing and measuring the print density after printing, it was determined that the printability of deinked paper is within the desired range. Eric's number was 128 ppm for sample number 8 and 138 ppm for sample number 12, which has decreased compared to the control sample with an Eric number of 571 ppm. Measuring the reflection before and after printing and measuring the print density after printing, show that the printability of decomposed ink paper is in the desired range. </em>

Malachite green dye is widely used in food and textile industries for various purposes and also used as biocide in the aquaculture industry to control fungal attacks and protozoan infections. Surface and ground water is contaminated by dyes due to discharge of untreated wastewater from industries. The presence of malachite green in water causes serious health effects such as mutagenesis, respiratory toxicity and carcinogenesis. Therefore, removal of malachite green from water by using various techniques is an essential concern for living beings as well as environment. In this study, the ability of isolated bacteria (from oil contaminated soil) for biodegradation of MG dye was investigated. The bacterium was able to grow in temperature range of 25 to 45°C and pH range of 5 to 9. Optimum temperature and pH for bacterial growth were determined as 37 °C and 7, respectively. Effect of temperature, initial concentration of dye and shaking condition on decolorization of dye solution was also tested. 20 ppm MG dye was efficiently degraded by bacteria in less than 2 h, and biodegradation of MB dye followed first-order kinetics model. These properties make the bacteria suitable for industrial wastewater treatment.