Biodegradable Polymeric Flocculants Based On Cassava Starch Grafted With Polydiallyldimethylammonium Chloride

• Main Author: Razali, Mohd Amin Ahmad
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: T Technology; TA404 Composite materials
• Online Access: http://eprints.usm.my/41779/1/Biodegradable_Polymeric_Flocculants_Based_On_Cassava_Starch_Grafted_With_Polydiallyldimethylammonium_Chloride.pdf; http://eprints.usm.my/41779/
• Institution: Universiti Sains Malaysia

Kerja penyelidikan ini telah dilakukan untuk meneroka penyediaan dan mengoptima proses pencangkukan, kelakuan penggumpalan dan kriteria pengaggregatan emping oleh kanji ubi kayu tercangkuk polidiallyldimethilammonium klorida (polyDADMAC). Proses optimum ditentukan dengan kaedah gerak balas permukaan (response surface method, RSM) yang terdiri daripada tiga peringkat dan empat pemboleh ubah berbentuk komposit pusat. Keadaan optimum yang diperolehi adalah 1.96 (nisbah mol DADMAC kepada kanji), 40°C (suhu tindak balas ) 0.09 mol/L (kepekatan pemula) dan 4.99 jam (masa tindak balas). Hasil eksperimen sebenar adalah 21.98% pada keadaan yang optimum, yang mana hampir dengan nilai maksimum yang diramalkan iaitu 22.80%. Selepas itu, keupayaan degradasi sampel dicangkukan telah diselidik dengan menggunakan kaedah penanaman tanah. Didapati bahawa peratusan cangkukan yang lebih tinggi menunjukkan penurunan berat yang lebih tinggi berbanding dengan sampel-sampel cangkuk yang lain dan kanji asli. Keupayaan degradasi itu disahkan dengan menganalisa kumpulan berfungsi mereka, berat molekul dan morfologi sampel. Keberkesanan penggumpalan bagi sampel yang dicangkukkan telah diselidik di dalam kaolin terampai. Keberkesanaan adalah berdasarkan penyingkiran kekeruhan dan jumlah pepejal terampai (total suspended solid,TSS). Ia menunjukkan bahawa mekanisme bagi sampel dicangkukan adalah peneutralan caj dan perapatan di mana ianya berlaku serentak. Ia juga didapati bahawa penyingkiran bertambah baik dengan peningkatan peratusan cangkuk. Kelakuan penggumpalan dikaji lebih mendalam dengan memerhatikan pengagregatan, kerosakan dan pertumbuhan semula emping dengan menggunakan penganalisis penyebaran photometrik (photometric dispersion analyser, PDA). Pembesaran emping meningkat dengan peningkatan peratusan cangkuk kerana peningkatan keupayaan dan partikel-partikel telah dinyah-stabilkan. Ia juga mendedahkan peningkatan ricihan dan masa akan mengurangkan faktor kekuatan dan pemulihan bagi emping-emping. ________________________________________________________________________________________________________________________ This research work was conducted to explore the preparation and optimization of grafting process, flocculation behaviour and flocs aggregation characteristic of cassava starch grafted with polydiallyldimethylammonium chloride (polyDADMAC). The optimization process was achieved by using response surface methodology (RSM) comprising three-levels and four-variables central composite design. The optimum condition derived were 1.96 (mole ratio of DADMAC to starch), 40°C (reaction temperature), 0.09 mol/L (initiator concentration) and 4.99 hour (reaction time). The actual experimental yield was 21.98% at optimum conditions, which was close to the maximum predicted value of 22.80%. Subsequently, the biodegradability of grafted samples was investigated by using soil burial method. It was found that higher grafting percentage shows higher weight loss compared to other grafted sample and native starch. The biodegradability was confirmed by analysis their functional groups, molecular weight and morphology of the samples. The effectiveness flocculation of grafted samples was investigated in kaolin suspension. The effectives were based on turbidity and total suspended solid (TSS) removal. It was shown that mechanism for grafted samples are charge neutralization and bridging which occurred concurrently. It was also found that removal was improved with increasing of grafting percentage. The flocculation behaviour was further studied in details by observing the aggregation, breakage and regrowth of flocs using photometric dispersion analyser (PDA). The flocs growth increase with increasing of grafting percentage because of the improvement of interaction between grafted flocculants and suspended. It was reveal the increased of the shear and time will reduce the strength and recovery factor of flocs.