Pre-ekstraksi alginat dari alga coklat dengan pelarut asam membutuhkan reaktan dan air dalam jumlah banyak, serta menghasilkan mengeluarkan banyak limbah. Penelitian ini bertujuan untuk mengoptimalkan penggunaan pelarut asam dengan melakukan penggunaan pelarut secara berulang dan mengetahui pengaruhnya terhadap mutu alginat, reduksi kebutuhan air dan reaktan, serta reduksi limbah pelarut. Penggunaan kembali pelarut asam pada proses pre-ekstraksi dilakukan dengan variasi penggunaan pelarut ke 0, 1, 2, 3, dan 4. Rancangan acak lengkap dengan tiga kali ulangan digunakan untuk menentukan pengaruh penggunaan pelarut berulang terhadap mutu alginat. Parameter yang diamati meliputi rendemen, viskositas, berat molekul alginat, kebutuhan air dan HCl, serta limbah pelarut asam. Hasil penelitian menunjukkan bahwa penggunaan pelarut berulang dapat menghasilkan alginat dengan rerata rendemen 26,7%. Penggunaan pelarut berulang ke 0-2 dapat menghasilkan alginat kualitas sedang dengan viskositas 270,9-360,0 mPa.s dan berat molekul alginat 122,04-175,44 kDa. Pre-ekstraksi makrolaga dengan pelarut berulang ke 0-2 dapat menurunkan kebutuhan air 22,2%, HCl 66,7%, dan limbah pelarut menurun 66,7%. Pre-ekstraksi makroalga dengan pelarut berulang mempunyai potensi efisiensi dan perlu dilakukan penelitian lebih lanjut pada skala yang lebih besar.

The brown alga has bioactive alginate and fucoidan, a potential for raw materials the biorefinery industry with core processing of fucoidan and alginate extraction. The research on sequential biorefinery of fucoidan and alginate was conducted in conventional and hydrothermal methods using a smart pressure-cooker, but the yield of fucoidan is low. The improvement was carried out by extracting fucoidan and alginate using microwave-assisted extraction (MAE). This study aimed  to obtain the MAE processing conditions that produced the maximum yield of fucoidan and alginate. The factorial design of 2k was used to determine the effect of MAE processing conditions, i.e.  temperature, time, and alga/water ratio on fucoidan and alginate yields. The parameters observed were fucoidan and alginate yield. Data analysis and prediction of first-order model and model accuracy was a regression modelling using a design expert program. The result showed that the elevate of temperature MAE processing to 80 oC,for 20 minutes, and alga/water ratio of 2:20 (w/v) increased fucoidan (4.5%) and alginate (40.6%)  yield, but it decreased the yield at 100 oC, for 30 minute, and alga/water ratio of 3:30 (w/v). The equation of the first-order model was quadratic, by wich the model test in curvature was found significant at α=0.05. The MAE sequential biorefinery extraction improved fucoidan and alginate yield and had a potential efficiency for commercialization. The maximum response of fucoidan and alginate yield was obtained from a MAE sequential biorefinery at 80 oC,for 20 minutes,and alga/water ratio 2:20 (w/v); further research is needed to optimizing the process.