Pengfei Qi

Bio: Pengfei Qi is an academic researcher from Qingdao University. The author has contributed to research in topics: Adsorption & Aqueous solution. The author has an hindex of 7, co-authored 9 publications receiving 268 citations. Previous affiliations of Pengfei Qi include University of Bremen.

Closer look at As(III) and As(V) adsorption onto ferrihydrite under competitive conditions.

Abstract: Batch experiments were conducted in order to investigate the competitive interaction of arsenite (As(III)) and arsenate (As(V)) onto ferrihydrite as a function of initial pH, adsorbent dosage, concentration of coexisting ligands, and order of addition. The pH generally had a great impact on adsorption under both single ion and competitive conditions. However, the amount of As(V) in solution was the controlling factor of adsorption behavior, and As(III) more or less outcompeted As(V) across the pH scale from 4 to 10. Under competitive conditions, i.e., both species were present at the same time, As(III) and As(V) were adsorbed almost equally up to a pH of 5 at an adsorbent dosage of 0.5 g/L and up to a pH of 6 at an adsorbent dosage of 1 g/L. This was contrary to the theoretical prediction that As(V) should adsorb more strongly than As(III) at pH values below the point of zero charge (pzc) of ferrihydrite of about 7 to 8. At low pH, As(V) impedes the adsorption of As(III) but to lesser degree than As(III) ...

Metal–organic framework-based materials: superior adsorbents for the capture of toxic and radioactive metal ions

Abstract: Highly efficient removal of metal ion pollutants, such as toxic and nuclear waste-related metal ions, remains a serious task from the biological and environmental standpoint because of their harmful effects on human health and the environment. Recently, highly porous metal–organic frameworks (MOFs), with excellent chemical stability and abundant functional groups, have represented a new addition to the area of capturing various types of hazardous metal ion pollutants. This review focuses on recent progress in reported MOFs and MOF-based composites as superior adsorbents for the efficient removal of toxic and nuclear waste-related metal ions. Aspects related to the interaction mechanisms between metal ions and MOF-based materials are systematically summarized, including macroscopic batch experiments, microscopic spectroscopy analysis, and theoretical calculations. The adsorption properties of various MOF-based materials are assessed and compared with those of other widely used adsorbents. Finally, we propose our personal insights into future research opportunities and challenges in the hope of stimulating more researchers to engage in this new field of MOF-based materials for environmental pollution management.

Removal of heavy metal ions from wastewater: a comprehensive and critical review

Abstract: Removal of heavy metal ions from wastewater is of prime importance for a clean environment and human health. Different reported methods were devoted to heavy metal ions removal from various wastewater sources. These methods could be classified into adsorption-, membrane-, chemical-, electric-, and photocatalytic-based treatments. This paper comprehensively and critically reviews and discusses these methods in terms of used agents/adsorbents, removal efficiency, operating conditions, and the pros and cons of each method. Besides, the key findings of the previous studies reported in the literature are summarized. Generally, it is noticed that most of the recent studies have focused on adsorption techniques. The major obstacles of the adsorption methods are the ability to remove different ion types concurrently, high retention time, and cycling stability of adsorbents. Even though the chemical and membrane methods are practical, the large-volume sludge formation and post-treatment requirements are vital issues that need to be solved for chemical techniques. Fouling and scaling inhibition could lead to further improvement in membrane separation. However, pre-treatment and periodic cleaning of membranes incur additional costs. Electrical-based methods were also reported to be efficient; however, industrial-scale separation is needed in addition to tackling the issue of large-volume sludge formation. Electric- and photocatalytic-based methods are still less mature. More attention should be drawn to using real wastewaters rather than synthetic ones when investigating heavy metals removal. Future research studies should focus on eco-friendly, cost-effective, and sustainable materials and methods.

A critical review on arsenic removal from water using iron-based adsorbents

Abstract: Intensive research efforts have been pursued to remove arsenic (As) contamination from water with an intention to provide potable water to millions of people living in different countries. Recent studies have revealed that iron-based adsorbents, which are non-toxic, low cost, and easily accessible in large quantities, offer promising results for arsenic removal from water. This review is focused on the removal of arsenic from water using iron-based materials such as iron-based nanoparticles, iron-based layered double hydroxides (LDHs), zero-valent iron (ZVI), iron-doped activated carbon, iron-doped polymer/biomass materials, iron-doped inorganic minerals, and iron-containing combined metal oxides. This review also discusses readily available low-cost adsorbents such as natural cellulose materials, bio-wastes, and soils enriched with iron. Details on mathematical models dealing with adsorption, including thermodynamics, kinetics, and mass transfer process, are also discussed. For elucidating the adsorption mechanisms of specific adsorption of arsenic on the iron-based adsorbent, X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) are frequently used. Overall, iron-based adsorbents offer significant potential towards developing adsorbents for arsenic removal from water.