Laying Waste to Mercury: Inexpensive Sorbents Made from Sulfur and Recycled Cooking Oils

Abstract

Mercury pollution threatens the environment and human health across the globe. This neurotoxic substance is encountered in artisanal gold mining, coal combustion, oil and gas refining, waste incineration, chloralkali plant operation, metallurgy, and areas of agriculture in which mercury‐rich fungicides are used. Thousands of tonnes of mercury are emitted annually through these activities. With the Minamata Convention on Mercury entering force this year, increasing regulation of mercury pollution is imminent. It is therefore critical to provide inexpensive and scalable mercury sorbents. The research herein addresses this need by introducing low‐cost mercury sorbents made solely from sulfur and unsaturated cooking oils. A porous version of the polymer was prepared by simply synthesising the polymer in the presence of a sodium chloride porogen. The resulting material is a rubber that captures liquid mercury metal, mercury vapour, inorganic mercury bound to organic matter, and highly toxic alkylmercury compounds. Mercury removal from air, water and soil was demonstrated. Because sulfur is a by‐product of petroleum refining and spent cooking oils from the food industry are suitable starting materials, these mercury‐capturing polymers can be synthesised entirely from waste and supplied on multi‐kilogram scales. This study is therefore an advance in waste valorisation and environmental chemistry.

Sustainable inverse-vulcanised sulfur polymers

“…In terms of capacity to stabilise sulfur against depolymerisation, both copolymers perform comparably to other reported sulfur polymeric materials, of which most can stabilise only up to $80 wt% sulfur, 5,20 and many only 60 wt%, 17 50 wt% 20 and even $30 wt%. 22 The detection of some S 8 crystals by DSC in the case of 20 wt% squalene suggests DSC to be a more sensitive method of detecting the trace presence of S 8 crystals than the pXRD results. Due to the concern that the laboratory pXRD was not detecting trace amounts of S 8 , that were picked up by DSC, it was decided to measure a sample at the extreme of sulfur content stabilisation by high intensity synchrotron pXRD.…”

“…However, so far it is only the industrially produced synthetic crosslinkers that have shown high glass transition temperatures, with most renewable crosslinkers leading to sub room temperature, or even sub 0 C, glass transitions at equal weight ratios of sulfur to crosslinker, such as limonene (À21 C), 10 rapeseed oil (approx. À10 C), 22 diallyl disulde (À14 C to 4 C) 15,28 and myrcene (5-10 C). 15 When compared to these reported inversevulcanised polymers synthesised directly from renewable crosslinkers, both squalene and perillyl alcohol have comparatively high glass transition temperatures, at 21 and 20 C respectively, for 50 wt% sulfur compositions ( Fig.…”

“…22 Organomercury compounds are generally more toxic than their inorganic counterparts, being more readily absorbed by the body, 33 and lipophilic nature.…”

“…Bio-renewable crosslinkers make a particularly desirable target for crosslinking with sulfur, and prominent examples are limonene, 10 vegetable oil, 21,22 and di-allyl disulphide. 15 Limonene is a by-product of the citrus industry, which isolates in excess of 70 000 tonnes per year from the zest of oranges, 23 making it ideal to combine with waste sulfur.…”

Electrospun Polyacrylonitrile Nanofibrous Membranes for Point‐of‐Use Water and Air Cleaning

“…Water and air pollution are increasing concern all over the world as a risk of human health . Air pollution can cause asthma, skin irritation, nausea, cancer, brain damage, birth defects, respiratory and heart problems due to gaseous pollutants and particulate matter (PM) .…”