KOMPOSIT POLIMER KARBOKSIMETIL SELULOSA-g-POLI(ASAM AKRILAT)/BENTONIT SEBAGAI SUPERABSORBEN AIR DAN UREA POLYMER COMPOSITE OF CARBOXYMETHYL CELLULOSE-g- POLY(ACRYLIC ACID)/BENTONITE AS SUPERABSORBENT OF WATER AND UREA

IKA NURUL KHOTIMAH, Bapak Prof. Dr. Sri Juari Santosa, M.Eng

2014 | Skripsi | KIMIA

Komposit polimer superabsorben (SAPC) merupakan polimer hidrofilik yang terhubung secara sambung silang yang mampu menyerap serta menahan air dan larutan dalam jumlah besar tanpa mengalami pelarutan. Karena karakteristiknya yang unggul, maka SAPC yang telah disintesis dalam penelitian ini diaplikasikan sebagai material penyerap air dan urea pada bidang pertanian. SAPC disintesis melalui proses polimerisasi dari bahan dasar asam akrilat, karboksimetil selulosa (CMC) dan residu pemurnian bentonit alam. Berat CMC dan residu pemurnian bentonit alam dibuat bervariasi dengan berat total tetap: 2,00:0; 1,50:0,50; 1,00:1,00; dan 0,50:1,50. N,N’-metilena bisakrilamida (MBA) digunakan sebagai agen penyambung-silang, amonium persulfat (APS) sebagai inisiator, dan natrium hidroksida (NaOH) sebagai penetral gugus akrilat sehingga terbentuklah SAPC karboksimetil selulosa-g-poli(asam akrilat)/bentonit. SAPC yang memiliki penyerapan air paling tinggi didapat pada berat CMC:residu pemurnian bentonit alam = 1:1 (SAPC C:B=1:1). SAPC C:B=1:1 mampu menyerap 785,00 g air murni per g SAPC dan memiliki waktu retensi air selama 40 hari. Keberadaan molekul urea dalam medium pengembangan SAPC C:B=1:1 hampir tidak mempengaruhi kapasitas pengembangan airnya. Molekul urea akan masuk ke dalam jaringan polimer SAPC bersamaan dengan masuknya molekul air. Semakin tinggi konsentrasi urea dalam medium pengembangan menyebabkan semakin banyak molekul urea yang masuk ke dalam jaringan polimer. Molekul urea yang telah masuk ke dalam jaringan polimer dapat dilepas kembali dalam waktu 30 menit. Kapasitas pengembangan air dan jumlah molekul urea yang diserap pada SAPC menurun dengan menaiknya konsentrasi dari larutan CaCO3 sebagai model dari air sadah.

Superabsorbent polymer composites (SAPC) are hydrophylic polymers connected by crosslinking which can absorb and retain extraordinary large amounts of water or aqueous solution without being dissolved. Because of their excellent characteristics, SAPC that have been synthesized in this research were applied as absorbent of water and urea for the agriculture purposes. SAPC were synthesized by polymerization proccess with acrylic acid, carboxymethyl cellulose (CMC), and residue of natural bentonite purification were used as main materials. CMC and residue of natural bentonite purification were added in various proportion of weight, i.e. 2.00:0, 1.50:0.50, 1.00:1.00, and 0.50:1.50 but their total weight was maintained constant. N,N’-methylene bisacrylamide (MBA) was used as crosslinker, ammonium persulphate (APS) as initiator, and sodium hydroxide (NaOH) as neutralizer of the acrylic group to form SAPC of carboxymethyl cellulose-g-poly(acrylic acid)/bentonite. The proportion of CMC:residue of natural bentonite purification = 1:1 (SAPC C:B=1:1) showed the highest swelling capacity. SAPC C:B=1:1 could absorb 785.00 g distilled water per g SAPC and had a retention time of water for 40 days. The presence of urea molecules in swelling medium of SAPC C:B=1:1had no obvious influences on the SAPC swelling capacity. Urea and water molecules entered into the polymer network concomitantly. The number of urea molecules entered into the polymer network increased as the concentration of urea molecules in the swelling medium were increased. Urea molecules inside the polymer network can be released within 30 minutes. The swelling capacity and number of absorbed urea molecules decreased by increasing the concentration of CaCO3 in swelling medium as a representative hard water.

Kata Kunci : asam akrilat, karboksimetil selulosa, bentonit, komposit polimer superabsorben