k[C_,{np_,nm_},{zp_,zm_},kT_]:=2C(np zp^2+nm zm^2)/kT

Module[{psi,r},
dhplot[C_,{np_,nm_},{zp_,zm_},kT_]:=
(psi=zp Exp[-k[C,{np,nm},{zp,zm},kT] r]/r;
f=Show[Plot[{psi, C np Exp[-zp/kT psi] ,C nm Exp[-zm/kT psi],zp/r },{r,0,2},PlotStyle->{Black,Red,Blue,Directive[Black,Dashed]},PlotLegends->{"(SubPlus[ψ])","(SubPlus[C])","(SubMinus[C])","(Subscript[V, Coulomb])"}],
Graphics[{Text[Style["C"<>ToString[np]<>"A"<>ToString[nm],FontSize->15],{2,3.5},{1,1}]}]
,PlotRange->{-0.02,3.5}1,Frame->True,FrameLabel->{"r","V,ρ"}]
)]

Manipulate[dhplot[c0,{LCM[zp,zm]/zp,LCM[zp,zm]/zm},{zp,-zm},t],
{{c0,1,"Concentration"},0.1,2,0.1,Appearance->"Labeled"},
{{t,1,"Temperature"},0.1,5,0.1,Appearance->"Labeled"},
{{zp,1,"Cationic charge"},1,3,1,Appearance->"Labeled"},
{{zm,1,"Anionic charge"},1,3,1,Appearance->"Labeled"},SaveDefinitions->True
]

Export["/tmp/dhplot.pdf",f,"PDF"]

k[C_,i_,kT_]:=2C i/kT

Module[{coul,disp,kappa,r},
hamaplot[C_,i_,A_,a_,zeta_,kT_]:=
(kappa=k[C,i,kT];
coul=kappa^2 zeta^2 a^2/d Exp[-kappa r]/.d->(r+2a);
disp=-A/6(2a^2/(d^2-4a^2)+2a^2/d^2+Log[1-4a^2/d^2])/.{d->r+2a};
f=Show[Plot[{coul+disp,coul,disp},{r,0,4a+3/kappa},PlotStyle->{Black,Red,Blue,Directive[Black,Dashed]},PlotLegends->{"U","Coul.","Disp."}
,PlotRange->{-1.3 coul/.r->0,1.3 coul/.r->0}1],Frame->True,FrameLabel->{"r","U"}]
)]

hamaplot[1,1,1,1,1,1]

Manipulate[hamaplot[c0,i,A,a,zeta,t],
{{c0,0.2,"Concentration"},0.01,2,0.1,Appearance->"Labeled"},
{{t,1,"Temperature"},0.1,5,0.1,Appearance->"Labeled"},
{{i,1,"Ionic force"},1,10,1,Appearance->"Labeled"},
{{A,1,"Hamaker constant"},0.1,10,0.1,Appearance->"Labeled"},
{{a,1,"Particle radius"},0.1,2,0.1,Appearance->"Labeled"},
{{zeta,1,"zeta potential"},0.1,1,0.1,Appearance->"Labeled"},SaveDefinitions->True
]