The persistence results for the targeted chemicals show that contaminated PPE materials, where re-use is desired, may require decontamination as the chemical is sufficiently persistent to be present on the material for at least 45min post-contamination event. The absence of a strong material dependence in persistence results can be attributed to the following two aspects: First, the evaporation from and possible absorption of the chemical into the material depends on the behavior of the droplet on the surface. This would be more noticeable when comparing impermeable materials against more absorptive materials. The selected PPE related materials in this study are either impermeable (stainless steel) or only marginally permeable based on good or excellent permeation ratings in chemical compatibility charts except for some material-chemical combinations that were excluded from the decontamination test matrix. Second, solvent extraction of a material as applied here extracts both chemical mass on the surface and chemical mass that may have permeated into the material unless the physiochemical binding forces with the material are too strong. All aspects combined can explain why the material dependence is not as noticeable as perhaps expected.
The short 2.0 min dwell time of the decontaminant against the chemical on the surface, which may still be an overestimate of a realistic dwell time during decontamination line procedures, resulted in low to only moderate decontamination efficacies. Decontamination efficacies varied strongly by chemical with no/very minimal efficacy observed for four decontaminants against nitrobenzene, chlordane, and phenol. Higher decontami- nation efficacies were observed for some of the solutions but not against all chemicals with an additional dependence on the material type.
This study indicates that full strength bleach and RSDL1 are the somewhat more efficacious decontamination solutions that were tested. This is not too surprising for both technologies as bleach has been used successfully for many types of (building) decontamina- tion [2–5] while RSDL1 is designed for decontamination of skin where effectiveness in a short period of time would be a highly critical parameter. Nevertheless, none of the decontamination solutions were able to neutralize more than 90%, which was observed for longer (30–60 min) contact times between, e.g., full strength bleach and CWAs like HD and VX [5].
The impact of the PPE material on the decontamination efficacy was negligible as the observed efficacy values are likely limited by the available amount of active ingredients and the short timescale (2min) during which neutralization occurred. Under these conditions, the material itself becomes of less importance when compared to building decontamination approaches where the amount of decontaminant applied is in general larger and the associated dwell time is typically 15–30 times (30–60 min) longer.
Efficacy results for diluted bleach, a frequent choice of responders, were not as good as for full strength bleach, in part because for diluted bleach, the stoichiometric conditions between hypochlorite anions in diluted bleach and the targeted chemical may not have been reached. For example, the decontamination of malathion with full strength bleach was conducted with a hypochlorite (8% concentration in full strength bleach) to malathion (10mg) molar ratio of 5.7. Consequently, the total of hypochlorite anions in 10-fold diluted bleach is insufficient to react with all malathion, let alone within a 2.0 min dwell time. The lower pH of diluted bleach would also reduce the basic hydrolysis rate if that is the primary reaction.
pH-Amended bleach was also found not to be efficacious against the targeted chemicals. The neutral pH shifts the balance from a hypochlorite anion solution to hypochlorous acid (HClO) solution, hereby reducing the concentration of the oxidizing active ingredient resulting in lower oxidation reaction rates. It should be noted that pH-Amended bleach liberates gaseous chlorine as a result of pH modification and appropriate respiratory and eye protection must be prescribed by health and safety professionals.
The persistence results for the targeted chemicals show that contaminated PPE materials, where re-use is desired, may require decontamination as the chemical is sufficiently persistent to be present on the material for at least 45min post-contamination event. The absence of a strong material dependence in persistence results can be attributed to the following two aspects: First, the evaporation from and possible absorption of the chemical into the material depends on the behavior of the droplet on the surface. This would be more noticeable when comparing impermeable materials against more absorptive materials. The selected PPE related materials in this study are either impermeable (stainless steel) or only marginally permeable based on good or excellent permeation ratings in chemical compatibility charts except for some material-chemical combinations that were excluded from the decontamination test matrix. Second, solvent extraction of a material as applied here extracts both chemical mass on the surface and chemical mass that may have permeated into the material unless the physiochemical binding forces with the material are too strong. All aspects combined can explain why the material dependence is not as noticeable as perhaps expected.เวลาเนินสั้น 2.0 นาทีของ decontaminant กับสารเคมีบนพื้นผิว ซึ่งอาจยังมีควรเลือกเวลาเป็นซีเควนซ์ที่สมจริงในระหว่างกระบวนการสายปนเปื้อน ผลในประสิทธิภาพกำจัดสิ่งปนเปื้อนที่ต่ำถึงปานกลางเท่านั้น ปนเปื้อนประสิทธิภาพน้อยมาก/ขอแตกต่างกันตามสารเคมีที่ไม่มีการศึกษาประสิทธิภาพสังเกต decontaminants สี่ nitrobenzene, chlordane และฟีนอล ประสิทธิภาพสูง decontami ประเทศถูกตั้งข้อสังเกตสำหรับบางส่วน ของการแก้ปัญหา แต่ไม่ กับทุกสารเคมีกับชนิดวัสดุการพึ่งพาเพิ่มเติมการศึกษานี้บ่งชี้ว่า bleach เต็มแรงและ RSDL1 เป็นโซลูชั่นเปื้อนข้างครบวงจรที่ทดสอบ นี้ไม่น่าแปลกใจมากสำหรับเทคโนโลยีทั้งสองเป็น bleach ใช้เรียบร้อยแล้วสำหรับหลายชนิด (อาคาร) decontamina-ทางการค้า [2-5] ในขณะที่ RSDL1 ถูกออกแบบมาสำหรับกำจัดสิ่งปนเปื้อนผิวที่ประสิทธิภาพในระยะเวลาสั้น ๆ จะเป็นพารามิเตอร์สำคัญ อย่างไรก็ตาม ไม่มีการแก้ปัญหาการปนเปื้อนก็สามารถที่จะต่อต้านมากกว่า 90% ซึ่งเป็นที่สังเกตอีกต่อไป (30-60 นาที) เวลาติดต่อระหว่าง เช่น bleach เต็มแรงและ CWAs HD และ VX [5]The impact of the PPE material on the decontamination efficacy was negligible as the observed efficacy values are likely limited by the available amount of active ingredients and the short timescale (2min) during which neutralization occurred. Under these conditions, the material itself becomes of less importance when compared to building decontamination approaches where the amount of decontaminant applied is in general larger and the associated dwell time is typically 15–30 times (30–60 min) longer.Efficacy results for diluted bleach, a frequent choice of responders, were not as good as for full strength bleach, in part because for diluted bleach, the stoichiometric conditions between hypochlorite anions in diluted bleach and the targeted chemical may not have been reached. For example, the decontamination of malathion with full strength bleach was conducted with a hypochlorite (8% concentration in full strength bleach) to malathion (10mg) molar ratio of 5.7. Consequently, the total of hypochlorite anions in 10-fold diluted bleach is insufficient to react with all malathion, let alone within a 2.0 min dwell time. The lower pH of diluted bleach would also reduce the basic hydrolysis rate if that is the primary reaction.pH-Amended bleach was also found not to be efficacious against the targeted chemicals. The neutral pH shifts the balance from a hypochlorite anion solution to hypochlorous acid (HClO) solution, hereby reducing the concentration of the oxidizing active ingredient resulting in lower oxidation reaction rates. It should be noted that pH-Amended bleach liberates gaseous chlorine as a result of pH modification and appropriate respiratory and eye protection must be prescribed by health and safety professionals.
การแปล กรุณารอสักครู่..
