<PAGE>

                                                                     Exhibit 4.3
                    REVOLVING LINE OF CREDIT PROMISSORY NOTE

$3,000,000.00                                                   January 28, 2003
                                                    Made, executed and delivered
                                                         in International Waters

     FOR VALUE RECEIVED, the undersigned, FLORIDA CARBON SOLUTIONS, L.L.C.,
EARTHFIRST TECHNOLOGIES, INCORPORATED and EARTHFIRST SOLID SOLUTIONS, INC.
(hereafter collectively the "Borrower"), hereby jointly and severally promise to
pay to the order of FLORIDA ENGINEERED CONSTRUCTION PRODUCTS CORPORATION
(hereinafter the "Lender"), in such coin or currency of the United States which
shall be legal tender in payment of all debts and dues, public and private, at
the time of payment, the principal sum of Three Million and 00/100 Dollars
($3,000,000.00), or so much as may be outstanding, together with interest from
and after the date hereof on the unpaid principal balance outstanding at the
rate of ten percent (10%). All principal, together with interest, shall be
payable in full upon demand.

     Borrower may prepay this Revolving Line of Credit Promissory Note (the
"Note") in whole or in part at any time during the term hereof, provided that
any such payment shall first be applied to any charges and costs then due and
payable hereunder, then to interest, and finally to principal.

     The occurrence of any default by Borrower hereunder shall entitle Lender,
at its option, to declare the then outstanding principal balance and accrued
interest hereof to be, and the same shall thereupon become, immediately due and
payable without notice to or demand upon Borrower, all of which Borrower hereby
expressly waives. If this Note is collected by or through an attorney at law,
then Borrower shall be obligated to pay, in addition to the principal balance
and accrued interest hereof, reasonable attorneys' fees and court costs at
trial, on any appeal, and in any bankruptcy proceedings.

     Time is of the essence of this Note. To the fullest extent permitted by
applicable law, Borrower, for itself and its legal representatives, successors
and assigns, expressly waives presentment, demand, protest, notice of dishonor,
notice of non-payment, notice of maturity, notice of protest, presentment for
the purpose of accelerating maturity, diligence in collection, and the benefit
of any exemption or insolvency laws.

     Wherever possible each provision of this Note shall be interpreted in such
a manner as to be effective and valid under applicable law, but if any provision
of this Note shall be prohibited or invalid under applicable law, such provision
shall be ineffective to the extent of such prohibition or invalidity without
invalidating the remainder of such provisions of this Note. No delay or failure
on the part of Lender in the exercise of any right or remedy hereunder shall
operate as a waiver thereof, nor as an acquiescence in any default, nor shall
any single or partial exercise by Lender of any right or remedy preclude any
other right or remedy.

<PAGE>

     This document has been made, executed and delivered in international
waters. This Note shall be governed by, and construed and enforced in accordance
with, the laws of the State of Florida, regardless of where made, executed or
delivered, and is intended to take effect as an instrument under seal,
constitutes a contract under the laws of the State of Florida, and shall be
enforceable in a court of competent jurisdiction in said State, without regard
to the place in which this Note is made, executed and delivered.

     This Note evidences borrowings in the principal amount of Three Million and
00/100 Dollars ($3,000,000.00) but notwithstanding such expression, the actual
indebtedness from time to time evidenced hereby shall be the sum of all advances
made to the undersigned, less the aggregate amount of all principal repayments
made by the undersigned; it being the intent and the purpose of this Note to
provide a revolving line of credit which the undersigned may draw against and
which the holder of this Note will advance from time to time, and which the
undersigned may repay in whole or in part from time to time and again draw
against, so that the principal amount outstanding hereunder may fluctuate in
accordance with such advances and repayments. Provided however, the aggregate
principal amount outstanding under this Note shall not at any time exceed the
principal sum of $3,000,000.00. Anything herein to the contrary notwithstanding
the right of the undersigned to request advances hereunder is subject to and
limited by any terms and conditions of the Agreement that may be established by
Lender from time to time at its sole discretion.

     IN WITNESS WHEREOF, Borrower has caused this Note to be duly made, executed
and delivered on the date first above written.

                                 "BORROWER"

                                 FLORIDA CARBON SOLUTIONS, L.L.C.

                                 By: /s/  John Stanton
                                    -------------------------------------------
                                          Its: Manager
                                              ---------------------------------
                                                       (Corporate Seal)

United States Territorial Waters or International Waters:
         Latitude          N27 41 83
         Longitude         W082 55 39

<PAGE>

          The foregoing instrument was acknowledged before me, Captain Dan
Coover, this 28th day of January 2003, on a vessel of which I am the Captain
located at Latitude N27 41 83 and Longitude W082 55 39 , which is located
outside the territorial limits of the State of Florida, by John Stanton as
Manager of Florida Carbon Solutions, L.L.C., who is either ___ personally known
to me or X has produced a Florida driver's license as identification.

                                 Captain's Signature: /s/ Captain Dan Coover
                                                      --------------------------
                                 Print Name:           Captain Dan Coover
                                                      --------------------------
                                 License Number:      1011115
                                                      --------------------------

                                 EARTHFIRST TECHNOLOGIES,
                                       INCORPORATED

                                 By: /s/ John Stanton
                                    --------------------------------------------
                                        Its: President
                                            ------------------------------------

                                                       (Corporate Seal)

United States Territorial Waters or International Waters:
         Latitude          N27 41 83
         Longitude         W082 55 39


     The foregoing instrument was acknowledged before me, Captain Dan Coover,
this 28th day of January 2003, on a vessel of which I am the Captain located at
Latitude N27 41 83 and Longitude W082 55 39 , which is located outside the
territorial limits of the State of Florida, by John Stanton as President of
EarthFirst Technologies, Incorporated, who is either ___ personally known to me
or X has produced a Florida driver's license as identification.

                                 Captain's Signature: /s/ Captain Dan Coover
                                                      --------------------------
                                 Print Name:           Captain Dan Coover
                                                      --------------------------
                                 License Number:      1011115
                                                      --------------------------

                                 EARTHFIRST SOLID SOLUTIONS, INC.

                                 By: /s/ John Stanton
                                    --------------------------------------------
                                       Its: President
                                           -------------------------------------

                                                       (Corporate Seal)

United States Territorial Waters or International Waters:
         Latitude          N27 41 83
         Longitude         W082 55 39

<PAGE>

     The foregoing instrument was acknowledged before me, Captain Dan Coover,
this 28th day of January 2003, on a vessel of which I am the Captain located at
Latitude N 27 41 83 and Longitude W082 55 39 , which is located outside the
territorial limits of the State of Florida, by John Stanton as President of
EarthFirst Solid Solutions, Inc., who is either ___ personally known to me or X
has produced a Florida driver's license as identification.

                                 Captain's Signature: /s/ Captain Dan Coover
                                                      --------------------------
                                 Print Name:           Captain Dan Coover
                                                      --------------------------
                                 License Number:      1011115
                                                      --------------------------