Release characteristics of single-wall carbon nanotubes during manufacturing and handling

Airborne engineered nanomaterials in the workplace—a review of release and worker exposure during nanomaterial production and handling processes

“…Collecting end-product materials from chemical synthesis [23]; batch collection by industrial cyclone [24]; emptying and tipping powder materials from bucket to bucket [25]; scooping spilt materials off a table [25]; opening a furnace and transferring materials to vials [6]; manually loading and unloading trays [6]; dumping materials into a mixing tank [6]; detaching and removing CNTs from growth substrate using a razor blade [26]; sieving powders with a vibratory sieve shaker [27,28] Physical & chemical synthesis Gas-phase production of metal-based nanoparticles [29]; flame spray pyrolysis technique (FSP) [30,31]; induced coupled plasma with electric atomizer [32,33]; reaction collection [23]; electric arc reaction [34]; hot-wall reaction [19]; combustion reaction [35]; chemical vapor deposition (CVD) [26,[36][37][38][39]; water-assisted CVD [40] Weighing & mixing…”

“…Spraying and filtration of CNT solutions [37]; spraying solution onto a bulk absorbent [6]; changing a spray dryer drum [6]; spraying a suspension [9]; flame-spraying for surface coating and modification [50]; sonicating materials with different surface coatings in a hood [6]; sonication in an unventilated enclosure [7]; pelletizing and bagging products in a warehouse [51]; purification and functionalization [47] integrating MWCNT powder in coatings, dispersions, and plastics [52] [53], Al2O3 [53], CeO2 [53], iron oxides [6], Mn [6], Ag [6,54], Co [6], Si [19]; Carbonaceous: carbon black [23], CNT [26], SWCNT [25,40,55], MWCNT [6,28,37,47], carbon nanofibers (CNFs) [6,48], carbon nanopearls [6], nano diamond [27], carbon nanodiscs/carbon nanocones [28], nanoscale graphene platelets [56].…”

Overview of Workplace Exposure to Nanomaterials

“…In the case of carbon nanotubes, various accounts of release during synthesis can be found in the literature [164], including an increase in peak concentration at CVD extraction points [60], while others report no emission [160]. If exposure to airborne individual carbon nanotubes cannot be excluded, they generally occur as agglomerates or aggregate Overview of Workplace Exposure to Nanomaterials Table 4 List of published studies on occupational exposure to various types of engineered and incidental nanomaterials (P: production; D: downstream manipulation; U: use as input material in industrial processes; M: maintenance and end-of-life operations; I: incidental) clusters [1].…”

“…Indeed, depending on the degree of agitation, large variations in the emitted particle size are obtained [136]. It may be noted that good correlations were obtained for particle size distribution profile between transfer, harvesting, and packing operations and vortex shaking laboratory tests [160]. An increase from 1% to 12% in the amount of emitted nanoparticles was observed when the pressure was raised from 0 to 140 kPa in a pressurized beaker experiment simulating a leak.…”

Exposure assessment of carbon nanotubes at pilot factory focusing on quantitative determination of catalytic metals

“…This indicates a potential hazard for workers handling MWCNTs. CNTs released in workplaces are often determined using thermal carbon analysis methods, such as National Institute for Occupational Safety and Health (NIOSH) method 5040 [5][6][7][8][9][10] or the IMPROVE protocol 11) , also used for quantifying CNTs [12][13][14][15] . In addition, by measuring respirable-sized MWCNT dust using both a black carbon monitor (BCM) and thermal carbon analysis, a relationship between the analytical methods was detected 16) .…”