ANNEX 3

Part B. Summary of Country Reports on Production of Super
water absorbent (SWA) by Radiation Processing(1) Bangladesh (Ms. Salma SULTANA, BAEC)SWA was prepared by gamma irradiation of carboxymethyl cellulose and acrylamide
monomer in solution. The resulting SWA irradiated at 25 kGy for 48 hours exhibitedwater absorption of around 200 g per g in distilled water and around 50 g per g whenswelled in NaCl solution. The product was analyzed for characteristic properties such as
gel content, soiling behavior, etc.
(2) China (Dr. Jing PENG, Peking University)
Many factors could affect the water adsorption and water remaining property of SWA,
such as monomer, crosslinker, particle size and measurement conditions and so on. The
commercial Starch-based SWA has been used in the growth of lemon. Treatment has noobvious affect on the temperature and humidity of soil during the field test. The SWA
could improve the height and yield per unit area of lemon and it is helpful to the fruit
setting. The validity of Starch-based SWA is about half year. It is easy to be degraded ordenatured. Different crops should use different SWA. For the plant with longer growth
cycle, synthetic SWA with good mechanical strength is better.
(3) Indonesia (Dr. Darmawan DARWIS, BATAN)
Super water absorbent hydrogel for application as soil conditioner was prepared byradiation grafting and crosslinking of cassava starch with acrylic acid in potassiumhydroxide solution using gamma ray with dose ranging from 5 to 20 kGy. The
characteristics of hydrogel produced such as gel fraction, swelling capacity in water,water retention of soil, and field capacity of different soil textures were evaluated. Theresults show that gel fraction increase with increase in acrylic acid concentration. At 5
kGy irradiation dose, gel fraction reached 80% for SWA prepared with composition ofcassava/acrylic acid/KOH (10/20/1.2 %). Increase in dose did not give significant
increase in gel content. The maximum water absorption was about 250 times of its dry
weight for hydrogel with of composition of cassava/acrylic acid/KOH (10/20/0.6 %). The
maximum water absorption (swelling) of gel was obtained after immersion in water for
8 hours. Water retention of podzolic soil with SWA (0.6g/kg of soil ) is 60 % after 14 days,while without SWA, water retention of podzolic soil is 40%. Water retention of sandy
1soil with SWA (0.6g/kg of soil) is 55 % after 14 days, while without SWA, water
retention of was only 30%. Field capacity of sandy soil and podzolic soil is 25 and 51,respectively.
(4) Japan (Prof. Mitsuhiro INOUE, Tottori University)
Country report showed that a combination of drip irrigation water with SWA
application can significantly enhance the usage efficiency of irrigation salty watercompared to fresh water. Understanding the characteristics of absorbents and theirinteractions with soils as well as the quality of irrigation water would be crucial to theuse of CMCs for water management in sandy soils.
(5)Malaysia (Dr. Kamaruddin BIN HASHIM, Nuclear Malaysia)
The super water absorbent (SWA) was made by irradiation of sago waste (SWASw) fiberwith acrylic acid solution. The SWA prepared via gamma irradiation exhibited
maximum water absorption of 148 g per g dry gel twice that of SWA prepared using EB
radiation. The study also revealed dependence of effectiveness of swelling on the size ofboth SWASw and SWA coconut fiber. The water absorption of SWA coconut is muchhigher than SWASw. Pot test study showed the release of water from the SWA is veryslow. It means both SWA is good retainer of water for agriculture application.
(6) Mongolia (Dr. Amartaivan TSENDDAVAA, Nuclear Research Center, NU ofMongolia)
For SWA production, raw materials can be chosen from agricultural waste materials.
And first of all, it would be wheat shell. Also SWA using potato and bentonite can beconsidered. Target for field and pot test is not decided yet.
(7) Philippines (Ms. Charito ARANILLA, PNRI)
The Philippine Nuclear Research Institute uses k-carrageenan as based material forsynthesis of SWA. Carboxmethylation of k-carrageenan renders it crosslinkable andfacilitates preparation of SWA hydrogel. The characteristics of the CMkC SWA in termsof equilibrium degree of swelling, water retention properties and biodegradability show
the potential of the material for soil amelioration and rehabilitation. In order to carryout field tests, a proposal will be submitted to Department of Science and Technology
for funding and collaboration with Department of Agriculture will be initiated.

2(8) Thailand (Dr. Phiriyatorn SUWANMALA, TINT)
Superabsorbent was synthesized by radiation-induced graft polymerization of acrylicacid onto cassava starch. The synthetic parameters such as absorbed dose and theamount of monomer were investigated in order to determine the optimum conditions forthe grafting polymerization. The criteria are emphasized by the optimum conditions ofimportant parameters to give a maximum amount of water absorption. In addition,water retention, germination percentage and germination energy were determined inorder to evaluate the possibility of superabsorbent in agricultural applications,especially in arid regions. The graft copolymer was characterized by FTIR. The results
indicated that the sand mixed with 0.1%wt superabsorbent can absorb more water than
the sand without superabsorbent. The germination energy of corn seeds mixed with
0.5% superabsorbent was obviously higher than those without superabsorbent. The
experimental results showed that the superabsorbent have considerable effect on seedgermination and the growth of young plant. The pot tests of Tagetes erecta L. with useof the superabsorbent were positive. The biodegradability test in soil indicated that theweight loss of SWA after nine months was 85%. The result support the role of SWA as agreen-material with potential as an alternative to non-biodegradable material for
agricultural application. Currently, preparation of superabsorbent in large scale isbeing done for a field test. The future plan for this project is to establish cooperation
with TINT’s Business Development Unit in order to carry out a case study for abusiness potential to commercialize the super water absorbent for agricultural purposes(9) Vietnam (Dr. LE Hai, VINATOM)The report presented research results of two SWAs which were prepared by radiation
grafting and cross-linking from coconut coir dust and bentonite clay with alkalized
acrylic. The characteristics of SWA as water swelling, structural changes, and otherfactors affect to the swelling has been evaluated. The pot test of strawberries and coffee
trees in sandy soil has been developed.
Super water absorbents have been prepared by radiation cross-linking/ and grafting ofalkalized acrylic onto the coconut coir dust/ and the bentonite lay. Gel fraction contentof both SWAs was around 50%, and swelling degree is 350g.g-1 and 550g.g-1 respectively.
The swelling rate of both types is 34g.g-1.min-1. The evaluation of SWA’s useful time andpot test for strawberry and coffee tree in sandy soil has been presented. The novel
application of SWA for flood bags was also suggested.
Nowadays SWAs products have been commercialized in Vietnam, and Thanh Phuongand PAS Companies are main distributors for these products.
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