Pengujian Pelepasan Hidrogel Karagenan sebagai Pembawa Pupuk pada Tanah

Abstract

Hidrogel adalah polimer hidrofilik yang mampu memuat air berkali lipat dari bobot aslinya. Hidrogel disintesis menggunakan karagenan, asam akrilat dan akrilamida, diikat silang dengan 1% N,N’-metilenbisakrilamida (MBA), serta 16% amonium pesulfat (APS). Hidrogel diuji dan dianalisis nilai swelling, kinetika swelling, fraksi gel, kapasitas adsorpsi, pemuatan pupuk, pelepasan pupuk, analisis gugus fungsi, serta morfologi permukaan hidrogel. Nilai swelling pada hidrogel dengan variasi pupuk urea 0%, 5% dan 10% dipengaruhi oleh kapasitas adsorpsi dan konstentrasi urea sehingga variasi urea 5% memiliki nilai swelling terbaik dan mampu memuat pupuk sebanyak 2273,5 mg/L (54,507%). Pelepasan pupuk urea 5% dan 10% diuji pada tanah pasirdan tanah andosol dipengaruhi oleh nilai swelling dan variasi tanah. Hidrogel pupuk 10% pada tanah pasir merupakan pelepasan pupuk paling lambat. Hidrogel pupuk 5% dan 10% termasuk ke dalam pupuk lepas lambat. Pelepasan pupuk yang lambat memiliki pori hidrogel yang kecil, serta memiliki nilai swelling dan kapasitas adsorpsi tidak terlalu tinggi.

Hydrogel is a hydrophilic polymer that can contain water many times its original weight. The hydrogel was synthesized using carrageenan, acrylic acid and acrylamide, cross-linked with 1% N,N’-methylenebisacrylamide (MBA), and 16% ammonium pesulfate (APS). The hydrogel was tested and analyzed for swelling value, swelling kinetics, gel fraction, adsorption capacity, fertilizer loading, fertilizer release, functional group analysis, and hydrogel surface morphology. The swelling value of the hydrogel with variations of 0%, 5% and 10% urea fertilizer is influenced by the adsorption capacity and urea concentration so that the 5% urea variation has the best swelling value and is able to contain fertilizer as much as 2273.5 mg/L (54.507%). The release of 5% and 10% urea fertilizer tested on sandy soil and Andosol soil was influenced by swelling values and soil variations. 10% fertilizer hydrogel in sandy soil is the slowest release of fertilizer. 5% and 10% fertilizer hydrogels are included in slow release fertilizers. Slow releasing fertilizer has small hydrogel pores, and has a swelling value and not too high adsorption capacity.