Synthesis of a Layered Organic-Inorganic Nanohybrid of 4-Chlorophenoxyacetate-zinc-Layered Hydroxide with Sustained Release Properties

Table 1

Carbon and hydrogen content, surface area and thermal property of ZnO, 4CPA, and ZCPA nanohybrid and the kinetic equations used for the fitting.

(a)

Sample	Mass (%)		Loading (%)	BET surface area/m^2g^−1	BJH pore diameter/Å
	Carbon	Hydrogen
4CPA	51.2	4.089	—	—	—
ZCPA(ZnO)	21.9	3.141	45.4	6.1 (3.9)	138 (208)

(b) XPS analysis (value in Ev)

	C1S	O1S	Znp3/2	Znp1/2	Clp3/2	Clp1/2
ZCPA	284.5	531.3	1021.7	1044.8	200.2	201.8
	286.0	533.1	—	—	—	—
	288.4	—	—	—	—	—

(c) Thermal property

	𝑇max/^∘C	Δm/%	𝑇max/^∘C	Δm/%	𝑇max/^∘C	Δm/%	𝑇max/^∘C	Δm/%
4CPA	—	—	—	—	243.5	97.5	—	—
ZnO	100.6	0.9	—	—	—	—	—	—
ZCPA	92.6	6.8	155.0	6.2	294.4	30.1	952.1	20.5

(d) ^aKinetic equations

Zeroth order	First order	Pseudo-second-order	Parabolic diffusion
𝑥=𝑘𝑡+𝑐	−log(1−𝑥)=𝑘𝑡+𝑐	𝑡/𝑀𝑖=1/𝑘2𝑀^2𝑓+(1/𝑀𝑓)⋅𝑡	𝑀𝑖/𝑀𝑓=𝑘𝑡^0.5+𝑐

^a𝑥 is the percentage release of 4CPA at time, 𝑡 (min), and 𝑐 is a constant. 𝑘, 𝑀_𝑖, and 𝑀_𝑓 are the rate constant, the initial, and final concentration of 4CPA, respectively.