Reduced graphene oxide as effective adsorbent for removal of heavy metals in groundwater of Amaravathi River basin, Tamil Nadu

Figures & data

Figure 1. Location of sampling sites on the Amaravathi River basin.

Figure 2. Map showing the (a) River (b) Geomorphology and Lineament (c) Soil and (d) Geology of the Karur district.

Table 1. The nine-fold lands-use/land-cover statistics for the district.

S. No.	Classification	Area (Ha)
1	Forests	6187
2	Barren & Uncultivable Lands	2901
3	Land put to non agricultural uses	37264
4	Cultivable Waste	67831
5	Permanent Pastures & other grazing lands	10801
6	Groves not included in the area sown	1278
7	Current Fallows	4774
8	Other Fallow Lands	46802
9	Net Area sown	111719
Total		289557

Table 2. Treated result for the adsorption process by graphene oxide.

Parameters	Before adsorption process	After adsorption process (60 mg)	After adsorption process (80 mg)	WHO limit	BIS limit
pH	7.82	7.90	7.98	7–8.5	6.5–8.5
EC	6560	6193	5892	1000–2000	750–2250
TDS	4546	4292	4083	500	500
TH	1933	1917	1894	300	300
Ca^2+	591	589	585	75	75
Mg^2+	116	109	104	50	50
Na^+	1529	1361	1278	200	200
K^+	14.24	10.78	8.16	12	12
HCO3^−	398	386	382	100	200
Cl^−	1619	1608	1596	200	250
F^−	1.6	1.5	1.5	1	1
SO4^2-	264	257	251	200	200
Cd^2+	0.069	0.056	0.052	0.01	0.003
Pb^2+	0.295	0.083	0.077	0.05	0.01
Cu^2+	0.036	0.033	0.032	0.05	2
Zn^2+	0.092	0.090	0.087	5	3
Mn^2+	0.002	bdl*	bdl*	0.1	0.4
Ni^2+	bdl*	bdl*	bdl*	-	0.02
Fe^2+	0.094	0.082	0.074	0.3	0.3

All the values are expressed in mg/L, except pH and EC in µS/cm, *bdl-below detectable limit

Figure 3. XRD pattern of graphene oxide before treatment (GO) after treatment (60 and 80 mg).

Figure 4. (a,b) SEM images of graphene oxide before treatment; (c) SEM images of graphene oxide (60 mg) and (d) SEM images of graphene oxide (80 mg) after treatment.

Figure 5. (a) EDS analysis of graphene oxide before treatment (b and c) EDS analysis of graphene oxide 60 mg and 80 mg after treatment.

Figure 6. (a) FTIR spectra of graphene oxide before treatment; (b & c) FTIR spectra of graphene oxide 60 mg and 80 mg after treatment