Reuse of Sodium Sulfate Recovered from Farm Drainage Salt of San Joaquin Valley in California, U.S.A. as Dyeing Builder of Levelling Dyes

미국 캘리포니아 San Joaquin Valley 농업관개수에서 회수한 Sodium Sulfate의 균염성 염료 조제로의 재활용

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 recrystalization 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 with nylon/wool fabrics. In nylon/wool fabrics, C.I. Acid Yellow 23 had similar exhaustions among Na₂SO₄ I, Na₂SO₄ II, Na₂SO₄ III and Na₂SO₄ Ⅴ which had similar ratios of sodium sulfate and sodium chloride in recovered salts. Na₂SO₄ Ⅳ had low exhaustion which had low ratios of sodium sulfate and sodium chloride. In nylon/wool fabrics, C.I. Acid Blue 158 had similar exhaustions among Na₂SO₄ I, Na₂SO₄ II, Na2₂SO₄ III, Na₂SO₄ IV and Na₂SO₄ Ⅴ despite of Na₂SO₄ Ⅳ had low ratios of sodium sulfate and sodium chloride Generally, the dyeing of levelling dyes using recovered salts from farm drainage has similar or low exhaustion than the dyeing of levelling dyes using commercial sodium sulfate.