Modern Carbon–Based Materials for Adsorptive Removal of Organic and Inorganic Pollutants from Water and Wastewater

Currently, a serious threat for living organisms and human life in particular, is water contamination with persistent organic and inorganic pollutants. To date, several techniques have been adopted to remove/treat organics and toxic contaminants. Adsorption is one of the most effective and economical methods for this purpose. Generally, porous materials are considered as appropriate adsorbents for water purification. Conventional adsorbents such as activated carbons have a limited possibility of surface modification (texture and functionality), and their adsorption capacity is difficult to control. Therefore, despite the significant progress achieved in the development of the systems for water remediation, there is still a need for novel adsorptive materials with tunable functional characteristics. This review addresses the new trends in the development of new adsorbent materials. Herein, modern carbon-based materials, such as graphene, oxidized carbon, carbon nanotubes, biomass-derived carbonaceous matrices—biochars as well as their composites with metal-organic frameworks (MOFs) and MOF-derived highly-ordered carbons are considered as advanced adsorbents for removal of hazardous organics from drinking water, process water, and leachate. The review is focused on the preparation and modification of these next-generation carbon-based adsorbents and analysis of their adsorption performance including possible adsorption mechanisms. Simultaneously, some weak points of modern carbon-based adsorbents are analyzed as well as the routes to conquer them. For instance, for removal of large quantities of pollutants, the combination of adsorption and other methods, like sedimentation may be recommended. A number of efficient strategies for further enhancing the adsorption performance of the carbon-based adsorbents, in particular, integrating approaches and further rational functionalization, including composing these adsorbents (of two or even three types) can be recommended. The cost reduction and efficient regeneration must also be in the focus of future research endeavors. The targeted optimization of the discussed carbon-based adsorbents associated with detailed studies of the adsorption process, especially, for multicomponent adsorbate solution, will pave a bright avenue for efficient water remediation.

Solidification/Stabilization of Textile Sludge as Subgrade: Usage of Binders and Skeleton Material

This study investigates the disposal of textile sludge via laboratory and field tests while protecting the eco-environment. Solidification/stabilization (S/S) technology and skeleton construction method are introduced to investigate the application of S/S sludge for subgrade material. S/S is to enhance the sludge strength and stabilize the metal(loid)s and hazardous organics in the textile sludge. Skeleton construction method aims to decrease the liquid-solid ratio in mixture to reduce the binder dosage and save binder cost. In the laboratory, binders and skeleton material are implemented to investigate the differences in unconfined compressive strength (UCS) to explore the optimal mixture. Results illustrate that UCS of binder-sludge is below 100 kPa and enhanced more than 400 kPa after adding gypsum and skeleton material. Skeleton soil material with high plasticity index and low moisture content improves UCS significantly. Scanning electron microscopy test shows the physical microstructure of sludge is greatly improved for the particular space grid structure formed by the particles and cementitious products. The leaching test shows the metal(loid)s and organics in leachate are decreased after S/S treatment and below the standard value. Finally, the textile sludge was disposed for subgrade via the technology. The strength and leaching results of field tests are in good agreement with the laboratory results. The bearing capacity of the practical subgrade meets the design requirements.