Table 1.
Physicochemical composition of longan seed.
Fig 1.
Structural illustration of the two main components of starch namely a) amylose and b) amylopectin, both are polymers constructed with glucose subunits (green hexagons).
To the right are the zoom in illustrations of the red frame on each of the polymers, respectively. a) Amylose, which is a long glucose chain connected by α-1,4-glycosidic bonds (green circles), and b) Amylopectin, which is a long glucose chain connected by α-1,4-glycosidic bonds, and has branches connected to the long chains connected by α-1,6-glycosidic bonds (yellow circles).
Table 2.
Wavenumber of FT-IR absorption and functional group assignments for commercial starch literature and starch produced from longan seed.
Fig 2.
The FT-IR spectra of starches.
a) FT-IR spectrum of Longan seed starch showing the wavenumber and the corresponding functional groups of the flour (yellow label). b) Spectral comparison of longan seed starch (red curve) to the reference spectra of rice starch (purple curve) and cornstarch (green curve) from the database from Raman Spectrometer (Nicolet iS50).
Fig 3.
Scanning electron microscope images of longan seeds power at a) 5000X, b) 2000X and c) 500X magnification.
Fig 4.
Effect of pH and alum dosage on percentage turbidity removal in synthetic turbid water (10, 25, 50, 100 and 200 NTU).
(a) Turbidity removal at 10 mg/L alum with varying pH (4, 5, 6, 7, 8 and 9). (b) Turbidity removal at pH 4 with varying alum concentration (0, 1, 2.5, 5, 10 and 15 mg/L) at pH 4. (c) Turbidity removal at 10 mg/L longan seed powder with varying pH (4, 5, 6, 7, 8 and 9). (d) Turbidity removal at pH 4 with varying concentration of longan seed powder (0, 1, 2.5, 5, 10, 15 mg/L). (e) Turbidity removal at 1 mg/L alum and 1 mg/L longan seed powder with varying pH (4, 5, 6, 7, 8 and 9). (f) Turbidity removal at 1 mg/L alum and pH 4 with varying concentration of longan seed powder (0, 0.25, 0.5, 1, 2.5 and 5 mg/L).
Fig 5.
Effect of pH and Alum as coagulant and longan seed powder as coagulant aid dosage on the efficiency of turbidity removal in raw water (approximately 51 NTU).
(a) Turbidity removal with 10 mg/L alum at varying pH (4, 5, 6, 7, 8 and 9) levels. (b) Turbidity removal at pH4 with varying alum concentrations (0, 1, 2.5, 5, 10 and 15 mg/L). (c) Turbidity removal with 1 mg/L alum and 1 mg/L longan seed powder at varying pH (4, 5, 6, 7, 8 and 9) levels. (d) Turbidity removal at pH 4 with 1 mg/L alum and varying longan seed powder concentrations (0, 0.25, 0.5, 1, 2.5 and 5 mg/L).
Fig 6.
Effect of addition of alum and longan seed powder on the pH and TDS of raw water.
Changes in a) pH and b) TDS with the addition of alum observed in experiment in Fig 5b, and Changes in c) pH, d) TDS with the addition of 1 mg/L alum and longan seed powder observed in experiment in Fig 5d.
Fig 7.
Illustration of coagulation-flocculation mechanisms with low concentration of alum (a); optimal concentration of alum (b); and excessive concentration of alum (c).
Fig 8.
Illustration of coagulation-flocculation mechanisms used concentration of Alum and initial turbidity remained constant with different concentrations of longan seed powders (a) Low concentration longan seed powders, (b) longan seed powders with the appropriate concentration and (c) longan seed powders with excessive concentration.
Table 3.
Summary of production cost of longan seed powder (per 1 kg) produced from 2.55 kg of longan seed.