Reuse of Sodium Sulfate Recovered from Farm Drainage Salt as Dyeing Builder of Levelling Dyes - Analysis of Color Difference -

Agricultural drainage salt generated during irrigation of crops in San Joaquin Valley, California, exceeds 600,000 tons annually and cumulates in the field in a rapid rate. As a result, the waste is taking out more farmlands for salt storage and disposal, imposing serious concerns to environment and local agricultural industry. In searching for a potential solution to reduce or eliminate the waste, this research explored feasibility of producing a value-added product, sodium sulfate, from the waste and utilizing the product in textile dyeing. The results indicated that sodium sulfate could be produced from the salt and could be purified by a recrystallization method in a temperature range within the highest and lowest daily temperatures in summer in the valley. The recovered sodium sulfate samples, with purities ranging from 67% to 99.91, were compared with commercially available sodium sulfate in the dyeing of levelling dyes. In nylon fabrics, the salt samples had little color difference in the dyeing with C.I. Acid Yellow 23 and C.I. Acid Blue 158. All salt samples' gray scale was 5 grade. In wool fabrics, the salt samples had little color difference in dyeing with C.I. Acid Yellow 23 and C.I. Arid Blue 158. All salt samples' gray scale was 5 grade. Generally, the dyeing of levelling dyes using recovered salts from farm drainage had little color difference than the dyeing of levelling dyes using commercial sodium sulfate.