The efficient handling of wastewater pollutants is a must, since they are continuously defiling limited fresh water resources, seriously affecting the terrestrial, aquatic, and aerial flora and fauna. Our vision is to undertake an exhaustive examination of current research trends with a focus on nanomaterials (NMs) to considerably improve the performance of classical wastewater treatment technologies, e.g. adsorption, catalysis, separation, and disinfection. Additionally, NM-based sensor technologies are considered, since they have been significantly used for monitoring water contaminants. We also suggest future directions to inform investigators of potentially disruptive NM technologies that have to be investigated in more detail. The fate and environmental transformations of NMs, which need to be addressed before large-scale implementation of NMs for water purification, are also highlighted.

Carbon nanotubes have been increasingly used in the fields of nanorobotics, electrochemical catalysis, microarray chips, and green adsorbents for pollutants, sensors and optoelectronics. Complicated physico-chemical aspects and novel schemes to synthesize controlled featured carbon nanotubes have added new ambiguities to their characterizations and applications and these must be resolved on an urgent basis. Most of the characterization tools such as scanning electron microscopy, transmission electron microscopy, scanning tunneling microscopy and atomic force microscopy probes only for characterizing the local features of carbon nanotubes. However, X-ray powder diffraction can reveal the local and global features of microstructure’s lattice and crystalline phases, domain sizes, and impurities. Thus it is worthwhile to highlight this technique for better understanding and utilization of its benefit to unravel the carbon nanotube ambiguities. To the best of our knowledge, no comprehensive reviews or systematic description of X-ray powder diffraction on carbon nanotubes characterization have been published yet. In this review, we filled-up this gap and provided a systematic presentation of X-ray powder diffraction application in carbon nanotubes characterization. This could be used as a reference guide for the utilization of X-ray powder diffraction to probe the various features of carbon nanotubes and carbon nanotubes based materials.

Although many methods have been documented for carbon nanotube (CNT) synthesis, still, we notice many arguments, criticisms, and appeals for its optimization and process control. Industrial grade CNT production is urgent such that invention of novel methods and engineering principles for large-scale synthesis are needed. Here, we comprehensively review arc discharge (AD) and laser ablation (LA) methods with highlighted features for CNT production. We also display the growth mechanisms of CNT with reasonable grassroots knowledge to make the synthesis more efficient. We postulate the latest developments in engineering carbon feedstock, catalysts, and temperature cum other minor reaction parameters to optimize the CNT yield with desired diameter and chirality. The rate limiting steps of AD and LA are highlighted because of their direct role in tuning the growth process. Future roadmap towards the exploration of CNT synthesis methods is also outlined.

Preparation of Carbonaceous Adsorbents from Lignocellulosic Biomass and Their Use in Removal of Contaminants from Aqueous Solution