Qian, et al (2024) Dyeing sludge-derived biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More for efficient removal of malachite green from dyeing wastewater. Water Emerging Contaminants & Nanoplastics. https://doi.org/10.20517/wecn.2024.25

The dyeing industry produces a significant amount of wastewater, contributing to environmental pollution. Malachite green (MG), a dye widely used in the textile industry, poses significant environmental and health risks due to its persistence and resistance to natural degradation. To tackle this problem, researchers from Zhongkai University of Agriculture and Engineering explored the use of biochar derived from dyeing sludge to efficiently remove MG from wastewater.

The study utilized a response surface methodology to optimize the preparation of ZnCl2 modified sludge biochar (ZSC). PyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperature was found to be the most critical factor, with an optimal temperature of 800°C. The highest MG adsorption capacity by ZSC reached 224.0962 mg/g, with a removal efficiency of 99.13% under optimal conditions. Even after five cycles of reuse, ZSC maintained a significant decolorization capability of 45%.

The preparation of ZSC involved mixing dried dyeing sludge with a ZnCl2 solution, followed by pyrolysis at varying temperatures and durations. The resulting biochar was characterized using various techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). These analyses revealed that ZSC had a high specific surface area of 495.38 m²/g and contained reactive functional groups, enhancing its adsorption capacity.

Adsorption experiments examined the effects of different environmental factors on MG removal, including pHpH is a measure of how acidic or alkaline a substance is. A pH of 7 is neutral, while lower pH values indicate acidity and higher values indicate alkalinity. Biochars are normally alkaline and can influence soil pH, often increasing it, which can be beneficial More, initial MG concentration, ZSC dosage, and temperature. The adsorption process conformed to the Langmuir isotherm model and pseudo-second-order kinetic model, indicating monolayer adsorption and chemisorption as dominant mechanisms.

The study demonstrated that ZSC’s adsorption of MG involved multiple mechanisms: electrostatic attraction, pore-filling, hydrogen bonding, and π-π stacking interactions. Higher pyrolysis temperatures increased the aromaticity and porosityPorosity of biochar is a key factor in its effectiveness as a soil amendment and its ability to retain water and nutrients. Biochar’s porosity is influenced by feedstock type and pyrolysis temperature, and it plays a crucial role in microbial activity and overall soil health. Biochar More of the biochar, enhancing its adsorption performance. The presence of functional groups such as –OH and C–O facilitated hydrogen bonding and π-π interactions with MG molecules.

This research offers a promising solution for transforming dyeing sludge, a waste product, into a valuable material for wastewater treatment. By converting sludge into ZSC, the study not only addresses the issue of dye removal from wastewater but also contributes to resource reclamation and environmental sustainability. The findings suggest that dyeing sludge-derived biochar can be an effective, economical, and environmentally friendly adsorbent for treating dye-laden wastewater, providing a dual benefit of waste reduction and water purification.