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Laboratory Revision Number: 6 <br /> Simplot Standard Operating Procedure Revision Date: 09/22/2022 <br /> Procedure Number: <br /> Lab Material Handling-R6 Lab Material Handling Page 2 of 7 <br /> 3. Used Material and Reagent Handling <br /> a. Neutralization of acidic or basic liquid test solutions <br /> i. All lab liquids that do not contain hazardous materials must be neutralized prior <br /> to disposal down the drains to the lined ponds. <br /> 1) pH 6-8 is ideal, but pH 5-9 is acceptable. <br /> 2) Neutralize no more than 3 gallons at a time. <br /> 3) Fill out the log sheet for every batch of solution neutralized documenting the <br /> amount, pH, date, time, and initials. An example of this log is included as <br /> Appendix A. <br /> ii. Concentrated acids and bases should be diluted to below about 10% before <br /> neutralization. This dilution should be performed in a fume hood by slowly adding <br /> the concentrated acid or base to the correct amount of water. <br /> iii. The wide range pH indicator solution may be used for clear to nearly clear solutions <br /> as a visual indicator with green being aboutpH 7.0. <br /> iv. Instrument sample and reagent solutions are to be captured in glass or plastic <br /> bottles, neutralized, and then discarded down the drains to the lined ponds with <br /> flushing. <br /> v. Kjeldahl test solutions from the distillation step are caustic and hot; cool to near <br /> room temperature and dilute before neutralizing and disposal. <br /> vi. Neutralize acidic solutions with sodium bicarbonate powder. <br /> 1) Liquid NaOH may be used as a backup or for strong acid neutralization. <br /> Neutralization of strong acids with NaOH must be performed in the hood with <br /> the sash down as far as possible and performed slowly due to the possible <br /> generation of heat and release of gases. <br /> vii. Neutralize basic (caustic) solutions with old phosphoric acid shipment samples. <br /> 1) Old shipment samples of sulfuric acid may be carefully diluted to about 50% <br /> for this purpose as well. This should be performed in a fume hood. <br /> Ai <br />