Effective recycling and reuse of resources is one sure way of achieving sustainable development. Adsorption, a nondestructive and low-cost technique, has been widely employed in recovering resources and removing contaminants. However, its adsorption efficiency decreases with the existence of several adsorbates which actively compete for limited active adsorption sites. Most of the proposed methods for improving the adsorption efficiency work by eliminating competition from other co-existent substances. In this way, the adsorption capacity of the target adsorbate is improved at the expense of other adsorbates. Whereas these methods are efficient for adsorbing single target adsorbates, developing methods for simultaneous and efficient adsorption of more than one adsorbate is highly desirable.
To this note, researchers at Nanchang Hangkong University: Lei Tian, Professor Hualin Jiang, Professor Pinghua Chen, Dr. Qi Wang, Pingping Niu, Yangming Shi, Minghui Zhou, Dr. Yuancheng Qing, and Professor Xvbiao Luo presented a new method for developing adsorbents with two functional domains for efficient adsorption and sequential recovery of valuable organic and inorganic resources. The synthesized nanohybrid adsorbent comprised of GO and PNIPAm domains. GO domain was responsible for adsorption of inorganic ions while the PNIPAm domain, prepared by molecular imprinting, was responsible for the adsorption of organic molecules. The work is published in the research journal, Chemical Engineering Journal.
The study showed that the two-functional domain structure prevented competition between the organic and inorganic adsorbates for the same adsorption active sites because different adsorption active sites were created for different adsorbates. Thus, both organic and inorganic adsorbates were simultaneously and efficiently adsorbed. Besides, it solved the eluate mixing problem often associated with the desorption of several adsorbents under the same desorption conditions.
As proof of the concept, Pb2+ and 4-Nitrophenol were used as model contaminants to validate the feasibility of selective adsorption and sequential desorption properties of hybrid GO/PNIPAm. Adsorption experiments and XPS analysis were used to confirm the location of Pb2+ and 4-NP. The novel hybrid exhibited high adsorption capacity, with high anti-interference ability, towards Pb2+ and 4-NP. The GO domain adsorbed Pb2+ while PNIPAm domain adsorbed 4-NP. Consequently, Pb2+ and 4-NP were sequentially desorbed and recovered due to different adsorption sites and mechanisms.
Owing to novel location selective adsorption capacity, sequential desorption property, high efficiency, and easy operation, the hybrid with two functional domains has proved to be significantly better than traditional adsorbents and is, with no doubt, a promising adsorbent for simultaneous adsorption and recovery of organic and inorganic resources. Regarding the useful highlights presented in their study, Professor Hualin Jiang explained that the work will pave way for designing new strategies and methods for the development of highly efficient and cost-effective adsorbents for recycling and reuse of resources.
Tian, L., Jiang, H., Chen, P., Wang, Q., Niu, P., Shi, Y., Zhou, M., Qing, Y., & Luo., X. (2018). A novel GO/PNIPAm hybrid with two functional domains can simultaneously effectively adsorb and recover valuable organic and inorganic resources. Chemical Engineering Journal, 343, 607-618.