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In last a few decades, significant improvements were made in both efficiency and economy for removal of heavy metals and metalloid (arsenic) from water using adsorbents. But less attention was paid to recycling of used adsorbents and recovery of the heavy metals from the desorbing agents. For regeneration and reuse of adsorbents, various possible regenerating agents such as acids, alkalis and chelating agents (such as ethylene diamine tetraacetic acid) were used by many researchers with very limited success in some of the studies only up to a limited number of adsorption-desorption cycles. Only a few of the reported studies were focused on recovery of adsorbed (from saturated adsorbents) and desorbed metals (from regenerating agents). Though the management of the used adsorbent and recovery of heavy metals is one of the most important aspects, but only a limited number of research works considered the fate of spent adsorbents before disposal. This review summarizes the removal efficiency of various adsorbents, desorption efficiency of various regenerating agents and recovery of the heavy metals from both saturated adsorbents and desorbing solvents used for regeneration. The study will help the scientific community working on adsorption studies to take up research initiatives required to address the feasible recovery methods of heavy metals from the used adsorbents, to study the possible reuse of the desorbing agents and to choose a suitable desorbing/regenerating agent for a particular adsorbent.

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To the best of our knowledge, there is no method in the literature for solving such differential equations in which all the parameters except independent variables are represented by intuitionistic fuzzy numbers. In this article, a new method is proposed for solving such nth-order time-dependent intuitionistic fuzzy linear differential equations. To show the application of the proposed method in real-life problems, the time-dependent intuitionistic fuzzy Kolmogorov's differential equations, obtained by Markov model of condensate system, are solved by the proposed method, and the obtained solution is used to analyze the intuitionistic fuzzy reliability of condensate system.

There are many infectious diseases that may be biofilm mediated, medical device-mediated or from some other agent, are now becoming life-threatening. Despite of availability of many antimicrobial agents, new drugs or therapeutics, these infections have continued to be a global health challenge. Nowadays, conventional antimicrobial agents have failed against many infections due to the emergence of multiple drug-resistant strains. Even, if there is a therapeutic efficacy of these drugs, there inappropriate amounts are resulting in an adequate therapeutic index, local and systematic side effects, including irritation, reduction in gut flora and other manifestations. To overcome such situations, nanostructures have exclusive physicochemical properties as they are ultra small, their size can be controlled, greater surface area to mass ratio, high reactivity and functionalizable structure. Encapsulation of antimicrobial drugs in these nanoparticle systems helps in reducing many side effects. It also helps in the sustained release of drug for a larger time period. Several metal and metal oxide nanoparticles such as silver, gold, zinc, etc. have shown a promising antimicrobial activity. Liposomes, polymeric nanoparticles, dendrimers, and solid lipid nanoparticles have achieved great success as efficient antimicrobial drug delivery systems. These nanoparticles use multiple biological pathways to exert their antimicrobial mechanism such as cell wall disruption, inhibition of RNA synthesis, protein synthesis, etc. Moreover,these preparations of nanoparticles are more cost-effective than that of antibiotic synthesis with lesser or no side effects.