Recent Progress, Challenges, and Opportunities of Membrane Distillation for Heavy Metals Removal

Abstract

Water is essential for the presence of life on this earth. However, water contamination due to the presence of heavy/toxic metals is one of the serious environmental issues for living beings. Several methods have been devoted to separating or removing those heavy metals from wastewater. Among them, membrane distillation (MD) has become one of the most attractive approaches due to its higher rejection rate than processes driven by pressure, lower energy consumption than traditional distillation processes. MD has gained significant attention for removing heavy metals than other techniques like ion exchange and adsorption in the last two decades. This review provides insight knowledge to the reader and focuses on how heavy metals impact humans and the environment, sources of heavy metals, current and especially removal methods using the MD method. Moreover, recent studies, challenges, and opportunities on MD membrane modules and heavy metal removal systems are discussed. More importantly, in this review, we have identified the gaps and opportunities that are required for enhancing the MD approach and its practical suitability for heavy metal removals. MD module and system showed high performance, proving their possible applications to remove heavy metal ions in water/wastewater treatment.

Alloy Profusion, Spice Metals, and Resource Loss by Design

“…It may occur to readers that some of the spice metals have from time to time been labeled "heavy metals" as a consequence of their possible health effects (e.g., Aposhian (1983) [77], Ordog (2006) [78], Aijaz et al, (2022) [79]). The use of the term "heavy metals" has, however, long been shown to be arbitrary and imprecise [80].…”

Water Cleaning Adsorptive Membranes for Efficient Removal of Heavy Metals and Metalloids

“…Finally, in all cases, the efficiency of the above membrane processes drops rapidly as soon as the feeding conditions depart from optimized pH and concentrations. An extensive treatise of all the membrane processes for metal ions removal is far beyond the scope of this review and further reading of the relevant publications on each subject as reported in Table 3 (entries 1-10) and recent reviews [101][102][103] are recommended. Among the various membrane processes for heavy metal removal, adsorptive membrane technology so-called also membrane adsorbers (Table 3, entry 11) has gained great attention [104][105][106][107] thanks to lower pressure demands and lower energy of membrane operation without compromising the adsorption selectivity.…”

Effective Membrane Distillation of Landfill Leachate Concentrate Using a Superhydrophobic SiO2/PVDF Membrane for Resource Recovery

“…Membrane distillation, an emerging technology known for its high separation efficiency and capability of extracting freshwater and useful resources from wastewater, , has attracted increasing interest during the past decade. − Zuo et al explored the feasibility of commercial hydrophobic polyethylene (PE) membranes used for membrane distillation of highly saline solutions (3.5% NaCl solution) . Their results revealed that the commercial hydrophobic PE membranes possessed promising desalination efficiency (99.9%) in treating NaCl solutions by membrane distillation with a permeation flux of 123.0 L·m –2 ·h –1 at a transmembrane temperature difference of 63 °C.…”