Development of a solid oxidizing reduction potential disinfectant and its efficiency as an air disinfectant

Objective To prepare a high solid oxidation potential disinfectant(SORPD)and to evaluate the effectiveness of the SORPD when used for air disinfection in a hospital.Methods The component formula for the SORPD to be prepared were tested with a L₉(3⁴)orthogonal design.Oxidation-reduction potential (ORP),effective chlorine,corrosiveness,and stability of the prepared SORPD were determined according to the requirements in “Disinfection Technology Standards” issued by Ministry of Health of China in 2002.The concentration of the SORPD solution used for the disinfection of air in a hospital was 30 mg/L and the solution was administered using a ultralow volume sprayer at the dose of 10 ml/m³.The bacteria in the air were sampled using agar plate natural sedimentation method and the changes in bacteria count of the air samples before and after the disinfection with SORPD were analyzed for the evaluation of SORPD disinfection.Results The prepared SORPD is consisted of calcium hypochlorite (main ingredient A),malic acid (main ingredient B)and three minor ingredients (sodium silicate,sodium bromide,and sodium triphosphate).The results of stability test showed 1.4%and 5.4%decrease in ORP for the prepared SORPD after storage for 14 days under the ambient temperature of 54 ℃ and for 6 months under the ambient temperature of 25 ℃,respectively.The ORP value of the prepared SORPD decreased slowly with the increase of dilution ratio and the value was greater than 800 mV at a dilution ratio of 128;the concentration of effective chlorine for the prepared SORPD also declined with the increase of dilution ratio.The prepared SORPD was not corrosive to stainless steel.Thirty minutes after the disinfection with prepared SORPD,the bacteria count in the air samples from outpatient hall and physiotherapy room reached to the lowest number (3.2±0.92 and 2.3±0.67 colony form unit cfu/per plate),with the corresponding bactericide rate of 90.7%and 93.5%;the bacteria count for the air samples from waiting room reached to the lowest number of 3.7±1.03 cfu/plate one hour after the disinfection with the prepared SORPD,with a bactericide rate of 87.9%.The bactericide rate maintained at a relatively high level (>75%)within 3 hours after the air disinfection using the prepared SORPD.Conclusion The prepared SORPD is an effective air disinfectant with a high ORP value,good stability,and low corrosiveness.